Decompression sickness: Difference between revisions

Jump to navigation Jump to search
 
(143 intermediate revisions by the same user not shown)
Line 22: Line 22:


==Overview==
==Overview==
Decompression sickness (DCS) is a multi-system condition characterized by a variety of clinical manifestations resulting from exposure to reduced barometric pressures that causes normally dissolved inert gases (mainly nitrogen) in body fluids and tissues to come out of physical solution, and develops a free gas phase by forming an intravascular and extravascular bubbles. The likelihood of DCS is related to the extent of bubble formation which results in minor symptoms from a few bubbles formation to a large bubble causing multiorgan failure and death. The severity and nature of the DCS injury vary from mild systemic, musculoskeletal and cutaneous manifestations to severe, life-threatening central nervous and cardiorespiratory symptoms. It is mostly observed in underwater [[decompression diving]] activities (e.g SCUBA) and depressurisation events such as emerging from a [[caisson]], flying in an [[unpressurised aircraft]] at altitude, and [[extravehicular activity]] from spacecraft. The clinical presentation can show an individual susceptibility by varying from day to day and under the same conditions. The classification of types of DCS by its symptoms has evolved since its origin and research done to prevent it. It is uncommon if the divers follow the appropriate procedures by using [[dive tables]] or [[dive computers]] to limit their exposure and control their ascent speed. If DCS is suspected, it is treated by airway stabilization, oxygen, and [[hyperbaric therapy]] in a recompression chamber. An early treatment ensures a significantly higher chance of successful recovery <ref name="urlDecompression sickness - Wikipedia">{{cite web |url=https://en.wikipedia.org/wiki/Decompression_sickness |title=Decompression sickness - Wikipedia |format= |work= |accessdate=}}</ref>.
Decompression sickness (DCS) is a multi-organ condition characterized by a varied clinical manifestations resulting from an exposure to reduced barometric pressures that leads to a normally dissolved inert gases (mainly nitrogen) in body fluids and tissues to come out of physical solution, and develops a free gas phase by forming an intravascular and extravascular bubbles. The likelihood of DCS is associated with the extent of bubble formation which subsequently causes minor symptoms from a few bubbles formation to a large bubble presenting with the multiorgan failure and death. The severity and nature of the DCS injury vary from mild systemic, musculoskeletal and cutaneous manifestations to severe, life-threatening neurological and cardiorespiratory complications. It is mostly observed in underwater decompression diving activities (e.g SCUBA) and depressurisation events such as emerging from a caisson, flying in an unpressurised aircraft at altitude, and extravehicular activity from spacecraft. The clinical presentation can show an individual susceptibility by varying from day to day under the similar circumstances. The classification of types of DCS based on its symptoms has evolved over years since its origin and research conducted to prevent it. It is not common to report it if the divers follow the recommended guidelines by using dive tables or dive computers to limit their period of exposure and control their rate of ascent speed. If DCS is suspected, it is treated by airway stabilization, high flow oxygen, and hyperbaric therapy in a recompression chamber. An early treatment ensures a significantly higher recovery rate.


==Historical Perspective==
==Historical Perspective==
{{Wikisource1911Enc|Caisson Disease}}
{{Wikisource1911Enc|Caisson Disease}}
*1670: [[Sir Robert Boyle]] performed an experiment with a viper in a vacuum. A bubble was observed in its eye and it displayed signs of extreme discomfort. This was the first recorded description of DCS in animals <ref name="DCS Acott">Acott, C. (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society Journal. 29 (2). ISSN 0813-1988. OCLC 16986801 </ref>.
*1670: Sir Robert Boyle described the first case of DCS in animals by conducting an experiment on a viper in a vacuum and observing the bubble formation in its eye with significant physical symptoms of discomfort. <ref name="DCS Acott">Acott, C. (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society Journal. 29 (2). ISSN 0813-1988. OCLC 16986801 </ref>
*1841: [[Jacques Triger]] documented the first cases of DCS in humans when two miners involved in pressurised [[caisson]] work developed symptoms <ref name="DCS Acott">Acott, C. (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society Journal. 29 (2). ISSN 0813-1988. OCLC 16986801 </ref>.
*1841: Jacques Triger proposed that the two miners while working in the pressurised caisson work developed the symptoms of DCS and thus, documented the first case of DCS in humans. <ref name="DCS Acott">Acott, C. (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society Journal. 29 (2). ISSN 0813-1988. OCLC 16986801 </ref>
*1847: The effectiveness of recompression for the treatment of DCS in caisson workers was described by B. Pol and T.J. Watelle <ref name="DCS Acott">Acott, C. (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society Journal. 29 (2). ISSN 0813-1988. OCLC 16986801 </ref> <ref name="DCS Hill"> Hill, L (1912). Caisson sickness, and the physiology of work in compressed air. London E. Arnold </ref>
*1847: The French physicians B. Pol and T.J. Watelle explained the effectiveness of recompression in caisson workers for the use of the treatment of DCS. <ref name="DCS Acott">Acott, C. (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society Journal. 29 (2). ISSN 0813-1988. OCLC 16986801 </ref> <ref name="DCS Hill"> Hill, L (1912). Caisson sickness, and the physiology of work in compressed air. London E. Arnold </ref>
*1857: [[Felix Hoppe-Seyler]] repeated Boyle's experiments and suggested that sudden death in compressed air workers was caused by bubble formation, and recommended recompression therapy <ref name="DCS Huggins"> Huggins, Karl E. (1992). "Dynamics of decompression workshop". Course Taught at the University of Michigan. ; Huggins 1992, chpt. 1 page 8 </ref>.
*1857: Felix Hoppe-Seyler supported Boyle's study findings. He further observed that the bubble formation is the underlying cause of sudden death in compressed air workers and recommended recompression therapy as the mode of treatment. <ref name="DCS Huggins"> Huggins, Karl E. (1992). "Dynamics of decompression workshop". Course Taught at the University of Michigan. ; Huggins 1992, chpt. 1 page 8 </ref>
*1861:  Bucquoy proposed the hypothesis that the blood gases return to the free state under the influence of decompression and cause accidents comparable to those of an injection of air in the veins" <ref>Trucco, Jean-Noël; Biard, Jef; Redureau, Jean-Yves; Fauvel, Yvon (3 May 1999). "Table Marine National 90 (MN90): Version du 03/05/1999" (PDF). Comité interrégional Bretagne & Pays de la Loire; Commission Technique Régionale. (in French). F.F.E.S.S.M. </ref>.
*1861:  Bucquoy proposed the hypothesis by comparing an injection of air in the veins with the blood gases returning to the free state under the process of decompression. <ref>Trucco, Jean-Noël; Biard, Jef; Redureau, Jean-Yves; Fauvel, Yvon (3 May 1999). "Table Marine National 90 (MN90): Version du 03/05/1999" (PDF). Comité interrégional Bretagne & Pays de la Loire; Commission Technique Régionale. (in French). F.F.E.S.S.M. </ref>
*1868: Alfred Le Roy de Méricourt described DCS as an occupational illness of sponge divers <ref name="DCS Hill"> Hill, L (1912). Caisson sickness, and the physiology of work in compressed air. London E. Arnold </ref>.
*1868: Alfred Le Roy de Méricourt labelled DCS as an occupational hazard for the sponge divers. <ref name="DCS Hill"> Hill, L (1912). Caisson sickness, and the physiology of work in compressed air. London E. Arnold </ref>
*1873: Dr. Andrew Smith first used the terms "caisson disease" and "compressed air illness", describing 110 cases of DCS as the physician in charge during construction of the Brooklyn Bridge.<ref name="DCS Huggins"> Huggins, Karl E. (1992). "Dynamics of decompression workshop". Course Taught at the University of Michigan. ; Huggins 1992, chpt. 1 page 8 </ref> <ref name="pmid15686275">{{cite journal| author=Butler WP| title=Caisson disease during the construction of the Eads and Brooklyn Bridges: A review. | journal=Undersea Hyperb Med | year= 2004 | volume= 31 | issue= 4 | pages= 445-59 | pmid=15686275 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15686275  }} </ref>. The nickname "the bends" was used after workers emerging from pressurized construction on the [[Brooklyn Bridge]] adopted a posture similar to fashionable ladies of the period "the Grecian Bend" <ref name="DCS Acott">Acott, C. (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society Journal. 29 (2). ISSN 0813-1988. OCLC 16986801 </ref>.
*1873: Dr. Andrew Smith studied 110 DCS cases during the construction of the Brooklyn Bridge and coined the terms "caisson disease" and "compressed air illness". Similarly, the term "the bends" was extracted from the fashionable ladies of the period "the Grecian Bend" as the workers emerging from pressurized construction on the Brooklyn Bridge adopted a posture similar to them.<ref name="DCS Acott">Acott, C. (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society Journal. 29 (2). ISSN 0813-1988. OCLC 16986801 </ref>  <ref name="DCS Huggins"> Huggins, Karl E. (1992). "Dynamics of decompression workshop". Course Taught at the University of Michigan. ; Huggins 1992, chpt. 1 page 8 </ref> <ref name="pmid15686275">{{cite journal| author=Butler WP| title=Caisson disease during the construction of the Eads and Brooklyn Bridges: A review. | journal=Undersea Hyperb Med | year= 2004 | volume= 31 | issue= 4 | pages= 445-59 | pmid=15686275 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15686275  }} </ref>  
*1878: [[Paul Bert]] determined that DCS is caused by nitrogen gas bubbles released from tissues and blood during or after decompression, and showed the advantages of breathing oxygen after developing DCS <ref> Bert, P. (1878). "Barometric Pressure: researches in experimental physiology". Translated By: Hitchcock MA and Hitchcock FA. College Book Company; 1943 </ref>.
*1878: Paul Bert found that the nitrogen gas bubbles released from tissues and blood during or after decompression are responsible for the development of the DCS and further showed that breathing oxygen after developing DCS can help in relieving its symptoms. <ref> Bert, P. (1878). "Barometric Pressure: researches in experimental physiology". Translated By: Hitchcock MA and Hitchcock FA. College Book Company; 1943 </ref>
*1889–90 - [[Ernest William Moir]] builds the first medical airlock when he noticed that about 25% of the workforce digging the [[Hudson River Tunnel]] were dying from DCS and realised that the solution was recompression <ref>8. John L. Phillips, The Bends: Compressed Air in the History of Science, Diving, and Engineering, Yale University Press (1998) - Google Books p 103 </ref> <ref>Moon, Richard (March 2000). "The Natural Progression of Decompression Illness and Development of Recompression Procedures" (PDF). SPUMS Journal. 30 (1): 39 </ref>.
*1889–90: Ernest William Moir made the first medical airlock when he realized that recompression is the main modality of the treatment to prevent the workforce digging the Hudson River Tunnel dying from DCS. <ref> John L. Phillips, The Bends: Compressed Air in the History of Science, Diving, and Engineering, Yale University Press (1998) - Google Books p 103 </ref> <ref>Moon, Richard (March 2000). "The Natural Progression of Decompression Illness and Development of Recompression Procedures" (PDF). SPUMS Journal. 30 (1): 39 </ref>
*1908 – [[John Scott Haldane]] prepared the first recognised decompression table for the British Admiralty. This table was based on experiments performed on goats using an end point of symptomatic DCS <ref name="DCS Acott">Acott, C. (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society Journal. 29 (2). ISSN 0813-1988. OCLC 16986801 </ref> <ref name="pmid20474365">{{cite journal| author=Boycott AE, Damant GC, Haldane JS| title=The Prevention of Compressed-air Illness. | journal=J Hyg (Lond) | year= 1908 | volume= 8 | issue= 3 | pages= 342-443 | pmid=20474365 | doi=10.1017/s0022172400003399 | pmc=2167126 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20474365  }} </ref>.
*1908:John Scott Haldane prepared the first recognized decompression table for the British Admiralty which was based on experiments performed on goats using an end point of symptomatic DCS. <ref name="DCS Acott">Acott, C. (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society Journal. 29 (2). ISSN 0813-1988. OCLC 16986801 </ref> <ref name="pmid20474365">{{cite journal| author=Boycott AE, Damant GC, Haldane JS| title=The Prevention of Compressed-air Illness. | journal=J Hyg (Lond) | year= 1908 | volume= 8 | issue= 3 | pages= 342-443 | pmid=20474365 | doi=10.1017/s0022172400003399 | pmc=2167126 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20474365  }} </ref>
*1912 Chief Gunner George D. Stillson of the [[United States Navy]] created a program to test and refine Haldane's tables <ref>Stillson, GD (1915). "Report in Deep Diving Tests". US Bureau of Construction and Repair, Navy Department. Technical Report </ref>.This program ultimately led to the first publication of the United States Navy Diving Manual and the establishment of a Navy Diving School in Newport, Rhode Island.
*1912: Chief Gunner George D. Stillson of the [[United States Navy]] created a program to evaluate and refine Haldane's tables which subsequently led to the first publication of the United States Navy Diving Manual and the establishment of a Navy Diving School in Newport, Rhode Island. <ref>Stillson, GD (1915). "Report in Deep Diving Tests". US Bureau of Construction and Repair, Navy Department. Technical Report </ref>


==Classification==
==Classification==


In 1960, The ''Golding Classification'' was introduced and categorized DCS into type 1 DCS and type 2 DCS <ref> 12. Golding FC , Griffi ths P , Hempleman HV , Paton WDM , Walder DN . Decompression sickness during construction of the Dartford tunnel . Br J Ind Med 1960 ; 17 : 167 – 80 </ref>.
*In 1960, The ''Golding Classification'' was introduced and categorized DCS into type 1 DCS and type 2 DCS. <ref>Golding FC , Griffi ths P , Hempleman HV , Paton WDM , Walder DN . Decompression sickness during construction of the Dartford tunnel . Br J Ind Med 1960 ; 17 : 167 – 80 </ref>


''Table 1'' shows the Golding classification of DCS:
'''''Table 1 shows the Golding classification of DCS:'''''
{| class="wikitable" style="text-align:center"  
{| class="wikitable" style="text-align:center"  


Line 79: Line 79:
|}
|}


Following advancement to the treatment protocols and variable presentations, this classification is now much less useful in making the diagnosis <ref name="DCS Brubakk"> {{cite book | last = Brubakk | first = Alf | title = Bennett and Elliott's physiology and medicine of diving | publisher = Saunders | location = Edinburgh New York | year = 2003 | isbn = 978-0-7020-2571-6 }} </ref>. All the manifestations, whether DCS or [[arterial gas embolism]] (AGE), were categorized under the general designation “[[decompression illness (DCI)]]” when the precise diagnosis cannot be made because they both results from the gas bubbles in the body, have overlapping of their spectra of symptoms, and similar treatment methods <ref>Francis, T James R; Smith, DJ (1991). "Describing Decompression Illness". 42nd Undersea and Hyperbaric Medical Society Workshop. 79(DECO)5–15–91. Archived from the original on 27 July 2011 </ref>.
*This classification is not frequently used in making the diagnosis of DCS following upgradation of the treatment protocols and variable presentations of signs and symptoms. <ref name="DCS Brubakk"> {{cite book | last = Brubakk | first = Alf | title = Bennett and Elliott's physiology and medicine of diving | publisher = Saunders | location = Edinburgh New York | year = 2003 | isbn = 978-0-7020-2571-6 }} </ref>  
 
*All the manifestations, whether DCS or [[arterial gas embolism]] (AGE), were categorized under the general term “[[decompression illness (DCI)]]” when the exact diagnosis cannot be finalized because both of them develops from the gas bubble formation in the body, have overlapping of their spectra of signs and symptoms, and similar treatment methods. <ref>Francis, T James R; Smith, DJ (1991). "Describing Decompression Illness". 42nd Undersea and Hyperbaric Medical Society Workshop. 79(DECO)5–15–91. </ref>


==Pathophysiology==
==Pathophysiology==


The pathophysiology of DCS is in accordance with ''Henry’s law''. It states that the solubility of a gas in a liquid is directly proportional to the pressure exerted on the gas and liquid. Thus, the amount of inert gases (eg, nitrogen, helium) dissolved in the blood and tissues increases at higher pressure, and hence depends on the depth and the duration of the dive.
*The pathophysiology of DCS is in accordance with '''''Henry’s law'''''. It states that the solubility of a gas in a liquid is directly proportional to the amount of the pressure exerted on the gas and liquid. Thus, the amount of inert gases (eg, nitrogen, helium) dissolved in the blood and tissues increases at higher pressure, and hence the development of DCS depends on the depth and the duration of the dive.
 
During a dive, the partial pressure of nitrogen and oxygen increases resulting in a diffusion gradient favoring uptake of nitrogen into the bloodstream and tissues. Under normal circumstances, the lungs functions as a vehicle for the gaseous exchange and elimination from the body. As the atmospheric pressure decrease during the ascent, more nitrogen precipitates from the tissues into the bloodstream and then diffuses back into the alveoli for exhalation process. If ascent occurs too rapidly or the elimination gradient is so steep, the gas quickly dissipates from the tissues and blood forming small air bubbles. This process is called ''“out gassing”'' or ''“off gassing”''. Slow ascent, on the other hand, allows for equilibrium to be gradually achieved, and prevents the rapid changes in partial pressure of nitrogen in the bloodstream. Hence, the amount of bubble formation depends on the depth and duration of the dive, and the rate of the ascent <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>.  


Venous bubbles may form ''de novo'' or result from the intravascular release of tissue bubbles <ref name="DCS Edmonds"> Edmonds, Lowry, Pennefather, Walker. Diving and Subaquatic Medicine 4th edition Arnold 2002 </ref>. The venous gas emboli usually get filtered at arteriole level on reaching the lungs. However, the bubbles may pass directly into the arterial circulation <ref>Gorman, Des. Accidental arterial gas embolism. Emergency Medicine. 14(4):364-370, December 2002</ref> if the pulmonary arterial pressure (PAP) rises after underwater diving.
*During a dive, the partial pressure of nitrogen and oxygen increases which results in creating a diffusion gradient favoring an uptake of nitrogen into the bloodstream and tissues. The physiology of the lungs is to functions as a vehicle for the gaseous exchange and elimination from the body under normal circumstances. As the atmospheric pressure decrease during the ascent, more nitrogen precipitates from the tissues into the bloodstream and then diffuses back into the alveoli for exhalation process. If ascent occurs too rapidly or the elimination gradient is so steep, the gas quickly dissipates from the tissues and blood forming small air bubbles. This process is called ''“out gassing”'' or ''“off gassing”''. Conversely, a slow ascent favors an equilibrium to be achieved gradually, and prevents the rapid changes in the partial pressure of nitrogen in the bloodstream. Hence, the amount of bubble formation depends on the depth and duration of the dive, and the rate of the ascent. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>


*Bubbles ''primarily'' travel to vital organs such as the nervous system; and get lodged in arterioles and capillary beds causing mass effect. These bubbles obstruct venous outflow and occlude arteries, as well as cause a shearing force on endovascular surfaces and impairs vascular integrity during their transit. The disturbed vascular permeability further leads to hemoconcentration, disturbance of microvascular flow, and a breakdown in the blood brain barrier <ref> NHS Commissioning Board. April 2013. Clinical Commissioning Policy: Hyperbaric Oxygen Therapy </ref>.
*Venous bubbles may form ''de novo'' or result from the intravascular release of tissue bubbles. The venous gas emboli usually get filtered at an arteriole level on reaching the lungs. However, the bubbles may pass directly into the arterial circulation if the pulmonary arterial pressure (PAP) rises after underwater diving. <ref name="DCS Edmonds"> Edmonds, Lowry, Pennefather, Walker. Diving and Subaquatic Medicine 4th edition Arnold 2002 </ref> <ref>Gorman, Des. Accidental arterial gas embolism. Emergency Medicine. 14(4):364-370, December 2002</ref>
*Bubbles cause ''secondary'' multiple biochemical effects by activating platelets, complement, leucocytes and the clotting cascade; and hence resulting in an inflammatory response in the affected tissues <ref>Kindwall E and Whelan H, Hyperbaric Medicine Practice, 3rd Edition (2008), Chapter 4 page 71-89 </ref>.
*''Autochthonous'' or ''extravascular'' bubbles arise spontaneously, and are more likely to form in tissues with high gas content and poor perfusion because the large amount of gas in the tissues such as spinal cord white matter, adipose tissue, and periarticular tissue cannot be removed by the low perfusing blood volume <ref name="DCS Edmonds"> Edmonds, Lowry, Pennefather, Walker. Diving and Subaquatic Medicine 4th edition Arnold 2002 </ref>.


Bubbles are responsible for the proximate cause of injury, whereas the several pro-inflammatory activated pathways leads to the progression of injury. Thus, DCS can have an evolving course with inflammatory mediated symptoms worsening over time.  
#Bubbles ''primarily'' travel to vital organs such as the nervous system; and get lodged in arterioles and capillary beds causing a mass effect. These bubbles obstruct venous outflow and occlude arteries, as well as cause a shearing force on endovascular surfaces and impairs vascular integrity during their transit. The disturbed vascular permeability consequently leads to hemoconcentration, disturbance of microvascular flow, and a breakdown in the blood brain barrier. <ref> NHS Commissioning Board. April 2013. Clinical Commissioning Policy: Hyperbaric Oxygen Therapy </ref>
#Bubbles cause ''secondary'' multiple biochemical effects by activating platelets, complement, leucocytes and the clotting cascade; and hence, results in an inflammatory response in the affected tissues. <ref>Kindwall E and Whelan H, Hyperbaric Medicine Practice, 3rd Edition (2008), Chapter 4 page 71-89 </ref>
#''Autochthonous'' or ''extravascular'' bubbles arise spontaneously, and are more likely to form in tissues with high gas content and poor perfusion because the large amount of gas in the tissues such as spinal cord white matter, adipose tissue, and periarticular tissue cannot be removed by the low perfusing blood volume. <ref name="DCS Edmonds"> Edmonds, Lowry, Pennefather, Walker. Diving and Subaquatic Medicine 4th edition Arnold 2002 </ref>


==Clinical Features/presentation==
*Bubbles are responsible for the proximate cause of damage, whereas the several pro-inflammatory activated pathways leads to the progression of an injury. Thus, DCS can have an evolving course with inflammatory mediated manifestations worsening with a period of time.


The presentation of DCS is frequently idiosyncratic as its "typical" pattern gives an atypical presentation. Symptoms of DCS (listed in decreasing order of overall prevalence) observed by the U.S. Navy are as follows in ''Table 2'' <ref name="DCS Powell">{{cite book | last = Powell | first = Mark | title = Deco for divers : a diver's guide to decompression theory and physiology | publisher = AquaPress | location = Southend-on-Sea, Essex | year = 2008 | isbn = 978-1-905492-07-7 }} </ref>:
==Clinical Features==


*'''''Clinical presentation''''': It is frequently idiosyncratic as its "typical" pattern gives an atypical presentation due to the origin of the bubble formation in any part of the body. The US Navy listed the symptoms of DCS in a decreasing order of their overall prevalence in '''''Table 2:''''' <ref name="DCS Powell">{{cite book | last = Powell | first = Mark | title = Deco for divers : a diver's guide to decompression theory and physiology | publisher = AquaPress | location = Southend-on-Sea, Essex | year = 2008 | isbn = 978-1-905492-07-7 }} </ref>
{| class="wikitable" style="text-align:center"  
{| class="wikitable" style="text-align:center"  


Line 158: Line 159:




''Onset'': The median time to symptom/sign onset is 30 minutes and severe neurologic symptoms tend to present within 10 minutes; and majority of them experience symptoms/signs within 24 to 48 hours of emerging from the water. The U.S. Navy and Technical Diving International have published a table that documents time to onset of first symptoms. The table does not differentiate between types of DCS, or types of symptom <ref>U.S. Navy Supervisor of Diving (2008). U.S. Navy Diving Manual (PDF). SS521-AG-PRO-010, revision 6. vol.5. U.S. Naval Sea Systems Command. pp. 20–25</ref> <ref>TDI Decompression Procedures Manual (Rev 1c), page 38 </ref>.
*'''''Onset''''': The median time to symptom/sign onset is 30 minutes and severe neurologic symptoms might present as early as within 10 minutes; and however, majority of symptoms and signs develops within 24 to 48 hours of emerging from the water. The U.S. Navy and Technical Diving International have published a table that documents time to onset of first presenting symptom. The table does not differentiate between types of DCS, or types of symptom. <ref>U.S. Navy Supervisor of Diving (2008). U.S. Navy Diving Manual (PDF). SS521-AG-PRO-010, revision 6. vol.5. U.S. Naval Sea Systems Command. pp. 20–25</ref> <ref>TDI Decompression Procedures Manual (Rev 1c), page 38 </ref>
 
'''''Table 3 shows the time of onset of symptoms among DCS suspected cases:'''''
''Table 3'' shows the time of onset of symptoms among DCS suspected cases:  
{| class="wikitable" style="text-align:center"  
{| class="wikitable" style="text-align:center"  


Line 201: Line 201:
|}  
|}  


While bubbles can originate in any part of the body, DCS is most frequently observed in the joints namely shoulders, elbows, knees, and ankles. ''Shoulder'' is the most common site for altitude and bounce diving; and the knees and hip joints for saturation and compressed air work. The symptoms of limb bends arises from increased intermedullary pressure in the ends of long bones; and gas phase separation along ligaments and tendon sheaths, and thus presenting painful discomfort from the simple mechanical distention and movement. ''Dermatological'' manifestations are due to the blood extravasated from the cutaneous vessels as a consequence of bubble induced endothelial injury. ''Pulmonary'' DCS ("the chokes") is rarely reported in divers; and believed to arise from an extremely huge load of venous bubbles in the pulmonary artery which results in an elevated pulmonary artery and right ventricular pressures, and further increasing the interstitial fluid and hence, leads to the development of the chokes or difficult breathing. ''Spinal cord'' DCS have two interrelated mechanisms. The first is obstruction of venous outflow of the spinal cord in the epidural plexus which is a series of blood vessels having a relatively slow blood flow. Once this process develops, it results in an ongoing and progressive diminution of blood flow to the cord, and thereafter, the second process either begins with the in-situ bubble formation within the tissue of the spinal cord <ref name="DCS Powell">{{cite book | last = Powell | first = Mark | title = Deco for divers : a diver's guide to decompression theory and physiology | publisher = AquaPress | location = Southend-on-Sea, Essex | year = 2008 | isbn = 978-1-905492-07-7 }}</ref> <ref>Frans Cronje (5 August 2014). All That Tingles Is Not Bends (video). DAN Southern Africa </ref>.
*''Joints'' DCS is most frequently noticed in shoulders, elbows, knees, and ankles. ''Shoulder'' is the most common site for altitude and bounce diving; and the ''knees'' and ''hip'' joints for saturation and compressed air work. The symptoms of limb bends arises from increased intermedullary pressure in the ends of long bones; and gas phase separation along ligaments and tendon sheaths, and thus presenting with an extreme discomfort from the simple mechanical distension and movement.  
*''Dermatological'' manifestations are due to the blood extravasated from the cutaneous vessels as a consequence of bubble induced endothelial injury.  
*''Pulmonary'' DCS ("the chokes") is rarely reported in divers; and believed to arise from an extremely huge load of venous bubbles in the pulmonary artery which results in an elevated pulmonary artery and right ventricular pressures, and further increasing the interstitial fluid and hence, leads to the development of the chokes or difficult breathing.
*''Spinal cord'' DCS have two interrelated mechanisms. The first is obstruction of venous outflow of the spinal cord in the epidural plexus which relatively have a slow blood perfusion rate. Once this process develops, it results in an ongoing and progressive diminution of blood flow to the cord, and thereafter, the second process proceeds with the in-situ bubble formation within the tissue of the spinal cord. <ref name="DCS Powell">{{cite book | last = Powell | first = Mark | title = Deco for divers : a diver's guide to decompression theory and physiology | publisher = AquaPress | location = Southend-on-Sea, Essex | year = 2008 | isbn = 978-1-905492-07-7 }}</ref> <ref>Frans Cronje (5 August 2014). All That Tingles Is Not Bends (video). DAN Southern Africa </ref>


''Table 4'' shows symptoms and signs of different DCS types <ref name="DCS Brubakk"> {{cite book | last = Brubakk | first = Alf | title = Bennett and Elliott's physiology and medicine of diving | publisher = Saunders | location = Edinburgh New York | year = 2003 | isbn = 978-0-7020-2571-6 }} </ref>:
'''''Table 4 shows symptoms and signs of different DCS types:''''' <ref name="DCS Brubakk"> {{cite book | last = Brubakk | first = Alf | title = Bennett and Elliott's physiology and medicine of diving | publisher = Saunders | location = Edinburgh New York | year = 2003 | isbn = 978-0-7020-2571-6 }} </ref>
{| class="wikitable" style="text-align:center"  
{| class="wikitable" style="text-align:center"  


Line 223: Line 226:
*Characteristics: Localized deep pain, ranging from mild to excruciating; dull ache (sometimes); sharp pain (rarely)
*Characteristics: Localized deep pain, ranging from mild to excruciating; dull ache (sometimes); sharp pain (rarely)
*Aggravating factor: Active and passive motion of the joint
*Aggravating factor: Active and passive motion of the joint
*Relieving factor: bending the joint to a comfortable position  
*Relieving factor: Bending the joint to a comfortable position  
*Onset: immediately or few hours later in case of altitude induced DCS
*Onset: Immediate or few hours later in case of altitude induced DCS


|-
|-
Line 235: Line 238:
*Site: Itching around the ears, face, neck, arms, and upper torso
*Site: Itching around the ears, face, neck, arms, and upper torso
*Formication: Sensation of tiny insects crawling over the skin  
*Formication: Sensation of tiny insects crawling over the skin  
*Cutis Marmorata: Mottled or marbled skin usually around the shoulders, upper chest and abdomen, with itching  
*Cutis Marmorata: Mottled or marbled skin usually around the shoulders, upper chest and abdomen with itching  
*Pitting edema: Swelling of the skin, accompanied by tiny scar-like skin depressions
*Pitting edema: Swelling of the skin accompanied by tiny scar-like skin depressions


|-
|-
Line 281: Line 284:
*Headache  
*Headache  
*Unexplained fatigue   
*Unexplained fatigue   
*Generalised malaise, poorly localised aches  
*Generalized malaise, poorly localized aches  
    
    
|-
|-
Line 320: Line 323:


==Differential Diagnosis==
==Differential Diagnosis==
*Differential diagnosis is the process by which medical personnel rule out which of the potential condition is most likely responsible for the presenting symptoms when two or more probable conditions have overlapping symptoms among the diving-related injuries.
*An alternative diagnosis should also be suspected if severe symptoms begin more than six hours following decompression without an altitude exposure or if any symptom occurs more than 24 hours after surfacing. <ref>Moon, Richard E (1998). "Assessment of patients with decompression illness". South Pacific Underwater Medicine Society Journal. 28 (1). </ref>


Differential diagnosis is the process by which medical personnel figure out which of the potential condition is most likely responsible for the symptoms when two or more conditions have overlapping symptoms among the many diving-related injuries. An alternative diagnosis should also be suspected if severe symptoms begin more than six hours following decompression without an altitude exposure or if any symptom occurs more than 24 hours after surfacing <ref>Moon, Richard E (1998). "Assessment of patients with decompression illness". South Pacific Underwater Medicine Society Journal. 28 (1). Archived from the original on 17 February 2012 </ref>.
'''''Table 5 below shows various different medical conditions mimicking the DCS:''''' <ref name="DCS Richard">Richard D Vann, Frank K Butler, Simon J Mitchell, Richard E Moon. Decompression illness. Vol 377 January 8, 2011; pg: 153-164 </ref>
 
''Table 5'' below shows various different medical conditions mimicking the DCS <ref name="DCS Richard">Richard D Vann, Frank K Butler, Simon J Mitchell, Richard E Moon. Decompression illness. Vol 377 January 8, 2011; pg: 153-164 </ref>:
{| class="wikitable" style="text-align:center"  
{| class="wikitable" style="text-align:center"  


Line 337: Line 340:


|  
|  
*Pulmonary Barotrauma: usually occurs when the air expands to cause the lung rupture and releases gas bubbles directly into the arterial circulation.  
*Pulmonary Barotrauma: It usually occurs when the air expands to cause the lung rupture and releases gas bubbles directly into the arterial circulation.  
*Typical presentation: a diver who surfaces unconscious and remains so, or who loses consciousness within minutes of surfacing.  
*Typical presentation: A diver who surfaces unconscious and remains so, or who loses consciousness within minutes of surfacing.  
*A true medical emergency condition
*A true medical emergency condition
*Rapid evacuation to a treatment facility is paramount.
*Rapid evacuation to a treatment facility is paramount.
Line 348: Line 351:
|  
|  
*Usually occurs during descent  
*Usually occurs during descent  
*Tinnitus, hearing loss, and persistent vertigo <ref>Klingmann C, Praetorius M, Baumann I, Plinkert PK. Barotrauma and decompression illness of the inner ear: 46 cases during treatment and follow-up. Otol Neurotol 2007; 28: 447–54</ref>.
*Tinnitus, hearing loss, and persistent vertigo <ref>Klingmann C, Praetorius M, Baumann I, Plinkert PK. Barotrauma and decompression illness of the inner ear: 46 cases during treatment and follow-up. Otol Neurotol 2007; 28: 447–54</ref>
*Middle-ear barotraumas: Conductive hearing loss seen
*Middle-ear barotrauma: Conductive hearing loss seen
*Both inner-ear and middle-ear barotrauma are usually preceded by difficulty in equalizing middle-ear pressure  
*Both inner-ear and middle-ear barotrauma are usually preceded by difficulty in equalizing middle-ear pressure  
*Alternobaric vertigo: transient vertigo during compression or decompression arises because of asymmetric middle-ear pressure equilibration <ref>Farmer JC Jr. Diving injuries to the inner ear. Ann Otol Rhinol Laryngol Suppl 1977; 86 (1 Pt 3 suppl 36): 1–20</ref>
*Alternobaric vertigo: transient vertigo during compression or decompression arises because of asymmetric middle-ear pressure equilibration <ref>Farmer JC Jr. Diving injuries to the inner ear. Ann Otol Rhinol Laryngol Suppl 1977; 86 (1 Pt 3 suppl 36): 1–20</ref>
Line 359: Line 362:
|  
|  
*It is caused by gas expansion during ascent and an obstructed eustachian tube or sinus ostium
*It is caused by gas expansion during ascent and an obstructed eustachian tube or sinus ostium
*Compresses the facial nerve and causes unilateral upper and lower facial weakness <ref>Molvaer OI, Eidsvik S. Facial baroparesis: a review. Undersea Biomed Res 1987; 14: 277–95</ref>, or
*Compresses the facial nerve causes unilateral upper and lower facial weakness, <ref>Molvaer OI, Eidsvik S. Facial baroparesis: a review. Undersea Biomed Res 1987; 14: 277–95</ref> or
*Compression of branches of the trigeminal nerve causing hypoaesthesia of the face <ref name="DCS Butler">Butler FK, Bove AA. Infraorbital hypesthesia after maxillary sinus barotrauma. Undersea Hyperb Med 1999; 26: 257–59</ref>
*Compression of branches of the trigeminal nerve causes hypoaesthesia of the face <ref name="DCS Butler">Butler FK, Bove AA. Infraorbital hypesthesia after maxillary sinus barotrauma. Undersea Hyperb Med 1999; 26: 257–59</ref>
   
   
|-
|-
Line 375: Line 378:


|  
|  
*Time of onset (e.g.: before, during, or after diving) and history of trauma or strain are helpful.
*Time of onset (e.g.: before, during, or after diving) and history of trauma or strain are helpful to rule it out.
*Pain is usually accompanied by tenderness or position-related or motion-related exacerbation on physical examination.
*Pain is usually accompanied by tenderness or position-related or motion-related exacerbation on physical examination.
    
    
Line 384: Line 387:
|  
|  
*Ingestion of toxins (e.g.: ciguatera, puffer fish, paralytic shellfish poisoning )  
*Ingestion of toxins (e.g.: ciguatera, puffer fish, paralytic shellfish poisoning )  
*Often associated with gastrointestinal symptoms, and can cause neurological manifestations within hours after ingestion <ref>Eastaugh J, Shepherd S. Infectious and toxic syndromes from fi sh and shellfi sh consumption. A review. Arch Intern Med 1989; 149: 1735–40</ref>.
*Often associated with gastrointestinal symptoms, and can cause neurological manifestations within hours after ingestion <ref>Eastaugh J, Shepherd S. Infectious and toxic syndromes from fi sh and shellfi sh consumption. A review. Arch Intern Med 1989; 149: 1735–40</ref>
   
   
|-
|-
Line 420: Line 423:
==Epidemiology and Demographics==
==Epidemiology and Demographics==


The incidence of DCS, fortunately, is rare. It is estimated in about 2 to 4/10,000 dives among recreational divers. The incidence among commercial divers, who often have minor musculoskeletal injuries, can be higher ranging from 1.5-10 per 10,000 dives. As explained, the incidence depends on the length and depth of the dive. The risk for DCS is 2.5 times greater for males than females <ref name="PollockButeau2017">{{cite journal|last1=Pollock|first1=Neal W.|last2=Buteau|first2=Dominique|title=Updates in Decompression Illness|journal=Emergency Medicine Clinics of North America|volume=35|issue=2|year=2017|pages=301–319|issn=07338627|doi=10.1016/j.emc.2016.12.002}}</ref>.
*The incidence of DCS, fortunately, is rare.
*Recreational divers: It is estimated in about 2 to 4/10,000 dives.
*Commercial divers: It can be higher ranging from 1.5-10 per 10,000 dives due to prior history of minor musculoskeletal injuries.  
*Its prevalence depends on the length and depth of the dive.  
*The risk for DCS is 2.5 times greater for males in relation to females. <ref name="PollockButeau2017">{{cite journal|last1=Pollock|first1=Neal W.|last2=Buteau|first2=Dominique|title=Updates in Decompression Illness|journal=Emergency Medicine Clinics of North America|volume=35|issue=2|year=2017|pages=301–319|issn=07338627|doi=10.1016/j.emc.2016.12.002}}</ref>


==Risk Factors==
==Risk Factors==
Various demographic, environmental, and diving factors are related to the predisposition of DCS. DeNoble et al in 2005 studied various multiple risk factors such as age, gender, body mass index, smoking, asthma, diabetes, cardiovascular disease, previous history of DCI, number of the years since certification, number of dives in the last year, number of diving days, number of dives in a repetitive series, last dive depth, nitrox use, and drysuit use. No significant correlation of DCS were found with asthma, diabetes, cardiovascular disease, smoking, or body mass index. Variable such as increased diving depth, previous DCS episodes, multiple consecutive days of diving and being male were found to be associated with an increased incidence of DCS. Contrarily, a lower risk was reported among nitrox and drysuit use, higher frequency of diving in the past year, increasing age, and years since certification possibly as indicators of more extensive training and experience. <ref>DeNoble, PJ; Vann, RD; Pollock, NW; Uguccioni, DM; Freiberger, JJ; Pieper, CF (2005). "A case-control study of decompression sickness (DCS) and arterial gas embolism (AGE)". Undersea and Hyperbaric Medical Society</ref>
*Various environmental, diving and individual factors are related to the predisposition of DCS.  
* In 2005, DeNoble et al conducted a study to find the association of various risk factors with the DCS<ref>DeNoble, PJ; Vann, RD; Pollock, NW; Uguccioni, DM; Freiberger, JJ; Pieper, CF (2005). "A case-control study of decompression sickness (DCS) and arterial gas embolism (AGE)". Undersea and Hyperbaric Medical Society</ref>
**''Multiple risk factors studied'': age, gender, body mass index, smoking, asthma, diabetes, cardiovascular disease, previous history of DCI, number of the years since certification, number of dives in the last year, number of diving days, number of dives in a repetitive series, last dive depth, nitrox use, and drysuit use.
**''No significant correlation'' with DCS: asthma, diabetes, cardiovascular disease, smoking, or body mass index.  
**''Positive correlation'' (higher risk): increased diving depth, previous DCS episodes, multiple consecutive days of diving and being male.  
**''Negative correlation'' (lower risk): nitrox and drysuit use, higher frequency of diving in the past year, increasing age, and years since certification possibly as indicators of more extensive training and experience.  


===Environmental factors===  
===Environmental factors===  
*'''Magnitude of the pressure reduction ratio''': DCS is more likely to be experienced with a larger pressure reduction ratio in comparison to a smaller reduction. <ref name="DCS Dehart">{{cite book | last = DeHart | first = Roy | title = Fundamentals of aerospace medicine | publisher = Lippincott Williams & Wilkins | location = Philadelphia | year = 2002 | isbn = 978-0-7817-2898-0 }} </ref>
*'''Magnitude of the pressure reduction ratio''': DCS is more likely to be experienced with a larger pressure reduction ratio in comparison to a smaller reduction. <ref name="DCS Dehart">{{cite book | last = DeHart | first = Roy | title = Fundamentals of aerospace medicine | publisher = Lippincott Williams & Wilkins | location = Philadelphia | year = 2002 | isbn = 978-0-7817-2898-0 }} </ref>
*'''Temperature''': Warm conditions may favor nitrogen uptake which results in an increased level of dissolved nitrogen and hence, putting a diver at higher risk of “out gassing” during ascent phase. Contrarily, the cold conditions slows the process; however, no definitive studies have demonstrated a direct relationship between thermal conditions and development of DCS. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>
*'''Repetitive exposures''': A shorter periods of break among similar repetitive dives and ascents to altitudes above 5,500 metres (18,000 ft) will raise the risk of DCS because excessive nitrogen remains dissolved in body tissues for at least 12 hours after each dive, and hence, repeated dives within 1 day predisposes the divers to it.<ref name="DCS Dehart">{{cite book | last = DeHart | first = Roy | title = Fundamentals of aerospace medicine | publisher = Lippincott Williams & Wilkins | location = Philadelphia | year = 2002 | isbn = 978-0-7817-2898-0 }} </ref>  
*'''Repetitive exposures''': A shorter periods of break among similar repetitive dives and ascents to altitudes above 5,500 metres (18,000 ft) will raise the risk of DCS because excessive nitrogen remains dissolved in body tissues for at least 12 hours after each dive, and hence, repeated dives within 1 day predisposes the divers to it.<ref name="DCS Dehart">{{cite book | last = DeHart | first = Roy | title = Fundamentals of aerospace medicine | publisher = Lippincott Williams & Wilkins | location = Philadelphia | year = 2002 | isbn = 978-0-7817-2898-0 }} </ref>  
*'''Rate of ascent''': the faster the ascent, the greater the risk of developing DCS. The U.S. Navy Diving Manual indicates that ascent rates greater than about 20 m/min (66 ft/min) when diving increase the chance of DCS, while recreational dive tables such as the Bühlmann tables require an ascent rate of 10 m/min (33 ft/min) with the last 6 m (20 ft) taking at least one minute <ref name="DCS Lipman">{{cite book | last = Lippmann | first = John | title = Deeper into diving : an in-depth review of decompression procedures, and of the physical and physiological aspects of deeper diving | publisher = J.L. Publications | location = Melbourne Australia | year = 2005 | isbn = 978-0-9752290-1-9 }} </ref>. An individual exposed to a rapid decompression (high rate of ascent) above 5,500 metres (18,000 ft) has a greater risk of altitude DCS than being exposed to the same altitude but at a lower rate of ascent <ref name="DCS Dehart">{{cite book | last = DeHart | first = Roy | title = Fundamentals of aerospace medicine | publisher = Lippincott Williams & Wilkins | location = Philadelphia | year = 2002 | isbn = 978-0-7817-2898-0 }} </ref>.
*'''Post dive air travel''': Divers who ascend to altitude soon after a dive increase their possibility of developing DCS even if the dive was performed within the dive table safe limits. <ref name="DCS Baset"> Bassett, Bruce E (1982). "Decompression Procedures for Flying After Diving, and Diving at Altitudes above Sea Level". US Air Force School of Aerospace Medicine Technical Report. SAM-TR-82-47</ref>
*'''Duration of exposure''': the longer the duration of the dive, the greater is the risk of DCS. Longer flights, especially to altitudes of 5,500 m (18,000 ft) and above, carry a greater risk of altitude DCS <ref name="DCS Dehart">{{cite book | last = DeHart | first = Roy | title = Fundamentals of aerospace medicine | publisher = Lippincott Williams & Wilkins | location = Philadelphia | year = 2002 | isbn = 978-0-7817-2898-0 }} </ref>.
*'''Diving before travelling to altitude''': DCS can occur even without flying if a diver moves to a high-altitude location on land immediately after diving; for example, scuba divers in Eritrea who drive from the coast to the Asmara plateau at 2,400 m (7,900 ft) increase their chances of DCS. <ref name="DCS Lipman">{{cite book | last = Lippmann | first = John | title = Deeper into diving : an in-depth review of decompression procedures, and of the physical and physiological aspects of deeper diving | publisher = J.L. Publications | location = Melbourne Australia | year = 2005 | isbn = 978-0-9752290-1-9 }} </ref>
*'''Post dive air travel''': Divers who ascend to altitude soon after a dive increase their risk of developing DCS even if the dive itself was within the dive table safe limits <ref name="DCS Baset"> Bassett, Bruce E (1982). "Decompression Procedures for Flying After Diving, and Diving at Altitudes above Sea Level". US Air Force School of Aerospace Medicine Technical Report. SAM-TR-82-47</ref>.
*'''Ambient temperature''': A very cold ambient temperatures may increase the risk of altitude DCS. However, increasing ambient temperature during decompression following the dives in cold water may reduce the risk levels. <ref name="DCS Fryere">{{cite book | last = Fryer | first = David | title = Subatmospheric decompression sickness in man | publisher = Technical P | location = London | year = 1969 | isbn = 978-0-85102-023-5 }}</ref> <ref>Gerth, Wayne A; Ruterbusch, VL; Long, Edward T (2007). "The Influence of Thermal Exposure on Diver Susceptibility to Decompression Sickness". United States Navy Experimental Diving Unit Technical Report. NEDU-TR-06-07</ref>
*'''Diving before travelling to altitude''': DCS can occur without flying if the person moves to a high-altitude location on land immediately after diving, for example, scuba divers in Eritrea who drive from the coast to the Asmara plateau at 2,400 m (7,900 ft) increase their risk of DCS <ref name="DCS Lipman">{{cite book | last = Lippmann | first = John | title = Deeper into diving : an in-depth review of decompression procedures, and of the physical and physiological aspects of deeper diving | publisher = J.L. Publications | location = Melbourne Australia | year = 2005 | isbn = 978-0-9752290-1-9 }} </ref>.
 
*'''Diving at altitude''': Diving in water whose surface altitude is above 300 m (980 ft); for example, Lake Titicaca is at 3,800 m (12,500 ft) and diving in it without using versions of decompression tables or dive computers that are modified for high-altitude <ref name="DCS Baset"> Bassett, Bruce E (1982). "Decompression Procedures for Flying After Diving, and Diving at Altitudes above Sea Level". US Air Force School of Aerospace Medicine Technical Report. SAM-TR-82-47</ref>.
===Diving factors===
*'''Rate of ascent''': A rate of ascent shows a positive correlation with faster the ascent, greater the risk. The U.S. Navy Diving Manual indicates that ascent rates greater than about 20 m/min (66 ft/min) from the diving depth increases the possibility of DCS, while other recreational dive tables such as the Bühlmann tables require an ascent rate of 10 m/min (33 ft/min) with the last 6 m (20 ft) taking at least one minute to lower its incidence. A diver exposed to a rapid decompression rate of ascent of above 5,500 metres (18,000 ft) has a greater risk of altitude DCS in comparison to being exposed to the same altitude but at a lower rate of ascent. <ref name="DCS Dehart">{{cite book | last = DeHart | first = Roy | title = Fundamentals of aerospace medicine | publisher = Lippincott Williams & Wilkins | location = Philadelphia | year = 2002 | isbn = 978-0-7817-2898-0 }} </ref> <ref name="DCS Lipman">{{cite book | last = Lippmann | first = John | title = Deeper into diving : an in-depth review of decompression procedures, and of the physical and physiological aspects of deeper diving | publisher = J.L. Publications | location = Melbourne Australia | year = 2005 | isbn = 978-0-9752290-1-9 }} </ref>
*'''Duration of diving''': A longer duration of the dive, the greater risk of DCS. Similarly, a longer flights, especially to altitudes of 5,500 m (18,000 ft) and above, holds a higher risk of altitude DCS. <ref name="DCS Dehart">{{cite book | last = DeHart | first = Roy | title = Fundamentals of aerospace medicine | publisher = Lippincott Williams & Wilkins | location = Philadelphia | year = 2002 | isbn = 978-0-7817-2898-0 }} </ref>  
*'''Diving at altitude''': Diving in water whose surface altitude is above 300 m (980 ft) have a higher risk of developing DCS; for example, Lake Titicaca is at 3,800 m (12,500 ft) and diving in it without using versions of decompression tables or dive computers that are modified for high-altitude predisposes the divers to DCS. <ref name="DCS Baset"> Bassett, Bruce E (1982). "Decompression Procedures for Flying After Diving, and Diving at Altitudes above Sea Level". US Air Force School of Aerospace Medicine Technical Report. SAM-TR-82-47</ref>


===Individual factors===  
===Individual factors===  
*'''[[Dehydration]]''': DCS could be reduced in aviators when the serum surface tension was raised by drinking isotonic saline, and the high surface tension of water is generally regarded as helpful in controlling bubble size <ref name="DCS Fryere">{{cite book | last = Fryer | first = David | title = Subatmospheric decompression sickness in man | publisher = Technical P | location = London | year = 1969 | isbn = 978-0-85102-023-5 }}</ref>. Therefore, maintaining adequate hydration is recommended <ref name="DCS Lipman">{{cite book | last = Lippmann | first = John | title = Deeper into diving : an in-depth review of decompression procedures, and of the physical and physiological aspects of deeper diving | publisher = J.L. Publications | location = Melbourne Australia | year = 2005 | isbn = 978-0-9752290-1-9 }} </ref>.
*'''[[Dehydration]]''': Drinking isotonic saline or adequate hydration will raise the serum surface tension which is helpful in controlling bubble size and hence, reduces the chances of DCS in aviators. Therefore, maintaining adequate hydration is recommended. <ref name="DCS Lipman">{{cite book | last = Lippmann | first = John | title = Deeper into diving : an in-depth review of decompression procedures, and of the physical and physiological aspects of deeper diving | publisher = J.L. Publications | location = Melbourne Australia | year = 2005 | isbn = 978-0-9752290-1-9 }} </ref> <ref name="DCS Fryere">{{cite book | last = Fryer | first = David | title = Subatmospheric decompression sickness in man | publisher = Technical P | location = London | year = 1969 | isbn = 978-0-85102-023-5 }}</ref>  
*'''[[Patent foramen ovale (PFO)]]''': A hole between the atrial chambers of the heart in the fetus is normally closed by a flap with the first breaths at birth. In about 20% of adults the flap does not completely seal, however, allowing blood through the hole when coughing or during activities that raise chest pressure. In diving, this can allow venous blood with microbubbles of inert gas to bypass the lungs, where the bubbles would otherwise be filtered out by the lung capillary system, and return directly to the arterial system (including arteries to the brain, spinal cord and heart) <ref>Moon, Richard E; Kisslo, Joseph (1998). "PFO and decompression illness: An update". South Pacific Underwater Medicine Society Journal. 28 (3). ISSN 0813-1988. OCLC 16986801 </ref>. In the arterial system, bubbles are far more dangerous because they block circulation and cause infarction. In the brain, infarction results in stroke, and in the spinal cord, it may predispose to paralysis <ref name="DCS Lipman">{{cite book | last = Lippmann | first = John | title = Deeper into diving : an in-depth review of decompression procedures, and of the physical and physiological aspects of deeper diving | publisher = J.L. Publications | location = Melbourne Australia | year = 2005 | isbn = 978-0-9752290-1-9 }} </ref>.
*'''Patent foramen ovale (PFO)''': At birth, a hole between the atrial chambers of the heart in the fetus gets normally closed by a flap with the first breath. However, in about 20% of adults, where the flap does not seal completely, allows blood through the hole during coughing or activities that raise chest pressure. During diving, PFO can allow venous blood with microbubbles of inert gas to bypass the lungs, where the bubbles would otherwise be filtered out by the lung capillary system, and return directly to the arterial system (including arteries to the brain, spinal cord and heart). In the arterial system, bubbles are highly dangerous because they block circulation and cause infarction. In the brain, infarction results in stroke; whereas in the spinal cord, it may predispose to paralysis. <ref name="DCS Lipman">{{cite book | last = Lippmann | first = John | title = Deeper into diving : an in-depth review of decompression procedures, and of the physical and physiological aspects of deeper diving | publisher = J.L. Publications | location = Melbourne Australia | year = 2005 | isbn = 978-0-9752290-1-9 }} </ref> <ref>Moon, Richard E; Kisslo, Joseph (1998). "PFO and decompression illness: An update". South Pacific Underwater Medicine Society Journal. 28 (3). ISSN 0813-1988. OCLC 16986801 </ref>
*'''Age''': A higher risk of altitude DCS with increasing age (especially >42 years of age) has been reported <ref name="DCS Fryere">{{cite book | last = Fryer | first = David | title = Subatmospheric decompression sickness in man | publisher = Technical P | location = London | year = 1969 | isbn = 978-0-85102-023-5 }}</ref>.
*'''Age''': An increasing age (especially >42 years of age) has been associated with a higher incidence of altitude DCS. <ref name="DCS Fryere">{{cite book | last = Fryer | first = David | title = Subatmospheric decompression sickness in man | publisher = Technical P | location = London | year = 1969 | isbn = 978-0-85102-023-5 }}</ref>
*'''Previous injury''': Recent joint or limb injuries may predispose individuals to developing decompression-related bubbles <ref> Karlsson, L; Linnarson, D; Gennser, M; Blogg, SL; Lindholm, Peter (2007). "A case of high doppler scores during altitude decompression in a subject with a fractured arm". Undersea and Hyperbaric Medicine. 34 (Supplement). ISSN 1066-2936. OCLC 26915585 </ref>.
*'''Previous injury''': Divers with a previous history of recent joint or limb injuries may have a higher susceptibility to development of the decompression-related bubbles. <ref> Karlsson, L; Linnarson, D; Gennser, M; Blogg, SL; Lindholm, Peter (2007). "A case of high doppler scores during altitude decompression in a subject with a fractured arm". Undersea and Hyperbaric Medicine. 34 (Supplement). ISSN 1066-2936. OCLC 26915585 </ref>
*'''Ambient temperature''': An individual exposure to very cold ambient temperatures may increase the risk of altitude DCS <ref name="DCS Fryere">{{cite book | last = Fryer | first = David | title = Subatmospheric decompression sickness in man | publisher = Technical P | location = London | year = 1969 | isbn = 978-0-85102-023-5 }}</ref>. which can be reduced by increasing ambient temperature during decompression following the dives in cold water <ref>Gerth, Wayne A; Ruterbusch, VL; Long, Edward T (2007). "The Influence of Thermal Exposure on Diver Susceptibility to Decompression Sickness". United States Navy Experimental Diving Unit Technical Report. NEDU-TR-06-07</ref>.
*'''Body type''': A diver with a high body fat content stores about the half the total amount of the nitrogen which predisposes them to a higher chances of DCS. This is due to five times greater solubility of nitrogen in fat than water, and hence, resulting in a higher levels of total body dissolved nitrogen during elevated atmospheric pressure. <ref name="DCS Fryere">{{cite book | last = Fryer | first = David | title = Subatmospheric decompression sickness in man | publisher = Technical P | location = London | year = 1969 | isbn = 978-0-85102-023-5 }}</ref> <ref name="BoycottDamant2009">{{cite journal|last1=Boycott|first1=A. E.|last2=Damant|first2=G. C. C.|title=Experiments on the Influence of Fatness on Susceptibility to Caisson Disease|journal=Epidemiology and Infection|volume=8|issue=4|year=2009|pages=445–456|issn=0950-2688|doi=10.1017/S0022172400015862}}</ref>
*'''Body type''': A person who has a high body fat content which stores about the half the total amount of the nitrogen is at greater risk of DCS <ref name="DCS Fryere">{{cite book | last = Fryer | first = David | title = Subatmospheric decompression sickness in man | publisher = Technical P | location = London | year = 1969 | isbn = 978-0-85102-023-5 }}</ref>.. This is due to nitrogen's five times greater solubility in fat than in water, leading to greater amounts of total body dissolved nitrogen during high atmospheric pressure <ref name="BoycottDamant2009">{{cite journal|last1=Boycott|first1=A. E.|last2=Damant|first2=G. C. C.|title=Experiments on the Influence of Fatness on Susceptibility to Caisson Disease|journal=Epidemiology and Infection|volume=8|issue=4|year=2009|pages=445–456|issn=0950-2688|doi=10.1017/S0022172400015862}}</ref>.  
*'''Alcohol consumption''': It increases chances of dehydration and inhibits pituitary release of antidiuretic hormone (ADH); and therefore may increase susceptibility to DCS. <ref name="DCS Fryere">{{cite book | last = Fryer | first = David | title = Subatmospheric decompression sickness in man | publisher = Technical P | location = London | year = 1969 | isbn = 978-0-85102-023-5 }}</ref> Contrarily, another study found no correlation between alcohol consumption and developing DCS. <ref>{{cite journal|title=RSA Abstracts|journal=Alcoholism: Clinical and Experimental Research|volume=29|year=2005|pages=6A–172A|issn=01456008|doi=10.1111/j.1530-0277.2005.tb03524.x}}</ref>
*'''Alcohol consumption''': It increases dehydration and inhibits pituitary release of antidiuretic hormone (ADH); and therefore may increase susceptibility to DCS <ref name="DCS Fryere">{{cite book | last = Fryer | first = David | title = Subatmospheric decompression sickness in man | publisher = Technical P | location = London | year = 1969 | isbn = 978-0-85102-023-5 }}</ref>.. Contrarily, another study found no evidence that alcohol consumption increases the incidence of DCS <ref>{{cite journal|title=RSA Abstracts|journal=Alcoholism: Clinical and Experimental Research|volume=29|year=2005|pages=6A–172A|issn=01456008|doi=10.1111/j.1530-0277.2005.tb03524.x}}</ref>.
*'''Work and exercise''':  DCS is strongly related with the level of work or exercise done at depth or shortly after diving because it promotes increased inert gas uptake. Therefore, any kind of strenuous exercise will promote bubble formation, and lighter exercise during ascent or stop phase will favor gas excretion. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>
*'''Work and exercise''': Work or exercise at depth or shortly after diving is strongly associated with DCS, as it promotes increased inert gas uptake. Light exercise during ascent or stop phase can promote gas excretion, but strenuous exercise will promote bubble formation <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>.
*'''[[Asthma]]''': Asthmatics are generally advised not to dive due to a theoretical risk of bronchospasm triggered by cold or changing environments, inability to have an immediate response to an asthma attack while being submerged, and supposed increased barotrauma during ascent. However, more studies are warranted as there is limited data to support preventing them from diving. Well-controlled asthmatics with normal PFTs can occasionally be permitted to dive, however, an assessment should be made on a case-by-case basis. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>
*'''Temperature''': Warm conditions may favor nitrogen uptake, and places a patient at higher risk of “out gassing” during ascent as more nitrogen has been dissolved. On the other hand, cold conditions slow the process, but no definitive studies have demonstrated a causal relationship between thermal conditions and development of DCS <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>.
*'''[[Asthma]]''': They are generally advised not to dive due to a theoretical risk of bronchospasm triggered by cold or changing environments, inability to quickly respond to an asthma attack while submerged, and supposed increased barotrauma during ascent. However, there is limited data to support preventing asthmatics from diving, so more studies are warranted. Well-controlled asthmatics with normal PFTs can occasionally be permitted to dive, but this should be assessed on a case-by-case basis <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>.


==Diagnosis==  
==Diagnosis==  
DCS is primarily a clinical diagnosis which can be assessed with a very thorough and detailed dive history from a conscious patient and the clinical examination, including the neurologic examination. The specific symptoms/signs and their particular time of onset (table 3 and 4) aid in suspecting and establishing the diagnosis. However, the relief of symptoms by recompression will make the definitive confirmation of the probable diagnosis. Hence, an immediate treatment should be begun with no delay for further diagnostic investigation.
*DCS is primarily a clinical diagnosis assessed with a thorough and detailed dive history from a conscious patient and the clinical examination, including the neurological exam.  
*The specific symptoms/signs and their particular time of onset (table 3 and 4) aid in suspecting and establishing the diagnosis.  
*However, the relief of symptoms by recompression will make the definitive confirmation of the probable diagnosis.  
*Hence, an immediate treatment should be begun with no delay for further diagnostic work up.


===Diagnostic criteria===  
===Diagnostic criteria===  
Line 458: Line 475:


===Laboratory findings===
===Laboratory findings===
DCS is associated with hemoconcentration, and elevated serum CK is seen in severe AGE. However, none of the laboratory studies make a definitive diagnosis of DCS. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>
*DCS is associated with hemoconcentration, and elevated serum CK is seen in severe AGE.  
*However, none of the laboratory studies make a definitive diagnosis of DCS. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>


===Radiological findings===
===Radiological findings===
No imaging study can confirm the diagnosis of DCS. ''Bubble formation'' can occasionally be identified on MRI or CT scans; however, they are not considered the best method to rule out DCS due to their low sensitivity level in making the diagnosis. Although, they might be used to rule out the other differential disorders that presents with the similar signs and symptoms (eg, herniated intervertebral disk, ischemic stroke, central nervous system hemorrhage). These studies should be performed with no delay as prompt intervention is important in the successful management of the DCS.  
*No imaging study can confirm the diagnosis of DCS.  
*''Bubble formation'' can occasionally be identified on MRI or CT scans; however, they are not considered the reliable method to rule out DCS due to their low sensitivity level in making the diagnosis.  
*Although, they might be used to rule out the other differential disorders that presents with the similar signs and symptoms (eg, herniated intervertebral disk, ischemic stroke, central nervous system hemorrhage).  
*These studies should be performed with no delay as prompt intervention is important in the successful management of the DCS.  


====Chest and Joints Radiography====
====Chest and Joints Radiography====
Pneumothorax, pneumomediastinum, pulmonary overexpansion injury, or pulmonary edema should always be ruled out with chest radiographs. Radiographs rarely detect ''bubble formation'' in joints affected by pain. Skeletal x-rays are not considered diagnostic for dysbaric osteonecrosis which may show joint degeneration;and hence cannot be used to differentiate between different joint disorders. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref> <ref name="DCS Richard">Richard D Vann, Frank K Butler, Simon J Mitchell, Richard E Moon. Decompression illness. Vol 377 January 8, 2011; pg: 153-164 </ref>
*Pneumothorax, pneumomediastinum, pulmonary overexpansion injury, or pulmonary edema should always be ruled out with chest radiographs.  
*Radiographs rarely detect ''bubble formation'' in joints affected by pain.  
*Skeletal x-rays are not considered diagnostic for dysbaric osteonecrosis which may show joint degeneration; and hence cannot be used to differentiate between different joint disorders. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref> <ref name="DCS Richard">Richard D Vann, Frank K Butler, Simon J Mitchell, Richard E Moon. Decompression illness. Vol 377 January 8, 2011; pg: 153-164 </ref>


====Computed Tomography Scan====
====Computed Tomography Scan====
*'''''Head CT''''': A “normal” head CT is not helpful in excluding DCS due to the very low chances of visibility of ''vascular gas bubbles'' on a head CT in the cases of suspected DCS. However, it should be strongly considered in any patient who presented with an altered mental status in order to evaluate alternative diagnoses, such as subdural or epidural hematoma. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref> <ref>Benson J, Adkinson C, Collier R. Hyperbaric oxygen therapy of iatrogenic cerebral arterial gas embolism. Undersea Hyperb Med 2003; 30: 117–26</ref>  
*'''''Head CT''''': A “normal” head CT is not reliable in excluding DCS due to the very low chances of visibility of ''vascular gas bubbles'' on CT films in the cases of suspected DCS. However, it should be strongly considered in any patient who presented with an altered mental status in order to evaluate alternative diagnoses, such as subdural or epidural hematoma. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref> <ref>Benson J, Adkinson C, Collier R. Hyperbaric oxygen therapy of iatrogenic cerebral arterial gas embolism. Undersea Hyperb Med 2003; 30: 117–26</ref>  


*'''''Chest CT''''': An extrapulmonary air can be detected on it, but it can be avoided due to its high radiation exposure. <ref name="DCS Richard">Richard D Vann, Frank K Butler, Simon J Mitchell, Richard E Moon. Decompression illness. Vol 377 January 8, 2011; pg: 153-164 </ref>.
*'''''Chest CT''''': An extrapulmonary air can be detected on it, but it should be avoided due to its high radiation exposure level. <ref name="DCS Richard">Richard D Vann, Frank K Butler, Simon J Mitchell, Richard E Moon. Decompression illness. Vol 377 January 8, 2011; pg: 153-164 </ref>


====Magnetic Resonance Imaging====
====Magnetic Resonance Imaging====
MRI can be falsely reassuring for detecting the spinal cord or brain abnormalities related to DCS. However, it can diagnose ischemic lesions of the brain or spinal cord due to the etiologies other than DCS. <ref>Gempp E, Blatteau JE, Stephant E, Pontier JM, Constantin P, Peny C. MRI fi ndings and clinical outcome in 45 divers with spinal cord decompression sickness. Aviat Space Environ Med 2008; 79: 1112–16</ref>.
*MRI can be falsely reassuring for detecting the spinal cord or brain abnormalities related to DCS.  
*However, it can diagnose ischemic lesions of the brain or spinal cord due to the etiologies other than DCS. <ref>Gempp E, Blatteau JE, Stephant E, Pontier JM, Constantin P, Peny C. MRI fi ndings and clinical outcome in 45 divers with spinal cord decompression sickness. Aviat Space Environ Med 2008; 79: 1112–16</ref>


===Other diagnostic studies===
===Other diagnostic studies===
Line 485: Line 509:
*'''''Pathology/Cytology/Genetics Study''''': None is considered in making or excluding the diagnosis. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>
*'''''Pathology/Cytology/Genetics Study''''': None is considered in making or excluding the diagnosis. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>


Although laboratory and radiological analyses are useful for detection of DCS related abnormalities in some cases; however, these studies are not considered as the deciding factor for the start of the recompression therapy, and hence, recompression should be given without any delay unless there is a strong suspicion of a non-diving related cause (eg, cerebral hemorrhage). <ref name="DCS Richard">Richard D Vann, Frank K Butler, Simon J Mitchell, Richard E Moon. Decompression illness. Vol 377 January 8, 2011; pg: 153-164 </ref>
Although laboratory and radiological analyses are helpful for detection of DCS related abnormalities in some cases; however, these studies are not considered as the deciding factor for the start of the recompression therapy, and hence, recompression should be given with no delay unless there is a strong suspicion of other non-diving related etiologies (eg, cerebral hemorrhage). <ref name="DCS Richard">Richard D Vann, Frank K Butler, Simon J Mitchell, Richard E Moon. Decompression illness. Vol 377 January 8, 2011; pg: 153-164 </ref>


==Treatment==
==Treatment==
The several elements to the effective management of DCS consist of initial treatment including on-the-scene evaluation and first aid; transportation; and definitive medical treatment.  
The several elements to the effective management of DCS consist of initial treatment including on-the-scene evaluation and first aid; transportation; and definitive medical treatment.  


''On the scene first aid'': The foundation of first aid is basic life support. If the patient experiences an altered mental status or is unconscious, initial management should focus on the treatment and stabilization of ABC's (airway, breathing, and circulation). All DCS suspected cases should have initial treatment with high flow oxygen at 15ltr/min via a non-rebreathe mask or pocket masks regardless of their oxygen saturations. This high-flow 100% oxygen enhances nitrogen washout by widening the nitrogen pressure gradient between the lungs and the circulation, thus accelerating reabsorption of embolic bubbles <ref name="urlDecompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition">{{cite web |url=https://www.msdmanuals.com/professional/injuries-poisoning/injury-during-diving-or-work-in-compressed-air/decompression-sickness |title=Decompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition |format= |work= |accessdate=}}</ref>.  
===On the scene first aid===
*The foundation of first aid is the basic life support.  
*An initial management should focus on the treatment and stabilization of ABC's (airway, breathing, and circulation) in the patients with an altered mental status or loss of consciouness.  
*All DCS suspected cases should have initial treatment with high flow oxygen at 15ltr/min via a non-rebreathe mask or pocket masks regardless of their oxygen saturation levels.  
*This high-flow 100% oxygen enhances nitrogen washout by widening the nitrogen pressure gradient between the lungs and the circulation, thus accelerating reabsorption of embolic bubbles. <ref name="urlDecompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition">{{cite web |url=https://www.msdmanuals.com/professional/injuries-poisoning/injury-during-diving-or-work-in-compressed-air/decompression-sickness |title=Decompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition |format= |work= |accessdate=}}</ref>  
*An early ''oxygen first aid'' is important and may reduce symptoms substantially, but this should not change the recommended treatment plan.
*However, an initial oxygen breathing may clears the symptoms of air embolism and serious DCS, but they may reappear later due to which always contact DAN at +1-919-684-9111 or a dive physician in all the cases of suspected DCI, even if the symptoms and signs appear to have resolved. <ref name="urlwww.diversalertnetwork.org">{{cite web |url=https://www.diversalertnetwork.org/health/decompression/Signs-and-symptoms-of-DCS |title=www.diversalertnetwork.org |format= |work= |accessdate=}}</ref>


{{familytree/start |summary=Sample 1}}
{{familytree/start |summary=Sample 1}}
Line 505: Line 534:
{{familytree | |G01| | | | | | | | | | | | | |G01=Hospitalisation for 24h}}
{{familytree | |G01| | | | | | | | | | | | | |G01=Hospitalisation for 24h}}
{{familytree/end}}
{{familytree/end}}
''Figure 1'': Treatment algorithm of Decompression Sickness (DCS)<ref name="TetzlaffShank2003">{{cite journal|last1=Tetzlaff|first1=Kay|last2=Shank|first2=Erik S.|last3=Muth|first3=Claus M.|title=Evaluation and management of decompression illness—an intensivist’s perspective|journal=Intensive Care Medicine|volume=29|issue=12|year=2003|pages=2128–2136|issn=0342-4642|doi=10.1007/s00134-003-1999-1}}</ref>
'''''Figure 1: Treatment algorithm of Decompression Sickness (DCS)'''''<ref name="TetzlaffShank2003">{{cite journal|last1=Tetzlaff|first1=Kay|last2=Shank|first2=Erik S.|last3=Muth|first3=Claus M.|title=Evaluation and management of decompression illness—an intensivist’s perspective|journal=Intensive Care Medicine|volume=29|issue=12|year=2003|pages=2128–2136|issn=0342-4642|doi=10.1007/s00134-003-1999-1}}</ref>
 
''Fluid administration'' is indicated to restore lost intravascular volume and minimize the dehydration. Oral resuscitation fluid (or plain water) is indicated for alert patients with mild manifestations. Isotonic IV fluid resuscitation and maintenance IV fluids should be administered to those with serious manifestations in order to counteract interstitial fluid shifts and decreases in plasma volume arising from endothelial injury <ref name="urlDecompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition">{{cite web |url=https://www.msdmanuals.com/professional/injuries-poisoning/injury-during-diving-or-work-in-compressed-air/decompression-sickness |title=Decompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition |format= |work= |accessdate=}}</ref>.
 
It is essential that the suspected cases should be stabilized at the nearest medical facility before transportation to a recompression chamber. Insert a catheter if there is any suspicion of the patient having the urinary retention.


Early ''oxygen first aid'' is important and may reduce symptoms substantially, but this should not change the treatment plan. Symptoms of air embolism and serious DCS often clear after initial oxygen breathing, but they may reappear later. Because of this, always contact DAN at +1-919-684-9111 or a dive physician in cases of suspected DCI, even if the symptoms and signs appear to have resolved <ref name="urlwww.diversalertnetwork.org">{{cite web |url=https://www.diversalertnetwork.org/health/decompression/Signs-and-symptoms-of-DCS |title=www.diversalertnetwork.org |format= |work= |accessdate=}}</ref>.
===Fluid administration===
*It is indicated to minimize the dehydration and restore lost intravascular volume.
*Oral resuscitation fluid (or plain water) is indicated for alert patients with mild manifestations.  
*Isotonic IV fluid resuscitation and maintenance IV fluids should be administered to those with serious manifestations in order to counteract interstitial fluid shifts and decrease in plasma volume arising from an endothelial injury.  
*Insert a catheter if there is any suspicion of the patient having urinary retention. <ref name="urlDecompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition">{{cite web |url=https://www.msdmanuals.com/professional/injuries-poisoning/injury-during-diving-or-work-in-compressed-air/decompression-sickness |title=Decompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition |format= |work= |accessdate=}}</ref>


''Positioning and transportation'': The supine position or the recovery position should be preferred if vomiting occurs. The Trendelenburg position and the left lateral decubitus position (Durant's maneuver) have beneficial effect if air emboli are suspected, however these positions are no longer recommended for extended duration due to concerns regarding cerebral edema <ref name="urlDecompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf">{{cite web |url=https://www.ncbi.nlm.nih.gov/books/NBK537264/ |title=Decompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf |format= |work= |accessdate=}}</ref>.   
===Positioning and transportation===
*The supine position or the recovery position should be preferred in case vomiting occurs.  
*The Trendelenburg position and the left lateral decubitus position (Durant's maneuver) have beneficial effect in cases where air emboli are suspected; however, these positions are no longer recommended for prolonged duration due to concerns regarding cerebral edema. <ref name="urlDecompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf">{{cite web |url=https://www.ncbi.nlm.nih.gov/books/NBK537264/ |title=Decompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf |format= |work= |accessdate=}}</ref>  
*It is essential that the suspected cases should be stabilized at the nearest medical center before transportation to a recompression chamber.
*However, patients with severe symptoms need an evacuation to a suitable recompression facility because time to treatment and severity of the injury are important determinants of outcome; and hence, transport should not be delayed for the performance of nonessential procedures.   


Patients with more severe symptoms need an evacuation to a suitable recompression facility because time to treatment and severity of the injury are important determinants of outcome and hence, transport should not be delayed for the performance of nonessential procedures. In case of aeromedical transport, pressurized aircraft with 1 atmosphere internal pressure is preferred.   If unpressurized aircraft, such as helicopters, are the only means of transport then flight altitude should be limited to 300 m or 1000 ft if possible <ref name="PollockButeau2017">{{cite journal|last1=Pollock|first1=Neal W.|last2=Buteau|first2=Dominique|title=Updates in Decompression Illness|journal=Emergency Medicine Clinics of North America|volume=35|issue=2|year=2017|pages=301–319|issn=07338627|doi=10.1016/j.emc.2016.12.002}}</ref> and oxygen should be given continuously. Instructions to fly the patient “as low as safely possible” should be given to helicopter transport. Commercial aircraft, although pressurized, typically have a cabin pressure equivalent to 2438 m (8000 ft) at normal cruise altitude, which may precipitate symptoms <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref> <ref name="urlDecompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition">{{cite web |url=https://www.msdmanuals.com/professional/injuries-poisoning/injury-during-diving-or-work-in-compressed-air/decompression-sickness |title=Decompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition |format= |work= |accessdate=}}</ref>.
'''''Aeromedical transport''''':
*Instructions to fly the patient “as low as safely possible” should be given to helicopter transport.  
*Pressurized aircraft with 1 atmosphere internal pressure is preferred.
*Unpressurized aircraft such as helicopters: The flight altitude should be limited to 300 m or 1000 ft if possible, and oxygen should be given continuously. <ref name="PollockButeau2017">{{cite journal|last1=Pollock|first1=Neal W.|last2=Buteau|first2=Dominique|title=Updates in Decompression Illness|journal=Emergency Medicine Clinics of North America|volume=35|issue=2|year=2017|pages=301–319|issn=07338627|doi=10.1016/j.emc.2016.12.002}}</ref>
*Commercial aircraft, although pressurized, typically have a cabin pressure equivalent to 2438 m (8000 ft) at normal cruise altitude, but it may precipitate DCS symptoms. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref> <ref name="urlDecompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition">{{cite web |url=https://www.msdmanuals.com/professional/injuries-poisoning/injury-during-diving-or-work-in-compressed-air/decompression-sickness |title=Decompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition |format= |work= |accessdate=}}</ref>


''Definitive treatment'': '''Hyperbaric Oxygen Therapy (HBOT)'''
===Definitive treatment===


The definitive treatment is hyperbaric oxygen (HBOT) therapy which delivers the pure 100% oxygen at a pressure substantially higher than that of atmospheric pressure in recompression chambers. It should be initiated as soon as possible. Delays of > 4 hours from the time of injury to recompression correlate with a marked elevation in the incidence of residual symptoms following therapy <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>.
====Hyperbaric Oxygen Therapy (HBOT)====
*The definitive treatment is hyperbaric oxygen (HBOT) therapy which delivers the pure 100% oxygen at a pressure substantially higher than that of atmospheric pressure in recompression chambers.  
*Delays of > 4 hours from the time of injury to recompression correlate with a significant increase in the incidence of residual symptoms following therapy and hence, it should be initiated as soon as possible. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>


''Indication'': All the patients except those whose symptoms are limited to itching, skin mottling, and fatigue which may be treated with oxygen therapy alone; however these patients should be observed for any kind of deterioration <ref name="urlDecompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition">{{cite web |url=https://www.msdmanuals.com/professional/injuries-poisoning/injury-during-diving-or-work-in-compressed-air/decompression-sickness |title=Decompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition |format= |work= |accessdate=}}</ref>.
=====Indication=====
*All the patients, except those whose symptoms are limited to itching, skin mottling, and fatigue, may be treated with oxygen therapy alone; however these patients should be observed for any kind of further deteriorating condition. <ref name="urlDecompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition">{{cite web |url=https://www.msdmanuals.com/professional/injuries-poisoning/injury-during-diving-or-work-in-compressed-air/decompression-sickness |title=Decompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition |format= |work= |accessdate=}}</ref>


''Effects of Recompression therapy''<ref name="urlDecompression Illness - RCEMLearning">{{cite web |url=https://www.rcemlearning.co.uk/reference/decompression-illness/#1567502920236-96a835e2-60e9 |title=Decompression Illness - RCEMLearning |format= |work= |accessdate=}}</ref>:
=====Effects of Recompression therapy=====
*Bubble crushing: as per Boyles law, increasing pressure decreases the volume of bubbles
*Bubble crushing: As per Boyles law, increasing pressure decreases the volume of bubbles.
*Flushing out the nitrogen bubbles with oxygen delivery by improving gradient
*Flushing out the nitrogen bubbles with oxygen delivery by improving gradient.
*Healing damaged tissue with hyperbaric oxygen
*Healing damaged tissue with hyperbaric oxygen <ref name="urlDecompression Illness - RCEMLearning">{{cite web |url=https://www.rcemlearning.co.uk/reference/decompression-illness/#1567502920236-96a835e2-60e9 |title=Decompression Illness - RCEMLearning |format= |work= |accessdate=}}</ref>
    
    
''Equipment'': It is conducted in an acrylic tube sized monoplace chamber to hold just one patient, or in a multiplace chamber which is sized to accommodate one or more patients with one or more technicians or other medical personnel. Multilock chambers are designed to allow patients, tenders or equipment to be transferred into and out of the chamber while treatment is ongoing <ref name="urlwww.diversalertnetwork.org">{{cite web |url=https://www.diversalertnetwork.org/health/decompression/Signs-and-symptoms-of-DCS |title=www.diversalertnetwork.org |format= |work= |accessdate=}}</ref> <ref>Kindwall, EP; Goldmann, RW; Thombs, PA (1988). "Use of the Monoplace vs. Multiplace Chamber in the Treatment of Diving Diseases". Journal of Hyperbaric Medicine; 3(1). Undersea and Hyperbaric Medical Society, Inc. pp. 5–10</ref>.
=====Equipment=====
 
*Monoplace chamber: An acrylic tube sized chamber which have a capacity of one patient
''Regimen'': A common HBOT regimen is the U.S. Navy Treatment Table 6 (USN 2008). According to this regimen, HBOT chamber is brought to 2.8 atmospheres absolute (ATA), (equivalent of depth of 60 feet/18 meters) over a few minutes and then 100% FiO2 is initiated. 100% FiO2 is used for 20 minutes at a time, alternating with 5 minute intervals of room air breathing to reduce the risk of oxygen toxicity. Upon completion, the pressure is increased by no more than 1 foot/minute, with a prolonged period of equilibration at 30 feet. The total therapy time is about 5 hours. The therapy can be continued daily for several days until no further improvement is seen in the patient's symptoms <ref name="urlwww.diversalertnetwork.org">{{cite web |url=https://www.diversalertnetwork.org/health/decompression/Signs-and-symptoms-of-DCS |title=www.diversalertnetwork.org |format= |work= |accessdate=}}</ref> <ref name="DCS manual">U.S. Navy Supervisor of Diving (2008). "Chapter 20: Diagnosis and Treatment of Decompression Sickness and Arterial Gas Embolism". U.S. Navy Diving Manual (PDF). SS521-AG-PRO-010, revision 6. volume 5. U.S. Naval Sea Systems Command. p. 41</ref>.
*Multiplace chamber: It is sized to accommodate one or more patients with one or more technicians or other medical personnel. They are designed to allow patients, tenders or equipment to be transferred into and out of the chamber while treatment is ongoing. <ref name="urlwww.diversalertnetwork.org">{{cite web |url=https://www.diversalertnetwork.org/health/decompression/Signs-and-symptoms-of-DCS |title=www.diversalertnetwork.org |format= |work= |accessdate=}}</ref> <ref>Kindwall, EP; Goldmann, RW; Thombs, PA (1988). "Use of the Monoplace vs. Multiplace Chamber in the Treatment of Diving Diseases". Journal of Hyperbaric Medicine; 3(1). Undersea and Hyperbaric Medical Society, Inc. pp. 5–10</ref>


''Mechanism of action'': The mechanism of HBOT is twofold. First, elevated atmospheric pressure in the chamber increases the partial pressure of gases and dissolution of nitrogen back into liquid (Henry’s law), and the increased pressure also decreases the volume of gas present in the body (Boyle’s law). Second, increased FiO2 results in decreased partial pressure of nitrogen in inspired gas. This enhances the diffusion gradient of nitrogen out of body tissues, favoring exhalation and elimination from the body, and blunting the neutrophillic response to injured endothelium <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>.
=====Regimen=====
*A common HBOT regimen: The U.S. Navy Treatment Table 6 (USN 2008).
*Regimen protocol:
**HBOT chamber is brought to 2.8 atmospheres absolute (ATA), (equivalent of depth of 60 feet/18 meters) over a few minutes; and  
**Then 100% FiO2 is initiated.  
**100% FiO2 is used for 20 minutes at a time, alternating with 5 minute intervals of room air breathing to reduce the risk of oxygen toxicity.
**Upon completion, the pressure is increased by no more than 1 foot/minute, with a prolonged period of equilibration at 30 feet.
**The total therapy time is about 5 hours.
**The therapy can be continued daily for several days until no further improvement is seen in the patient's symptoms. <ref name="urlwww.diversalertnetwork.org">{{cite web |url=https://www.diversalertnetwork.org/health/decompression/Signs-and-symptoms-of-DCS |title=www.diversalertnetwork.org |format= |work= |accessdate=}}</ref> <ref name="DCS manual">U.S. Navy Supervisor of Diving (2008). "Chapter 20: Diagnosis and Treatment of Decompression Sickness and Arterial Gas Embolism". U.S. Navy Diving Manual (PDF). SS521-AG-PRO-010, revision 6. volume 5. U.S. Naval Sea Systems Command. p. 41</ref>


'''''Risks'''''<ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref> <ref name="HeyboerSharma2017">{{cite journal|last1=Heyboer|first1=Marvin|last2=Sharma|first2=Deepali|last3=Santiago|first3=William|last4=McCulloch|first4=Norman|title=Hyperbaric Oxygen Therapy: Side Effects Defined and Quantified|journal=Advances in Wound Care|volume=6|issue=6|year=2017|pages=210–224|issn=2162-1918|doi=10.1089/wound.2016.0718}}</ref>:
=====Mechanism of action=====
*The mechanism of HBOT is twofold.
**An elevated atmospheric pressure in the chamber increases the partial pressure of gases and dissolution of nitrogen back into liquid (Henry’s law), and the increased pressure also decreases the volume of gas present in the body (Boyle’s law).
**An increased FiO2 results in decreased partial pressure of nitrogen in inspired gas. This enhances the diffusion gradient of nitrogen out of body tissues, favoring exhalation and elimination from the body, and blunting the neutrophillic response to injured endothelium. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>


=====Risks=====
<ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref> <ref name="HeyboerSharma2017">{{cite journal|last1=Heyboer|first1=Marvin|last2=Sharma|first2=Deepali|last3=Santiago|first3=William|last4=McCulloch|first4=Norman|title=Hyperbaric Oxygen Therapy: Side Effects Defined and Quantified|journal=Advances in Wound Care|volume=6|issue=6|year=2017|pages=210–224|issn=2162-1918|doi=10.1089/wound.2016.0718}}</ref>
*'''Barotrauma''':
*'''Barotrauma''':
**Middle ear barotrauma: most common adverse effect of HBOT; generally requires supportive care. Bilateral tympanostomy tubes may be required in severe cases.
**Middle ear barotrauma: most common adverse effect of HBOT; generally requires supportive care. Bilateral tympanostomy tubes may be required in severe cases.
**Pulmonary barotrauma: risk of pneumothorax; chest tube can be inserted
**Pulmonary barotrauma: risk of pneumothorax; chest tube can be inserted.
**Pneumomediastinum: managed conservatively
**Pneumomediastinum: managed conservatively.
**Similar mechanism and management as barotrauma caused by diving
**Similar mechanism and management as barotrauma caused by diving.
*'''Oxygen toxicity''':
*'''Oxygen toxicity''':
**Pulmonary toxicity: small airways dysfunction observed on exceeding the treatment duration and pressure beyond the recommended therapeutic protocols
**Pulmonary toxicity: small airways dysfunction observed on exceeding the treatment duration and pressure beyond the recommended therapeutic protocols.
**CNS toxicity: generalized tonic-clonic seizures occur with an incidence of approximately 1-4 per 10,000 patient treatments. Risk is higher in patients who are hypercapnic, acidemia and/or septic.  
**CNS toxicity: generalized tonic-clonic seizures occur with an incidence of approximately 1-4 per 10,000 patient treatments. Risk is higher in patients who are hypercapnic, acidemia and/or septic.  
*'''Seizures''': mechanisms not well-understood
*'''Seizures''': mechanisms not well-understood.
**CNS toxicity: managed by decreased FiO2 with same elevated atmospheric pressure
**CNS toxicity: managed by decreased FiO2 with same elevated atmospheric pressure.
**Ocular toxicity: myopia can be seen in those who undergo prolonged daily therapy  
**Ocular toxicity: myopia can be seen in those who undergo prolonged daily therapy.
*'''Confinement anxiety''': Managed with anxiolytics
*'''Confinement anxiety''': Managed with anxiolytics.
*'''Fire''': due to elevated FiO2
*'''Fire''': due to elevated FiO2.


''In-water recompression (IWR) therapy'': It is practical only with a substantial amount of planning, support, equipment and personnel; appropriate water conditions; and suitable patient status. Critical challenges can arise due to changes in the patient's consciousness, oxygen toxicity, gas supply, and even thermal stress. An unsuccessful in-water recompression may leave the patient in worse shape than had the attempt not been made. Hence, it would only be suitable for an organized and disciplined group of divers with suitable equipment and practical training in the procedure <ref name="urlDecompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf">{{cite web |url=https://www.ncbi.nlm.nih.gov/books/NBK537264/ |title=Decompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf |format= |work= |accessdate=}}</ref> <ref name="urlwww.diversalertnetwork.org">{{cite web |url=https://www.diversalertnetwork.org/health/decompression/Signs-and-symptoms-of-DCS |title=www.diversalertnetwork.org |format= |work= |accessdate=}}</ref>.
====In-water recompression (IWR) therapy====
*It is beneficial only with a substantial amount of planning, support, equipment and personnel; appropriate water conditions; and suitable patient status.  
*Critical challenges can arise from the changes in the patient's consciousness, oxygen toxicity, gas supply, and even thermal stress.  
*An unsuccessful IWR may leave the patient in worse shape than had the attempt not been made.  
*Hence, it would be suitable for an organized and disciplined group of divers with suitable equipment and practical training in the procedure. <ref name="urlDecompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf">{{cite web |url=https://www.ncbi.nlm.nih.gov/books/NBK537264/ |title=Decompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf |format= |work= |accessdate=}}</ref> <ref name="urlwww.diversalertnetwork.org">{{cite web |url=https://www.diversalertnetwork.org/health/decompression/Signs-and-symptoms-of-DCS |title=www.diversalertnetwork.org |format= |work= |accessdate=}}</ref>  


[[Image:Oxymask.JPG|right|thumb|145px|Breathing pure oxygen to remove nitrogen from the bloodstream]]
[[Image:Oxymask.JPG|right|thumb|145px|Breathing pure oxygen to remove nitrogen from the bloodstream]]


''Adjuvant treatment'': Aspirin, NSAIDs, and corticosteroids have all been studied and not shown to have benefit in DCS. These drugs may mask the symptoms and can exacerbate micro-haemorrhages caused by DCS leading to a permanent sequelae. Opiates should also be avoided as they can increase the risk of oxygen toxicity. Oxygen is usually sufficient to control pain <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref> <ref name="urlDecompression Illness - RCEMLearning">{{cite web |url=https://www.rcemlearning.co.uk/reference/decompression-illness/#1567502920236-96a835e2-60e9 |title=Decompression Illness - RCEMLearning |format= |work= |accessdate=}}</ref>.  
====Adjuvant treatment====
*Aspirin, NSAIDs, and corticosteroids have all been studied and shown no beneficial use in the management of DCS. However, they may mask the symptoms and exacerbate micro-haemorrhages caused by DCS resulting in a permanent sequelae.  
*Opiates should also be avoided as they can increase the risk of oxygen toxicity.  
*Oxygen is usually sufficient to control pain. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref> <ref name="urlDecompression Illness - RCEMLearning">{{cite web |url=https://www.rcemlearning.co.uk/reference/decompression-illness/#1567502920236-96a835e2-60e9 |title=Decompression Illness - RCEMLearning |format= |work= |accessdate=}}</ref>
 
====Follow-up evaluation and return to diving====
*Follow-up treatments along with physical therapy is required in the severe cases where significant residual neurological dysfunction may be present even after the most aggressive treatment.
 
*Clearing a diver after DCS to return to diving is a complex undertaking with potential medical and legal risks. A careful risk and benefit assessment to ensure that the diver is completely asymptomatic and back to his or her pre-dive baseline function must be conducted by both the diver and the physician. A referral of the patient to a diving medicine specialist is appropriate in case of improperly clearing a diver to return to diving keeping in mind the potential life-threatening implications. Divers should be instructed to refrain from diving for the remainder of their lives in the cases where the risks clearly outweigh the benefits. Furthermore, a diver who has had multiple bouts of DCS even if symptoms were not severe and resolves completely must take special considerations. In such cases, a Diving Medical Specialist must be consulted to determine if diving can be resumed safely.
 
*The physician must also consider when it is safe for a patient to fly home or drive at altitude. A retrospective review of 126 DCS cases demonstrated that those who flew home on commercial flights < 72 hours after recompression had a higher likelihood of recurrence of symptoms and signs of DCS. Similarly, physicians should be wary if patients must drive through high-altitude areas, as the drop in atmospheric pressure could, at least theoretically, potentiate a recurrence. <ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>
*The US Navy has recommended the guidelines for returning to diving after treatment with limited time off for the professional divers as their operations should not get compromised; whereas diving is not a livelihood for the recreational divers, so a more conservative approach should be adopted to further minimize the chance for the recurrence of a diving injury. <ref name="DCS dan"> {{cite web |url=https://www.diversalertnetwork.org/medical/articles/Decompression_Illness_What_Is_It_and_What_Is_The_Treatment |title=Decompression Illness: What Is It and What Is The Treatment? — DAN &#124; Divers Alert Network — Medical Dive Article |format= |work= |accessdate=}} </ref>
 
'''''Table 6 elaborate the recommendations given by the US Navy for return to diving:'''''
 
{| class="wikitable" style="text-align:center"
 
|-
 
! style="background:#4479BA; color: #FFFFFF;" | Clinical features
 
! style="background:#4479BA; color: #FFFFFF;" | Professional Divers
 
! style="background:#4479BA; color: #FFFFFF;" | Recreational divers
 
|-
 
| style="background:#DCDCDC;" align="center" | Pain-only DCI with no neurological symptoms
 
| May resume diving two to seven days after treatment
 
|A minimum of two weeks without diving is recommended
 
|-
 
| style="background:#DCDCDC;" align="center" | Minor neurological symptoms
 
| May resume diving two to four weeks after treatment depending on symptom severity
 
| Six weeks without diving is recommended


'''''Follow-up evaluation and return to diving''''':
|-


If the DCI was severe, significant residual neurological dysfunction may be present, even after the most aggressive treatment. In these cases, there may be follow-up treatments, along with physical therapy.
| style="background:#DCDCDC;" align="center" | Severe neurological symptoms or any residual symptoms


Clearing a diver after DCS to return to diving is a complex undertaking with potential medical and legal risks. A careful risk/benefit assessment to ensure that the diver is completely asymptomatic and back to his or her pre-dive baseline function must be conducted by both the diver and the physician. Given the potential life-threatening implications of improperly clearing a diver to return to diving, referral of the patient to a diving medicine specialist is appropriate. In cases in which the risks clearly outweigh the benefits, divers should be instructed to refrain from diving for the remainder of their lives. Furthermore, a diver who has had multiple bouts of DCS even if symptoms were not severe and resolves completely must take special considerations. In these cases, a Diving Medical Specialist must be consulted to determine if diving can be resumed safely.
|  Must be reevaluated three months after treatment and get clearance from a Diving Medical Officer


The physician must also consider when it is safe for a patient to fly home or drive at altitude. A retrospective review of 126 DCS cases demonstrated that those who flew home on commercial flights < 72 hours after recompression had a higher likelihood of recurrence of symptoms and signs of DCS. Similarly, physicians should be wary if patients must drive through high-altitude areas, as the drop in atmospheric pressure could, at least theoretically, potentiate a recurrence<ref name="urlwww.pulmonologyadvisor.com">{{cite web |url=https://www.pulmonologyadvisor.com/home/decision-support-in-medicine/pulmonary-medicine/diving-medicine-and-medical-complications-of-diving-dcs-and-barotrauma/ |title=www.pulmonologyadvisor.com |format= |work= |accessdate=}}</ref>.
| No further diving is recommended


The U.S. Navy has set down the following rules for returning to diving after treatment for professionals where time off must be minimized so operations are not compromised <ref name="DCS dan"> {{cite web |url=https://www.diversalertnetwork.org/medical/articles/Decompression_Illness_What_Is_It_and_What_Is_The_Treatment |title=Decompression Illness: What Is It and What Is The Treatment? — DAN &#124; Divers Alert Network — Medical Dive Article |format= |work= |accessdate=}} </ref>.
|}
*For pain-only DCI where there are no neurological symptoms, divers may begin diving two to seven days after treatment
*If there are neurological symptoms, the diver may resume diving two to four weeks after treatment, depending on symptom severity.
*For very severe symptoms, the diver must be reevaluated three months after treatment and cleared by a Diving Medical Officer.
For recreational divers, where diving is not a livelihood, a more conservative approach is called for to further minimize the chance that a diving injury will recur {{cite web <ref name="DCS dan"> {{cite web |url=https://www.diversalertnetwork.org/medical/articles/Decompression_Illness_What_Is_It_and_What_Is_The_Treatment |title=Decompression Illness: What Is It and What Is The Treatment? — DAN &#124; Divers Alert Network — Medical Dive Article |format= |work= |accessdate=}} </ref>
*After pain-only DCI where there are no neurological symptoms, a minimum of two weeks without diving is recommended.
*If there are minor neurological symptoms, six weeks without diving is recommended.
*If there are severe neurological symptoms or any residual symptoms, no further diving is recommended.


==Prognosis==
==Prognosis==
Prognosis is severity dependent. It also depends upon on other factors such as the time to recompression, availability and time to surface oxygen, previous episode, and supportive care <ref name="urlDecompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf">{{cite web |url=https://www.ncbi.nlm.nih.gov/books/NBK537264/ |title=Decompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf |format= |work= |accessdate=}}</ref>.
Prognosis is severity dependent. It also depends upon on other factors such as the time to recompression, availability and time to surface oxygen, previous episode, and supportive care. <ref name="urlDecompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf">{{cite web |url=https://www.ncbi.nlm.nih.gov/books/NBK537264/ |title=Decompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf |format= |work= |accessdate=}}</ref>


==Prevention==
==Prevention==
Significant bubble formation can usually be avoided by limiting the depth and duration of dives to a range that does not need decompression stops during ascent (called no-stop limits) or by ascending with decompression stops as specified in published guidelines (eg, the decompression table in the US Navy Diving Manual) <ref name="DCS manual">U.S. Navy Supervisor of Diving (2008). "Chapter 20: Diagnosis and Treatment of Decompression Sickness and Arterial Gas Embolism". U.S. Navy Diving Manual (PDF). SS521-AG-PRO-010, revision 6. volume 5. U.S. Naval Sea Systems Command. p. 41</ref> <ref name="DCS navy">US Navy Diving Manual Rev. 7 Change A. SS521-AG-PRO-010 / 0910-LP-115-1921. US DIVING MANUAL_REV7_ChangeA-6.6.18.pdf; Apr 2018 </ref>.  
*Avoided by limiting the depth and duration of dives to a range that does not need decompression stops during ascent (called no-stop limits) or by ascending with decompression stops as specified in published guidelines (eg, the decompression table in the US Navy Diving Manual). <ref name="DCS manual">U.S. Navy Supervisor of Diving (2008). "Chapter 20: Diagnosis and Treatment of Decompression Sickness and Arterial Gas Embolism". U.S. Navy Diving Manual (PDF). SS521-AG-PRO-010, revision 6. volume 5. U.S. Naval Sea Systems Command. p. 41</ref> <ref name="DCS navy">US Navy Diving Manual Rev. 7 Change A. SS521-AG-PRO-010 / 0910-LP-115-1921. US DIVING MANUAL_REV7_ChangeA-6.6.18.pdf; Apr 2018 </ref>   


Many divers wear a portable dive computer that continually tracks depth and time at depth and calculates a decompression schedule. Computer divers should be cautious in approaching no-decompression limits, especially when diving deeper than 100 feet (30 meters).
*Wearing a portable dive computer that continually tracks depth and time at depth and calculates a decompression schedule. Computer divers should be cautious in approaching no-decompression limits, especially when diving deeper than 100 feet (30 meters).


In addition to suggested guidelines <ref name="DCS navy">US Navy Diving Manual Rev. 7 Change A. SS521-AG-PRO-010 / 0910-LP-115-1921. US DIVING MANUAL_REV7_ChangeA-6.6.18.pdf; Apr 2018 </ref>, many divers make a safety stop for a few minutes at about 4.6 m (15 ft) below the surface. However, cases can occur after appropriately identified no-stop dives and despite widespread use of dive computers.
*Making a safety stop for a few minutes at about 4.6 m (15 ft) below the surface. <ref name="DCS navy">US Navy Diving Manual Rev. 7 Change A. SS521-AG-PRO-010 / 0910-LP-115-1921. US DIVING MANUAL_REV7_ChangeA-6.6.18.pdf; Apr 2018 </ref>


Recreational divers should dive conservatively, whether they are using dive tables or computers.  
*Recreational divers should dive conservatively, whether they are using dive tables or computers.  


Experienced divers often select a table depth (versus actual depth) of 10 feet (3 meters) deeper than called for by standard procedure. This practice is highly recommended for all divers, especially when diving in cold water or under strenuous conditions <ref name="DCS dan"> {{cite web |url=https://www.diversalertnetwork.org/medical/articles/Decompression_Illness_What_Is_It_and_What_Is_The_Treatment |title=Decompression Illness: What Is It and What Is The Treatment? — DAN &#124; Divers Alert Network — Medical Dive Article |format= |work= |accessdate=}} </ref>.
*Experienced divers often select a table depth (versus actual depth) of 10 feet (3 meters) deeper than called for by standard procedure. This practice is highly recommended for all divers, especially when diving in cold water or under strenuous conditions. <ref name="DCS dan"> {{cite web |url=https://www.diversalertnetwork.org/medical/articles/Decompression_Illness_What_Is_It_and_What_Is_The_Treatment |title=Decompression Illness: What Is It and What Is The Treatment? — DAN &#124; Divers Alert Network — Medical Dive Article |format= |work= |accessdate=}} </ref>


Avoiding the risk factors noted above (deep / long dives, exercise at depth or after a dive) will decrease the chance of DCS occurring.  
*Avoiding the risk factors noted above (deep/long dives, exercise at depth or after a dive) will decrease the chance of DCS.  


====Altitude DCS: Things to remember====
====Altitude DCS: Things to remember====
Line 604: Line 693:
* Be prepared for a future emergency by finding where [[hyperbaric chamber]]s are available in your area of operations. However, keep in mind that not all of the available hyperbaric treatment facilities have personnel qualified to handle altitude DCS emergencies. To obtain information on the locations of hyperbaric treatment facilities capable of handling altitude DCS emergencies, call the Diver's Alert Network at (USA phone number) (919) 684-9111.
* Be prepared for a future emergency by finding where [[hyperbaric chamber]]s are available in your area of operations. However, keep in mind that not all of the available hyperbaric treatment facilities have personnel qualified to handle altitude DCS emergencies. To obtain information on the locations of hyperbaric treatment facilities capable of handling altitude DCS emergencies, call the Diver's Alert Network at (USA phone number) (919) 684-9111.


''MORE INFORMATION'':   
'''''FOR MORE INFORMATION''''':   
*Divers Alert Network: [[www.diversalertnetwork.org]] 24-hour emergency hotline, 919-684-9111
*Divers Alert Network: [[www.diversalertnetwork.org]] 24-hour emergency hotline, 919-684-9111
*Duke Dive Medicine: [[www.dukedivemedicine.org]] Physician-to-physician consultation, 919-684-8111
*Duke Dive Medicine: [[www.dukedivemedicine.org]] Physician-to-physician consultation, 919-684-8111
Line 611: Line 700:


==Decompression sickness in popular culture==
==Decompression sickness in popular culture==
*In the 1880s, Decompression sickness became known as ''The Bends'' because afflicted individuals characteristically arched their backs in a manner reminiscent of a then-popular women's fashion called the [[Grecian Bend]].
*In the 1880s, DCS became known as ''The Bends'' because afflicted individuals characteristically arched their backs in a manner reminiscent of a then-popular women's fashion called the [[Grecian Bend]].
*A diver with decompression sickness flying in an aircraft was part of the plot in the episode ''[[Airborne (House episode)|Airborne]]'' of [[House (TV series)|''House, M.D.'']], first aired Tuesday [[April 11]], [[2007]].
*A diver with DCS flying in an aircraft was part of the plot in the episode ''[[Airborne (House episode)|Airborne]]'' of [[House (TV series)|''House, M.D.'']], first aired Tuesday [[April 11]], [[2007]].
*Rock band [[Radiohead]] released an album entitled ''[[The Bends]]'', a reference to decompression sickness.
*Rock band [[Radiohead]] released an album entitled ''[[The Bends]]'', a reference to DCS.
*Decompression sickness played a part in the anime visual novel "[[Ever 17]]"* A character in the series "Dive" by [[Gordan Korman]] experiences a case of Decompression sickness.
*DCS played a part in the anime visual novel "Ever 17"
*In an episode of "[[Jackie Chan Adventures]]" titled Clash of the Titanics, Jackie experienced decompression sickness
* A character in the series "Dive" by [[Gordan Korman]] experiences a case of DCS.
*[[Box (comics)|Roger Bochs]], a character in the [[Marvel Comics]] series [[Alpha Flight]], experiences decompression sickness after battling alongside the [[Avengers (comics)|Avengers]] in [[Atlantis (Marvel Comics)|Atlantis]].
*In an episode of "[[Jackie Chan Adventures]]" titled Clash of the Titanics, Jackie experienced DCS.
*[[Box (comics)|Roger Bochs]], a character in the [[Marvel Comics]] series [[Alpha Flight]], experiences DCS after battling alongside the [[Avengers (comics)|Avengers]] in [[Atlantis (Marvel Comics)|Atlantis]].


==References==
==References==

Latest revision as of 08:00, 1 August 2020

Template:DiseaseDisorder infobox

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Mahshid Mir, M.D. [2] Jaspinder Kaur, MBBS[3]

WikiDoc Resources for Decompression sickness

Articles

Most recent articles on Decompression sickness

Most cited articles on Decompression sickness

Review articles on Decompression sickness

Articles on Decompression sickness in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Decompression sickness

Images of Decompression sickness

Photos of Decompression sickness

Podcasts & MP3s on Decompression sickness

Videos on Decompression sickness

Evidence Based Medicine

Cochrane Collaboration on Decompression sickness

Bandolier on Decompression sickness

TRIP on Decompression sickness

Clinical Trials

Ongoing Trials on Decompression sickness at Clinical Trials.gov

Trial results on Decompression sickness

Clinical Trials on Decompression sickness at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Decompression sickness

NICE Guidance on Decompression sickness

NHS PRODIGY Guidance

FDA on Decompression sickness

CDC on Decompression sickness

Books

Books on Decompression sickness

News

Decompression sickness in the news

Be alerted to news on Decompression sickness

News trends on Decompression sickness

Commentary

Blogs on Decompression sickness

Definitions

Definitions of Decompression sickness

Patient Resources / Community

Patient resources on Decompression sickness

Discussion groups on Decompression sickness

Patient Handouts on Decompression sickness

Directions to Hospitals Treating Decompression sickness

Risk calculators and risk factors for Decompression sickness

Healthcare Provider Resources

Symptoms of Decompression sickness

Causes & Risk Factors for Decompression sickness

Diagnostic studies for Decompression sickness

Treatment of Decompression sickness

Continuing Medical Education (CME)

CME Programs on Decompression sickness

International

Decompression sickness en Espanol

Decompression sickness en Francais

Business

Decompression sickness in the Marketplace

Patents on Decompression sickness

Experimental / Informatics

List of terms related to Decompression sickness

Synonyms and keywords: Decompression illness; DCS; the diver's disease; the bends; Caisson disease; aerobullosis

Overview

Decompression sickness (DCS) is a multi-organ condition characterized by a varied clinical manifestations resulting from an exposure to reduced barometric pressures that leads to a normally dissolved inert gases (mainly nitrogen) in body fluids and tissues to come out of physical solution, and develops a free gas phase by forming an intravascular and extravascular bubbles. The likelihood of DCS is associated with the extent of bubble formation which subsequently causes minor symptoms from a few bubbles formation to a large bubble presenting with the multiorgan failure and death. The severity and nature of the DCS injury vary from mild systemic, musculoskeletal and cutaneous manifestations to severe, life-threatening neurological and cardiorespiratory complications. It is mostly observed in underwater decompression diving activities (e.g SCUBA) and depressurisation events such as emerging from a caisson, flying in an unpressurised aircraft at altitude, and extravehicular activity from spacecraft. The clinical presentation can show an individual susceptibility by varying from day to day under the similar circumstances. The classification of types of DCS based on its symptoms has evolved over years since its origin and research conducted to prevent it. It is not common to report it if the divers follow the recommended guidelines by using dive tables or dive computers to limit their period of exposure and control their rate of ascent speed. If DCS is suspected, it is treated by airway stabilization, high flow oxygen, and hyperbaric therapy in a recompression chamber. An early treatment ensures a significantly higher recovery rate.

Historical Perspective

Template:Wikisource1911Enc

  • 1670: Sir Robert Boyle described the first case of DCS in animals by conducting an experiment on a viper in a vacuum and observing the bubble formation in its eye with significant physical symptoms of discomfort. [1]
  • 1841: Jacques Triger proposed that the two miners while working in the pressurised caisson work developed the symptoms of DCS and thus, documented the first case of DCS in humans. [1]
  • 1847: The French physicians B. Pol and T.J. Watelle explained the effectiveness of recompression in caisson workers for the use of the treatment of DCS. [1] [2]
  • 1857: Felix Hoppe-Seyler supported Boyle's study findings. He further observed that the bubble formation is the underlying cause of sudden death in compressed air workers and recommended recompression therapy as the mode of treatment. [3]
  • 1861: Bucquoy proposed the hypothesis by comparing an injection of air in the veins with the blood gases returning to the free state under the process of decompression. [4]
  • 1868: Alfred Le Roy de Méricourt labelled DCS as an occupational hazard for the sponge divers. [2]
  • 1873: Dr. Andrew Smith studied 110 DCS cases during the construction of the Brooklyn Bridge and coined the terms "caisson disease" and "compressed air illness". Similarly, the term "the bends" was extracted from the fashionable ladies of the period "the Grecian Bend" as the workers emerging from pressurized construction on the Brooklyn Bridge adopted a posture similar to them.[1] [3] [5]
  • 1878: Paul Bert found that the nitrogen gas bubbles released from tissues and blood during or after decompression are responsible for the development of the DCS and further showed that breathing oxygen after developing DCS can help in relieving its symptoms. [6]
  • 1889–90: Ernest William Moir made the first medical airlock when he realized that recompression is the main modality of the treatment to prevent the workforce digging the Hudson River Tunnel dying from DCS. [7] [8]
  • 1908:John Scott Haldane prepared the first recognized decompression table for the British Admiralty which was based on experiments performed on goats using an end point of symptomatic DCS. [1] [9]
  • 1912: Chief Gunner George D. Stillson of the United States Navy created a program to evaluate and refine Haldane's tables which subsequently led to the first publication of the United States Navy Diving Manual and the establishment of a Navy Diving School in Newport, Rhode Island. [10]

Classification

  • In 1960, The Golding Classification was introduced and categorized DCS into type 1 DCS and type 2 DCS. [11]

Table 1 shows the Golding classification of DCS:

FEATURES TYPE 1 TYPE 2
Systems involved Joints, skin, and lymphatics Neurological, inner ear, and cardiopulmonary
Onset of symptoms Build in intensity Gradual or abrupt
Severity Mild Severe
  • This classification is not frequently used in making the diagnosis of DCS following upgradation of the treatment protocols and variable presentations of signs and symptoms. [12]
  • All the manifestations, whether DCS or arterial gas embolism (AGE), were categorized under the general term “decompression illness (DCI)” when the exact diagnosis cannot be finalized because both of them develops from the gas bubble formation in the body, have overlapping of their spectra of signs and symptoms, and similar treatment methods. [13]

Pathophysiology

  • The pathophysiology of DCS is in accordance with Henry’s law. It states that the solubility of a gas in a liquid is directly proportional to the amount of the pressure exerted on the gas and liquid. Thus, the amount of inert gases (eg, nitrogen, helium) dissolved in the blood and tissues increases at higher pressure, and hence the development of DCS depends on the depth and the duration of the dive.
  • During a dive, the partial pressure of nitrogen and oxygen increases which results in creating a diffusion gradient favoring an uptake of nitrogen into the bloodstream and tissues. The physiology of the lungs is to functions as a vehicle for the gaseous exchange and elimination from the body under normal circumstances. As the atmospheric pressure decrease during the ascent, more nitrogen precipitates from the tissues into the bloodstream and then diffuses back into the alveoli for exhalation process. If ascent occurs too rapidly or the elimination gradient is so steep, the gas quickly dissipates from the tissues and blood forming small air bubbles. This process is called “out gassing” or “off gassing”. Conversely, a slow ascent favors an equilibrium to be achieved gradually, and prevents the rapid changes in the partial pressure of nitrogen in the bloodstream. Hence, the amount of bubble formation depends on the depth and duration of the dive, and the rate of the ascent. [14]
  • Venous bubbles may form de novo or result from the intravascular release of tissue bubbles. The venous gas emboli usually get filtered at an arteriole level on reaching the lungs. However, the bubbles may pass directly into the arterial circulation if the pulmonary arterial pressure (PAP) rises after underwater diving. [15] [16]
  1. Bubbles primarily travel to vital organs such as the nervous system; and get lodged in arterioles and capillary beds causing a mass effect. These bubbles obstruct venous outflow and occlude arteries, as well as cause a shearing force on endovascular surfaces and impairs vascular integrity during their transit. The disturbed vascular permeability consequently leads to hemoconcentration, disturbance of microvascular flow, and a breakdown in the blood brain barrier. [17]
  2. Bubbles cause secondary multiple biochemical effects by activating platelets, complement, leucocytes and the clotting cascade; and hence, results in an inflammatory response in the affected tissues. [18]
  3. Autochthonous or extravascular bubbles arise spontaneously, and are more likely to form in tissues with high gas content and poor perfusion because the large amount of gas in the tissues such as spinal cord white matter, adipose tissue, and periarticular tissue cannot be removed by the low perfusing blood volume. [15]
  • Bubbles are responsible for the proximate cause of damage, whereas the several pro-inflammatory activated pathways leads to the progression of an injury. Thus, DCS can have an evolving course with inflammatory mediated manifestations worsening with a period of time.

Clinical Features

  • Clinical presentation: It is frequently idiosyncratic as its "typical" pattern gives an atypical presentation due to the origin of the bubble formation in any part of the body. The US Navy listed the symptoms of DCS in a decreasing order of their overall prevalence in Table 2: [19]
Symptoms Features in %
Local joint pain 89
Arm symptoms 70
Leg symptoms 30
Dizziness 5.3
Paralysis 2.3
Shortness of breath 1.6
Extreme fatigue 1.3
Collapse/unconsciousness 0.5


  • Onset: The median time to symptom/sign onset is 30 minutes and severe neurologic symptoms might present as early as within 10 minutes; and however, majority of symptoms and signs develops within 24 to 48 hours of emerging from the water. The U.S. Navy and Technical Diving International have published a table that documents time to onset of first presenting symptom. The table does not differentiate between types of DCS, or types of symptom. [20] [21]

Table 3 shows the time of onset of symptoms among DCS suspected cases:

Time to onset Percentage of cases
Within 1 hour 42%
Within 3 hour 60%
Within 8 hour 83%
Within 24 hour 98%
Within 48 hour 100%
  • Joints DCS is most frequently noticed in shoulders, elbows, knees, and ankles. Shoulder is the most common site for altitude and bounce diving; and the knees and hip joints for saturation and compressed air work. The symptoms of limb bends arises from increased intermedullary pressure in the ends of long bones; and gas phase separation along ligaments and tendon sheaths, and thus presenting with an extreme discomfort from the simple mechanical distension and movement.
  • Dermatological manifestations are due to the blood extravasated from the cutaneous vessels as a consequence of bubble induced endothelial injury.
  • Pulmonary DCS ("the chokes") is rarely reported in divers; and believed to arise from an extremely huge load of venous bubbles in the pulmonary artery which results in an elevated pulmonary artery and right ventricular pressures, and further increasing the interstitial fluid and hence, leads to the development of the chokes or difficult breathing.
  • Spinal cord DCS have two interrelated mechanisms. The first is obstruction of venous outflow of the spinal cord in the epidural plexus which relatively have a slow blood perfusion rate. Once this process develops, it results in an ongoing and progressive diminution of blood flow to the cord, and thereafter, the second process proceeds with the in-situ bubble formation within the tissue of the spinal cord. [19] [22]

Table 4 shows symptoms and signs of different DCS types: [12]

DCS type Bubble location Signs and symptoms
Musculoskeletal: BENDS Mostly large joints (elbows, shoulders, hip, wrists, knees, ankles)
  • Characteristics: Localized deep pain, ranging from mild to excruciating; dull ache (sometimes); sharp pain (rarely)
  • Aggravating factor: Active and passive motion of the joint
  • Relieving factor: Bending the joint to a comfortable position
  • Onset: Immediate or few hours later in case of altitude induced DCS
Cutaneous: SKIN BENDS Skin
  • Site: Itching around the ears, face, neck, arms, and upper torso
  • Formication: Sensation of tiny insects crawling over the skin
  • Cutis Marmorata: Mottled or marbled skin usually around the shoulders, upper chest and abdomen with itching
  • Pitting edema: Swelling of the skin accompanied by tiny scar-like skin depressions
Neurologic Brain
  • Most common: Headache and visual disturbances
  • Visual changes: Spots in visual field (scotoma), tunnel vision, double vision (diplopia), or blurry vision
  • Confusion or memory loss
  • Unexplained extreme fatigue or behavior changes
  • Seizures, dizziness, vertigo, nausea, vomiting and unconsciousness may occur
Neurologic Spinal cord
  • Abnormal sensations such as burning, stinging, and tingling around the lower chest and back
  • Symptoms may spread from the feet up and may be accompanied by ascending weakness or paralysis
  • Girdling abdominal or chest pain
Neurologic Peripheral Nerves
  • Urinary and rectal incontinence
  • Abnormal sensations, such as numbness, burning, stinging, tingling and paresthesia
  • Muscle weakness or twitching
Constitutional Whole body
  • Headache
  • Unexplained fatigue
  • Generalized malaise, poorly localized aches
Audiovestibular Inner ear
  • Loss of balance
  • Dizziness, vertigo, nausea, vomiting
  • Hearing loss
Pulmonary CHOKES Lungs
  • Dry persistent cough
  • Burning chest pain under the sternum, aggravated by breathing
  • Shortness of breath
Dysbaric osteonecrosis [23] Bones
  • Late manifestation and often occurs without any previous symptoms
  • An insidious form caused by prolonged or closely repeated exposures to increased pressure
  • Typically found in people working in compressed air and in deep commercial rather than recreational divers
  • Deterioration of shoulder and hip articular surfaces cause chronic pain and severe joint disability

Differential Diagnosis

  • Differential diagnosis is the process by which medical personnel rule out which of the potential condition is most likely responsible for the presenting symptoms when two or more probable conditions have overlapping symptoms among the diving-related injuries.
  • An alternative diagnosis should also be suspected if severe symptoms begin more than six hours following decompression without an altitude exposure or if any symptom occurs more than 24 hours after surfacing. [24]

Table 5 below shows various different medical conditions mimicking the DCS: [25]

Medical condition Clinical characteristics
Arterial Gas Embolism (AGE) [14]
  • Pulmonary Barotrauma: It usually occurs when the air expands to cause the lung rupture and releases gas bubbles directly into the arterial circulation.
  • Typical presentation: A diver who surfaces unconscious and remains so, or who loses consciousness within minutes of surfacing.
  • A true medical emergency condition
  • Rapid evacuation to a treatment facility is paramount.
Inner-ear barotrauma
  • Usually occurs during descent
  • Tinnitus, hearing loss, and persistent vertigo [26]
  • Middle-ear barotrauma: Conductive hearing loss seen
  • Both inner-ear and middle-ear barotrauma are usually preceded by difficulty in equalizing middle-ear pressure
  • Alternobaric vertigo: transient vertigo during compression or decompression arises because of asymmetric middle-ear pressure equilibration [27]
Middle-ear or maxillary sinus overinflation
  • It is caused by gas expansion during ascent and an obstructed eustachian tube or sinus ostium
  • Compresses the facial nerve causes unilateral upper and lower facial weakness, [28] or
  • Compression of branches of the trigeminal nerve causes hypoaesthesia of the face [29]
Contaminated diving gas and oxygen toxic effects
  • Carbon monoxide poisoning: contaminated breathing gas can cause encephalopathy and convulsions.
  • Oxygen toxicity: most common in divers using enriched oxygen breathing mixtures; and can cause convulsions at depth.
Musculoskeletal strains or trauma sustained [29]
  • Time of onset (e.g.: before, during, or after diving) and history of trauma or strain are helpful to rule it out.
  • Pain is usually accompanied by tenderness or position-related or motion-related exacerbation on physical examination.
Seafood toxin ingestion
  • Ingestion of toxins (e.g.: ciguatera, puffer fish, paralytic shellfish poisoning )
  • Often associated with gastrointestinal symptoms, and can cause neurological manifestations within hours after ingestion [30]
Immersion pulmonary edema
  • This disorder usually begins during descent or at depth, whereas the onset of cardiorespiratory DCS occurs after the dive
  • They might get confused since both cause dyspnea and cough [31]
Water aspiration
  • Water aspiration could be mistaken for cardiorespiratory DCS
  • Both can cause pulmonary edema, although the diver is usually aware of aspiration
Coincidental, unrelated acute neurological disorder
  • Diagnosis of stroke, hypothermia, hypoglycemia, and spinal hematoma is made with conventional techniques
Thermal stress
  • Usually occur due to cold exposure but sometimes excessive heat can be responsible

Epidemiology and Demographics

  • The incidence of DCS, fortunately, is rare.
  • Recreational divers: It is estimated in about 2 to 4/10,000 dives.
  • Commercial divers: It can be higher ranging from 1.5-10 per 10,000 dives due to prior history of minor musculoskeletal injuries.
  • Its prevalence depends on the length and depth of the dive.
  • The risk for DCS is 2.5 times greater for males in relation to females. [32]

Risk Factors

  • Various environmental, diving and individual factors are related to the predisposition of DCS.
  • In 2005, DeNoble et al conducted a study to find the association of various risk factors with the DCS[33]
    • Multiple risk factors studied: age, gender, body mass index, smoking, asthma, diabetes, cardiovascular disease, previous history of DCI, number of the years since certification, number of dives in the last year, number of diving days, number of dives in a repetitive series, last dive depth, nitrox use, and drysuit use.
    • No significant correlation with DCS: asthma, diabetes, cardiovascular disease, smoking, or body mass index.
    • Positive correlation (higher risk): increased diving depth, previous DCS episodes, multiple consecutive days of diving and being male.
    • Negative correlation (lower risk): nitrox and drysuit use, higher frequency of diving in the past year, increasing age, and years since certification possibly as indicators of more extensive training and experience.

Environmental factors

  • Magnitude of the pressure reduction ratio: DCS is more likely to be experienced with a larger pressure reduction ratio in comparison to a smaller reduction. [34]
  • Temperature: Warm conditions may favor nitrogen uptake which results in an increased level of dissolved nitrogen and hence, putting a diver at higher risk of “out gassing” during ascent phase. Contrarily, the cold conditions slows the process; however, no definitive studies have demonstrated a direct relationship between thermal conditions and development of DCS. [14]
  • Repetitive exposures: A shorter periods of break among similar repetitive dives and ascents to altitudes above 5,500 metres (18,000 ft) will raise the risk of DCS because excessive nitrogen remains dissolved in body tissues for at least 12 hours after each dive, and hence, repeated dives within 1 day predisposes the divers to it.[34]
  • Post dive air travel: Divers who ascend to altitude soon after a dive increase their possibility of developing DCS even if the dive was performed within the dive table safe limits. [35]
  • Diving before travelling to altitude: DCS can occur even without flying if a diver moves to a high-altitude location on land immediately after diving; for example, scuba divers in Eritrea who drive from the coast to the Asmara plateau at 2,400 m (7,900 ft) increase their chances of DCS. [36]
  • Ambient temperature: A very cold ambient temperatures may increase the risk of altitude DCS. However, increasing ambient temperature during decompression following the dives in cold water may reduce the risk levels. [37] [38]

Diving factors

  • Rate of ascent: A rate of ascent shows a positive correlation with faster the ascent, greater the risk. The U.S. Navy Diving Manual indicates that ascent rates greater than about 20 m/min (66 ft/min) from the diving depth increases the possibility of DCS, while other recreational dive tables such as the Bühlmann tables require an ascent rate of 10 m/min (33 ft/min) with the last 6 m (20 ft) taking at least one minute to lower its incidence. A diver exposed to a rapid decompression rate of ascent of above 5,500 metres (18,000 ft) has a greater risk of altitude DCS in comparison to being exposed to the same altitude but at a lower rate of ascent. [34] [36]
  • Duration of diving: A longer duration of the dive, the greater risk of DCS. Similarly, a longer flights, especially to altitudes of 5,500 m (18,000 ft) and above, holds a higher risk of altitude DCS. [34]
  • Diving at altitude: Diving in water whose surface altitude is above 300 m (980 ft) have a higher risk of developing DCS; for example, Lake Titicaca is at 3,800 m (12,500 ft) and diving in it without using versions of decompression tables or dive computers that are modified for high-altitude predisposes the divers to DCS. [35]

Individual factors

  • Dehydration: Drinking isotonic saline or adequate hydration will raise the serum surface tension which is helpful in controlling bubble size and hence, reduces the chances of DCS in aviators. Therefore, maintaining adequate hydration is recommended. [36] [37]
  • Patent foramen ovale (PFO): At birth, a hole between the atrial chambers of the heart in the fetus gets normally closed by a flap with the first breath. However, in about 20% of adults, where the flap does not seal completely, allows blood through the hole during coughing or activities that raise chest pressure. During diving, PFO can allow venous blood with microbubbles of inert gas to bypass the lungs, where the bubbles would otherwise be filtered out by the lung capillary system, and return directly to the arterial system (including arteries to the brain, spinal cord and heart). In the arterial system, bubbles are highly dangerous because they block circulation and cause infarction. In the brain, infarction results in stroke; whereas in the spinal cord, it may predispose to paralysis. [36] [39]
  • Age: An increasing age (especially >42 years of age) has been associated with a higher incidence of altitude DCS. [37]
  • Previous injury: Divers with a previous history of recent joint or limb injuries may have a higher susceptibility to development of the decompression-related bubbles. [40]
  • Body type: A diver with a high body fat content stores about the half the total amount of the nitrogen which predisposes them to a higher chances of DCS. This is due to five times greater solubility of nitrogen in fat than water, and hence, resulting in a higher levels of total body dissolved nitrogen during elevated atmospheric pressure. [37] [41]
  • Alcohol consumption: It increases chances of dehydration and inhibits pituitary release of antidiuretic hormone (ADH); and therefore may increase susceptibility to DCS. [37] Contrarily, another study found no correlation between alcohol consumption and developing DCS. [42]
  • Work and exercise: DCS is strongly related with the level of work or exercise done at depth or shortly after diving because it promotes increased inert gas uptake. Therefore, any kind of strenuous exercise will promote bubble formation, and lighter exercise during ascent or stop phase will favor gas excretion. [14]
  • Asthma: Asthmatics are generally advised not to dive due to a theoretical risk of bronchospasm triggered by cold or changing environments, inability to have an immediate response to an asthma attack while being submerged, and supposed increased barotrauma during ascent. However, more studies are warranted as there is limited data to support preventing them from diving. Well-controlled asthmatics with normal PFTs can occasionally be permitted to dive, however, an assessment should be made on a case-by-case basis. [14]

Diagnosis

  • DCS is primarily a clinical diagnosis assessed with a thorough and detailed dive history from a conscious patient and the clinical examination, including the neurological exam.
  • The specific symptoms/signs and their particular time of onset (table 3 and 4) aid in suspecting and establishing the diagnosis.
  • However, the relief of symptoms by recompression will make the definitive confirmation of the probable diagnosis.
  • Hence, an immediate treatment should be begun with no delay for further diagnostic work up.

Diagnostic criteria

In 2004 Freiberger identified important five diagnostic factors in their order of importance using simulated diving injury cases:[43]

  • (1) A neurologic symptom as the primary presenting symptom,
  • (2) onset time to symptoms,
  • (3) joint pain as a presenting symptom,
  • (4) any relief after recompression treatment, and
  • (5) maximum depth of the last dive

Laboratory findings

  • DCS is associated with hemoconcentration, and elevated serum CK is seen in severe AGE.
  • However, none of the laboratory studies make a definitive diagnosis of DCS. [14]

Radiological findings

  • No imaging study can confirm the diagnosis of DCS.
  • Bubble formation can occasionally be identified on MRI or CT scans; however, they are not considered the reliable method to rule out DCS due to their low sensitivity level in making the diagnosis.
  • Although, they might be used to rule out the other differential disorders that presents with the similar signs and symptoms (eg, herniated intervertebral disk, ischemic stroke, central nervous system hemorrhage).
  • These studies should be performed with no delay as prompt intervention is important in the successful management of the DCS.

Chest and Joints Radiography

  • Pneumothorax, pneumomediastinum, pulmonary overexpansion injury, or pulmonary edema should always be ruled out with chest radiographs.
  • Radiographs rarely detect bubble formation in joints affected by pain.
  • Skeletal x-rays are not considered diagnostic for dysbaric osteonecrosis which may show joint degeneration; and hence cannot be used to differentiate between different joint disorders. [14] [25]

Computed Tomography Scan

  • Head CT: A “normal” head CT is not reliable in excluding DCS due to the very low chances of visibility of vascular gas bubbles on CT films in the cases of suspected DCS. However, it should be strongly considered in any patient who presented with an altered mental status in order to evaluate alternative diagnoses, such as subdural or epidural hematoma. [14] [44]
  • Chest CT: An extrapulmonary air can be detected on it, but it should be avoided due to its high radiation exposure level. [25]

Magnetic Resonance Imaging

  • MRI can be falsely reassuring for detecting the spinal cord or brain abnormalities related to DCS.
  • However, it can diagnose ischemic lesions of the brain or spinal cord due to the etiologies other than DCS. [45]

Other diagnostic studies

  • Doppler ultrasonography and Echocardiography: They are not considered the diagnostic tests for DCS; but done to rule out right to left shunt and for research purposes into venous gas emboli. [46]
  • Neurophysiological tests (eg, audiometry and electronystagmography for inner-ear decompression sickness): They can usually be delayed until after recompression. [25]
  • Non invasive pulmonary diagnostic test: None of them are used in making or excluding the diagnosis. [14]
  • Pulmonary diagnostic procedures (e.g.: Bronchoscopy): None is required in making or excluding the diagnosis. [14]
  • Pathology/Cytology/Genetics Study: None is considered in making or excluding the diagnosis. [14]

Although laboratory and radiological analyses are helpful for detection of DCS related abnormalities in some cases; however, these studies are not considered as the deciding factor for the start of the recompression therapy, and hence, recompression should be given with no delay unless there is a strong suspicion of other non-diving related etiologies (eg, cerebral hemorrhage). [25]

Treatment

The several elements to the effective management of DCS consist of initial treatment including on-the-scene evaluation and first aid; transportation; and definitive medical treatment.

On the scene first aid

  • The foundation of first aid is the basic life support.
  • An initial management should focus on the treatment and stabilization of ABC's (airway, breathing, and circulation) in the patients with an altered mental status or loss of consciouness.
  • All DCS suspected cases should have initial treatment with high flow oxygen at 15ltr/min via a non-rebreathe mask or pocket masks regardless of their oxygen saturation levels.
  • This high-flow 100% oxygen enhances nitrogen washout by widening the nitrogen pressure gradient between the lungs and the circulation, thus accelerating reabsorption of embolic bubbles. [23]
  • An early oxygen first aid is important and may reduce symptoms substantially, but this should not change the recommended treatment plan.
  • However, an initial oxygen breathing may clears the symptoms of air embolism and serious DCS, but they may reappear later due to which always contact DAN at +1-919-684-9111 or a dive physician in all the cases of suspected DCI, even if the symptoms and signs appear to have resolved. [47]
 
 
 
 
 
 
 
Decompression sickness
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Mild Symptoms:
•Inhalation of oxygen with FiO2 1.0;
•Fluid administration (i.v. if possible,otherwise oral in unconscious patient)
 
 
 
 
 
 
 
Severe Symptoms with pain, neurological and/or pulmonary impairment
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Complete relief of symptoms within 30 minutes
 
 
 
 
 
 
 
Emergency treatment:
•Flat supine position;
•CPR if necessary;
•Insufflation of 100% inspired Oxygen;
•Intubation when unconscious;
•Intravenous line;
•Infusion therapy;
•HBOT as soon as possible
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
If no
 
 
 
 
 
Hyperbaric Oxygen Therapy:
•Treatment protocol most widespread: Table 6 USN;
•When intubated: paracentesis recommended;
•Lung ventilated at both sides?;
•Pneumothorax?
 
 
 
 
 
 
 
If yes
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Further drug therapy (scientifically not finally proven);
•Corticosteroids, Aspirin, Lidocaine
 
 
 
 
 
Further measures:
•Foley catheters;
•Renal protection;
•Early rehabilitation measures;
•Physiotherapeutic excercise between treatments
 
Hospitalisation for 24h
 
 
 
 
 
 
 
 
 
 
 
 
 

Figure 1: Treatment algorithm of Decompression Sickness (DCS)[48]

Fluid administration

  • It is indicated to minimize the dehydration and restore lost intravascular volume.
  • Oral resuscitation fluid (or plain water) is indicated for alert patients with mild manifestations.
  • Isotonic IV fluid resuscitation and maintenance IV fluids should be administered to those with serious manifestations in order to counteract interstitial fluid shifts and decrease in plasma volume arising from an endothelial injury.
  • Insert a catheter if there is any suspicion of the patient having urinary retention. [23]

Positioning and transportation

  • The supine position or the recovery position should be preferred in case vomiting occurs.
  • The Trendelenburg position and the left lateral decubitus position (Durant's maneuver) have beneficial effect in cases where air emboli are suspected; however, these positions are no longer recommended for prolonged duration due to concerns regarding cerebral edema. [49]
  • It is essential that the suspected cases should be stabilized at the nearest medical center before transportation to a recompression chamber.
  • However, patients with severe symptoms need an evacuation to a suitable recompression facility because time to treatment and severity of the injury are important determinants of outcome; and hence, transport should not be delayed for the performance of nonessential procedures.

Aeromedical transport:

  • Instructions to fly the patient “as low as safely possible” should be given to helicopter transport.
  • Pressurized aircraft with 1 atmosphere internal pressure is preferred.
  • Unpressurized aircraft such as helicopters: The flight altitude should be limited to 300 m or 1000 ft if possible, and oxygen should be given continuously. [32]
  • Commercial aircraft, although pressurized, typically have a cabin pressure equivalent to 2438 m (8000 ft) at normal cruise altitude, but it may precipitate DCS symptoms. [14] [23]

Definitive treatment

Hyperbaric Oxygen Therapy (HBOT)

  • The definitive treatment is hyperbaric oxygen (HBOT) therapy which delivers the pure 100% oxygen at a pressure substantially higher than that of atmospheric pressure in recompression chambers.
  • Delays of > 4 hours from the time of injury to recompression correlate with a significant increase in the incidence of residual symptoms following therapy and hence, it should be initiated as soon as possible. [14]
Indication
  • All the patients, except those whose symptoms are limited to itching, skin mottling, and fatigue, may be treated with oxygen therapy alone; however these patients should be observed for any kind of further deteriorating condition. [23]
Effects of Recompression therapy
  • Bubble crushing: As per Boyles law, increasing pressure decreases the volume of bubbles.
  • Flushing out the nitrogen bubbles with oxygen delivery by improving gradient.
  • Healing damaged tissue with hyperbaric oxygen [50]
Equipment
  • Monoplace chamber: An acrylic tube sized chamber which have a capacity of one patient
  • Multiplace chamber: It is sized to accommodate one or more patients with one or more technicians or other medical personnel. They are designed to allow patients, tenders or equipment to be transferred into and out of the chamber while treatment is ongoing. [47] [51]
Regimen
  • A common HBOT regimen: The U.S. Navy Treatment Table 6 (USN 2008).
  • Regimen protocol:
    • HBOT chamber is brought to 2.8 atmospheres absolute (ATA), (equivalent of depth of 60 feet/18 meters) over a few minutes; and
    • Then 100% FiO2 is initiated.
    • 100% FiO2 is used for 20 minutes at a time, alternating with 5 minute intervals of room air breathing to reduce the risk of oxygen toxicity.
    • Upon completion, the pressure is increased by no more than 1 foot/minute, with a prolonged period of equilibration at 30 feet.
    • The total therapy time is about 5 hours.
    • The therapy can be continued daily for several days until no further improvement is seen in the patient's symptoms. [47] [52]
Mechanism of action
  • The mechanism of HBOT is twofold.
    • An elevated atmospheric pressure in the chamber increases the partial pressure of gases and dissolution of nitrogen back into liquid (Henry’s law), and the increased pressure also decreases the volume of gas present in the body (Boyle’s law).
    • An increased FiO2 results in decreased partial pressure of nitrogen in inspired gas. This enhances the diffusion gradient of nitrogen out of body tissues, favoring exhalation and elimination from the body, and blunting the neutrophillic response to injured endothelium. [14]
Risks

[14] [53]

  • Barotrauma:
    • Middle ear barotrauma: most common adverse effect of HBOT; generally requires supportive care. Bilateral tympanostomy tubes may be required in severe cases.
    • Pulmonary barotrauma: risk of pneumothorax; chest tube can be inserted.
    • Pneumomediastinum: managed conservatively.
    • Similar mechanism and management as barotrauma caused by diving.
  • Oxygen toxicity:
    • Pulmonary toxicity: small airways dysfunction observed on exceeding the treatment duration and pressure beyond the recommended therapeutic protocols.
    • CNS toxicity: generalized tonic-clonic seizures occur with an incidence of approximately 1-4 per 10,000 patient treatments. Risk is higher in patients who are hypercapnic, acidemia and/or septic.
  • Seizures: mechanisms not well-understood.
    • CNS toxicity: managed by decreased FiO2 with same elevated atmospheric pressure.
    • Ocular toxicity: myopia can be seen in those who undergo prolonged daily therapy.
  • Confinement anxiety: Managed with anxiolytics.
  • Fire: due to elevated FiO2.

In-water recompression (IWR) therapy

  • It is beneficial only with a substantial amount of planning, support, equipment and personnel; appropriate water conditions; and suitable patient status.
  • Critical challenges can arise from the changes in the patient's consciousness, oxygen toxicity, gas supply, and even thermal stress.
  • An unsuccessful IWR may leave the patient in worse shape than had the attempt not been made.
  • Hence, it would be suitable for an organized and disciplined group of divers with suitable equipment and practical training in the procedure. [49] [47]
Breathing pure oxygen to remove nitrogen from the bloodstream

Adjuvant treatment

  • Aspirin, NSAIDs, and corticosteroids have all been studied and shown no beneficial use in the management of DCS. However, they may mask the symptoms and exacerbate micro-haemorrhages caused by DCS resulting in a permanent sequelae.
  • Opiates should also be avoided as they can increase the risk of oxygen toxicity.
  • Oxygen is usually sufficient to control pain. [14] [50]

Follow-up evaluation and return to diving

  • Follow-up treatments along with physical therapy is required in the severe cases where significant residual neurological dysfunction may be present even after the most aggressive treatment.
  • Clearing a diver after DCS to return to diving is a complex undertaking with potential medical and legal risks. A careful risk and benefit assessment to ensure that the diver is completely asymptomatic and back to his or her pre-dive baseline function must be conducted by both the diver and the physician. A referral of the patient to a diving medicine specialist is appropriate in case of improperly clearing a diver to return to diving keeping in mind the potential life-threatening implications. Divers should be instructed to refrain from diving for the remainder of their lives in the cases where the risks clearly outweigh the benefits. Furthermore, a diver who has had multiple bouts of DCS even if symptoms were not severe and resolves completely must take special considerations. In such cases, a Diving Medical Specialist must be consulted to determine if diving can be resumed safely.
  • The physician must also consider when it is safe for a patient to fly home or drive at altitude. A retrospective review of 126 DCS cases demonstrated that those who flew home on commercial flights < 72 hours after recompression had a higher likelihood of recurrence of symptoms and signs of DCS. Similarly, physicians should be wary if patients must drive through high-altitude areas, as the drop in atmospheric pressure could, at least theoretically, potentiate a recurrence. [14]
  • The US Navy has recommended the guidelines for returning to diving after treatment with limited time off for the professional divers as their operations should not get compromised; whereas diving is not a livelihood for the recreational divers, so a more conservative approach should be adopted to further minimize the chance for the recurrence of a diving injury. [54]

Table 6 elaborate the recommendations given by the US Navy for return to diving:

Clinical features Professional Divers Recreational divers
Pain-only DCI with no neurological symptoms May resume diving two to seven days after treatment A minimum of two weeks without diving is recommended
Minor neurological symptoms May resume diving two to four weeks after treatment depending on symptom severity Six weeks without diving is recommended
Severe neurological symptoms or any residual symptoms Must be reevaluated three months after treatment and get clearance from a Diving Medical Officer No further diving is recommended

Prognosis

Prognosis is severity dependent. It also depends upon on other factors such as the time to recompression, availability and time to surface oxygen, previous episode, and supportive care. [49]

Prevention

  • Avoided by limiting the depth and duration of dives to a range that does not need decompression stops during ascent (called no-stop limits) or by ascending with decompression stops as specified in published guidelines (eg, the decompression table in the US Navy Diving Manual). [52] [55]
  • Wearing a portable dive computer that continually tracks depth and time at depth and calculates a decompression schedule. Computer divers should be cautious in approaching no-decompression limits, especially when diving deeper than 100 feet (30 meters).
  • Making a safety stop for a few minutes at about 4.6 m (15 ft) below the surface. [55]
  • Recreational divers should dive conservatively, whether they are using dive tables or computers.
  • Experienced divers often select a table depth (versus actual depth) of 10 feet (3 meters) deeper than called for by standard procedure. This practice is highly recommended for all divers, especially when diving in cold water or under strenuous conditions. [54]
  • Avoiding the risk factors noted above (deep/long dives, exercise at depth or after a dive) will decrease the chance of DCS.

Altitude DCS: Things to remember

  • Altitude DCS is a risk every time you fly in an un-pressurized aircraft above 18,000 feet (or at a lower altitude if you scuba dive prior to the flight).
  • Be familiar with the signs and symptoms of altitude DCS. Monitor all aircraft occupants, including yourself, any time you fly an unpressurized aircraft above 18,000 feet.
  • Avoid unnecessary strenuous physical activity prior to flying an un-pressurized aircraft above 18,000 feet, and for 24 h after the flight.
  • Even if you are flying a pressurized aircraft, altitude DCS can occur as a result of a sudden loss of cabin pressure (in-flight rapid decompression).
  • Put on your oxygen mask immediately and switch the regulator to 100% oxygen.
  • Begin an emergency descent and land as soon as possible. Even if the symptoms disappear during descent, you should still land and seek medical evaluation while continuing to breathe oxygen.
  • If one of your symptoms is joint pain, keep the affected area still; do not try to work the pain out by moving the joint around.
  • After exposure to an in-flight rapid decompression, do not fly for at least 24 h. In the meantime, stay vigilant for the possible onset of delayed symptoms or signs of altitude DCS. If you present delayed symptoms or signs of altitude DCS, seek medical attention at once.
  • Keep in mind that breathing 100% oxygen during flight (ascent, en route, descent) without oxygen pre-breathing before take-off does not prevent altitude DCS.
  • Do not ignore any symptoms or signs that go away during the descent. This could confirm that you are suffering altitude DCS. You should be medically evaluated from an aviation authority medical officer, aviation medical examiner (AME), military flight surgeon, or a hyperbaric medicine specialist. Be aware that a physician not specialized in aviation or hypobaric medicine may not be familiar with this type of medical problem. Therefore, be your own advocate.
  • If there is any indication that you may have experienced altitude DCS, do not fly again until you are cleared to do so.
  • Allow at least 24 hours to elapse between scuba diving and flying.
  • Be prepared for a future emergency by finding where hyperbaric chambers are available in your area of operations. However, keep in mind that not all of the available hyperbaric treatment facilities have personnel qualified to handle altitude DCS emergencies. To obtain information on the locations of hyperbaric treatment facilities capable of handling altitude DCS emergencies, call the Diver's Alert Network at (USA phone number) (919) 684-9111.

FOR MORE INFORMATION:

Decompression sickness in popular culture

  • In the 1880s, DCS became known as The Bends because afflicted individuals characteristically arched their backs in a manner reminiscent of a then-popular women's fashion called the Grecian Bend.
  • A diver with DCS flying in an aircraft was part of the plot in the episode Airborne of House, M.D., first aired Tuesday April 11, 2007.
  • Rock band Radiohead released an album entitled The Bends, a reference to DCS.
  • DCS played a part in the anime visual novel "Ever 17"
  • A character in the series "Dive" by Gordan Korman experiences a case of DCS.
  • In an episode of "Jackie Chan Adventures" titled Clash of the Titanics, Jackie experienced DCS.
  • Roger Bochs, a character in the Marvel Comics series Alpha Flight, experiences DCS after battling alongside the Avengers in Atlantis.

References

  1. 1.0 1.1 1.2 1.3 1.4 Acott, C. (1999). "A brief history of diving and decompression illness". South Pacific Underwater Medicine Society Journal. 29 (2). ISSN 0813-1988. OCLC 16986801
  2. 2.0 2.1 Hill, L (1912). Caisson sickness, and the physiology of work in compressed air. London E. Arnold
  3. 3.0 3.1 Huggins, Karl E. (1992). "Dynamics of decompression workshop". Course Taught at the University of Michigan. ; Huggins 1992, chpt. 1 page 8
  4. Trucco, Jean-Noël; Biard, Jef; Redureau, Jean-Yves; Fauvel, Yvon (3 May 1999). "Table Marine National 90 (MN90): Version du 03/05/1999" (PDF). Comité interrégional Bretagne & Pays de la Loire; Commission Technique Régionale. (in French). F.F.E.S.S.M.
  5. Butler WP (2004). "Caisson disease during the construction of the Eads and Brooklyn Bridges: A review". Undersea Hyperb Med. 31 (4): 445–59. PMID 15686275.
  6. Bert, P. (1878). "Barometric Pressure: researches in experimental physiology". Translated By: Hitchcock MA and Hitchcock FA. College Book Company; 1943
  7. John L. Phillips, The Bends: Compressed Air in the History of Science, Diving, and Engineering, Yale University Press (1998) - Google Books p 103
  8. Moon, Richard (March 2000). "The Natural Progression of Decompression Illness and Development of Recompression Procedures" (PDF). SPUMS Journal. 30 (1): 39
  9. Boycott AE, Damant GC, Haldane JS (1908). "The Prevention of Compressed-air Illness". J Hyg (Lond). 8 (3): 342–443. doi:10.1017/s0022172400003399. PMC 2167126. PMID 20474365.
  10. Stillson, GD (1915). "Report in Deep Diving Tests". US Bureau of Construction and Repair, Navy Department. Technical Report
  11. Golding FC , Griffi ths P , Hempleman HV , Paton WDM , Walder DN . Decompression sickness during construction of the Dartford tunnel . Br J Ind Med 1960 ; 17 : 167 – 80
  12. 12.0 12.1 Brubakk, Alf (2003). Bennett and Elliott's physiology and medicine of diving. Edinburgh New York: Saunders. ISBN 978-0-7020-2571-6.
  13. Francis, T James R; Smith, DJ (1991). "Describing Decompression Illness". 42nd Undersea and Hyperbaric Medical Society Workshop. 79(DECO)5–15–91.
  14. 14.00 14.01 14.02 14.03 14.04 14.05 14.06 14.07 14.08 14.09 14.10 14.11 14.12 14.13 14.14 14.15 14.16 "www.pulmonologyadvisor.com".
  15. 15.0 15.1 Edmonds, Lowry, Pennefather, Walker. Diving and Subaquatic Medicine 4th edition Arnold 2002
  16. Gorman, Des. Accidental arterial gas embolism. Emergency Medicine. 14(4):364-370, December 2002
  17. NHS Commissioning Board. April 2013. Clinical Commissioning Policy: Hyperbaric Oxygen Therapy
  18. Kindwall E and Whelan H, Hyperbaric Medicine Practice, 3rd Edition (2008), Chapter 4 page 71-89
  19. 19.0 19.1 Powell, Mark (2008). Deco for divers : a diver's guide to decompression theory and physiology. Southend-on-Sea, Essex: AquaPress. ISBN 978-1-905492-07-7.
  20. U.S. Navy Supervisor of Diving (2008). U.S. Navy Diving Manual (PDF). SS521-AG-PRO-010, revision 6. vol.5. U.S. Naval Sea Systems Command. pp. 20–25
  21. TDI Decompression Procedures Manual (Rev 1c), page 38
  22. Frans Cronje (5 August 2014). All That Tingles Is Not Bends (video). DAN Southern Africa
  23. 23.0 23.1 23.2 23.3 23.4 "Decompression Sickness - Injuries; Poisoning - MSD Manual Professional Edition".
  24. Moon, Richard E (1998). "Assessment of patients with decompression illness". South Pacific Underwater Medicine Society Journal. 28 (1).
  25. 25.0 25.1 25.2 25.3 25.4 Richard D Vann, Frank K Butler, Simon J Mitchell, Richard E Moon. Decompression illness. Vol 377 January 8, 2011; pg: 153-164
  26. Klingmann C, Praetorius M, Baumann I, Plinkert PK. Barotrauma and decompression illness of the inner ear: 46 cases during treatment and follow-up. Otol Neurotol 2007; 28: 447–54
  27. Farmer JC Jr. Diving injuries to the inner ear. Ann Otol Rhinol Laryngol Suppl 1977; 86 (1 Pt 3 suppl 36): 1–20
  28. Molvaer OI, Eidsvik S. Facial baroparesis: a review. Undersea Biomed Res 1987; 14: 277–95
  29. 29.0 29.1 Butler FK, Bove AA. Infraorbital hypesthesia after maxillary sinus barotrauma. Undersea Hyperb Med 1999; 26: 257–59
  30. Eastaugh J, Shepherd S. Infectious and toxic syndromes from fi sh and shellfi sh consumption. A review. Arch Intern Med 1989; 149: 1735–40
  31. Adir Y, Shupak A, Gil A, Peled N, et al. Swimming-induced pulmonary edema: clinical presentation and serial lung function. Chest 2004; 126: 394–99
  32. 32.0 32.1 Pollock, Neal W.; Buteau, Dominique (2017). "Updates in Decompression Illness". Emergency Medicine Clinics of North America. 35 (2): 301–319. doi:10.1016/j.emc.2016.12.002. ISSN 0733-8627.
  33. DeNoble, PJ; Vann, RD; Pollock, NW; Uguccioni, DM; Freiberger, JJ; Pieper, CF (2005). "A case-control study of decompression sickness (DCS) and arterial gas embolism (AGE)". Undersea and Hyperbaric Medical Society
  34. 34.0 34.1 34.2 34.3 DeHart, Roy (2002). Fundamentals of aerospace medicine. Philadelphia: Lippincott Williams & Wilkins. ISBN 978-0-7817-2898-0.
  35. 35.0 35.1 Bassett, Bruce E (1982). "Decompression Procedures for Flying After Diving, and Diving at Altitudes above Sea Level". US Air Force School of Aerospace Medicine Technical Report. SAM-TR-82-47
  36. 36.0 36.1 36.2 36.3 Lippmann, John (2005). Deeper into diving : an in-depth review of decompression procedures, and of the physical and physiological aspects of deeper diving. Melbourne Australia: J.L. Publications. ISBN 978-0-9752290-1-9.
  37. 37.0 37.1 37.2 37.3 37.4 Fryer, David (1969). Subatmospheric decompression sickness in man. London: Technical P. ISBN 978-0-85102-023-5.
  38. Gerth, Wayne A; Ruterbusch, VL; Long, Edward T (2007). "The Influence of Thermal Exposure on Diver Susceptibility to Decompression Sickness". United States Navy Experimental Diving Unit Technical Report. NEDU-TR-06-07
  39. Moon, Richard E; Kisslo, Joseph (1998). "PFO and decompression illness: An update". South Pacific Underwater Medicine Society Journal. 28 (3). ISSN 0813-1988. OCLC 16986801
  40. Karlsson, L; Linnarson, D; Gennser, M; Blogg, SL; Lindholm, Peter (2007). "A case of high doppler scores during altitude decompression in a subject with a fractured arm". Undersea and Hyperbaric Medicine. 34 (Supplement). ISSN 1066-2936. OCLC 26915585
  41. Boycott, A. E.; Damant, G. C. C. (2009). "Experiments on the Influence of Fatness on Susceptibility to Caisson Disease". Epidemiology and Infection. 8 (4): 445–456. doi:10.1017/S0022172400015862. ISSN 0950-2688.
  42. "RSA Abstracts". Alcoholism: Clinical and Experimental Research. 29: 6A–172A. 2005. doi:10.1111/j.1530-0277.2005.tb03524.x. ISSN 0145-6008.
  43. Freiberger JJ, Lyman SJ, Denoble PJ, et al. Consensus factors used by experts in the diagnosis of decompression illness. Aviat Space Environ Med 2004;75(12): 1023–8
  44. Benson J, Adkinson C, Collier R. Hyperbaric oxygen therapy of iatrogenic cerebral arterial gas embolism. Undersea Hyperb Med 2003; 30: 117–26
  45. Gempp E, Blatteau JE, Stephant E, Pontier JM, Constantin P, Peny C. MRI fi ndings and clinical outcome in 45 divers with spinal cord decompression sickness. Aviat Space Environ Med 2008; 79: 1112–16
  46. Gempp E, Blatteau JE, Pontier JM, Balestra C, Louge P. Preventive eff ect of pre-dive hydration on bubble formation in divers. Br J Sports Med 2009; 43: 224–28
  47. 47.0 47.1 47.2 47.3 "www.diversalertnetwork.org".
  48. Tetzlaff, Kay; Shank, Erik S.; Muth, Claus M. (2003). "Evaluation and management of decompression illness—an intensivist's perspective". Intensive Care Medicine. 29 (12): 2128–2136. doi:10.1007/s00134-003-1999-1. ISSN 0342-4642.
  49. 49.0 49.1 49.2 "Decompression Sickness (DCS, Bends, Caisson Disease) - StatPearls - NCBI Bookshelf".
  50. 50.0 50.1 "Decompression Illness - RCEMLearning".
  51. Kindwall, EP; Goldmann, RW; Thombs, PA (1988). "Use of the Monoplace vs. Multiplace Chamber in the Treatment of Diving Diseases". Journal of Hyperbaric Medicine; 3(1). Undersea and Hyperbaric Medical Society, Inc. pp. 5–10
  52. 52.0 52.1 U.S. Navy Supervisor of Diving (2008). "Chapter 20: Diagnosis and Treatment of Decompression Sickness and Arterial Gas Embolism". U.S. Navy Diving Manual (PDF). SS521-AG-PRO-010, revision 6. volume 5. U.S. Naval Sea Systems Command. p. 41
  53. Heyboer, Marvin; Sharma, Deepali; Santiago, William; McCulloch, Norman (2017). "Hyperbaric Oxygen Therapy: Side Effects Defined and Quantified". Advances in Wound Care. 6 (6): 210–224. doi:10.1089/wound.2016.0718. ISSN 2162-1918.
  54. 54.0 54.1 "Decompression Illness: What Is It and What Is The Treatment? — DAN | Divers Alert Network — Medical Dive Article".
  55. 55.0 55.1 US Navy Diving Manual Rev. 7 Change A. SS521-AG-PRO-010 / 0910-LP-115-1921. US DIVING MANUAL_REV7_ChangeA-6.6.18.pdf; Apr 2018

External links