Respiratory alkalosis: Difference between revisions

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| <figure-inline><figure-inline><figure-inline><figure-inline><figure-inline><figure-inline><figure-inline><figure-inline>[[File:Siren.gif|link=Respiratory alkalosis resident survival guide|41x41px]]</figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline></figure-inline>
| [[Respiratory alkalosis resident survival guide|'''Resident'''<br>'''Survival'''<br>'''Guide''']]
|}
{{Infobox_Disease |
{{Infobox_Disease |
   Name          = Respiratory alkalosis |
   Name          = Respiratory alkalosis |
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{{SI}}
{{SI}}
{{CMG}}; {{AE}} [[Priyamvada Singh|Priyamvada Singh, M.D.]] [mailto:psingh13579@gmail.com]{{MSI}}
{{CMG}}; {{AE}}{{MSI}} [[Priyamvada Singh|Priyamvada Singh, M.D.]] [mailto:psingh13579@gmail.com], {{EG}}
==Overview==
==Overview==
Acid-base status of an organism is determined by the extracellular fluid (ECF) hydrogen ion concentration [H+] since pH is equal to minus log of [H+] i.e. pH = -log[H+]. Normal pH of human blood is 7.40 (7.35-7.45). Acidosis raises ECF [H+] thereby lowering pH  whereas alkalosis lowers ECF [H+] thereby raising pH of the ECF.  
Acid-base status of an organism is determined by the [[extracellular fluid]] [[Extracellular fluid|(ECF)]] hydrogen ion concentration [H+] since [[pH]] is equal to minus log of [H+] i.e. pH = -log[H+]. Normal [[pH]] of human blood is 7.40 (7.35-7.45). Acidosis raises [[Extracellular fluid|ECF]] [[Hydrogen ion|[H+]]] thereby lowering [[pH]] whereas alkalosis lowers [[Extracellular fluid|ECF]] [H+] thereby raising pH of the [[Extracellular fluid|ECF]]. Respiratory alkalosis is an [[Acid-base imbalance|acid-base disorder]], primarily a decrease in [[partial pressure]] of [[carbon dioxide]] in arterial [[blood]] means PaCo2 [normal PaCo2 is 40 mm Hg on average with range between 35-45mm Hg (4.7-6.0kPa)] with or without compensatory decrease in serum [[bicarbonate]] [[Bicarbonate|[HCO3-]]] (normal [[bicarbonate]] is 22-30mEq/L in arterial blood gas analysis) and [[pH]] being alkaline (normal [[pH]] of blood is 7.35-7.45).
==Pathophysiology==
Production of [[Carbon dioxide|CO2]] in body tissues by intracellular [[Metabolism|metabolic]] process (from oxidation of [[fat]], [[carbohydrate]] and carbon skeleton of [[Amino acid|amino acids]] in normal metabolic process produces [[carbon dioxide]] and [[water]]) and elimination of [[Carbon dioxide|CO2]] through [[Lung|lungs]] are in equilibrium under normal physiology. [[Carbon dioxide|CO2]] in body tissues from normal [[Metabolism|metabolic]] process enters [[blood]] in the [[Tissue (biology)|tissues]] because its local [[partial pressure]] in [[Tissue (biology)|tissues]] is greater than the [[partial pressure]] in blood flowing through the [[Tissue (biology)|tissues]] due to property of gases to diffuse from high pressure to low pressure. Flowing [[blood]] transports the [[Carbon dioxide|CO2]] to the [[Lung|lungs]], where it diffuses into the [[Pulmonary alveolus|alveoli]] and then to the atmosphere by pulmonary [[Ventilation (physiology)|ventilation]]. The reversible combination of [[Carbon dioxide|CO2]] with [[water]] in the [[Red blood cell|red blood cells]] under the influence of [[carbonic anhydrase]] enzyme forms [[carbonic acid]] [[Carbonic acid|(H2CO3)]] which dissociates into [[hydrogen]] and [[bicarbonate]]  ions ([[Hydrogen|H+]] and [[Bicarbonate|HCO3−]]) ions. [[Bicarbonate|HCO3−]] diffuse from the [[Red blood cell|red blood cells]] into the [[Blood plasma|plasma]], while [[chloride]] ions diffuse into the [[Red blood cell|red blood cells]] to take their place ([[chloride shift]]). Hence, most of tissue [[Carbon dioxide|CO2]] is brought to [[Lung|lungs]] as [[Blood plasma|plasma]] venous [[bicarbonate]] ions that accounts for about 70 percent of the [[Carbon dioxide|CO2]] transported from the [[Tissue (biology)|tissues]] to the [[Lung|lungs]]. Remaining [[Carbon dioxide|CO2]] is transported as [[carbaminohemoglobin]] (23%) and as dissolved [[Carbon dioxide|CO2]] in fluids of [[blood]](7%).  


'''Respiratory alkalosis''' is an acid-base disorder, primarily a decrease in partial pressure of carbon dioxide in arterial blood i.e.PaCo2 [normal PaCo2 is 40 mm Hg on average with range between 35-45mm Hg(4.7-6.0kPa)] with or without compensatory decrease in serum bicarbonate [HCO3-] (normal bicarbonate is 22-30mEq/L in arterial blood gas analysis) and pH being alkaline (normal pH of blood is 7.35-7.45). Respiratory alkalosis in almost all cases results from increased [[alveoli|alveolar]] respiration ([[hyperventilation]]) leading to decrease in blood [[carbon dioxide]] concentration measured as PaCO2. This leads to decreased hydrogen ion [H+] and [[bicarbonate]] [HCO3-] concentrations. Decreased [H+] leads to increase in pH leading to alkalosis.
Respiratory alkalosis in almost all cases results from increased [[alveoli|alveolar]] respiration ([[hyperventilation]]) leading to decrease in blood [[carbon dioxide]] concentration measured as PaCO2. This leads to decreased hydrogen ion [H+] and [[bicarbonate]] [HCO3-] concentrations. Decreased [[Hydrogen|[H+]]] leads to increase in [[pH]] leading to [[alkalosis]].
==Pathophysiology==
Production of CO2 in body tissues by intracellular metabolic process(from oxidation of fat, carbohydrate and carbon skeleton of amino acids in normal metabolic process produces carbon dioxide and water) and elimination of CO2 through lungs are in equilibrium under normal physiology. CO2 in body tissues from normal metabolic process enters blood in the tissues because its local partial pressure is greater than the partial pressure in blood flowing through the tissues. Flowing blood transports the CO2 to the lungs, where it diffuses into the alveoli and then to the atmosphere by pulmonary ventilation. Most of tissue CO2 is brought to lungs as plasma venous bicarbonate ions.


===Compensation in respiratory alkalosis===
===Compensation in respiratory alkalosis===
compensation for respiratory alkalosis is mostly mediated through plasma buffers and proteins (eg. hemoglobin in RBC, plasma proteins) in acute stage and by kidneys in chronic compensatory stage.
compensation for respiratory [[alkalosis]] is mostly mediated through plasma buffers and [[Protein|proteins]] (eg. [[hemoglobin]] in [[Red blood cell|RBC]], [[Blood proteins|plasma proteins]]) in acute stage and by [[Kidney|kidneys]] in chronic compensatory stage.


====Acute compensatory stage====
====Acute compensatory stage====
* Starts within minutes to hours and consists of cellular uptake of HCO3- and buffered by intracellular phosphates and proteins<ref name="pmidhttps://doi.org/10.1016/j.cvsm.2016.10.005">{{cite journal| author=Schmoldt A, Benthe HF, Haberland G| title=Digitoxin metabolism by rat liver microsomes. | journal=Biochem Pharmacol | year= 1975 | volume= 24 | issue= 17 | pages= 1639-41 | pmid=https://doi.org/10.1016/j.cvsm.2016.10.005 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10  }}</ref>
* Starts within minutes to hours and mediated by body's non-bicarbonate buffers ([[hemoglobin]], intracellular [[Protein|proteins]] and [[Phosphate|phosphates]], plasma [[Protein|proteins]]) and it consists of cellular uptake of [[Bicarbonate|HCO3-]] and buffered by intracellular [[Phosphate|phosphates]] and [[Protein|proteins]]<ref name="pmidhttps://doi.org/10.1016/j.cvsm.2016.10.005">{{cite journal| author=Schmoldt A, Benthe HF, Haberland G| title=Digitoxin metabolism by rat liver microsomes. | journal=Biochem Pharmacol | year= 1975 | volume= 24 | issue= 17 | pages= 1639-41 | pmid=https://doi.org/10.1016/j.cvsm.2016.10.005 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10  }}</ref>
* For every PaCO2 decrease of 10 mm Hg, serum bicarbonate decreases by 1-2mEq/L
* For every PaCO2 decrease of 10 mm Hg, serum [[bicarbonate]] decreases by 1-2mEq/L
* Change in pH is unpredictable
* Change in [[pH]] is unpredictable
====Chronic compensatory stage====
====Chronic compensatory stage====
* Renal mediated process where reduction in PaCO2 leads to decreased renal tubular H+ secretion. Within the renal tubular cells, CO2, under the influence of carbonic anhydrase enzyme, combines with H2O to form carbonic acid (H2CO3), which then dissociates into HCO3- and H+. Alkalosis inhibits carbonic anhydrase activity, resulting in reduced H+ secretion into the renal tubule. As a result, there is not enough H+ in the renal tubular fluid to react with all the filtered HCO3− from glomerular capillaries of the kidneys. Therefore, the HCO3− that cannot react with H+ is not reabsorbed  and is excreted in the urine.
* Renal mediated process where reduction in PaCO2 leads to decreased renal tubular [[Hydrogen|H+]] secretion. Within the renal tubular cells, [[Carbon dioxide|CO2]], under the influence of [[carbonic anhydrase]] [[enzyme]], combines with [[Water|H2O]] to form [[carbonic acid]] [[Carbonic acid|(H2CO3)]], which then dissociates into [[Bicarbonate|HCO3-]] and [[Hydrogen|H+]]. [[Alkalosis]] inhibits [[carbonic anhydrase]] activity, resulting in reduced [[Hydrogen|H+]] secretion into the [[renal tubule]]. As a result, there is not enough H+ in the renal tubular fluid to react with all the filtered [[Bicarbonate|HCO3−]] from [[Glomerulus|glomerular capillaries]] of the kidneys. Therefore, the [[Bicarbonate|HCO3−]] that cannot react with [[Hydrogen|H+]] is not reabsorbed  and is excreted in the [[urine]]. This causes a decrease in urinary net acid excretion(mostly ammonium ions [[Ammonia production|NH4+]]) and due to increased [[bicarbonate]] excretion, body's [[bicarbonate]] stores is reduced.
* Starts after 24-36 hours and renal compensation for sustained hypocapnia is complete in 36-72 hours
* Starts after 24-36 hours and renal compensation for sustained [[hypocapnia]] is complete in 36-72 hours
* For every PaCO2 decrease of 10 mm Hg, serum bicarbonate decreases by 5mEq/L
* For every PaCO2 decrease of 10 mm Hg, serum [[bicarbonate]] decreases by 5mEq/L
* pH in chronic compensation is near normal
* [[pH]] in chronic compensation is near normal
==Classification==
==Classification==
There are two types of respiratory alkalosis: chronic and acute.
There are two types of respiratory [[alkalosis]]: chronic and acute.
===Acute respiratory alkalosis===
===Acute respiratory alkalosis===
* Lasting for less than 24-48 hours
* Lasting for less than 24-48 hours
* Increased levels of carbon dioxide are "blown off" by the lungs, which are hyperventilating.
* Increased levels of [[carbon dioxide]] are "blown off" by the lungs, which are [[Hyperventilation|hyperventilating]].
* During acute respiratory alkalosis, the person may lose consciousness where the rate of ventilation will resume to normal.
* During acute respiratory [[alkalosis]], the person may lose consciousness where the rate of [[Ventilation (physiology)|ventilation]] will resume to normal.
===Chronic respiratory alkalosis===
===Chronic respiratory alkalosis===
* Lasting for longer than 24-48 hours
* Lasting for longer than 24-48 hours
* For every 10 mM drop in pCO<sub>2</sub> in blood, there is a corresponding 5 mM of bicarbonate ion drop.
* For every 10 mM drop in pCO<sub>2</sub> in blood, there is a corresponding 5 mM of [[bicarbonate]] ion drop.
* The drop of 5 mM of bicarbonate ion is a compensation effect which reduces the alkalosis effect of the drop in pCO<sub>2</sub> in blood. This is termed metabolic compensation.
* The drop of 5 mM of [[bicarbonate]] ion is a compensation effect which reduces the [[alkalosis]] effect of the drop in pCO<sub>2</sub> in blood. This is termed metabolic compensation.
 
==Risk Factors==
===Common Risk Factors===
*Common risk factors in the development of respiratory [[alkalosis]] include:
**[[Old age]]
**[[Mechanical ventilation]]
**[[Respiratory disease|Lung diseases]]
**[[Hepatic failure]]
**[[Infection]]
**[[Altitude sickness|High altitude]]
**[[Anxiety|Anxiety disorder]]
**[[Central nervous system infection|CNS infection]]
 
===Less Common Risk Factors===
*Less common risk factors in the development of respiratory [[alkalosis]] include:
**[[:Category:Drugs|Drugs]]
**[[Poisoning]]


==Causes<ref name="pmid21267134">{{cite journal| author=Bear RA| title=A clinical approach to the diagnosis of Acid-base disorders. | journal=Can Fam Physician | year= 1986 | volume= 32 | issue=  | pages= 823-7 | pmid=21267134 | doi= | pmc=2327641 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21267134  }}</ref>==
==Causes<ref name="pmid21267134">{{cite journal| author=Bear RA| title=A clinical approach to the diagnosis of Acid-base disorders. | journal=Can Fam Physician | year= 1986 | volume= 32 | issue=  | pages= 823-7 | pmid=21267134 | doi= | pmc=2327641 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21267134  }}</ref>==
===Lung and airways===
===Tissue hypoxia (hypoxemia)===
* [[Pneumonia]]
* [[Aspiration (medicine)|Aspiration]] of [[foreign body]], [[food]] or vomitus
* [[Pulmonary embolus|Pulmonary embolism]]
* [[Bronchospasm]]/[[laryngospasm]] (eg. in [[asthma]])
* [[Drowning]]
* [[Anemia]]
* [[High altitude]]
* [[Cyanotic heart disease]]
* [[Congestive heart failure (patient information)|Circulatory failure]] or [[hypotension]]
 
===Stimulation of chest receptors===
* [[Pneumonia]]
* [[Pneumonia]]
* [[Pulmonary embolus]]
* [[Asthma]]
* [[Bronchospasm]]
* [[Pneumothorax]]/[[hemothorax]]
* [[Restrictive lung disease]]
* [[Flail chest]]
===Central respiratory drive===
* [[Congestive heart failure|Cardiac failure]]
* [[Pulmonary edema]] (non-cardiogenic)
* Adult/infant [[respiratory distress syndrome]]
* [[Interstitial lung disease]]
 
=== Stimulators of central respiratory drive===
* [[Pain]]
* [[Pain]]
* [[Anxiety]]
* [[Anxiety]]
Line 69: Line 98:
===Systemic diseases===
===Systemic diseases===
* [[Sepsis]]
* [[Sepsis]]
* [[Salicylates]]
* [[Liver failure]]
* [[Liver failure]]
* [[Hyperthyroid]]
* [[Hyperthyroidism]]
* [[Pregnancy]]
* [[Pregnancy]]
* [[Hypotension]]
* [[CHF]]
* [[Anxiety]], [[hysteria]], and [[Stress (medicine)|stress]]
* [[Iatrogenic]]ally during [[mechanical ventilation]] of patients
* [[Iatrogenic]]ally during [[mechanical ventilation]] of patients
* [[Carbon monoxide poisoning]]
* Recovery from [[metabolic acidosis]]
* [[Heat]] exposure
====Special considerations====
====Special considerations====
* [[Sepsis]] or [[salicylate toxicity]] are the only single disorders that cause both an elevated anion gap [[metabolic acidosis]] and a respiratory alkalosis.
* [[Sepsis]] or [[salicylate toxicity]] are the only single disorders that cause both an elevated anion gap [[metabolic acidosis]] and a respiratory [[alkalosis]].
* [[Ischemia]], [[infection]] or [[infarction]] of the central respiratory centers may result either [[respiratory acidosis]] (decreased respiratory drive) or respiratory alkalosis (increased respiratory drive)
* [[Ischemia]], [[infection]] or [[infarction]] of the central respiratory centers may result either [[respiratory acidosis]] (decreased respiratory drive) or respiratory [[alkalosis]] (increased respiratory drive)
* [[Asthma]], and [[Pneumonia]] can also present with either repiratory alkalosis or acidosis. Asthma typically presents with a respiratory alkalosis, however as the patient tires, respiratory acidosis may occur.
* [[Asthma]], and [[Pneumonia]] can also present with either repiratory [[alkalosis]] or [[acidosis]]. [[Asthma]] typically presents with a respiratory [[alkalosis]], however as the patient tires, respiratory [[acidosis]] may occur.
* [[Pulmonary embolus]] can be a life threatening condition and often presents as respiratory alkalosis.
* [[Pulmonary embolus]] can be a life threatening condition and often presents as respiratory [[alkalosis]].
* [[Progesterone]] is sometimes used as a respiratory stimulant in [[obstructive sleep apnea]] and [[hypoventilation]].
* [[Progesterone]] is sometimes used as a respiratory stimulant in [[obstructive sleep apnea]] and [[hypoventilation]].
* Respiratory alkalosis is the most common acid base abnormality in critically ill patients.
* Respiratory [[alkalosis]] is the most common acid base abnormality in [[Intensive care unit|critically ill]] patients.
 
==Differential Diagnosis==
<small>'''''Abbreviations:''''' '''ABG ('''[[arterial blood gas]]'''); ACE ('''[[Angiotensin-converting enzyme|angiotensin converting enzyme]]'''); BMI ('''[[body mass index]]'''); CBC ('''[[Complete blood counts|complete blood count]]'''); CSF ('''[[cerebrospinal fluid]]'''); CXR ('''[[chest X-ray]]'''); DOE ('''dyspnea on [[exercise]]'''); ECG ('''[[electrocardiogram]]'''); FEF ('''[[Spirometry|forced expiratory flow rate]]'''); FEV1 ('''[[forced expiratory volume]]'''); FVC ('''[[forced vital capacity]]'''); JVD ('''[[jugular vein distention]]''');''' '''MCV ('''[[mean corpuscular volume]]'''); Plt ('''[[platelet]]'''); RV ('''[[residual volume]]'''); SIADH ('''[[syndrome of inappropriate antidiuretic hormone]]'''); TSH ('''[[thyroid stimulating hormone]]'''); Vt ('''[[tidal volume]]''');''' '''WBC ('''[[White blood cells|white blood cell]]''');'''</small>
 
 
{|
|- style="background: #4479BA; color: #FFFFFF; text-align: center;"
! colspan="3" rowspan="3" |Organ system
! rowspan="3" |Diseases
! colspan="13" |Clinical manifestations
! colspan="5" rowspan="2" |Diagnosis
! rowspan="3" |Other features
|- style="background: #4479BA; color: #FFFFFF; text-align: center;"
! colspan="8" |Symptoms
! colspan="5" |Physical exam
|- style="background: #4479BA; color: #FFFFFF; text-align: center;"
!Loss of consciousness
!Agitation
!Weight loss
!Fever
!Chest pain
!Cough
!Orthopnea
!DOE
!Cyanosis
!Clubbing
!JVD
!Peripheral edema
!Auscultation
!CBC
!ABG
!Imaging
!Spirometry
!Gold standard
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
! rowspan="15" |Acute Dyspnea
! rowspan="6" |[[Respiratory system]]
! rowspan="6" |[[Chest]] and [[Pleurae|Pleura]],
Lower [[airway]]
![[Asthma attack]]<ref name="pmid19858243">{{cite journal| author=Hodder R, Lougheed MD, Rowe BH, FitzGerald JM, Kaplan AG, McIvor RA| title=Management of acute asthma in adults in the emergency department: nonventilatory management. | journal=CMAJ | year= 2010 | volume= 182 | issue= 2 | pages= E55-67 | pmid=19858243 | doi=10.1503/cmaj.080072 | pmc=2817338 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19858243  }}</ref>
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |[[Wheeze]]
! style="background: #F5F5F5; padding: 5px;" |↑ [[Eosinophil]]
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |↓ [[FEV1]], [[Peak expiratory flow|PEF]]
! style="background: #F5F5F5; padding: 5px;" |[[Physical examination|Physical exam]] and
[[Spirometry]]
! style="background: #F5F5F5; padding: 5px;" |[[Chest pain]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
![[COPD exacerbation resident survival guide|COPD exacerbation]]<ref name="pmid25177479">{{cite journal| author=Qureshi H, Sharafkhaneh A, Hanania NA| title=Chronic obstructive pulmonary disease exacerbations: latest evidence and clinical implications. | journal=Ther Adv Chronic Dis | year= 2014 | volume= 5 | issue= 5 | pages= 212-27 | pmid=25177479 | doi=10.1177/2040622314532862 | pmc=4131503 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=25177479  }}</ref>
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |[[Wheeze]], [[Rhonchi]], and [[Crackles]]
! style="background: #F5F5F5; padding: 5px;" |↑[[WBC]], ↑[[RBC]]
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Hyperexpansion
! style="background: #F5F5F5; padding: 5px;" |↓ [[FEV1]]/[[FVC]]
! style="background: #F5F5F5; padding: 5px;" |[[Clinical]] assessment
! style="background: #F5F5F5; padding: 5px;" |[[Chronic bronchitis|Acute '''exacerbations''' of chronic bronchitis (AECB)]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
![[Pneumonia]]<ref name="pmid25165554">{{cite journal| author=Simonetti AF, Viasus D, Garcia-Vidal C, Carratalà J| title=Management of community-acquired pneumonia in older adults. | journal=Ther Adv Infect Dis | year= 2014 | volume= 2 | issue= 1 | pages= 3-16 | pmid=25165554 | doi=10.1177/2049936113518041 | pmc=4072047 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=25165554  }}</ref>
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |[[Wheeze]], [[Rhonchi]], and [[Crackles]]
! style="background: #F5F5F5; padding: 5px;" |↑[[WBC]], [[neutrophilia]]
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |[[Consolidation (medicine)|Lobar consolidation]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Chest X-ray]] and CT Scan
! style="background: #F5F5F5; padding: 5px;" |[[productive cough]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
![[Pneumothorax]]<ref name="pmid17621614">{{cite journal| author=Currie GP, Alluri R, Christie GL, Legge JS| title=Pneumothorax: an update. | journal=Postgrad Med J | year= 2007 | volume= 83 | issue= 981 | pages= 461-5 | pmid=17621614 | doi=10.1136/pgmj.2007.056978 | pmc=2600088 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17621614  }}</ref>
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |Diminished [[breath sounds]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |↓[[Oxygen|O2]], ↑[[CO2]]
! style="background: #F5F5F5; padding: 5px;" |Radiolucency without [[lung]] marking
! style="background: #F5F5F5; padding: 5px;" |↓[[Tidal volume|Vt]]
! style="background: #F5F5F5; padding: 5px;" |CXR and [[Computed tomography|Chest CT scan]]
! style="background: #F5F5F5; padding: 5px;" |[[Tracheal deviation]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
![[Pulmonary embolism]]<ref name="pmid23940438">{{cite journal| author=Bĕlohlávek J, Dytrych V, Linhart A| title=Pulmonary embolism, part I: Epidemiology, risk factors and risk stratification, pathophysiology, clinical presentation, diagnosis and nonthrombotic pulmonary embolism. | journal=Exp Clin Cardiol | year= 2013 | volume= 18 | issue= 2 | pages= 129-38 | pmid=23940438 | doi= | pmc=3718593 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23940438  }}</ref>
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Lung|Pulmonary]] [[CT angiography]]
! style="background: #F5F5F5; padding: 5px;" |[[Pleuritic chest pain]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
![[Rib fractures]] ([[flail chest]])<ref name="pmid27984449">{{cite journal |vauthors=Swart E, Laratta J, Slobogean G, Mehta S |title=Operative Treatment of Rib Fractures in Flail Chest Injuries: A Meta-analysis and Cost-Effectiveness Analysis |journal=J Orthop Trauma |volume=31 |issue=2 |pages=64–70 |date=February 2017 |pmid=27984449 |doi=10.1097/BOT.0000000000000750 |url= |author=}}</ref>
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Fracture marks
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Chest X-ray]]
! style="background: #F5F5F5; padding: 5px;" |[[Pneumothorax]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
! colspan="2" rowspan="4" |[[Cardiovascular system]]
![[Acute myocardial ischemia]]<ref name="pmid18307844">{{cite journal| author=Bruyninckx R, Aertgeerts B, Bruyninckx P, Buntinx F| title=Signs and symptoms in diagnosing acute myocardial infarction and acute coronary syndrome: a diagnostic meta-analysis. | journal=Br J Gen Pract | year= 2008 | volume= 58 | issue= 547 | pages= 105-11 | pmid=18307844 | doi=10.3399/bjgp08X277014 | pmc=2233977 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18307844  }}</ref>
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Cardiac troponin I (cTnI) and T (cTnT)|Cardiac troponin I]]
! style="background: #F5F5F5; padding: 5px;" |[[Nausea and vomiting]], Positive pertinent risk factors, such as [[hypertension]], [[diabetes]], and [[smoking]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
![[Acute heart failure]]<ref name="GagginJanuzzi20132">{{cite journal|last1=Gaggin|first1=Hanna K.|last2=Januzzi|first2=James L.|title=Biomarkers and diagnostics in heart failure|journal=Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease|volume=1832|issue=12|year=2013|pages=2442–2450|issn=09254439|doi=10.1016/j.bbadis.2012.12.014}}</ref>
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |[[S4|S]]3
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |↑ [[Cardiothoracic ratio]]
! style="background: #F5F5F5; padding: 5px;" |↓[[Tidal volume|Vt]]
! style="background: #F5F5F5; padding: 5px;" |[[B-type natriuretic peptide|B-type natriuretic peptide (BNP)]] and [[N-terminal pro b-type natriuretic peptide|N-terminal proBNP (NT-proBNP)]]
! style="background: #F5F5F5; padding: 5px;" |[[Excessive sweating]], [[high blood pressure]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
![[Tachyarrhythmia]]<ref name="pmid18307844" />
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |High [[pulse rate]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[ECG]]
! style="background: #F5F5F5; padding: 5px;" |[[Palpitation]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
![[Pulmonary edema]]<ref name="MartindaleNoble2013">{{cite journal|last1=Martindale|first1=Jennifer L.|last2=Noble|first2=Vicki E.|last3=Liteplo|first3=Andrew|title=Diagnosing pulmonary edema|journal=European Journal of Emergency Medicine|volume=20|issue=5|year=2013|pages=356–360|issn=0969-9546|doi=10.1097/MEJ.0b013e32835c2b88}}</ref>
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |Basal [[Crackles|crackle]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Bat wing pattern, air bronchograms
! style="background: #F5F5F5; padding: 5px;" |↓[[Tidal volume|Vt]], ↑[[Residual volume|RV]]
! style="background: #F5F5F5; padding: 5px;" |[[Coronary catheterization|Cardiac Catheterization]]
! style="background: #F5F5F5; padding: 5px;" |[[Tachypnea]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
! colspan="2" rowspan="2" |[[Central nervous system]]
![[Encephalitis]]<ref name="pmid15489354">{{cite journal| author=Debiasi RL, Tyler KL| title=Molecular methods for diagnosis of viral encephalitis. | journal=Clin Microbiol Rev | year= 2004 | volume= 17 | issue= 4 | pages= 903-25, table of contents | pmid=15489354 | doi=10.1128/CMR.17.4.903-925.2004 | pmc=523566 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15489354  }}</ref>
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |↑[[WBC]], [[neutrophilia]]
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[CSF]] [[PCR]]
! style="background: #F5F5F5; padding: 5px;" |[[Confusion]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
![[Traumatic brain injury]]<ref name="pmid22033563">{{cite journal| author=McAllister TW| title=Neurobiological consequences of traumatic brain injury. | journal=Dialogues Clin Neurosci | year= 2011 | volume= 13 | issue= 3 | pages= 287-300 | pmid=22033563 | doi= | pmc=3182015 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22033563  }}</ref>
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |[[Intracerebral hemorrhage]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Ct scan|Brain CT scan]]
! style="background: #F5F5F5; padding: 5px;" |[[Lucid interval]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
! colspan="2" |[[Toxic]]/[[Metabolic]]
![[Salicylate poisoning]]<ref name="pmid20440389">{{cite journal| author=Chin RL, Olson KR, Dempsey D| title=Salicylate toxicity from ingestion and continued dermal absorption. | journal=Cal J Emerg Med | year= 2007 | volume= 8 | issue= 1 | pages= 23-5 | pmid=20440389 | doi= | pmc=2859737 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20440389  }}</ref>
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Metabolic acidosis]], [[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Blood test]]
! style="background: #F5F5F5; padding: 5px;" |[[Vomiting]], [[Tinnitus]], [[Confusion]], [[Hyperthermia]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
! colspan="2" rowspan="2" |[[Systemic]]
![[Pregnancy]]<ref name="pmid28805596">{{cite journal |vauthors=Lee SY, Chien DK, Huang CH, Shih SC, Lee WC, Chang WH |title=Dyspnea in pregnancy |journal=Taiwan J Obstet Gynecol |volume=56 |issue=4 |pages=432–436 |date=August 2017 |pmid=28805596 |doi=10.1016/j.tjog.2017.04.035 |url= |author=}}</ref>
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |↑[[WBC]], [[RBC]]
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |↓[[Tidal volume|Vt]], ↑[[Residual volume|RV]]
! style="background: #F5F5F5; padding: 5px;" |[[Human chorionic gonadotropin|βhCG]]
! style="background: #F5F5F5; padding: 5px;" |Missed period, Hyperemesis
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
![[Sepsis]]<ref name="pmid27216810">{{cite journal| author=Askim Å, Mehl A, Paulsen J, DeWan AT, Vestrheim DF, Åsvold BO et al.| title=Epidemiology and outcome of sepsis in adult patients with Streptococcus pneumoniae infection in a Norwegian county 1993-2011: an observational study. | journal=BMC Infect Dis | year= 2016 | volume= 16 | issue=  | pages= 223 | pmid=27216810 | doi=10.1186/s12879-016-1553-8 | pmc=4877975 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=27216810  }}</ref>
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |↑[[WBC]], [[neutrophilia]]
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[SIRS|SIRS criteria]]
! style="background: #F5F5F5; padding: 5px;" |[[Chills]], [[Confusion]]
|- style="background: #4479BA; color: #FFFFFF; text-align: center;"
! colspan="3" rowspan="3" |Organ system
! rowspan="3" |Diseases
! colspan="13" |Clinical manifestations
! colspan="5" rowspan="2" |Diagnosis
! rowspan="3" |Other features
|- style="background: #4479BA; color: #FFFFFF; text-align: center;"
! colspan="8" |Symptoms
! colspan="5" |Physical exam
|- style="background: #4479BA; color: #FFFFFF; text-align: center;"
!Loss of consciousness
!Agitation
!Weight loss
!Fever
!Chest pain
!Cough
!Orthopnea
!DOE
!Cyanosis
!Clubbing
!JVD
!Peripheral edema
!Auscultation
!CBC
!ABG
!Imaging
!Spirometry
!Gold standard
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
! rowspan="5" |Chronic Dyspnea
! rowspan="3" |[[Respiratory system]]
! rowspan="3" |[[Chest]] and [[Pleura]],
Lower [[airway]]
![[Bronchial asthma]]<ref name="pmid19858243" />
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |[[Wheeze]]
! style="background: #F5F5F5; padding: 5px;" |↑ [[Eosinophil]]
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]], [[Metabolic acidosis]]
! style="background: #F5F5F5; padding: 5px;" |[[Pulmonary]] hyperinflation,
 
[[Bronchial]] wall thickening
! style="background: #F5F5F5; padding: 5px;" |↓ [[FEV1]]/[[FVC]]
! style="background: #F5F5F5; padding: 5px;" |[[Spirometry]] before and after [[bronchodilator]]
! style="background: #F5F5F5; padding: 5px;" |Paroxysmal [[respiratory distress]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
![[COPD]]<ref name="pmid25177479" />
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |[[Wheeze|Expiratory wheeze]]
! style="background: #F5F5F5; padding: 5px;" |↑ [[RBC]]
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]], [[Metabolic acidosis]]
! style="background: #F5F5F5; padding: 5px;" |↑ Bronchovascular markings, [[Cardiomegaly]]
! style="background: #F5F5F5; padding: 5px;" |↓ [[FEV1]]/[[FVC]]
! style="background: #F5F5F5; padding: 5px;" |[[Physical examination|Physical exam]] and
[[Spirometry]]
! style="background: #F5F5F5; padding: 5px;" |[[Heavy smoking]] history
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
![[Emphysema]]<ref name="pmid18453358">{{cite journal| author=Sharafkhaneh A, Hanania NA, Kim V| title=Pathogenesis of emphysema: from the bench to the bedside. | journal=Proc Am Thorac Soc | year= 2008 | volume= 5 | issue= 4 | pages= 475-7 | pmid=18453358 | doi=10.1513/pats.200708-126ET | pmc=2645322 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18453358  }}</ref>
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |[[Wheeze|Expiratory wheeze]], Hyperinflation
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]], [[Metabolic acidosis]]
! style="background: #F5F5F5; padding: 5px;" |Flattening of [[diaphragm]], vertical [[heart]]
! style="background: #F5F5F5; padding: 5px;" |↓ [[FEV1]]/[[FVC]]
! style="background: #F5F5F5; padding: 5px;" |[[Physical examination|Physical exam]] and
[[Spirometry]]
! style="background: #F5F5F5; padding: 5px;" |[[Barrel chest]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
! colspan="2" |[[Toxic]]/[[Metabolic]]
![[Metabolic acidosis]]<ref name="pmid8350272">{{cite journal| author=Lane R, Adams L| title=Metabolic acidosis and breathlessness during exercise and hypercapnia in man. | journal=J Physiol | year= 1993 | volume= 461 | issue=  | pages= 47-61 | pmid=8350272 | doi= | pmc=1175244 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8350272  }}</ref>
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Metabolic acidosis]], [[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Arterial blood gas|ABG]]
! style="background: #F5F5F5; padding: 5px;" |[[Confusion]], [[Vomiting]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
! colspan="2" |[[Systemic]]
![[Anxiety]]<ref name="pmid15200799">{{cite journal |vauthors=Bailey PH |title=The dyspnea-anxiety-dyspnea cycle--COPD patients' stories of breathlessness: "It's scary /when you can't breathe" |journal=Qual Health Res |volume=14 |issue=6 |pages=760–78 |date=July 2004 |pmid=15200799 |doi=10.1177/1049732304265973 |url= |author=}}</ref>
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |+
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |+/-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |-
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Respiratory alkalosis]]
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |Normal
! style="background: #F5F5F5; padding: 5px;" |[[Psychological|Psychological interview]]
! style="background: #F5F5F5; padding: 5px;" |[[Sweating]], [[Palpitation]]
|- style="background: #DCDCDC; padding: 5px; text-align: center;" |
|}
 
 
==History and Symptoms==
*Symptoms of respiratory [[alkalosis]] depends upon duration of disease and underlying diseases. Symptoms of acute respiratory [[alkalosis]] are related to decrease [[blood]] [[carbon dioxide]] levels (PaCO2) that leads to reduced cerebral blood flow resulting from vasoconstriction of cerebral vessels. Most of the symptoms arise when PaCO2 falls below 30 mm Hg.
===History===
Patients with respiratory [[alkalosis]] may have a positive history of:
*[[Anxiety|Anxiety disorders]] or primary neurologic diseases
*[[Lung]] or [[liver]] diseases
*[[Intensive care unit|Critical illness]] with [[mechanical ventilation]]
 
===Common Symptoms===
Common symptoms of acute respiratory [[alkalosis]] include:
*[[Dizziness|Light-headedness]]
*[[Syncope]]
*[[Confusion]]
*[[Seizure]]
*Peripheral and circumoral [[paresthesia]] and [[cramp]]
*[[Chest pain]] and [[Dyspnea|shortness of breath]] are seen in patients hyperventilating due to [[pain]] or [[anxiety]]
*Chronic respiratory [[alkalosis]] is generally well tolerated without apparent clinical symptoms


==Symptoms==
* Symptoms of acute respiratory alkalosis are related to the decrease blood carbon dioxide levels (PaCO2) that leads to reduced cerebral blood flow resulting from vasoconstriction of cerebral vessels. Most of the symptoms arise when PaCO2 falls below 30 mm Hg and include:
** Light-headedness, syncope
** Confusion,
** Seizures,
** Peripheral and circumoral paresthesias, and cramps. 
** Chest pain and shortness of breath are seen in patients hyperventilating due to pain or anxiety. 
** Chronic respiratory alkalosis is generally well tolerated without apparent clinical symptoms 
* Signs include:  
* Signs include:  
** Tachypnea or hyperpnea
** [[Trousseau sign|Carpopedal spasm]] due to [[tetany]] as a result of decreased levels of ionized calcium in the blood (ionized calcium [[Calcium ion|[Ca++]]] are driven inside cells in exchange for hydrogen ion [[Hydrogen ion|[H+]]] as compensatory mechanism to correct [[pH]]) with no fall in total serum calcium level. [[Alkalosis]] also increases protein-bound fraction of calcium reducing free calcium.
** Carpopedal spasm due to tetany  as a result of decreased levels of ionized calcium in the blood (ionized calcium are driven inside cells in exchange for hydrogen ion [H+] as compensatory mechanism to correct pH) with no fall in total serum calcium level. Alkalosis also increases protein-bound fraction of calcium reducing free calcium.
 
** Respiratory patterns in respiratory alkalosis my be regular with increased rate and tidal volume OR Cheyne-Stokes type
==Physical Examination==
*Physical examination findings of patients with respiratory [[alkalosis]] is related to the underlying causes.
 
===Appearance of the Patient===
*Patients with acute respiratory [[alkalosis]] usually appear anxious in primary hyperventilation syndrome, OR are ill appearing in mechanically ventilation whereas are comfortable in chronic respiratory [[alkalosis]].
 
===Vital Signs===
 
*High-grade / low-grade [[fever]]
*[[Tachycardia]] may be present
*[[Tachypnea]] or hyperpnea is present with both increase in [[respiratory rate]] and tidal volume
*[[Cheyne-Stokes respiration|Cheyne-Stokes]] type of breathing may be seen in upper pontine lesion or [[Congestive heart failure|heart failure]]
*[[Hypotension|Low blood pressure]] in mechanically ventilated patients with respiratory [[alkalosis]]
 
===Skin===
*[[Cyanosis]] is present in [[Hypoxia (medical)|hypoxic]] patient
*[[Jaundice]] may be present in liver disease
 
===HEENT===
* HEENT examination of patients with respiratory [[alkalosis]] is usually normal.
===Neck===
* Neck examination of patients with respiratory [[alkalosis]] is usually normal
===Lungs===
*Lungs are dull to percussion in [[hemothorax]]/[[Resonant|hyperresonant]] in [[pneumothorax]]
*Fine/coarse [[crackles]] upon auscultation of the lung suggest [[interstitial lung disease]]/[[pneumonia]] as a cause of respiratory [[alkalosis]]
 
===Heart===
* Cardiovascular examination of patients with respiratory [[alkalosis]] is usually normal except in patients with [[Coronary heart disease|coronary artery disease]]
===Abdomen===
[[Hepatomegaly]] and right upper quadrant tenderness may be seen in [[cirrhosis]]
 
===Back===
* Back examination of patients with respiratory [[alkalosis]] is usually normal.
===Genitourinary===
* Genitourinary examination of patients with respiratory [[alkalosis]] is usually normal
 
===Neuromuscular===
* Focal neurologic signs and depressed level of consciousness is seen in respiratory alkalosis of neurologic cause
 
===Extremities===
* Extremities examination of patients with respiratory [[alkalosis]] show positive [[Trousseau sign]] in acute [[hypocapnia]] as a result of [[tetany]].
==Approach to acid-base disorders==
 
{{familytree/start |summary=Sample 1}}
{{familytree | | | | | | | | A01 |A01=Check pH on ABG}}
{{familytree | | | | |,|-|-|-|^|-|-|-|-|.| | | }}
{{familytree | | | B01 | | | | | | | |B02| | |B01=pH<7.35=Acidosis|B02=pH>7.45=Alkalosis}}
{{familytree | | | |!| | | | | | | | | |!| }}
{{familytree | | | C01 | | | | | | | | |!| |C01=Check PaCO2}}
{{familytree | |,|-|^|.| | | | | | | | |!| }}
{{familytree | D01 | | D02 | | | | | | D03 |D01=PaCO2 > 45mm Hg = Respiratory acidosis    Primary cause: hypoventilation|D02= PaCO2 Normal or < 35mm Hg = Metabolic acidosis|D03=Check PaCO2}}
{{familytree | | | | | | | | | | | |,|-|^|.| }}
{{familytree | | | | | | | | | | |E02| | E03 | |E02=PaCO2 > 45mm Hg = Metabolic alkalosis|E03=PaCO2 < 35mm Hg = Respiratory alkalosis    Primary cause: hyperventilation}}
{{familytree | | | | | | | | | | |!| | | | |!| }}
{{familytree | | | | | | | | | | F01 | | | F02 |F01=HCO3- > 29 eg. vomiting|F02=Check HCO3-}}
{{Familytree | | | | | | | | | | | | |,|-|-|^|-|-|.| | }}
{{Familytree | | | | | | | | | | | |C01 | | | | C02 |C01= Normal or slight decrease = Acute respiratory alkalosis eg. fever, panic attack| C02= Decreased < 24 = Chronic respiratory alkalosis eg. Anemia, CNS causes}}
{{familytree/end}}


==Laboratory Findings==
==Laboratory Findings==
*Arterial blood gas analysis(ABG):  
*Arterial blood gas analysis(ABG):  
**It is the diagnostic test of choice for respiratory alkalosis  
**It is the diagnostic test of choice for respiratory [[alkalosis]]
**primary respiratory alkalosis has pH> 7.45, PaCO2 <35mm Hg or 4.7kPa while PaO2 is normal(>80mm Hg or 10.7kPa)
**primary respiratory alkalosis has pH> 7.45, PaCO2 <35mm Hg or 4.7kPa while PaO2 is normal(>80mm Hg or 10.7kPa)
*Serum electrolytes: Decrease in [HCO3-],[Na+], [K+] and ionized [Ca++] are seen in acute hypocapnia due to intracellular shift whereas decreased [HCO3-] and hyperphosphatemia are seen in sustained hypocapnia.<ref name="pmid1405350">{{cite journal| author=Krapf R, Jaeger P, Hulter HN| title=Chronic respiratory alkalosis induces renal PTH-resistance, hyperphosphatemia and hypocalcemia in humans. | journal=Kidney Int | year= 1992 | volume= 42 | issue= 3 | pages= 727-34 | pmid=1405350 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1405350  }}</ref>
*Serum electrolytes: Decrease in [HCO3-],[Na+], [K+] and ionized [Ca++] are seen in acute hypocapnia due to intracellular shift whereas decreased [HCO3-] and hyperphosphatemia are seen in sustained hypocapnia.<ref name="pmid1405350">{{cite journal| author=Krapf R, Jaeger P, Hulter HN| title=Chronic respiratory alkalosis induces renal PTH-resistance, hyperphosphatemia and hypocalcemia in humans. | journal=Kidney Int | year= 1992 | volume= 42 | issue= 3 | pages= 727-34 | pmid=1405350 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1405350  }}</ref>
*Other laboratory test and imaging studies that may be useful in respiratory alkalosis to find out the causes includes:  
*Other laboratory test and imaging studies that may be useful in respiratory alkalosis to find out the causes includes:
**CBC: elevated WBC in sepsis  
**Urine pH and urinalysis
**Blood/sputum/urine C/S: for sepsis  
**CBC: elevated WBC in [[sepsis]]
**EKG and ECHO: for congestive heart failure  
**Blood/sputum/urine C/S: for [[sepsis]]
**EKG and ECHO: for [[congestive heart failure]]
**Drug screening test  
**Drug screening test  
**Thyroid function test: to rule out hyperthyroidism  
**Thyroid function test: to rule out [[hyperthyroidism]]
**Liver function test: abnormal in hepatic causes  
**Liver function test: abnormal in hepatic causes  
**pulmonary function test: to rule out chest infections
**pulmonary function test: to rule out chest infections
**V/Q scan: to rule out pulmonary embolism  
**V/Q scan: to rule out [[pulmonary embolism]]
**Chest X-ray: for chest infection  
**Chest X-ray: for chest infection  
**CT scan: for pulmonary embolism  
**CT scan: for [[pulmonary embolism]]
**MRI brain: to rule out CNS cause of hyperventilation  
**MRI brain: to rule out CNS cause of hyperventilation  


Line 119: Line 719:
*Respiratory alkalosis is not a life threatening disorder, so treatment is directed at the underlying causes of the disorder.
*Respiratory alkalosis is not a life threatening disorder, so treatment is directed at the underlying causes of the disorder.
**patients with hyperventilation disorder (eg. anxiety, conversion disorder) are benefited from rebreathing mask.
**patients with hyperventilation disorder (eg. anxiety, conversion disorder) are benefited from rebreathing mask.
**High altitude sickness is treated with acetazolamide 250mg 12 hourly, Dexamethasone 4mg 6 hourly, oxygen therapy and descent to lower altitude in severe cases.
**High altitude sickness is treated with [[acetazolamide]] 250mg 12 hourly, [[Dexamethasone]] 4mg 6 hourly, [[oxygen therapy]] and descent to lower altitude in severe cases.
**For critically ill patients on mechanical ventilation with respiratory alkalosis, tidal volume and respiratory rate needs to be decreased with adequate pain control.
**For [[Intensive care unit|critically ill]] patients on [[mechanical ventilation]] with respiratory alkalosis, [[Lung volumes|tidal volume]] and [[respiratory rate]] needs to be decreased with adequate pain control.
**Sedatives and antidepressants should not be used in cases of respiratory alkalosis.
**[[Sedative|Sedatives]] and [[antidepressants]] should not be used in cases of respiratory alkalosis.
   
   



Latest revision as of 19:33, 16 April 2018

Respiratory alkalosis
ICD-10 E87.3
ICD-9 276.3
DiseasesDB 406

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Madhu Sigdel M.B.B.S.[2] Priyamvada Singh, M.D. [3], Eiman Ghaffarpasand, M.D. [4]

Overview

Acid-base status of an organism is determined by the extracellular fluid (ECF) hydrogen ion concentration [H+] since pH is equal to minus log of [H+] i.e. pH = -log[H+]. Normal pH of human blood is 7.40 (7.35-7.45). Acidosis raises ECF [H+] thereby lowering pH whereas alkalosis lowers ECF [H+] thereby raising pH of the ECF. Respiratory alkalosis is an acid-base disorder, primarily a decrease in partial pressure of carbon dioxide in arterial blood means PaCo2 [normal PaCo2 is 40 mm Hg on average with range between 35-45mm Hg (4.7-6.0kPa)] with or without compensatory decrease in serum bicarbonate [HCO3-] (normal bicarbonate is 22-30mEq/L in arterial blood gas analysis) and pH being alkaline (normal pH of blood is 7.35-7.45).

Pathophysiology

Production of CO2 in body tissues by intracellular metabolic process (from oxidation of fat, carbohydrate and carbon skeleton of amino acids in normal metabolic process produces carbon dioxide and water) and elimination of CO2 through lungs are in equilibrium under normal physiology. CO2 in body tissues from normal metabolic process enters blood in the tissues because its local partial pressure in tissues is greater than the partial pressure in blood flowing through the tissues due to property of gases to diffuse from high pressure to low pressure. Flowing blood transports the CO2 to the lungs, where it diffuses into the alveoli and then to the atmosphere by pulmonary ventilation. The reversible combination of CO2 with water in the red blood cells under the influence of carbonic anhydrase enzyme forms carbonic acid (H2CO3) which dissociates into hydrogen and bicarbonate ions (H+ and HCO3−) ions. HCO3− diffuse from the red blood cells into the plasma, while chloride ions diffuse into the red blood cells to take their place (chloride shift). Hence, most of tissue CO2 is brought to lungs as plasma venous bicarbonate ions that accounts for about 70 percent of the CO2 transported from the tissues to the lungs. Remaining CO2 is transported as carbaminohemoglobin (23%) and as dissolved CO2 in fluids of blood(7%).

Respiratory alkalosis in almost all cases results from increased alveolar respiration (hyperventilation) leading to decrease in blood carbon dioxide concentration measured as PaCO2. This leads to decreased hydrogen ion [H+] and bicarbonate [HCO3-] concentrations. Decreased [H+] leads to increase in pH leading to alkalosis.

Compensation in respiratory alkalosis

compensation for respiratory alkalosis is mostly mediated through plasma buffers and proteins (eg. hemoglobin in RBC, plasma proteins) in acute stage and by kidneys in chronic compensatory stage.

Acute compensatory stage

Chronic compensatory stage

  • Renal mediated process where reduction in PaCO2 leads to decreased renal tubular H+ secretion. Within the renal tubular cells, CO2, under the influence of carbonic anhydrase enzyme, combines with H2O to form carbonic acid (H2CO3), which then dissociates into HCO3- and H+. Alkalosis inhibits carbonic anhydrase activity, resulting in reduced H+ secretion into the renal tubule. As a result, there is not enough H+ in the renal tubular fluid to react with all the filtered HCO3− from glomerular capillaries of the kidneys. Therefore, the HCO3− that cannot react with H+ is not reabsorbed and is excreted in the urine. This causes a decrease in urinary net acid excretion(mostly ammonium ions NH4+) and due to increased bicarbonate excretion, body's bicarbonate stores is reduced.
  • Starts after 24-36 hours and renal compensation for sustained hypocapnia is complete in 36-72 hours
  • For every PaCO2 decrease of 10 mm Hg, serum bicarbonate decreases by 5mEq/L
  • pH in chronic compensation is near normal

Classification

There are two types of respiratory alkalosis: chronic and acute.

Acute respiratory alkalosis

Chronic respiratory alkalosis

  • Lasting for longer than 24-48 hours
  • For every 10 mM drop in pCO2 in blood, there is a corresponding 5 mM of bicarbonate ion drop.
  • The drop of 5 mM of bicarbonate ion is a compensation effect which reduces the alkalosis effect of the drop in pCO2 in blood. This is termed metabolic compensation.

Risk Factors

Common Risk Factors

Less Common Risk Factors

Causes[2]

Tissue hypoxia (hypoxemia)

Stimulation of chest receptors

Stimulators of central respiratory drive

Systemic diseases

Special considerations

Differential Diagnosis

Abbreviations: ABG (arterial blood gas); ACE (angiotensin converting enzyme); BMI (body mass index); CBC (complete blood count); CSF (cerebrospinal fluid); CXR (chest X-ray); DOE (dyspnea on exercise); ECG (electrocardiogram); FEF (forced expiratory flow rate); FEV1 (forced expiratory volume); FVC (forced vital capacity); JVD (jugular vein distention); MCV (mean corpuscular volume); Plt (platelet); RV (residual volume); SIADH (syndrome of inappropriate antidiuretic hormone); TSH (thyroid stimulating hormone); Vt (tidal volume); WBC (white blood cell);


Organ system Diseases Clinical manifestations Diagnosis Other features
Symptoms Physical exam
Loss of consciousness Agitation Weight loss Fever Chest pain Cough Orthopnea DOE Cyanosis Clubbing JVD Peripheral edema Auscultation CBC ABG Imaging Spirometry Gold standard
Acute Dyspnea Respiratory system Chest and Pleura,

Lower airway

Asthma attack[3] - + - - +/- + - - + - - - Wheeze Eosinophil Respiratory alkalosis Normal FEV1, PEF Physical exam and

Spirometry

Chest pain
COPD exacerbation[4] - + - + + + + - + +/- +/- +/- Wheeze, Rhonchi, and Crackles WBC, ↑RBC Respiratory alkalosis Hyperexpansion FEV1/FVC Clinical assessment Acute exacerbations of chronic bronchitis (AECB)
Pneumonia[5] - - - + + + - - - - - - Wheeze, Rhonchi, and Crackles WBC, neutrophilia Respiratory alkalosis Lobar consolidation Normal Chest X-ray and CT Scan productive cough
Pneumothorax[6] - - - - + - - - - - +/- - Diminished breath sounds Normal O2, ↑CO2 Radiolucency without lung marking Vt CXR and Chest CT scan Tracheal deviation
Pulmonary embolism[7] - - - - + - - +/- - - - - Normal Normal Respiratory alkalosis Normal Normal Pulmonary CT angiography Pleuritic chest pain
Rib fractures (flail chest)[8] - + - - + - - - - - - - Normal Normal Respiratory alkalosis Fracture marks Normal Chest X-ray Pneumothorax
Cardiovascular system Acute myocardial ischemia[9] +/- + - +/- + - + + - - - - Normal Normal Respiratory alkalosis Normal Normal Cardiac troponin I Nausea and vomiting, Positive pertinent risk factors, such as hypertension, diabetes, and smoking
Acute heart failure[10] +/- + - - +/- + +/- + + - + + S3 Normal Respiratory alkalosis Cardiothoracic ratio Vt B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) Excessive sweating, high blood pressure
Tachyarrhythmia[9] +/- + - - +/- - - - - - - - High pulse rate Normal Respiratory alkalosis Normal Normal ECG Palpitation
Pulmonary edema[11] +/- + - + + + + + + + + + Basal crackle Normal Respiratory alkalosis Bat wing pattern, air bronchograms Vt, ↑RV Cardiac Catheterization Tachypnea
Central nervous system Encephalitis[12] + + - + - - - - - - - - Normal WBC, neutrophilia Respiratory alkalosis Normal Normal CSF PCR Confusion
Traumatic brain injury[13] + +/- - - - - - - - - - - Normal Normal Respiratory alkalosis Intracerebral hemorrhage Normal Brain CT scan Lucid interval
Toxic/Metabolic Salicylate poisoning[14] + - - - - - - - + - - - Normal Normal Metabolic acidosis, Respiratory alkalosis Normal Normal Blood test Vomiting, Tinnitus, Confusion, Hyperthermia
Systemic Pregnancy[15] - - - - +/- - - - - - - + Normal WBC, RBC Respiratory alkalosis Normal Vt, ↑RV βhCG Missed period, Hyperemesis
Sepsis[16] +/- - - + - - - - - - - - Normal WBC, neutrophilia Respiratory alkalosis Normal Normal SIRS criteria Chills, Confusion
Organ system Diseases Clinical manifestations Diagnosis Other features
Symptoms Physical exam
Loss of consciousness Agitation Weight loss Fever Chest pain Cough Orthopnea DOE Cyanosis Clubbing JVD Peripheral edema Auscultation CBC ABG Imaging Spirometry Gold standard
Chronic Dyspnea Respiratory system Chest and Pleura,

Lower airway

Bronchial asthma[3] - + +/- - +/- + - - + + - - Wheeze Eosinophil Respiratory alkalosis, Metabolic acidosis Pulmonary hyperinflation,

Bronchial wall thickening

FEV1/FVC Spirometry before and after bronchodilator Paroxysmal respiratory distress
COPD[4] - - +/- - - + + + + + + +/- Expiratory wheeze RBC Respiratory alkalosis, Metabolic acidosis ↑ Bronchovascular markings, Cardiomegaly FEV1/FVC Physical exam and

Spirometry

Heavy smoking history
Emphysema[17] - - - - - +/- - - + + - - Expiratory wheeze, Hyperinflation Normal Respiratory alkalosis, Metabolic acidosis Flattening of diaphragm, vertical heart FEV1/FVC Physical exam and

Spirometry

Barrel chest
Toxic/Metabolic Metabolic acidosis[18] - - + - - - - - - - - - Normal Normal Metabolic acidosis, Respiratory alkalosis Normal Normal ABG Confusion, Vomiting
Systemic Anxiety[19] + + + - +/- +/- - - - - - - Normal Normal Respiratory alkalosis Normal Normal Psychological interview Sweating, Palpitation


History and Symptoms

  • Symptoms of respiratory alkalosis depends upon duration of disease and underlying diseases. Symptoms of acute respiratory alkalosis are related to decrease blood carbon dioxide levels (PaCO2) that leads to reduced cerebral blood flow resulting from vasoconstriction of cerebral vessels. Most of the symptoms arise when PaCO2 falls below 30 mm Hg.

History

Patients with respiratory alkalosis may have a positive history of:

Common Symptoms

Common symptoms of acute respiratory alkalosis include:

  • Signs include:
    • Carpopedal spasm due to tetany as a result of decreased levels of ionized calcium in the blood (ionized calcium [Ca++] are driven inside cells in exchange for hydrogen ion [H+] as compensatory mechanism to correct pH) with no fall in total serum calcium level. Alkalosis also increases protein-bound fraction of calcium reducing free calcium.

Physical Examination

  • Physical examination findings of patients with respiratory alkalosis is related to the underlying causes.

Appearance of the Patient

  • Patients with acute respiratory alkalosis usually appear anxious in primary hyperventilation syndrome, OR are ill appearing in mechanically ventilation whereas are comfortable in chronic respiratory alkalosis.

Vital Signs

Skin

HEENT

  • HEENT examination of patients with respiratory alkalosis is usually normal.

Neck

  • Neck examination of patients with respiratory alkalosis is usually normal

Lungs

Heart

Abdomen

Hepatomegaly and right upper quadrant tenderness may be seen in cirrhosis

Back

  • Back examination of patients with respiratory alkalosis is usually normal.

Genitourinary

  • Genitourinary examination of patients with respiratory alkalosis is usually normal

Neuromuscular

  • Focal neurologic signs and depressed level of consciousness is seen in respiratory alkalosis of neurologic cause

Extremities

Approach to acid-base disorders

 
 
 
 
 
 
 
Check pH on ABG
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
pH<7.35=Acidosis
 
 
 
 
 
 
 
pH>7.45=Alkalosis
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Check PaCO2
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
PaCO2 > 45mm Hg = Respiratory acidosis Primary cause: hypoventilation
 
PaCO2 Normal or < 35mm Hg = Metabolic acidosis
 
 
 
 
 
Check PaCO2
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
PaCO2 > 45mm Hg = Metabolic alkalosis
 
PaCO2 < 35mm Hg = Respiratory alkalosis Primary cause: hyperventilation
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
HCO3- > 29 eg. vomiting
 
 
Check HCO3-
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Normal or slight decrease = Acute respiratory alkalosis eg. fever, panic attack
 
 
 
Decreased < 24 = Chronic respiratory alkalosis eg. Anemia, CNS causes

Laboratory Findings

  • Arterial blood gas analysis(ABG):
    • It is the diagnostic test of choice for respiratory alkalosis
    • primary respiratory alkalosis has pH> 7.45, PaCO2 <35mm Hg or 4.7kPa while PaO2 is normal(>80mm Hg or 10.7kPa)
  • Serum electrolytes: Decrease in [HCO3-],[Na+], [K+] and ionized [Ca++] are seen in acute hypocapnia due to intracellular shift whereas decreased [HCO3-] and hyperphosphatemia are seen in sustained hypocapnia.[20]
  • Other laboratory test and imaging studies that may be useful in respiratory alkalosis to find out the causes includes:
    • Urine pH and urinalysis
    • CBC: elevated WBC in sepsis
    • Blood/sputum/urine C/S: for sepsis
    • EKG and ECHO: for congestive heart failure
    • Drug screening test
    • Thyroid function test: to rule out hyperthyroidism
    • Liver function test: abnormal in hepatic causes
    • pulmonary function test: to rule out chest infections
    • V/Q scan: to rule out pulmonary embolism
    • Chest X-ray: for chest infection
    • CT scan: for pulmonary embolism
    • MRI brain: to rule out CNS cause of hyperventilation

Treatment

  • Respiratory alkalosis is not a life threatening disorder, so treatment is directed at the underlying causes of the disorder.


Related Chapters

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