Cyanosis pathophysiology On the Web
American Roentgen Ray Society Images of Cyanosis pathophysiology
Cyanosis is a bluish or purplish discoloration of skin and mucous membranes. Two mechanisms are involved in the development of cyanosis, systemic arterial oxygen desaturation and increased oxygen absorption by tissues. Cyanosis is evident when arterial oxygen desaturation falls below 85% or the concentration of deoxygenated hemoglobin (Hb) exceeds 5 gm/dl. Several factors can affect the appearance of cyanosis which include: skin pigmentation, Hemoglobin (Hb) levels, oxygen affinity to the hemoglobin (Hb).
- Cyanosis is a bluish or purplish discoloration of the skin and mucous membranes.
- Appearance of cyanosis depends on the absolute amount of deoxygenated hemoglobin(Hb) present in the blood rather than the ratio of reduced hemoglobin (Hb) to oxygenated hemoglobin (Hb).
- Arterial hemoglobin desaturation can be caused by following mechanisms :
- According to Lundsgaard and Van Slyke (1923), as well as subsequent investigators, cyanosis is evident when the subpapillary capillaries contain from 4 to 6 gm/dl of deoxygenated hemoglobin and oxygenation of hemoglobin or oxygen saturation falls below 85% (normal ABG PaO2 85-100%).
- Cyanosis occurs due to following mechanisms:
- Systemic arterial oxygen desaturation.
- Reduced arterial oxygenation can result if the amount of oxygen in the alveoli is lowered or if the gradient between the alveolar oxygen and the arterial oxygen is elevated.
- Increased oxygen extraction by the tissues
- Sluggish movement of blood through the capillary circulation is responsible for increased oxygen extraction by the tissues.
- Systemic arterial oxygen desaturation.
- Central cyanosis:
- Central cyanosis is caused by reduced arterial oxygen saturation or the presence of abnormal hemoglobin derivatives (methemoglobin or sulfhemoglobin).
- Central cyanosis is evident when the systemic arterial deoxygenated hemoglobin concentration in the blood exceeds 5 g/dL (oxygen saturation ≤85 percent).
- The increased amount of deoxygenated hemoglobin is the result of either increased amount of venous admixture or reduced capillary arterial oxygen tension.
- Peripheral cyanosis:
- In peripheral cyanosis, systemic arterial oxygen saturation is normal.
- Increased oxygen extraction by tissues causes wide systemic arteriovenous oxygen difference and increased deoxygenated blood on the venous side of the capillary beds.
- The increased oxygen extraction by tissues results from the sluggish movement of blood through the capillary circulation.
- Causes for reduced blood flow through capillary circulation include:
- Factors can affect the development of cyanosis:
Genetics, Associated Conditions, Gross Pathology, Microscopic Pathology
For detailed information on the genetics, associated conditions, gross and microscopic pathological features associated with conditions causing cyanosis, click the links below.
- Tetralogy of Fallot
- Tricuspid atresia
- Ebstein's anomaly
- Tricuspid stenosis
- Transposition of great arteries (TGA)
- Pulmonary stenosis
- Truncus arteriosus
- Coarctation of aorta
- Aortic stenosis
- Eisenmenger's syndrome
- HLHS (Spectrum of hypoplastic left heart syndrome)
- Left-sided heart failure
- Acute chest syndrome
- Foreign body aspiration
- Carbon monoxide poisoning
- Hydrogen cyanide poisoning
- Bacterial tracheitis
- Respiratory distress syndrome (Hyaline membrane disease)
- Pleural effusion
- Cystic fibrosis
- Bronchopulmonary dysplasia
- Alveolar capillary dysplasia
- Pulmonary embolism
- Pulmonary hypertension
- High Altitude
- Intracranial hemorrhage
- Choanal atresia
- Micrognathia or retrognathia
- Congenital diaphragmatic hernia
- Myasthenia gravis
- Apnea of prematurity
- Obstructive sleep apnea
- Pulmonary edema
- Pulmonary hemorrhage
- Pulmonary arteriovenous malformation
- Methemoglobinemia (congenital or acquired)
- Polycythemia vera
- Disseminated intravascular coagulation
- Amniotic fluid embolism
- Cold exposure
- Raynaud's phenomenon
- Raynaud's disease
- Peripheral vascular disease
- Buergers disease
- Deep vein thrombosis
- Superior vena cava syndrome
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- Ananthakrishna R, Moorthy N, Rao DP, Nanjappa MC (2015). "An adult with central cyanosis and differential pulmonary vascularity". Ann Pediatr Cardiol. 8 (3): 253–4. doi:10.4103/0974-2069.150701. PMC 4608209. PMID 26556978.
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- Bailliard F, Anderson RH (January 2009). "Tetralogy of Fallot". Orphanet J Rare Dis. 4: 2. doi:10.1186/1750-1172-4-2. PMC 2651859. PMID 19144126.
- Martins P, Castela E (October 2008). "Transposition of the great arteries". Orphanet J Rare Dis. 3: 27. doi:10.1186/1750-1172-3-27. PMC 2577629. PMID 18851735.
- Jain A, Patel A, Hoppe IC (2016). "Benzocaine-Induced Cyanosis". Eplasty. 16: ic18. PMC 4879862. PMID 27257469.
- Baranoski G, Van Leeuwen SR, Chen TF (July 2017). "On the detection of peripheral cyanosis in individuals with distinct levels of cutaneous pigmentation". Conf Proc IEEE Eng Med Biol Soc. 2017: 4260–4264. doi:10.1109/EMBC.2017.8037797. PMID 29060838. Vancouver style error: initials (help)
- Das S, Maiti A (November 2013). "Acrocyanosis: an overview". Indian J Dermatol. 58 (6): 417–20. doi:10.4103/0019-5154.119946. PMC 3827510. PMID 24249890.