Cyanosis
Basics
Description
Abnormal bluish discoloration of the skin or mucous membranesDescription
- Caused by abnormal elevations of deoxygenated hemoglobin or hemoglobin derivatives in the capillaries:
- Deoxygenated hemoglobin >5 g/dL
- Methemoglobin >1.5 g/dL
- Sulfhemoglobin >0.5 g/dL
- The absolute amount of deoxygenated hemoglobin is the pigment that creates the bluish tint:
- The amount of oxyhemoglobin does not affect the blood's color
- Cyanosis is more common in patients with polycythemia and less common in patients with anemia
- Cyanosis varies based on skin thickness or pigment
- Accumulation of deoxygenated hemoglobin may be systemic producing central cyanosis or localized producing peripheral cyanosis
- Central cyanosis:
- Hypoxemia
- Anatomic right to left shunts
- Abnormal hemoglobin derivatives
- Peripheral cyanosis:
- Tissue extracts more than normal amounts of O2 from the blood
- Hypoperfusion
- Vasoconstriction to cold air or water
- Arterial insufficiency
- Venous insufficiency
- Acrocyanosis: Painless, symmetrical, cyanosis in distal parts of body, the pathophysiologic cause of which is not known
- Central cyanosis:
Etiology
Central cyanosis:Etiology
- Upper airway obstructive causes
- Impaired pulmonary function:
- Hypoventilation:
- Pneumonia
- Chronic obstructive pulmonary disease
- Pulmonary edema
- Chest wall trauma limiting pulmonary exchange
- Ventilation/perfusion mismatch:
- Asthma
- Pulmonary embolus
- Diffusion problems:
- Interstitial lung disease
- Anatomic shunts
- Pulmonary arteriovenous fistula:
- Hereditary hemorrhagic telangiectasia
- High-altitude related, with decreased atmospheric pressure at 16,000 ft
- Decreased inspired oxygen house fire/poison gas
- Hypoventilation:
- Cardiac abnormalities with right to left shunt:
- Eisenmenger syndrome:
- Pulmonary hypertension
- Longstanding intracardiac shunt (VSD, patent ductus arteriosus, ASD)
- Reversal of flow through detected when pulmonary artery pressure exceeds threshold
- Eisenmenger syndrome:
- Abnormal hemoglobin:
- Low-oxygen affinity hemoglobin mutants:
- Hb Kansas
- Hb Beth Israel
- Hb St. Mande
- Congenital methemoglobinemia:
- Cytochrome b5 reductase deficiency
- Hemoglobin M disease
- Acquired methemoglobinemia:
- Aniline dyes
- Chloroquine, primaquine
- Dapsone
- Local anesthetic agents such as lidocaine
- High doses of methylene blue
- Naphthalene
- Nitrites, nitroglycerine
- Sulfonamides
- Fava beans
- Sulfhemoglobin:
- Generally benign
- Irreversible alteration of hemoglobin
- Caused by many medications
- Dimethyl sulfoxide
- Paint
- Phenacetin
- Phenazopyridine
- Phenylenediamine
- Phenylhydroxylamine
- Sulfanilamide
- Sulfapyridine
- Sulfathiazole
- Sulfur compounds
- Low-oxygen affinity hemoglobin mutants:
- Shock
- Exposure to cold
- Arterial insufficiency
- Venous insufficiency
- Raynaud phenomenon
- Acrocyanosis
Pediatric Considerations
- Cardiac:
- Cyanotic congenital defects:
- Tetralogy of Fallot
- Transposition of great vessels
- Truncus arteriosus
- Pulmonary and tricuspid atresia
- Ebstein anomaly
- Pseudocoarctation
- Patent ductus arteriosus
- Total anomalous pulmonary venous return
- Cyanotic congenital defects:
- Pulmonary stenosis:
- Any right-to-left shunting
- Respiratory:
- Upper airway disorders/obstruction:
- Croup
- Bacterial tracheitis
- Epiglottitis
- Retropharyngeal abscess
- Foreign body
- Lower airway disorders:
- Asthma
- Bronchiolitis
- Pneumonia
- Cystic fibrosis
- Pulmonary edema/CHF
- Pulmonary embolism
- Upper airway disorders/obstruction:
- Neurologic:
- Breath holding
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Citation
Schaider, Jeffrey J., et al., editors. "Cyanosis." 5-Minute Emergency Consult, 6th ed., Lippincott Williams & Wilkins, 2020. Emergency Central, emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307432/all/Cyanosis.
Cyanosis. In: Schaider JJJ, Barkin RMR, Hayden SRS, et al, eds. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307432/all/Cyanosis. Accessed December 11, 2024.
Cyanosis. (2020). In Schaider, J. J., Barkin, R. M., Hayden, S. R., Wolfe, R. E., Barkin, A. Z., Shayne, P., & Rosen, P. (Eds.), 5-Minute Emergency Consult (6th ed.). Lippincott Williams & Wilkins. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307432/all/Cyanosis
Cyanosis [Internet]. In: Schaider JJJ, Barkin RMR, Hayden SRS, Wolfe RER, Barkin AZA, Shayne PP, Rosen PP, editors. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. [cited 2024 December 11]. Available from: https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307432/all/Cyanosis.
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