Peripheral cyanosis may be normal in neonates and may also occur in which situation?

• A. Decreased Cardiac Output
• B. Normal PaO2
• C. Polycythemia
• D. High Blood Pressure

Answer: (A)

Peripheral cyanosis happens when deoxygenated hemoglobin in the skin capillaries increases. In newborns, some peripheral cyanosis can be normal due to immature circulation and variable peripheral perfusion. But when cardiac output is decreased, forward blood flow to tissues drops, so tissues extract more oxygen and the venous blood in the skin becomes more deoxygenated. This produces a blue discoloration in the extremities even if the arterial oxygen level (PaO2) is normal. That’s why decreased cardiac output best explains peripheral cyanosis in this context. The other options don’t fit as well: normal PaO2 argues against systemic hypoxemia; polycythemia and high blood pressure don’t cause the peripheral deoxygenation pattern in the same direct way as reduced perfusion does.