Central cyanosis detection depends on which factor?

• A. Blood pH
• B. Total Desaturated Hemoglobin
• C. Glucose Level
• D. Heart Rate

Answer: (B)

Central cyanosis appears when enough deoxygenated hemoglobin is present in the systemic arterial blood. The visible blue color depends on the total amount of desaturated hemoglobin, with a threshold around 5 g/dL of desaturated Hb needed to produce cyanosis. This is why the key factor is how much hemoglobin is in the deoxygenated state, not the pH, glucose level, or heart rate. Peripheral cyanosis, by contrast, reflects slowed blood flow to the extremities rather than a global decrease in oxygenation.