Which term is defined as bluish discoloration due to hypoxia?

• A. Hypercarbia
• B. Oxygen Therapy
• C. Cyanosis
• D. Hypoxemia

Answer: (C)

Bluish discoloration of the skin and mucous membranes occurs when there is not enough oxygen in the blood, causing more hemoglobin to be in the deoxygenated form. This visible sign is cyanosis. It appears when arterial oxygen saturation falls or when there is increased deoxyhemoglobin in the capillaries, and is most noticeable around the lips, tongue, and nail beds. Central cyanosis reflects systemic hypoxemia, while peripheral cyanosis can result from reduced blood flow rather than truly low oxygen content. The other terms describe either a treatment (oxygen therapy) or a condition or gas level (hypoxemia, hypercarbia) rather than the bluish discoloration itself.