Stagnant hypoxia is caused by

• A. Blood-circulation is Inadequate.
• B. Low oxygen content in inspired air.
• C. Blood viscosity increases, causing reduced flow.
• D. Inadequate oxygen transport due to anemia.

Answer: (A)

Stagnant hypoxia occurs when the lungs and blood have adequate oxygen, but the circulatory system isn’t delivering it efficiently to the tissues. Oxygen delivery depends on cardiac output and blood flow; if circulation is inadequate—due to things like venous pooling, shock, heart failure, or high-G forces—the tissues don’t receive enough oxygen even though arterial oxygen content is normal. This is why the core factor is insufficient blood circulation.

For context, the other scenarios describe different routes to hypoxia: low inspired oxygen reduces the amount of oxygen entering the lungs, causing hypoxic hypoxia; anemia reduces the blood’s oxygen-carrying capacity, causing hypemic hypoxia; increased blood viscosity can slow flow but isn’t the defining mechanism of stagnant hypoxia, though it can contribute by hindering circulation.