BCSE Practice Exam 2025 – Complete Study Resource

The physiological condition characterized by an increased arteriovenous oxygen difference (a-v)O2 greater than 50 is associated with stagnant hypoxia. In this scenario, the body experiences a reduced delivery of oxygen to tissues despite normal or even elevated oxygen levels in the blood.

Stagnant hypoxia results from inadequate blood flow, which could be due to conditions such as shock or cardiac failure, affecting the ability of tissues to receive sufficient oxygen. The body compensates for this reduced oxygen delivery by extracting a larger portion of the oxygen available in the blood, leading to an elevated (a-v)O2 difference as tissues pull more oxygen from the blood to meet their metabolic needs.

On the other hand, histotoxic hypoxia occurs when cells are unable to utilize oxygen effectively due to the presence of toxic substances (like cyanide), rather than issues with blood flow. Hypoxic hypoxia is linked to low levels of oxygen availability in the arterial blood, often due to high altitude or respiratory issues, while hypoxemic respiratory failure generally refers to conditions where there is inadequate oxygen exchange in the lungs, which may not lead to a significantly increased (a-v)O2.