Ischemia and Hypoxia

Ischemia is insufficient blood flow to provide adequate oxygenation. This, in turn, leads to tissue hypoxia (reduced oxygen) or anoxia (absence of oxygen). Ischemia always results in hypoxia; however, hypoxia can occur without ischemia if, for example, arterial hypoxia occurs.

The most common causes of ischemia are acute arterial thrombus formation, chronic narrowing (stenosis) of a supply artery that is often caused by atherosclerotic disease, and arterial vasospasm.   As blood flow is reduced to an organ, oxygen extraction increases.  When the tissue is unable to extract adequate oxygen, the partial pressure of oxygen within the tissue falls (hypoxia) leading to a reduction in mitochondrial respiration and oxidative metabolism.

RK Revised 04/06/2007