Stagnant hypoxia leads to increased oxygen extraction by tissues due to the prolonged presence of blood, potentially resulting in cell death and impaired tissue function if persistent, especially in critical tissues like the brain or heart.
When blood flow to a tissue is reduced due to vessel narrowing, a condition called ischemia occurs, and as a result, the affected tissue experiences hypoxia, which is a decreased supply of oxygen. This stagnant hypoxia means the blood remains in the tissues for an extended period, allowing tissues to extract more oxygen from the blood.
Over time, if hypoxia persists, especially in vital tissues like the brain or cardiac muscle, it can lead to cell death and significant impairment of function. Increased concentrations of carbon dioxide in the blood, resulting from reduced oxygen levels, can decrease the pH and reduce the affinity of hemoglobin for oxygen, prompting more oxygen to be released to the tissues. However, when the oxygen demand is high and the supply is low, it can lead to symptoms of oxygen deprivation and potentially serious health consequences.