What is the difference between hypoxic and hypemic hypoxia?

The distinction between hypoxic and hypemic hypoxia is fundamentally about the source of the deficiency in oxygen reaching the tissues.

Hypoxic hypoxia occurs when there is insufficient oxygen available in the environment, such as at high altitudes or in situations where the atmospheric pressure is low. This type of hypoxia is characterized by reduced partial pressure of oxygen in the air, leading to decreased oxygen availability for the lungs to absorb and transport to the bloodstream.

On the other hand, hypemic hypoxia arises from issues related to hemoglobin, specifically when there is a deficiency in the amount of hemoglobin available or its ability to carry oxygen. This can be due to conditions like anemia, carbon monoxide poisoning, or other factors that impair hemoglobin's function. As a result, even if the oxygen levels in the environment are normal, the oxygen-carrying capacity of the blood is compromised.

Understanding these mechanisms is crucial for pilots and aviation medical personnel, as they have implications for flight safety and performance under various environmental conditions.