ANAEMIC HYPOXIA is due to reduction of the oxygen carrying capacity of the blood as a result of a decrease in the total hemoglobin or an alteration of the hemoglobin constituents. May be due to a medical condition (anaemia - iron deficiency) or to carbon monoxide poisoning.

HYPOXIC HYPOXIA is a situation where the partial pressure of oxygen within the lungs is not sufficient to oxygenate the arterial blood and fulfil the metabolic demand. It can be caused by a reduced rate of breathing, a lower percetage of oxygen in the air, or, more commonly in aviation, by a decreasing total air pressure with corresponding reduction is oxygen partial pressure.

HISTOTOXIC HYPOXIA, also known as cytotoxic hypoxia - happens at the cell level. This means that the cell expecting and needing the oxygen is impaired and cannot use the oxygen to support metabolism. This may occur in the case of poisoning by toxic fumes or liquids during an accident. However, it is more commonly observed in aviation with passengers due to excessive intake of alcohol or drugs and self-medication.

STAGNANT HYPOXIA, also known as Ischemic hypoxia, is a condition where certain body parts or organs are not adequately supplied with blood. Even if the blood is sufficiently oxygenated. The main reason for the occurence of this type of hypoxia, in aviation, is positive acceleration along the vertical axis of the body. This makes the blood pool in the legs and restricts blood flow to the brain. Heart insufficiency may also cause stagnat hypoxia by reducing bloof perfusion throughout the body.