Hypoxia - from extreme altitudes to ICU

Cellular hypoxia is a fundamental finding not only in high-altitude mountaineers but also in critically ill patients in whom it may occur either as a cause or as a result of various diseases. In recent years, it has been suggested that the same cellular mechanisms that are advantageous at high altitudes may also be so in cases of hypoxaemia of the critically ill. Increasing evidence suggests that oxygen consumption rather than oxygen delivery is modified at high altitudes and in critical illness in order to maintain adequate tissue oxygenation. A better understanding of the underlying microvascular and cellular processes may help to improve the clinical management of hypoxaemia. The present review will summarise the fundamental mechanisms of high altitude physiology and pathology and outline how knowledge gained from high altitude studies may be translated into the clinical management of hypoxic patients in general and during critical illness.