[Cardiopulmonary adaptation to acute hypoxia (author's transl)]

The most important adaptive mechanism to acute hypoxia is alveolar hyperventilation which improves the oxygen uptake in the lung. The delivery of oxygen to the particular organs is regulated according to their vital function. An essential adaptive mechanism can not be observed above an inspiratory O2 partial pressure of 100 mm mercury, corresponding to an altitude of about 3000 m in normals. In contrast, in patients with cardio-pulmonary disturbances adaptive mechanisms take place at far lower altitudes. Especially in patients with arterial hypoxemia, pulmonary hypertension and occlusive vascular disease moderate hypoxia may lead to decompensation of an a priori unstable equilibirum.