[Pathophysiological aspects of the development of circulatory hypoxia in artificial circulation]

Metabolic status of 650 patients operated on under artificial circulation for various cardiac diseases was studied. Circulatory hypoxia was found to underlie all metabolic disorders in artificial circulation which manifest by loss of buffer bases and lactate accumulation. Development of circulatory hypoxia in artificial circulation is caused by inadequate oxygen supply to tissues due to initially present disorders of the peripheral bloodstream which augment during perfusion by circulation centralization and due to changes of blood rheology, particularly so in increase of hypothermia and prolongation of perfusion. Lactate concentration during artificial circulation is an objective criterion of tissue hypoxia which sufficiently well correlates with development of heart failure in the early postperfusion period. When correcting circulatory hypoxia during artificial circulation the anesthesiologist and perfusiologist should aim at changing the vascular tone towards an increase of the peripheral bloodflow. This is particularly important during prolonged hypothermic perfusions in patients with initially low reserve potential of the myocardium.