The role of hyperoxidation in changes of lipid peroxidation and tissue metabolism in patients undergoing surgery with artificial circulation

53 patients with various heart diseases subject to cardiopulmonary bypass surgery have been examined. To assess the state of tissue metabolism indexes of arterial and mixed venous blood oxygen balance, lactate concentration, the activity of energy-dependent lymphocyte enzymes and indexes of free-radical plasma processes have been studied. It has been shown that cardiopulmonary bypass in conditions of marked normobaric hyperoxidation (PaO2 more than 300 mm Hg) is accompanied by tissue metabolism intensification and disturbance. Inability of protective antioxidant mechanisms to react to the intensity of free-radical formation due probably both to surgical stress and cardiopulmonary bypass procedure performed in hypothermia leads to negative hyperoxidation effect on metabolism even in conditions of adequate perfusion. A relatively high dependence of the frequency of myocardial depression on the degree of hyperoxidation suggests that myocardial reperfusion by blood with high PaO2 upon anoxic arrest is advisable in hypothermic cardiopulmonary bypass with attenuated activity of the antioxidant systems protecting cells from oxygen free radicals.