Effects of free oxygen radicals on impaired lung oxygenating function at aortocoronary bypass surgery

: Fifty five patients with coronary heart disease were examined. Of them 10 patients underwent multiple aortocoronary bypass surgery using intrathoracic or radial arteries under natural circulation, 45 had the same surgery under extracorporeal circulation (ECC). In the patients operated on without ECC, increases in active oxygen forms were rather moderate and practically always occurred with enhancement of antioxidative protective enzymes, the oxygen balance of arterial blood was in the normal range during and after surgery. The ECC patients displayed a considerable creatinine phosphokinase (CPK) with a lower antioxidative protection coefficient particularly when ECC was changed to natural circulation and when the lung was involved in circulation. In the postoperative period, the oxygenation index decreased from 1.7 to 1.3 in virtually all patients, the functional shunt rising from 15 to 30%. In 55% of the patients, varying arterial hypoxemia preserved in the early postoperative period. The damaging factors of ECC (hyperoxia, reperfusion syndrome, etc.) that impair the permeability of lung membranes have been shown to contribute to the activation of CPK, which causes early postoperative' arterial hypoxemia in patients operated on for coronary heart diseases.