Arterial air embolism

Abstract

The incidence and outcome of systemic air embolism in 340 consecutive patients who underwent cardiac surgery under cardio-pulmonary bypass in this unit for congenital defects of the cardiac septa and diseases involving the aortic and mitral valves were studied. This occurred in 40 patients, 10 of whom died. The distribution of air embolism according to the types of operation undertaken was as follows 6 of 127 for atrial septal defect; 6 of 36 for ventricular septal defect; 7 of 42 for mitral valve replacement; 7 of 47 for aortic valve debride-ment; and 14 of 55 for aortic valve replacement The cause was considered to the systolic ejection of air into the aorta, which following cardiotomy, were trapped in the pulmonary veins, the left atrium, the ventricular trabeculae and the aortic root. Since the adoption of a more rigid debubbling routine, air embolism has not occurred. The incidence of pulmonary complications occurring in these patients after bypass was studied. Unilateral atelectasis, which occurred in 5 patients, resulted from retained bronchial secretions in all, and was cured by bronchoscopic aspiration. The cause of bilateral atelectases, occurring in 9 patients and fatal in 8 of these, appeared to be related to cardiopulmonary factors and not to air embolism. Acute air injection made into the pulmonary artery of a dog resulted in pulmonary hypertension and a grossly deficient pulmonary circulation, but changes were largely resolved within a week. Pulmonary air embolism may temporarily embarrass the right heart after the repair of a ventricular septal defect in a patient with an elevated pulmonary vascular resistance and diminished pulmonary vascular bed.