Metabolic Measurements in the Human Heart-Lung Preparation During Hypothermic Cardioplegia

Summary

Forty-one patients undergoing coronary artery surgery of 3 grafts or more, with hypothermic cardioplegia, were randomly selected and divided into 3 groups. A known volume of hypothermic (4 ° C) cardioplegic solution (200 - 1000 ml) was infused into the ascending aorta during cardiopulmonary bypass. The pump blood was kept at 30 ° C. Five minutes after completion of infusion, the solution was siphoned off from the ascending aorta as well as an isolated right atrial siphon. Group I consisted of 17 patients in whom simultaneous sampling was drawn from the pump and aortic siphon drainage; group II consisted of 12 patients in whom simultaneous sampling was drawn from the pump, aorta, and right atrium; group III consisted of 10 patients who had sequential sampling from the pump, aorta, and right atrium after completion of each distal anastomosis. In this group, the pulmonary artery was also cross-clamped through the transverse sinus with the aorta. The samples were analyzed for routine blood count, biochemistry, and blood gas determinations. Dilution factors were calculated to compare results of the various samples. Calculations were also done to determine the bronchial flow, oxygen consumption of the heart, and the oxygen consumption of the lung. Bronchial flow was found to be 15 ml/min ± 6 ml/min. The oxygen consumption of the heart was 0.76 ± 0.7 ml/100 ml coronary flow/min. The oxygen consumption of the lung was found to be 0.31 ± 0.12 ml/100 ml bronchial flow/min. A method analyzing the metabolism of the heart and lung during cardiopulmonary bypass has been developed. With minor technical adjustments, it is adaptable to all techniques of hypothermic cardioplegia.

Key words

Hypothermic cardioplegic arrest - Oxygen consumption of heart and lung - Bronchial blood flow