Effect of closed minimized cardiopulmonary bypass on cerebral tissue oxygenation and microembolization

Abstract

Coronary artery bypass grafting with cardiopulmonary bypass carries a risk for neurologic complications because of cerebral hypoperfusion and microembolization. The basic goals of a novel closed minimized extracorporeal circulation are to prevent excessive hemodilution and to avoid blood-air interface. The aim of this prospective randomized study was to determine the effect of using the minimized extracorporeal circulation system compared with open conventional extracorporeal circulation on cerebral tissue oxygenation and microembolization. Forty patients undergoing coronary artery bypass grafting (20 in each group) were continuously monitored for changes in cerebral oxygenated hemoglobin and tissue oxygenation index by using near-infrared spectroscopy. Total microembolic count and gaseous embolic count in both median cerebral arteries were monitored with multifrequency transcranial Doppler instrumentation. In the conventional extracorporeal circulation group there was a highly significant reduction in both cerebral oxygenated hemoglobin and tissue oxygenation index from the start to the end of cardiopulmonary bypass (P < .01). The rate of decrease in cerebral oxygenated hemoglobin after aortic cannulation was faster in the conventional extracorporeal circulation group (F test = 9.03, P < .001). No significant changes with respect to cerebral oxygenated hemoglobin or tissue oxygenation index occurred in the minimized extracorporeal circulation group, except at the beginning of rewarming (P < .01). Total embolic count, as well as gaseous embolic count, in the left and right median cerebral arteries was significantly lower in the minimized extracorporeal circulation group (all P < .05). Postoperative bleeding was greater (P < .05) and the transfusion rate was higher (P < .05) in the conventional extracorporeal circulation group. Use of closed minimized cardiopulmonary bypass compared with conventional open cardiopulmonary bypass preserves cerebral tissue oxygenation and reduces cerebral microembolization.