effects of hypothermic versus normothermic cardiopulmonary bypass on hepatic blood flow

ABSTRACT

To explore Trans-esophageal Echo [TEE] as a monitoring device for hepatic blood flow during cardiac1 surgery and to correlate between the hepatic venous blood flow measurements and the liver function tests during normothermic and hypothermic cardiopulmonary bypass. Forty patients scheduled for cardiac surgery were randomly divided into 2 groups group 1 [Gl] undergoing normothermic cardiopulmonary bypass [CPB] and group 2 [G2] undergoing hypothermic CPB. Serum AST, ALT, billirubin and hyalurinic acid levels were measured before, during and 6 hours after the bypass. During these same phases, TEE was used to measure both cardiac index [Cl] and middle hepatic vein blood flow. During CPB there were no significant differences in demographic data, AST, ALT or billirubin levels between the 2 groups. There was, however, a significant increase [P<0.001], in both groups, in serum hyalurinic acid levels during CBP in relation to the baseline and in Cl 6 hours after bypass in relation to pre and intra bypass phases. The middle hepatic venous blood flow was significantly higher amongst Gl patients six hours following the procedure in relation to the pre and intra bypass phases, whereas G2 patients showed a significant decrease in middle hepatic venous flow during the bypass followed by a significant increase 6 hours after the procedure in relation to the baseline. Hepatic venous blood flow is reduced significantly more during hypothermic bypass than during normothermic bypass. This may cause disturbances in sinusoidal endothelial cell [SEC] function. However, this change may be well tolerated by the healthy liver. Multiplan TEE may be used to monitor hepatic blood flow during CPB