Study in three different types of cardiopulmonary bypass on arterial ketone body ratio: its prognostic implication and participation of body temperature

The aim of this study was to investigate the change of hepatic metabolic activity presented by the ketone body ratio (AKBR) during and after cardiopulmonary bypass (CPB) and to evaluate the prognostic value. AKBR were measured in 20 cases of coronary aortic bypass grafting using moderate hypothermic CPB (group M), ten cases of aortic arch surgery using deep hypothermia with selective cerebral perfusion (DHSCP) with an open technique (group D) and 15 cases of descending thoracic aortic replacement using partial CPB (group N). AKBR decreased significantly in all groups 5 min after CPB compared with the value before CPB. There was a significant difference in AKBR 1 h after CPB among the three groups and AKBR returned to the prebypass value in group N (group M, 0.32 +/- 0.16; group D, 0.14 +/- 0.04; group N, 0.48 +/- 0.14; P < 0.0001). AKBR rose significantly after the discontinuation of CPB compared with the value during CPB and returned to the prebypass value in groups M and D. The patients who underwent DHSCP with an open technique had a value of AKBR below 0.2, but liver function still recovered normally. The value of AKBR correlated with temperature significantly and a very low level of AKBR below 0.2 was observed during core cooling to 20 degrees C without negative prognostic implications. AKBR decreased 5 min after CPB in group N which suggested decreased hepatic perfusion at an early stage of partial CPB. The prognostic implication of AKBR during CPB is whether low level AKBR recovers or not.