[Significance of arterial ketone body ratio as a parameter of oxygen metabolism in cardiac surgery].

Postoperative course after cardiac surgery is characterized by a progressive increased cellular oxygen demand and limited oxygen supply. It is mandatory to assess the adequacy of tissue oxygenation and to correct inadequate oxygenation rapidly in cardiac surgery. The present study was designed to evaluate the relationship between the arterial ketone body ratio (AKBR) and the status of oxygen demand and supply relationship in cardiac surgery. We measured oxygen consumption, oxygen delivery, oxygen extraction, mixed venous oxygen saturation, lactate, lactate/pyruvate (L/P) and AKBR in 43 patients undergoing open heart surgery at selected 10 periods before, during and after cardiopulmonary bypass (CPB). AKBR significantly decreased immediately after the beginning of CPB and returned to pre-CPB level more quickly than lactate and L/P did. AKBR at several periods a significant correlation with lactate and L/P at delayed periods. There was a significant correlation between AKBR and L/P during and after CPB. Furthermore, oxygen consumption, oxygen extraction, mixed venous oxygen saturation, and lactate were correlated with AKBR significantly. But there was no correlation between the parameter of oxygen metabolism and both lactate and L/P. In conclusion, it appears from these data that AKBR in cardiac surgery may be helpful as a rapid guide for estimating the degree of anaerobiosis.