Effects of extracorporeal circulation on blood ketone body ratio reflecting hepatic energy metabolism during cardiac operation.

To examine the effects of extracorporeal circulation using an artificial heart and lung machine on hepatic energy metabolism in patients with cardiac operation using hypothermia, the arterial blood ketone body ratio (AKBR) reflecting the hepatic mitochondrial redox state was determined in 12 patients who had undergone cardiac operation using extracorporeal circulation from March to August 1991. Changes in AKBR were compared with those before and after extracorporeal circulation. AKBR decreased significantly after the beginning of extracorporeal circulation (p < 0.001) and remained at a lower level throughout extracorporeal circulation. On termination of extracorporeal circulation, the initial level was immediately resumed. The extent of decrease in ketone body ratio at ten minutes before termination of extracorporeal circulation was correlated with short term postoperative hepatic insufficiency. The patients whose ratio decreased below 0.4 showed increased levels in glutamic-pyruvic transaminase at the end of the first and second week after operation. Changes in AKBR were significantly associated with those in blood pressure (r = 0.433; p < 0.005) and body temperature (r = 0.472; p < 0.005). It was concluded that blood pressure and body temperature influence the blood ketone body ratio during extracorporeal circulation.