Reduced arterial ketone body ratio during laparotomy: an evaluation of operative stress through the changes in hepatic mitochondrial redox potential.

The present article discusses the evaluation of surgical stress on the basis of the hepatic functional capacity of each patient. The changes in arterial blood ketone body ratio (KBR; acetoacetate/beta-hydroxybutyrate), which reflects hepatic mitochondrial redox potential, following intraoperative procedures were investigated in 60 laparotomy cases, including 30 cases with partial hepatectomy. The time course of changes in KBR was obtained by serial measurement during operation. The total area below the KBR level of 0.7 was defined as the hepatic stress score (HSS). HSS was significantly greater in the cases with hepatectomy (43.5 +/- 9.1; mean +/- SE) than in others (16.5 +/- 4.2; p less than 0.01). HSS in 13 patients accompanied by postoperative complications (60.4 +/- 17.7) was also significantly greater than that in the patients with uneventful postoperative courses (22.1 +/- 4.3; p less than 0.05). The former was also accompanied by significantly larger postoperative catabolic response preceding the clinical onset of complications (p less than 0.001). In the cases with uneventful postoperative courses, analysis of variance revealed that nitrogen balance and catabolic index in the first postoperative week were dependent on HSS negatively and positively, respectively (p less than 0.005), indicating a causative relationship between the suppression of hepatic energy metabolism during operation and the enhanced postoperative catabolic response. These results suggest that total surgical stress in major laparotomy can be quantitated and evaluated through the magnitude of decrease in hepatic mitochondrial redox potential, and that this evaluation may provide valuable information for intraoperative and postoperative patient care.