TITLE: THE CRITICAL LEVEL OF INTRAOPERATIVE HEPATIC VENOUS HEMOGLOBIN OXYGEN SATURATION DEFINED BY PLASMA AGST CONCENTRATION DURING HEPATECTOMY

AUTHORS: Yoshifumi Kotake, MD, PhD¹, Midori Matsumoto, MD, PhD², Hiroshi Morisaki, MD, PhD³, Junzo Takeda, MD, PhD³
AFFILIATION: ¹Keio University, School of Medicine, Chofu, Japan; ²Tachikawa Kyosai Hospital, Tachikawa, Japan; ³Keio University, School of Medicine, Shinjuku, Japan.

INTRODUCTION: Precise assessment of liver perfusion is of great consequence for anesthetic management during hepatectomy. Recent development of hepatic venous hemoglobin oxygen saturation (ShvO2) monitoring enabled us to evaluate liver perfusion (1,2), however, the critical level of ShvO2 needs further consideration. The purpose of this study was to better delineate the threshold level of ShvO2 by measuring plasma alpha glutathione S-transferase (aGST) concentration, an early and sensitive marker of liver damage (3).
METHODS: With IRB approval and informed consent, 7 patients undergoing hepatectomy under inhalational anesthesia with continuous thoracic epidural block were studied. Anesthesia was maintained with nitrous oxide, sevoflurane. A fiberoptic thermodilution catheter (7.5Fr, Baxter) was placed in the hepatic vein of unresected lobe under fluoroscopic guidance. We defined a new parameter, AUC<50% as the area under the ShvO2<50% line of ShvO2 plot and used this as an indicator of hepatic hypoperfusion. Arterial blood samples were obtained for measurements of aGST every 3-hour interval for 24 hours and peak aGST concentration were compared with AUC<50%. The levels of conventional liver enzymes such as AST and ALT 24 hr postoperatively were also analyzed.
RESULTS: Four patients showed hvO2 desaturation (<50%) over 10 min. during the surgery. In these patients, the AUC<50% was significantly higher than those in other 3 patients (2610 ± 1275 vs. 11±20 min·%). Peak aGST in patients with low intraoperative ShvO2 was significantly higher than that of patients with high ShvO2 (307±30 vs. 83±38 µg/l, p<0.05). Pearson's correlation coefficient analysis revealed a significant correlation of AUC<50% with peak aGST (r=.84, p=.02). Postoperative AST and ALT concentration also correlated with AUC<50% (r=0.96 with both parameters, p<.01).
CONCLUSION: These preliminary data suggest that AUC<50% derived from ShvO2 monitoring can be a promising indicator during hepatectomy to predict subsequent liver injury.
REFERENCES:

(1) Anesthesiology 74:49-52,1991

(2) Anesthesiology 76:379-385,1992

(3) Br J Anaesth 77:404-407,1996.