Biliary indocyanine green excretion as a predictor of hepatic adenosine triphosphate levels in patients with obstructive jaundice

Abstract

Background: Correlation of the hepatic adenosine triphosphate (ATP) level with indocyanine green (ICG) excretion into bile was examined in patients with obstructive jaundice after the relief of hyperbilirubinemia by preoperative percutaneous transhepatic biliary drainage (PTBD). Methods: Patients with complete bile duct obstruction, the mean serum total bilirubin concentration being 13.6 ± 8.5 (SD) mg/dL, underwent PTBD prior to surgery. Within a few days before surgery when the mean serum total bilirubin level decreased to 1.2 mg/dL, ICG (0.5 mg/kg) was intravenously injected, and the whole bile was collected at 1-hour intervals for 5 hours. The ICG concentration in bile, bile flow rate, amount of ICG excreted in bile, and biliary ICG excretion rate as percentage of the injected dose were determined. At the time of surgery, a small liver tissue sample was obtained immediately after laparotomy without any ischemic procedures, and ATP concentrations were determined. Results of hepatic ATP levels were correlated with laboratory and clinical determinations. Results: The bile flow rate was essentially constant during the 5-hour period, the mean value being 21 mL/hour. The ICG concentrations in bile gradually increased, reached the maximal level in 3 hour, and declined thereafter. The biliary ICG excretion rate for 5 hours was 40% ± 18% of its injected dose. The biliary ICG excretion rate and amount of ICG excreted in bile for 5 hours significantly ( P <0.05) correlated with the hepatic ATP level. The decline index of serum bilirubin during PTBD was also correlated with the hepatic ATP level. The serum ICG retention rate, bile flow rate, maximal ICG concentration in bile, and other liver function tests including serum albumin and cholinesterase levels did not correlate with the hepatic ATP level. Conclusions: Both the amount of and excretion rate of ICG in bile reflect the hepatic ATP level. Determination of biliary ICG excretion contributes to precise evaluation of hepatic energy status before surgery in patients with obstructive jaundice.