Predetermining postoperative hepatic function for hepatectomies

To perform major resections safely in liver cancer operations, we have developed a reliable preoperative method to estimate postoperative liver function. We first conducted a series of studies using dogs to determine the various correlations between the volume of the remaining liver and postresectional hepatic function. We calculated Indocyaningreen (ICG) plasma disappearance and retention rates 15 minutes after intravenous injection of ICG at 0.5 mg/kg and found a 1:1 ratio, thus: ICG(K) postop. = ICG(K) preop. x functional remaining rate. This was applicable in our study of dogs with normal livers; in clinical cases complicated by liver cirrhosis and cancer, however, the functional rate of the remaining liver cannot be calculated only by the volumetric ratio of the whole liver and the remaining part. In clinical cases it must also be calculated by using hepatic vein catheterization and by measuring the ICG extraction rate of each segment of the part to be resected and the part to remain. By using this segmental liver function test, the postoperative hepatic function can be estimated accurately before the operation, thus enabling the surgeon to perform major hepatectomies safely and efficiently.