How do we determine the safe limit of hepatectomy based on multiple crucial factors?

Abstract This study reports how to prevent posthepatectomy liver failure and the crucial factors in evaluation of hepatic reserve. In 1980, we established a prediction score (PS) system for predicting the safe limit of hepatectomy. We used a multiple regression equation: Y(PS)=−84.6+0.933X 1 +1.12X 2 +1.0X 3 , where X 1 is computed tomographic scan‐estimated resection rate (%), X 2 is ICG retention rate (%) and X 3 is patient's age. Of the clinically available liver function tests, ICG retention rate or clerance had the highest correlation with biomechanically estimated liver consistency and morpho‐metrically estimated collagen content, both of which affect liver regenerative capacity. With the further accumulation of a subsequent 10 years' experience (1981—1990), the system was refined. If a PS greater than 55 was given to a planned resection part it was classified as a risky zone; a PS of 45—55, as a borderline zone; and a PS less than 45, as a safe zone. In the borderline zone, the pattern of the glucose tolerance curve and the presence or absence of coexistent liver disease were determined to be additional prognostic factors. Even if patients were assessed as being in the safe zone by reducing resection range, patients with disturbed glucose tolerance, lower platelet count, and higher ICG retention rate were found to be at a high risk for liver failure secondary to septic postoperative complications. Mortality by liver failure has been reduced with the use of these systems, from 16% before 1980 to 6.3% (24/376, 1981—1990) and to 0.9% (2/202, 1991—1995). Avoidance of excessive resection unmatched to individual hepatic reserve and avoidance of septic complications are mandatory in patients with a limited safe margin of hepatic reserve.