OPTIMAL CYCLES OF HEPATIC ISCHEMIA AND REPERFUSION FOR INTERMITTENT PEDICLE CLAMPING DURING LIVER SURGERY

Objectives: To evaluate the intermittent clamping of hepatic vessels d uring liver surgery and to determine the optimal duration of ischemia and reperfusion.Participants: One hundred nine adult male Sprague-Dawl ey rats. Methods: Partial (70%) ischemia of the rat liver was induced by clamping of the left pedicle. To assess the influence of a single p eriod of ischemia, the rats were divided into three groups for 15, 20, or 30 minutes of ischemia. To evaluate the influence of reperfusion d uration, reperfusion following 15-minute ischemia was repeated 10 time s in three groups for 5, 10, or 15 minutes of reperfusion duration. He patic tissue blood flow (HTBF) and hepatic beta-adenosine triphosphate (beta-ATP) levels were measured serially, and histopathological speci mens were studied following single episodes of ischemia. In the reperf usion experiments, hepatic enzyme levels, survival rates, HTBF, beta-A TP, and histopathological findings were analyzed. Results: When the si ngle period of ischemia was 15 minutes, HTBF and beta-ATP levels recov ered after 1 hour of reperfusion. However, both HTBF and beta-ATP leve ls did not return to preischemic levels when the duration of the ische mia was 20 or 30 minutes. Levels of beta-ATP and HTBF were higher, wit h improvement in both the histopathological findings and the survival rate, when the duration of the repeated reperfusion periods was 15 min utes, compared with 5 or 10 minutes. Conclusions: The maximum period o f ischemia without irreversible damage was 15 minutes in rat liver. Th e damage was less severe when the duration of the repeated reperfusion periods was 15 minutes rather than 5 or 10 minutes.