Hypotheses: Temporary vascular clampage (Pringle maneuver) during liver surgery can cause ischemia-reperfusion injury. In this process, activation of polymorphonuclear leukocytes (PMNLs) might play a major role. Thus, we investigated the effects of hepatic ischemic preconditioning on PMNL functions.
Design: Prospective randomized study. Patients who underwent partial liver resection were randomly assigned to 3 groups: group 1 without Pringle maneuver; group 2 with Pringle maneuver, and group 3 with ischemic preconditioning using 10 minutes of ischemia and 10 minutes of reperfusion prior to Pringle maneuver for resection.
Setting: University hospital, Munich, Germany.
Patients: Seventy-five patients underwent hepatic surgery mostly owing to metastasis.
Main outcome measures: Perioperative factors for PMNL activation, inflammation, and postoperative hepatocellular integrity.
Results: Ischemia-reperfusion of the human liver (mean +/- SD time to perform the Pringle maneuver, 35.5 +/- 2.6 minutes) caused (1) a decrease in the number of circulating PMNLs, (2) their intrahepatic sequestration, (3) their systemic activation, and (4) a significant correlation between the degree of their postischemic activation and the postoperative rise in liver enzyme serum levels. In parallel, cytokines with proinflammatory and chemotactic properties were released reaching the highest values when stimulation of PMNLs was most pronounced. When ischemic preconditioning preceded the Pringle maneuver, activation of PMNLs and cytokine plasma levels was reduced as evidenced by the attenuation of superoxide anion production, beta(2)-integrin up-regulation, and interleukin 8 serum concentrations, followed by a significant reduction in serum alanine aminotransferase levels on the first and second postoperative days.
Conclusions: These results demonstrate in humans that ischemic preconditioning reduces activation of PMNLs elicited by the Pringle maneuver. The down-regulation of potentially cytotoxic functions of PMNLs might be one of yet unknown important pathways that altogether mediate protection by ischemic preconditioning.