Prolonged continuous or intermittent vascular inflow occlusion during hemihepatectomy in pigs

Objective To assess ischemia and reperfusion (I/R) injury in a hemihepatectomy model in pigs after prolonged continuous or intermittent vascular inflow occlusio n in the liver. Summary Background Data Massive intraoperative blood loss during liver resections can be prevented by temporary vascular inflow occlusion, consequently leading to ischemia an d reperfusion injury in the remnant liver. Previously, in a pig liver resec tion model in which only limited I/R injury was induced during brief (90 mi n) vascular inflow occlusion, the authors demonstrated reduced I/R injury a fter continuous (CNT) occlusion, compared to intermittent (INT). This liver resection study on pigs was undertaken to assess I/R injury after prolonge d (120 min) CNT or INT occlusion. Methods In pigs (37.0 +/- 1.5 kg), liver ischemia during 2 hours was CNT (n = 6) or INT (n = 6) (eight subsequent periods of 12 min ischemia and 3 min recircu lation), followed by 6 hours of reperfusion. A left hemihepatectomy (45.5% +/- 1.4%) was performed within the first 12 minutes of ischemia. No hepatic pedicle clamping or liver resection was performed in control experiments ( n = 6). Microvascular damage was assessed by hyaluronic acid (HA) uptake ca pacity of the liver (parameter of early sinusoidal endothelia; cell damage) and restoration of intrahepatic tissue pO(2) during reperfusion. Hepatocel lular damage was tested by plasma concentrations of aspartate aminotransfer ase (AST), alanine aminotransferase, and lactate dehydrogenase(LDH). Results Hyaluronic acid uptake after 6 hours of reperfusion, compared to preischemi c uptake, was unaltered in the control group, but was significantly reduced in both resection groups. However, more HA was taken up after INT occlusio n, compared to CNT (60.4% +/- 5.6% and 39.5% +/- 3.7%, respectively; ANOVA: p = 0.001). Intrahepatic tissue pO(2) distribution after 8 hours of reperf usion more closely returned to preischemic configuration in the INT group t han in the CNT group, indicating reduced microcirculatory disturbances afte r INT occlusion. Release of AST and LDH after 6 hours of reperfusion was si gnificantly increased in both CNT and INT groups. Lower AST levels, however , ware found after INT occlusion than after CNT occlusion (267.0 +/- 74.7 U /l and 603.3 +/- 132.4 U/l, respectively; p = 0.06). Conclusions Intermittent hepatic vascular inflow occlusion during prolonged liver ische mia in pigs resulted in less microcirculatory and hepatocellular injury, co mpared to continuous occlusion. Intermittent clamping is preferable when pr olonged periods of vascular inflow occlusion are applied during liver resec tions.