INTRAHEPATIC TISSUE PO2 DURING CONTINUOUS OR INTERMITTENT VASCULAR INFLOW OCCLUSION IN A PIG-LIVER RESECTION MODEL

Background: Temporary vascular inflow occlusion of the liver (clamping of the hepatic pedicle) can prevent massive blood loss during liver r esections. In this study, intrahepatic tissue pO(2) was assessed as pa rameter of microcirculatory disturbances induced by ischemia and reper fusion (I/R) in the liver following continuous (Cnt) or intermittent ( Int) clamping in a hemihepatectomy model in the pig. Methods: Pigs (20 -34 kg) were divided into 2 groups: I/R without hemihepatectomy (-HH; n = 10) and I/R with hemihepatectomy (+HH; n = 8). Ischemia during 90 min was Cnt or Int (6 sequential periods of 12 min of ischemia and 3 m in of reperfusion), followed by 120 min of reperfusion. Intrahepatic p O(2) histograms (polarographic pO(2) needle electrode) were constructe d before ischemia, at the end of 90 min of ischemia and after 120 min of reperfusion, along with assessment of plasma AST, ALT and LDH. Bile production was monitored continuously. Results: Cumulative frequency distribution curves (CFDC) after 120 min of reperfusion in the Cnt-HH group were not different from preischemic CFDC (means +/- SEM), wherea s in the Int-HH group a left shift occurred indicating more hypo(non)p erfused liver areas (pO(2) < 10 mm Hg: 2.6 +/- 1.2 and 41.0 +/- 17.5% in Cnt-HH and Int-HH; p < 0.01). In the Cnt+HH group, a left shift in the CFDC occurred. In the Int+HH group, a left and a right shift occur red simultaneously, indicating both hypo(non)- and hyperperfused (shun ting) liver areas (pO(2) < 10 mm Hg 4.0 +/- 2.7 and 9.6 +/- 8.5%, n.s. , and pO(2) > 60 mm Hg: 2.0 +/- 2.0 and 17.3 +/- 6.4%, p = 0.015, in C nt+HH and Inti-HH). Plasma AST, ALT and LDH levels were not increased after 120 min of reperfusion, except for AST in Cnt+HH and Int+HH (fro m 54.6 +/- 14.0 to 270.4 +/- 42.8 U/1, p < 0.01, and from 47.8 +/- 9.4 to 176.5 +/- 55.9 U/1, n.s.). Bile production (percentage of mean pre ischemic value) during 120 min of reperfusion was significantly reduce d in the Int-HH group, as compared to the Cnt-HH group (57.0 and 117.0 % after 120 min of reperfusion, p = 0.002). In Cnt+HH and Int+HH, bile production was significantly reduced (33.3 +/- 20.0%, p = 0.05, and 3 8.5 +/- 7.9%, p = 0.007); however it was not different between the two groups. Conclusions: (1) Intrahepatic tissue pO(2) as indicator of mi crovascular perfusion is a parameter of early I/R injury; (2) continuo us vascular inflow occlusion resulted in less microcirculatory disturb ances, when compared to intermittent occlusion.