The Effect of Hepatic Vascular Inflow Occlusion on Liver Tissue pH, Carbon Dioxide, and Oxygen Partial Pressures: Defining the Optimal Clamp/Release Regime for Intermittent Portal Clamping 1

BackgroundThe optimal duration of hepatic vascular inflow occlusion (Pringle maneuver) and reperfusion during liver resection are not defined. The aim of this study was to describe the changes that occur in liver tissue pH, partial pressure of carbon dioxide (PLCO2), and partial pressure of oxygen (PLO2) and by using the PLCO2 as a predictor of hepatocellular damage define the optimal clamp/release regime for intermittent portal clamping during liver resection.MethodsContinuous pH, PLCO2, and PLO2 measurements were obtained using a Paratrend multi-parameter sensor (Diametrics Medical Inc., Roseville, MN) in 13 patients undergoing elective partial liver resection. Patients were randomly allocated to undergo a 10-min clamp/5-min release regime (group 1) or a 20-min clamp/10-min release regime (group 2).ResultsIn group 1 (n = 6) PLCO2 increased and pH decreased significantly after 10 min of clamping and returned to baseline within 5 min of reperfusion. In group 2 (n = 7) the PLCO2 increased and pH decreased significantly after 10 min of clamping, with a further significant change after 20 min. Following 10 min of reperfusion, pH and PLCO2 had not returned to baseline. PLO2 did not change significantly with either intermittent portal clamping regime.ConclusionsA reperfusion of 5 min is sufficient to restore the PLCO2 and liver tissue pH to normal after 10 min of clamping, but more than 10 min of reperfusion is required after 20 min of clamping. To minimize hepatic ischemia during liver resection, a 10-min clamp/5-min release regime should be used.