Hemi-hepatic Vascular Occlusion Versus Pringle Manoeuvre In Liver Resection

Background:The number of deaths caused by hepatocellular carcinoma ranks third among all cancers worldwide. Currently, the most effectual treatment for hepatocellular carcinoma are partial liver resection and orthotopic liver transplantation. Haemorrhage is a major risk in liver resection and the amount of blood loss is proportionally linked to mortality and peri-operative morbidity. Intra-operative blood loss not only affects the short-term prognosis, but also affects the long-term prognosis. In addition, blood transfusion is associated with tumour recurrence after liver resection. The development of various hepatic vascular occlusion techniques greatly improve the success rate of hepatectomy and the patient outcomes. The Pringle manoeuvre (PM) is the best known and historic method of hepatic vascular control during hepatectomy, and also the easiest and most effective one. The□hemi-hepatic vascular occlusion (HHO) is a mothod that selectively interrupts the right or left hemi-liver’s arterial and venous inflow. It can maintain the portal flow to the remnant liver, without causing splanchnic congestion and affecting the hemodynamic stability. Many prospective randomized controlled trials and retrospective clinical trials have assessed the feasibility, safety and effectiveness of HHO and PM. However, the sample size of these studies are small and the conclusions are different. Therefore, the optimal method of vascular occlusion during hepatectomy remains controversial.Aim:To make a systematic review that compare the outcomes of HHO and PM using meta-analysis. To provide evidence for vascular occlusion technique choosing during liver resection.Methods:The author searched the Cochrane Library, PubMed, CNKI, WanFang Database and VIP Database until April2014. The literature filter was done following the inclusion and exclusion criteria strictly, only randomized controlled trials comparing HHO and PM were considered for this meta-analysis. The risk of bias of every included study was evaluated. The primary outcomes concerned in this study are:1) mortality,2) liver failure morbidity,3) peri-operative morbidity (include re-operation, abdominal collections, wound infection, pulmonary complications, cardiac insufficiency, portal vein thrombosis, bile leak, ascites and haemorrhage),4) operating time (min),5) ischemic duration (min),6) intra-operative blood loss (mL),7) number needing transfusion,8) number of units transfused (unit). The secondary outcomes concerned in this study are:1) hospital stay (d),2) biochemical markers of liver function (include post-operative bilirubin levels (μmol/L) and post-operative albumin levels (g/L)),3) biochemical markers of liver injury (include post-operative Aspartate aminotransferase (AST) levels (U/L) and post-operative Alanine aminotransferase (ALT) levels (U/L)). The meta-analysis was done using software Review Manager5.2after data extraction. The estimated effect measures were risk ratio (RR) for dichotomous outcomes and mean difference (MD) for continuous outcomes, both reported with95%confidence intervals (CI). Heterogeneity was detected by chi-squared test and there was considered statistically significant heterogeneity among the studies when P<0.01. The quantity of heterogeneity was measured by I2and I2>30%was considered statistically significant heterogeneity. A fixed-effects model was used to synthesize data when heterogeneity was absent, otherwise a random effects model would be used. The final results were showed by forest plot. A funnel plot was used to explore bias and asymmetry in funnel plot was used to assess bias.Results:5randomized controlled trials including458patients met the inclusion criteria. There were231and227patients undergone HHO and PM, respectively. Meta-analysis of the trials indicated significant difference between HHO and PM in terms of operating time (MD:19.79;95%CI:[10.89,28.69]), number of units transfused (MD:-0.15;95%CI:[-0.23,-0.07]), bilirubin levels on post-operative days3(MD:-5.07;95%CI:[-8,45,-1.70]) and7(MD:-6.53;95%CI:[-11.87,-1.20]), albumin levels on post-operative days1(MD:3.72;95%CI:[0.52,6.92]) and3(MD:4.57;95%CI:[2.38,6.76]), AST levels on post-operative days1(MD:-311.32;95%CI:[-408.76,-213.88]) and5(MD:-43.94;95%CI:[-64.20,-23.68]), ALT levels on post-operative days5(MD:-49.49;95%CI:[-92.16,-6.82]). Meta-analysis of the trials showed no significant difference between HHO and PM in terms of mortality, liver failure morbidity, peri-operative morbidity, ischemic duration, intra-operative blood loss, number needing transfusion, hospital stay, bilirubin levels on post-operative days1and5, albumin levels on post-operative days5and7, AST levels on post-operative days3and7, ALT levels on post-operative days1,3and7.Conclusion:The current evidence shows no advantage of HHO over PM in terms of mortality, liver failure morbidity, peri-operative morbidity, ischemic duration, intra-operative blood loss, number needing transfusion, hospital stay. In addition, the operating time of HHO is longer than PM. However, the number of units transfused is fewer, the post-operative liver function recovery is better and post-operative liver injury is lighter in HHO when compared with PM. More randomized controlled trials needed to be done in the further to assess optimal technique of hepatic vascular occlusion, especially for the patients with chronic and the patients who undergo major liver resection.