More than 1000 elective liver resections (planned operation) are performed annually in the United Kingdom alone. When liver resection is performed, the inflow of blood to the liver can be blocked (vascular occlusion), thereby potentially reducing the blood loss. When employed during liver resection, the vascular occlusion is generally achieved by occluding the hepatic artery and portal vein (blood vessels which supply the blood to the liver) either continuously or intermittently (when varying periods of occlusion and no occlusion are carried out in cycles till liver resection is complete). This is called portal triad clamping. However, there are many variations to this technique. These include hepatic vascular exclusion, where in addition to the occlusion of hepatic artery and portal vein, the veins draining blood from the liver are occluded with an intention of further decreasing the blood loss; selective inflow occlusion when only the vessels supplying the portion of the liver to be resected is occluded; and ischaemic preconditioning, where in order to prepare the liver for lack of blood flow, a vascular occlusion is performed briefly, after which the blood flow is re-established (reperfusion). This review is aimed at evaluating the different methods of vascular occlusion in liver resection.
Ten trials including 657 patients were included in this review. All were of high risk of bias (systematic error) and play of chance (random error). Only one or two trials were included under each comparison. There was no difference in mortality, liver failure, or post-operative complications between any of the comparisons. Hepatic vascular occlusion does not decrease the blood transfusion requirements. It decreases the cardiac output (amount of blood pumped by the heart in one second) and increases the systemic vascular resistance (resistance to the flow of blood in the vessels), which may have potential problems in patients with heart disorders.
Although there was no statistically significant difference in the incidence of liver failure between continuous portal triad clamping and intermittent portal triad clamping (5/60; 8.5% versus 0/61), most of them occurred in patients with chronic liver diseases undergoing the liver resections using continuous portal triad clamping.
There was no benefit in selective inflow occlusion compared to portal triad clamping. There was no statistically significant difference in the incidence of liver failure between the two groups (4/41; 9.8% versus 0/39), but all patients with liver failure occurred in the selective inflow occlusion group.
There were no significant differences in any of the important outcomes between the different methods of intermittent portal triad clamping or between ischaemic preconditioning followed by continuous vascular occlusion and intermittent vascular occlusion in non-cirrhotic patients undergoing liver resections.
Further randomised trials of low risk of bias are needed to determine the optimal technique of vascular occlusion.
In elective liver resection, hepatic vascular occlusion cannot be recommended over portal triad clamping. Intermittent portal triad clamping seems to be better than continuous portal triad clamping at least in patients with chronic liver disease. There is no evidence to support selective inflow occlusion over portal triad clamping. The optimal method of intermittent portal triad clamping is not clear. There is no evidence for any difference between the ischaemic preconditioning followed by vascular occlusion and intermittent vascular occlusion for liver resection in patients with non-cirrhotic livers. Further randomised trials of low risk of bias are needed to determine the optimal technique of vascular occlusion.
Vascular occlusion is used to reduce blood loss during liver resection surgery. Various methods of vascular occlusion have been suggested.
To compare the benefits and harms of different methods of vascular occlusion during elective liver resection.
We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until August 2008.
We included randomised clinical trials comparing different methods of vascular occlusion during elective liver resections (irrespective of language or publication status).
Two authors independently assessed trials for inclusion and independently extracted the data. We calculated the risk ratio or mean difference with 95% confidence intervals using fixed-effect and random-effects models based on intention-to-treat or available data analysis.
Ten trials including 657 patients compared different methods of vascular occlusion. All trials were of high risk of bias. Only one or two trials were included under each comparison. There was no statistically significant differences in mortality, liver failure, or other morbidity between any of the comparisons.
Hepatic vascular occlusion does not decrease the blood transfusion requirements. It decreases the cardiac output and increases the systemic vascular resistance. In the comparison between continuous portal triad clamping and intermittent portal triad clamping, four of the five liver failures occurred in patients with chronic liver diseases undergoing the liver resections using continuous portal triad clamping. In the comparison between selective inflow occlusion and portal triad clamping, all four patients with liver failure occurred in the selective inflow occlusion group. There was no difference in any of the other important outcomes in any of the comparisons.