The authors concluded that hepatic vascular exclusion techniques did not offer any benefit for the clinical outcomes of patients undergoing liver resection compared with portal triad clamping alone. The authors' conclusions appeared to reflect the results of the review but, given the limited quality of a small number of trials containing few patients, these findings should be interpreted with caution.

To compare portal triad clamping versus hepatic vascular exclusion for vascular control in patients undergoing liver resection.

MEDLINE, EMBASE, Science Citation Index and the Cochrane Library were searched from inception to November 2007; search terms were reported. Additional studies were sought through manual searches of the reference lists of retrieved articles and by contacting experts in the field of hepatic surgery.

Randomised controlled trials (RCTs) in adults undergoing hepatic resection that compared portal triad clamping to any technique of hepatic vascular exclusion were eligible for inclusion. Trials that assessed laparoscopic techniques or those which were undertaken on patients undergoing liver transplantation were excluded, as were trials for which insufficient outcomes data were reported.

The primary outcome measures were overall postoperative morbidity (number of patients that developed at least one complication after surgery) and mortality (in-hospital death due to any cause); a number of secondary outcomes were also assessed.

Included trials compared portal triad clamping with selective hepatic vascular exclusion, total hepatic vascular exclusion, and a modified technique of hepatic vascular exclusion. Half of the trials enrolled non-cirrhotic patients only, whilst the other trials included those with Child A cirrhosis or only patients with Child A and B cirrhosis. Major and minor hepatic resections were performed in all trials, although one trial only included patients undergoing major hepatectomy. The mean age of included patients ranged from 39.7 to 62 years; most were male (except for one trial).

Two reviewers independently assessed the studies for inclusion; disagreements were resolved by discussion with a third reviewer.

The methodological quality of the included trials was assessed based on the following criteria: allocation sequence generation, randomisation efficacy, allocation concealment, sample size calculation, description of outcomes, description of drop-outs and withdrawals, and statistical analysis of individual trials.

Two authors independently performed the validity assessment.

Two reviewers independently extracted data to calculate odds ratios (ORs) for dichotomous outcomes and weighted mean differences (WMDs) for continuous outcomes. Associated 95% confidence intervals (CIs) were calculated for each of these outcomes. Disagreements were resolved by discussion with a third reviewer.

A random-effects model was used to pool odds ratios, weighted mean differences and their 95% confidence intervals. Heterogeneity was assessed using the I² statistic.

Clinical heterogeneity was evaluated by assessing trial populations and interventions, definition of outcome measures, concomitant treatment, and perioperative management, as well as the different techniques of hepatic vascular exclusion being compared to portal triad clamping.

Publication bias was assessed using funnel plots.

Four RCTs were included in the review (n=320 patients). The overall trial quality was reported to be moderate. None of the trials reported adequate allocation sequence generation, sample size calculation or clearly reported statistical methods. Other flaws included lack of reporting of withdrawals and drop-outs. Two trials compared portal triad clamping with selective hepatic vascular exclusion (n=150 patients. One trial compared portal triad clamping with a modified technique of hepatic vascular exclusion (n=118 patients). One trial compared portal triad clamping with total hepatic vascular exclusion (n=52 patients).

Morbidity and mortality: There was no significant difference in either morbidity or mortality between portal triad clamping and any of the techniques of hepatic vascular exclusion (four RCTs). There was significantly reduced overall morbidity for the portal triad clamping group compared with the total hepatic vascular exclusion group (OR 0.27, 95% CI 0.08 to 0.94; one RCT). No significant heterogeneity was found.

Intraoperative blood loss: Compared with the selective hepatic vascular exclusion group, there was significantly higher blood loss for both the portal triad clamping group (WMD 116.00mL, 95% CI 4.33 to 227.67; two RCTs) and the modified technique of hepatic vascular exclusion group (WMD 350.00mL, 95% CI 246.16 to 453.84; two RCTs).

Blood transfusion: Compared with the total hepatic vascular exclusion group, there was no difference in the numbers of patients in the portal triad clamping group requiring blood transfusion (four RCTs). Significantly fewer patients required blood transfusion from the hepatic vascular exclusion groups when portal triad clamping was compared with selective hepatic vascular exclusion (OR 2.86, 95% CI 1.31 to 6.22) and the modified technique of hepatic vascular exclusion (OR 5.66, 95% CI 2.29 to 14.00). This advantage of hepatic vascular exclusion was also present for all identified trials (OR 3.38; 95% CI 1.94 to 5.86; four RCTs; I²=6.4%).

Warm ischaemic time: Patients receiving portal triad clamping had a significantly reduced warm ischaemic time compared to total hepatic vascular exclusion patients (WMD −7.00 minutes, 95% CI −13.21 to −0.79; one RCT).

Aspartate aminotransferase level: Postoperative aspartate aminotransferase values were significantly lower in the portal triad clamping than the selective hepatic vascular exclusion group (WMD −100.00U/L, 95% CI −131.01 to −68.99; two studies).

Funnel plots suggested a low likelihood of publication bias.

Hepatic vascular exclusion did not offer any benefit regarding outcome of patients undergoing hepatic resection compared with portal triad clamping alone.

The review question was clear and supported by appropriate inclusion criteria. Multiple sources were searched to identify relevant evidence. It was unclear whether language restrictions were applied or unpublished studies were sought, so some studies may have been missed. The likelihood of publication bias was considered to be low, but this finding was of limited value given the small number of included trials. Attempts were made to minimise errors and bias in all parts of the review process.

Trial quality was assessed using appropriate criteria. The decision to use meta-analyses was appropriate. Reasonable measures were used to assess and explore heterogeneity between trials.

The authors' conclusions appeared to reflect the results of the review but, given the limited quality of a small number of trials containing few patients, these findings should be interpreted with caution.

Practice: The authors stated that the surgeon’s experience and the location of the lesions should determine the preferred method in the case of required vascular control, whilst total and selective hepatic vascular exclusions appear favourable for tumours involving the inferior vena cava and the hepatic veins.

Research: The authors stated that well-designed RCTs that assess the most effective technique of hepatic vascular control in patients with underlying liver disease are required.

Not stated.

Rahbari NN, Wente MN, Schemmer P, Diener MK, Hoffman K, Motschall E, Schmidt J, Weitz J, Buchler MW. A systematic review and meta-analysis of the impact of portal triad clamping on outcome after hepatic resection. British Journal of Surgery 2008;95(4):424-432.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.