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 reducing the blood loss. There are concerns about liver damage when the blood supply is blocked. Ischaemic preconditioning involves ischaemia (blocking the blood supply) and reperfusion (unblocking the blood supply) for a short period of time before exposure to prolonged vascular occlusion. The aim of this review was to assess the role of ischaemic preconditioning in liver resections performed utilising vascular occlusion. Four randomised clinical trials including 271 patients undergoing open liver resections fulfilled the inclusion criteria of this review. The patients were randomised to ischaemic preconditioning (n = 135) and no ischaemic preconditioning (n = 136) prior to continuous vascular occlusion. All the trials excluded cirrhotic patients. We assessed all the four trials as having high risk of bias (high risk of systematic error). There was no difference in mortality, liver failure, post-operative complications, hospital stay, intensive therapy unit stay, and operating time between the two groups. The proportion of patients requiring blood transfusion was lower in the ischaemic preconditioning group. The reasons for this are not clear. There was no difference in blood loss or enzyme markers of liver function between the two groups. The enzyme markers of liver injury were lower in the ischaemic preconditioning group on the first post-operative day. Currently, there is no evidence to suggest a protective effect of ischaemic preconditioning in non-cirrhotic patients undergoing liver resection under continuous vascular occlusion. Ischaemic preconditioning reduces the blood transfusion requirements in patients undergoing liver resection. Further high quality randomised clinical trials are necessary to assess the role of ischaemic preconditioning. Further studies are necessary to understand the mechanism of ischaemic preconditioning.
Vollständige Zusammenfassung lesen
Vascular occlusion is used to reduce blood loss during liver resection surgery. The enzyme markers of liver injury are elevated if vascular occlusion is employed during liver resection. It is not clear whether ischaemic preconditioning prior to vascular occlusion has a protective effect during elective liver resections.
Zielsetzungen
To assess the advantages (decreased ischaemia-reperfusion injury) and any potential disadvantages of ischaemic preconditioning prior to vascular occlusion during liver resections.
Suchstrategie
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.
Auswahlkriterien
We included randomised clinical trials comparing ischaemic preconditioning versus no ischaemic preconditioning prior to vascular occlusion (irrespective of the method of vascular occlusion) during elective liver resections (irrespective of language or publication status).
Datensammlung und ‐analyse
Two authors independently assessed trials for inclusion and independently extracted the data. We analysed the data with both the fixed-effect and the random-effects models using RevMan Analysis. We calculated the risk ratio, mean difference, or standardised mean difference with 95% confidence intervals based on intention-to-treat or available data analysis.
Hauptergebnisse
We included four trials with 271 patients undergoing open liver resections. The patients were randomised to ischaemic preconditioning (n = 135) and no ischaemic preconditioning (n = 136) prior to continuous vascular occlusion (portal triad clamping in three trials and hepatic vascular exclusion in one trial). All the trials excluded cirrhotic patients. We assessed all the four trials as having high risk of bias. There was no difference in mortality, liver failure, other peri-operative morbidity, hospital stay, intensive therapy unit stay, and operating time between the two groups. The proportion of patients requiring blood transfusion was lower in the ischaemic preconditioning group. There was also a trend towards a lower amount of red cell transfusion favouring ischaemic preconditioning group. There was no difference in the haemodynamic changes, blood loss, bilirubin, or prothrombin activity between the two groups. The enzyme markers of liver injury were lower in the ischaemic preconditioning group on the first post-operative day.
Schlussfolgerungen der Autoren
Currently, there is no evidence to suggest a protective effect of ischaemic preconditioning in non-cirrhotic patients undergoing liver resection under continuous vascular occlusion. Ischaemic preconditioning reduces the blood transfusion requirements in patients undergoing liver resection.
