A Cochrane review [Abstract] 1 included 4 studies with a total of 271 subjects undergoing open liver resections (all the studies excluded cirrhotic patients). When liver resection is performed, the inflow of blood to the liver can be blocked (vascular occlusion). 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.
There was no difference in mortality (RR 1.27, 95% CI 0.35 to 4.68), liver failure (RR 0.84, 95% CI 0.41 to 1.71), other peri-operative morbidity, hospital stay (MD -1.43 days, 95% CI -3.52 to 0.66), intensive therapy unit stay (MD -0.69 days, 95% CI -1.71 to 0.34), and operating time (MD -14.18 minutes, 95% CI -34.25 to 5.88) between ischaemic preconditioning and no ischaemic preconditioning. The proportion of patients requiring blood transfusion was lower in the ischaemic preconditioning group (RR 0.43, 95% CI 0.25 to 0.75). There was no difference in blood loss (MD -6.51 ml, 95% CI -35.69 to 22.68) or enzyme markers of liver function (bilirubin level 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. However, there was no difference in the peak levels of these enzymes between the groups in the only trial that reported this outcome.
Comment: The quality of evidence is downgraded by study quality (lack of blinding and possible selective outcome reporting), by inconsistency (heterogeneity in outcomes and variability in results across studies), and by imprecise results (limited study size for each comparison).
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