COMPARE trial: new hope for organ preservation

The addition of oxygen to machine perfusion has been proposed as a method to support mitochondrial function and ATP synthesis.5 Given that renal tubular epithelial cells, particularly within the proximal tubule, are the primary site of damage in ischaemia–reperfusion injury due to high metabolic demand, oxygen supplementation is a plausible strategy to reduce cellular damage. Ina Jochmans and colleagues7 report the results of an investigator-driven, multicentre study in The Lancet, done by the Consortium for Organ Preservation in Europe, comparing HMP with HMPO2 in kidney pairs donated after circulatory death from donors aged 50 years and older. 197 kidney pairs were randomised using a computer-generated randomisation scheme, stratified by organ allocation region: one kidney was assigned to HMPO2 and the contralateral kidney to standard HMP. The administration of supraphysiological concentrations of oxygen resulted in fewer severe complications (HMPO2 46 [11%] of 417, 95% CI 8–14 vs HMP 76 [16%] of 474, 13–20; p=0·032), reduced biopsy-proven acute rejection episodes (relative risk reduction 44% [relative risk ratio 0·56, 95% CI 0·31–0·98]), and lower rates of graft failure with HMPO2 (three [3%] of 106) compared with HMP (11 [10%] of 106, hazard ratio 0·27, 95% CI 0·07–0·95; p=0·028).