Despite higher rates of delayed graft function (DGF) and reduced long-term graft survival,1,2 patients receiving expanded criteria donor (ECD) kidneys survive longer than those remaining on dialysis.3 As such, strategies are needed to help improve the outcomes for patients receiving ECD kidneys. One such approach in preserving kidney function may be through the use of hypothermic machine perfusion (MP). Studies have shown that MP of ECD kidneys improves graft survival during the first year post-transplant and lowers the rate of DGF compared with cold storage (CS).4,5 A single center, observational, retrospective study was conducted by a team at the Hospital Universitari de Bellvitge in Barcelona, Spain, in order to investigate the effects of MP versus CS on ECD kidney transplants.6
A total of 88 patients were enrolled in the trial, with 51 receiving a CS kidney and 37 receiving an MP kidney. An analysis of the results showed a difference in glomerular filtration rate after just 48 hours post-transplant (11 ml/min for CS versus 16 ml/min for MP; p=0.021), which widened to 29 ml/min versus 42 ml/min upon discharge (p=<0.0001). Patients receiving CS kidneys also stayed in the renal transplant unit longer (2.43 days versus 1.76; p=0.006) and required a higher number of dialysis sessions (7 versus 3.2; p=0.036). MP kidneys also showed reduced DGF in comparison (35.1 versus 47.1%; p=0.03), which is important as reduced DGF is associated with a decreased risk of post-operative dialysis. The 1-year survival rate was 95% for MP kidneys and 84% for CS kidneys (p=0.025).
As demonstrated, the data suggest that preservation of ECD kidneys is better with MP compared with CS. The most likely explanation for this is the fact that during MP, kidneys are supplied with oxygen and metabolic substrates such as adenine and adenosine, preventing calcium cell influx and influencing vascular flow, thus controlling solution and tissue acidosis.7 One of the additional advantages of MP is that it allows for longer storage of the kidney, which gives physicians time to evaluate histological measures and fully assess the extent of ischemic damage.8 MP of kidneys may be of real significance in optimizing patient outcomes when combined in a comprehensive treatment approach which incorporates donor management and pre- and post-conditioning of the kidney.