Hypothermic Perfusion Mitigates Extended Cold Ischemia Time in Kidney Transplantation

Key Points Compared with ≤ 12 hours of static cold storage, hypothermic machine perfusion up to 36 hours did not increase death-censored graft failure. Hypothermic machine perfusion reduced delayed graft function for kidneys with ≤36 hours of cold ischemia time. When cold ischemia time exceeded 36 hours, hypothermic machine perfusion no longer affected outcomes. Background Extended cold ischemia time (CIT) is associated with higher incidences of delayed graft function (DGF) and graft failure. Kidneys on hypothermic machine perfusion (HMP) perform better than comparable kidneys in static cold storage (SCS). This study aimed to determine whether hypothermic perfusion was associated with lowering the deleterious effects of extended CIT. Methods Data from the United Network of Organ Sharing database were examined to identify adult first-time, kidney-only recipients from 2005 to 2022. Multivariable models for death-censored graft failure (dcGF), uncensored graft failure, DGF, and patient mortality were constructed and adjusted for donor, recipient, and transplant factors. Kidneys with ≤12 hours SCS, an accepted standard for optimal transplantation, served as the reference group for each model. Results Among 120,438 allografts, 63% were in SCS and 37% were preserved with hypothermic perfusion. DcGF was higher in a dose-dependent fashion as CIT increased. Kidneys on HMP for ≤24 hours had less dcGF than reference (≤12 hours in SCS) kidneys. Perfusion for 24–36 hours did not differ from reference. After 36 hours, all kidneys had higher dcGF, regardless of the storage method. HMP lowered the incidence of DGF at every level of CIT. Conclusions HMP is an effective strategy for lowering the negative effect of prolonged CIT, providing transplant teams with greater flexibility to optimize donor and recipient logistics, without compromising long-term graft outcomes.