Does Oxygen Work? Evidence for Oxygenation During Kidney Graft Preservation: A Review

Kidney transplantation (KT) is the gold-standard treatment of end-stage kidney disease (ESKD). Traditional preservation methods, such as static cold storage (SCS), have been replaced by modern and more effective preservation methods, especially hypothermic machine perfusion (HMP). Regardless of improved preservation, ischemia-reperfusion injury (IRI) is inevitable, limiting graft functionality through delayed graft function (DGF) and graft survival. Supplementing the ischemic kidney graft with oxygen during hypothermic preservation has been used in different methods as an attempt to counteract IRI and its effects on graft function and survival. Various oxygenation methods have been studied, from adaptations of classic and well-known preservation strategies, like the addition of oxygen carriers to SCS, or more innovative preservation methods, like hyperbaric oxygenation or retrograde oxygen persufflation. In this review, we will attempt to provide a summary of the available evidence on oxygen carriers, hyperbaric oxygenation, the two-layer method, retrograde oxygen persufflation, and hypothermic oxygenated machine perfusion (HOPE) and discuss the effect these strategies have on kidney graft functionality.