Cortex kidney tissue partial oxygen pressure depends on percentage of active oxygenation during oxygenated hypothermic machine perfusion

Abstract Background Preclinical and clinical studies have demonstrated the advantages of oxygenated hypothermic machine perfusion (HMPO2) during kidney preservation. However, the optimal oxygenation levels during HMPO2 remain undetermined. The aim of this study was to compare different levels of oxygenation (0%, 21%, 50%, and 100%) during 22 h of active oxygenated HMP (HMPO2) using oxygen preloading by bubbling oxygenation in the preservation solution and continuous surface oxygenation during MP in a porcine DCD model. Methods After 60 min of warm ischemia time, both kidneys of an 80 kg pig were procured and randomized to one of the following groups: (1) 22‐h static cold storage (n = 6), (2) 22‐h HMP without active oxygenation (n = 6), (3) 22‐h HMPO2 21% O2 (n = 6), (4) 22‐h HMPO2 50% O2 (n = 6), and (5) 22‐h HMPO2 100% O2 (n = 6). The primary outcome measure was to compare the different oxygen levels among the different groups assessed by cortex kidney tissue oxygen partial pressures (tpO2). Results Continuous HMPO2 resulted in a significant modification of cortex kidney tpO2. In addition, tpO2 was dependent on the percentage of oxygenation. One hundred percent oxygen resulted in a significantly higher tpO2 compared to all other study groups. In line with that, ATP resynthesis was significantly higher in the HMPO2 100% group. Conclusions This study demonstrates that continuous HMPO2 results in a significant modification of tpO2 compared with SCS, and the degree of tpO2 is positively correlated with the percentage of active oxygenation during HMP. Metabolic profile analyses (ATP resynthesis) suggest that the aerobic mechanism is better supported with higher oxygen levels (50% and 100% oxygenation).