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 (HMPO 2 ) during kidney preservation. However, the optimal oxygenation levels during HMPO 2 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 (HMPO 2 ) 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 HMPO 2 21% O 2 ( n = 6), (4) 22‐h HMPO 2 50% O 2 ( n = 6), and (5) 22‐h HMPO 2 100% O 2 ( 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 (tpO 2 ). Results Continuous HMPO 2 resulted in a significant modification of cortex kidney tpO 2 . In addition, tpO 2 was dependent on the percentage of oxygenation. One hundred percent oxygen resulted in a significantly higher tpO 2 compared to all other study groups. In line with that, ATP resynthesis was significantly higher in the HMPO 2 100% group. Conclusions This study demonstrates that continuous HMPO 2 results in a significant modification of tpO 2 compared with SCS, and the degree of tpO 2 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).