Normothermic machine perfusion (NMP) provides a platform for kidney quality assessment. Donation after circulatory death (DCD) donor kidneys are associated with great ischemic injury and high intrarenal resistance (IRR). This experimental study aims to investigate the impact of different perfusion pressures on marginal kidney function and injury during NMP. Twenty-seven slaughterhouse porcine kidneys were retrieved and subjected to 60min of warm ischemia time to mimic DCD condition. These kidneys were randomized into 75mmHg (subphysiological, n=9), 95mmHg (physiological, n=9), and 115mmHg NMP (high physiological, n=9). Renal function and injury were assessed during NMP. Three groups showed comparable IRR, with the 115mmHg group exhibiting the highest blood flow. The 95mmHg group [0.48 (0.36-1.15) ml/min/100g] and 115mmHg group [0.93 (0.45-1.41) ml/min/100g] showed significantly higher creatinine clearance compared to the 75mmHg group [0.16 (0.08-0.37) ml/min/100g] during the first hour of NMP (p=0.049, p=0.009, respectively). The 115mmHg group exhibited significantly higher oxygen consumption compared to the 75mmHg group at 30min of NMP [1.37 (1.05-1.92) versus 0.72 (0.61-0.82) mlO2/min/100g, p=0.009]. Perfusate neutrophil gelatinase-associated lipocalin (NGAL) levels were consistently lowest in the 95mmHg group and highest in the 75mmHg group. Aspartate aminotransferase (AST) levels of the 115mmHg group were significantly higher than the 75mmHg group. For kidneys with high IRR, both 95mmHg and 115mmHg perfusion pressures enable an early improvement in renal hemodynamics and function compared to 75mmHg during NMP, while a high physiological perfusion can cause additional injury.
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