Hypothermic machine perfusion of kidney grafts: which pressure is preferred?

To assess the effect of the perfusion pressure (PP) during machine perfusion (MP) on the preservation quality of kidney grafts, we compared mean PPs of 25 and 30 mmHg using a porcine autotransplantation model. After assessment of the microcirculation, animals underwent left nephrectomy. Thereafter, kidneys were washed out followed by 20 h of MP at 25 mmHg (MP25, n = 7) or 30 mmHg (MP30, n = 7) using a novel MP system for hypothermic pulsatile perfusion. After MP preservation, the contralateral kidneys were removed and the preserved kidneys heterotopically autotransplanted. Ten minutes after reperfusion, the microcirculation was reassessed. Seven days posttransplant, animals were euthanized and the kidney grafts removed for histological analysis. MP using a mean PP of 25 mmHg resulted in higher capillary blood flow after reperfusion. In the MP30 group, 6 out of 7 animals survived, whereas in the MP25 group all animals survived. Overall, improvement in recovery of renal function and a better preservation of structural integrity were seen in the MP25 group compared to the MP30 group. Using a novel system for hypothermic MP, a mean PP of 25 mmHg is preferred over a mean PP of 30 mmHg.