Capsulotomy of Ischemically Damaged Donor Kidneys: A Pig Study

Background: Ischemia-reperfusion injury of donor kidneys may worsen transplant outcome. Kidneys with severe injury, such as kidneys of donors after circulatory death, develop edema, which may lead to renal compartment syndrome with reduced tissue perfusion. Objective: We studied the effect of capsulotomy during hypothermic machine perfusion (HMP) of ischemically damaged porcine kidneys. Methods: Eight pairs of kidneys from slaughterhouse pigs were assigned to two groups (20 and 45 min of warm ischemia). After 21 h of HMP, capsulotomy was performed, and perfusion was continued for 2 h. During perfusion, machine flow (Q), renal resistance (RR), renovascular circulating volume (RCV), intraparenchymal pressure (IPP) and weight were recorded. Parenchymal injury was examined with methylene blue infusion. Results: Mean Q and RCV increased directly after capsulotomy [percentage increase (95% confidence interval): Delta Q = 32% (17, 47), p = 0.001, and Delta RCV = 19% (3, 35), p = 0.023]. Mean RR decreased [Delta RR = -23% (-31, -15), p <0.001]. Subanalysis comparing both warm ischemia groups showed no significantly different effect of capsulotomy between groups. There was no methylene blue leakage after capsulotomy in any kidney. Conclusions: Renovascular perfusion can be improved with capsulotomy during HMP, without damaging the renal parenchyma. Follow-up studies need to determine which donor kidneys may benefit from capsulotomy.