Effect of the Second Warm Ischemia Time and Its Components on Early and Long-term Kidney Graft Function

• Increased recipient's age, but not and body mass index elongate second warm ischemia time
• Primary graft nonfunction frequently occurs in patients with longer second warm ischemia time
• Anastomosis time does not affect long-term kidney graft excretory function

BackgroundDuring kidney transplantation, the total time of organ ischemia consists of first warm ischemia time (WIT1), cold ischemia time (CIT), and a second WIT (WIT2). Rising graft temperature during WIT2, which comprises the creation of vascular anastomoses, increases oxygen demand and tissue damage, especially in the kidney tubular cells. The aim of this study was to analyze the influence of WIT2 on early and long-term kidney graft function.MethodsWe performed a retrospective analysis of 554 consecutive adult recipients, who received their first kidney graft from a deceased donor between 2003 and 2013.ResultsMean WIT2 was 25.2 min. Donors' sex, age, presence of hypertension, body mass index (BMI), and the cause of brain death showed no effect on WIT2. Weak positive correlations were found between the duration of WIT2 and both recipients' age (r = 0.11; P < .01) and BMI (r = 0.14; P < .01). Multivariate regression analysis confirmed the independent influence of age (β = 0.107 [95% confidence interval, 0.017 to 0.197] per year; P = .02) but not BMI (P = .09). WIT2 influenced early graft function and was significantly longer in patients with primary graft nonfunction than in other recipients (35.3 vs 24.9 min; P < .01). According to receiver-operating characteristic curve analysis, a WIT2 value >26 min was predictive of primary graft nonfunction, with 64% specificity and 58% sensitivity. No correlations were found between WIT2 and estimated glomerular filtration rate in the long-term follow-up period.ConclusionsThis study found that WIT2 may significantly influence the early graft function. We also found that the creation time of vascular anastomoses does not affect the long-term kidney graft excretory function.