Extraction Time of Kidneys from Deceased Donors and Impact on Outcomes

Abstract

Cold ischemia time (from flush to out-of-ice) and warm ischemia time (from out-of-ice to reperfusion) are known to impact delayed graft function (DGF) rates and long-term allograft survival following deceased donor kidney transplantation. We propose an additional ischemia time, extraction time, beginning with aortic cross-clamp and perfusion/cooling of the kidneys, and ending with removal of the kidneys and placement on ice on the backtable. During this time the kidneys rewarm, suffering an additional ischemic insult, which may impair transplant function. We measured extraction times of 576 kidneys recovered and transplanted locally between January 2006 and December 2008, then linked to Scientific Registry of Transplant Recipients (SRTR) data for outcomes. Extraction time ranged from 14 to 123 min, with a mean of 44.7 min. In SRTR-adjusted analyses, longer extraction time and DGF were statistically associated (odds ratio [OR] = 1.19 per 5 min beyond 60 min, 95% confidence interval [CI] 1.02-1.39, p = 0.03). Up to 60 min of extraction time, DGF incidence was 27.8%; by 120 min it doubled to nearly 60%. Although not statistically significant (OR = 1.19, 95% CI 0.96-1.49, p = 0.11), primary nonfunction rate also rose dramatically to nearly 20% by 120 min extraction time. Extraction time is a novel and important factor to consider when evaluating a deceased donor kidney offer and when strategizing personnel for kidney recovery.