To evaluate the impact of extended warm ischemia on incidence of acute kidney injury (AKI) and ultimate functional recovery after partial nephrectomy (PN), incorporating rigorous control for loss of parenchymal mass, and embedded within comparison to cohorts of patients managed with hypothermia or limited warm ischemia.

From 2007 to 2014, 277 patients managed with PN had appropriate studies to evaluate changes in function/mass specifically within the operated kidney. Recovery from ischemia was defined as %function saved/%parenchymal mass saved. AKI was based on global renal function and defined as a ≥1.5-fold increase in serum creatinine above the preoperative level.

Hypothermia was utilized in 112 patients (median = 27 minutes) and warm ischemia in 165 (median = 21 minutes). AKI strongly correlated with solitary kidney (P < .001) and duration (P < .001) but not type (P = .49) of ischemia. Median recovery from ischemia in the operated kidney was 100% (interquartile range [IQR] = 88%-109%) for cold ischemia, with 6 (5%) noted to have <80% recovery from ischemia. For the warm ischemia group, median recovery from ischemia was 91% (IQR = 82%-101%, P < .001 compared with hypothermia), and 34 (21%) had recovery from ischemia <80% (P < .001). For warm ischemia subgrouped by duration <25 minutes (n = 114), 25-35 minutes (n = 35), and >35 minutes (n = 16), median recovery from ischemia was 92% (IQR = 86%-100%), 90% (IQR = 78%-104%), and 91% (IQR = 80%-96%), respectively (P = .77).

Our results suggest that AKI after PN correlates with duration but not with type of ischemia. However, subsequent recovery, which ultimately defines the new baseline glomerular filtration rate, is most reliable with hypothermia. However, most patients undergoing PN with warm ischemia still recover relatively strongly from ischemia, even if extended to 35-45 minutes.