The Impact of Ischemia Time During Open Nephron Sparing Surgery on Solitary Kidneys: A Multi-Institutional Study

Purpose: The safe duration of ischemia during nephron sparing surgery remains controversial. We performed a multi-institutional study to evaluate the renal effects of vascular clamping in patients with solitary kidneys. Materials and Methods: Using the Cleveland Clinic and Mayo Clinic databases, we identified 537 patients with solitary kidneys who underwent open nephron sparing surgery. Renal complications were compared among patients who did not require vascular clamping (85), and those who had warm ischemia (174) and cold ischemia (278). Results: Median patient age (63, 65, 64 years) and preoperative creatinine (1.4, 1.3, 1.4 mg/dl) were similar among patients with no ischemia, warm ischemia and cold ischemia, respectively. Median tumor size was smaller in patients with no ischemia (2.5 cm), compared to patients with warm (3.5 cm) and cold (4.0 cm) ischemia (p <0.001). Warm and cold ischemia was associated with a significantly increased risk of urine leak (p = 0.006), acute (p <0.001) and chronic (p = 0.027) renal failure, and temporary dialysis (p = 0.028) compared to patients with no ischemia. Warm ischemia longer than 20 minutes and cold ischemia longer than 35 minutes were associated with a higher incidence of acute renal failure (p = 0.002 and p = 0.003, respectively). Additionally, warm ischemia more than 20 minutes was associated with an increased risk of chronic renal insufficiency (41% vs 19%, p = 0.008), increase in creatinine greater than 0.5 (42% vs 15%, p <0.001) and permanent dialysis (10% vs 4%, p = 0.145). Conclusions: Vascular clamping during open nephron sparing surgery is associated with a higher incidence of renal complications. Attempts to limit warm ischemia to 20 minutes and cold ischemia to 35 minutes should be used when vascular clamping is necessary.