Does prolonged warm ischemia after partial nephrectomy under pneumoperitoneum cause irreversible damage to the affected kidney?

Purpose: We determined the effects of warm ischemia time on the recovery of renal function after partial nephrectomy under pneumoperitoneum. Materials and Methods: In this prospective study 37 consecutive patients who underwent laparoscopic partial nephrectomy or robot-assisted partial nephrectomy between June 2008 and May 2009 to remove a single cT1 renal tumor were evaluated using ^99mTc-diethylenetriamine pentaacetic acid renal scintigraphy preoperatively, and at 3 and 12 months postoperatively. Results: The most significant reduction in the glomerular filtration rate of the affected kidney at 3 and 12 months after surgery (p = 0.018, p = 0.036, respectively) was seen for a warm ischemia time cutoff of 28 minutes. The glomerular filtration rate of the affected kidney was consistently and significantly reduced at 3 and 12 months postoperatively (-22.4% to -30.6%, p <0.001) in patients with a warm ischemia time greater than 28 minutes. In contrast, no significant glomerular filtration rate change was seen in patients with a warm ischemia time of 28 minutes or less. In terms of the contributional change of the affected kidney to total renal function, there is a trend toward a recovery after an initial decrease in both groups with a warm ischemia time greater than 28 minutes vs 28 minutes or less. On multivariate analysis warm ischemia time was a strong independent predictor of glomerular filtration rate reduction even 12 months after surgery (β = -1.3; 95% CI -1.8, -0.7; p <0.001). Conclusions: If the warm ischemia time is greater than 28 minutes during laparoscopic partial nephrectomy or robot-assisted partial nephrectomy, the functional damage to the affected kidney progresses even up to 1 year after surgery.