Factors affecting renal function after open partial nephrectomy - A comparison of clampless and clamped warm ischemic technique

Objective: To analyze factors impacting postoperative renal function after open partial nephrectomy using both the clampless and clamped warm-ischemic technique. Methods: We studied a cohort of patients who underwent clamped partial nephrectomy (n = 164) and clampless partial nephrectomy (n = 64) from March 2002 to March 2009 with <12-months follow-up. Clamped partial nephrectomy used hilar occlusion before resection. Clampless partial nephrectomy used focal radio frequency coagulation to facilitate hemostasis before resection, nonischemic dissection/resection with hydro-dissection, or sharp resection after local compression. Demographics, tumor characteristics/RENAL nephrometry scores, perioperative variables, and complications were compared between the two methods. Multivariable analysis was performed to identify factors predicting de novo estimated glomerular filtration rate <60. Results: Patient characteristics were similar between groups. Mean RENAL score was greater in clamped (6.9) vs clampless (6.4, P =.026); complications (P =.430) and urine leaks (clampless partial nephrectomy 3.1% vs clamped-PN 7.3%, P =.360) were similar. Mean warm ischemia time (min) was 24.5 for clamped partial nephrectomy. De novo estimated glomerular filtration rate <60(%) at last follow up was 13.5 (clamped) vs 3.1 (clampless) (P =.071). Multivariable analysis of the entire cohort revealed increasing body mass index (OR 1.1, P =.042) and RENAL score (OR 1.71, P =.002) as being independently associated with development of postoperative de novo estimated glomerular filtration rate <60. Multivariable analysis of the clamped subgroup demonstrated increasing body mass index (OR 1.12, P =.028), RENAL score (OR 1.56, P =.010), and ischemia time (OR 1.15, P =.042) as independent factors associated with de novo estimated glomerular filtration rate <60. Conclusion: Body mass index and RENAL score were factors predictive of development of de novo estimated glomerular filtration rate <60 after partial nephrectomy, with increasing warm ischemia time also being predictive in clamped partial nephrectomy patients. Further investigation and long-term functional data are requisite.