Use of Main Renal Artery Clamping Predominates Over Minimal Clamping Techniques During Robotic Partial Nephrectomy for Complex Tumors

Introduction: Hilar clamping is often performed to facilitate robotic partial nephrectomy (RPN). Minimal clamping techniques may reduce renal ischemia, including early unclamping, selective clamping, and off-clamp RPN. We assess the utilization of clamping techniques in a large international consortium of surgeons performing RPN for complex tumors. Methods: We retrospectively evaluated 721 patients with complex tumors, who underwent RPN at 11 centers worldwide between 2008 and 2014. Complex tumors were defined as renal masses with a nephrometry score > 6. Total clamping was defined as complete clamping of the main renal artery. Minimal clamping techniques included early unclamping, selective clamping, and off-clamp RPN. Clamping techniques were additionally assessed in patients with estimated glomerular filtration rate (eGFR) < 60 and in patients with a solitary kidney. Two-tailed t-tests (p < 0.05) were used to statistically analyze differences in mean warm ischemia time (WIT). Results: Most patients underwent complete clamping (75.1%). Minimal clamping (24.9%) included early unclamping (10.8%), selective clamping (8.7%), and off-clamp (5.4%). Mean WIT of total clamping, selective clamping, and early unclamping was 22.2, 21.2, and 17.3 minutes, respectively. Of patients with an eGFR < 60 (n = 90), 26.6% underwent minimal clamping, including 15.5% early unclamping, 4.4% selective clamping, and 6.7% off-clamp. Of patients with solitary kidneys (n = 12), 10 (83%) were performed with total clamping with mean WIT of 14.9 minutes. Conclusions: In this large international series of RPN for complex tumors, most patients underwent total clamping of the main renal artery. Minimal clamping techniques, including early unclamping, selective clamping, and off-clamp techniques, were used in a minority of cases. There was no significant increase in use of minimal clamping, even in patients with chronic kidney disease or solitary kidneys. However, mean WIT was low (< 23 minutes) in all patient groups.