Is Off Clamp Always Beneficial During Robotic Partial Nephrectomy? A Propensity Score-Matched Comparison of Clamp Technique in Patients with Two Kidneys

Abstract

OBJECTIVE: The majority of patients undergoing partial nephrectomy (PN) present with a clinical T1a tumor with both kidneys present. Some groups have advocated using off-clamp (Off-C) techniques to eliminate warm ischemia whenever possible, even when elective. We evaluated whether Off-C technique during robotic PN (RPN) provides any functional benefit over main arterial clamping (MAC) in these patients. Subjects/Patients and Methods: A total of 351 patients with a R.E.N.A.L. nephrometry score (RNS) <10, T1a tumor, and two kidneys who underwent RPN from five high-volume surgeons between 2008 and 2016 were retrospectively identified from a multi-institutional database. MAC and Off-C patients were 2 to 1 nearest neighbor propensity score matched on tumor size, RNS, % endophytic, tumor location, age, gender, body mass index, comorbidities, baseline estimated glomerular filtration rates (eGFRs), and surgeon performing the RPN. Preoperative, surgical, and postoperative outcomes were compared. RESULTS: After propensity score matching, 82 MAC and 41 Off-C RPN patients were compared with no remaining statistically significant differences in baseline demographic or tumor-specific characteristics, including tumor size (p = 0.203) or RNS (p = 0.744). There were no significant differences in complications (p = 0.141), positive surgical margins (p = 0.625), or non-neoplastic parenchymal volume removed (p = 0.138). Off-C RPN had significantly higher estimated blood loss (100 mL vs 50 mL, p < 0.001), but no increased rate of transfusion (p = 0.328). There were no significant differences in rates of acute kidney injury (p = 0.132) nor percentage change in eGFRs (p = 0.763) at discharge. Freedom from progression of chronic kidney disease (CKD) stage was 87.7% for MAC and 91.1% for Off-C at 12 months. The percentage change in eGFRs (p = 0.457) and CKD stage progression (p = 0.866) was not different at last follow-up (median 9.2 months). CONCLUSION: Our data showed that the use of Off-C RPN marginally increased blood loss without providing a renal function benefit. In two-kidney patients presenting with a T1a renal tumor, Off-C RPN may not be necessary.