Is Off Clamp Always Beneficial During Robotic Partial Nephrectomy? A Propensity Score-Matched Comparison of Clamp...

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.

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).

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.