The impact of ischemia on long-term renal function after partial nephrectomy in the two kidney model

Purpose: To determine whether on-clamp partial nephrectomy (ON-PN) has any significant impact on long-term renal function in a two kidney model. Patients and Methods: From November 1999 to July 2013, 607 patients underwent PN at our institution. After excluding patients with solitary kidneys, multiple renal masses, and follow-up less than 90 days, 331 remained. Patient demographics were assessed, as was renal function based on pre- and postoperative mercaptoacetyltriglycine (MAG-3) renal scans and change in estimated glomerular filtration rate (eGFR) using the preoperative and most recent recorded creatinine levels. Results: There were a total of 236 patients who underwent ON-PN and 95 who underwent off-clamp PN (OFF-PN) during the study period. The longest follow-up was 12.6 years with mean follow-up of 3 years. Mean ischemia time of patients undergoing ON-PN was 25 minutes (range 8-63 min). No differences were noted between the ON-PN and OFF-PN cohorts with respect to estimated change in eGFR (ON-PN: -6.07 mL/min/1.73 m² vs OFF-PN: -6.00 mL/min/1.73 m², P=0.69). No differences were noted in the % change in the MAG-3 renal scans (ON-PN: -0.77% vs OFF-PN: -1.1%, P=0.94). A post hoc sensitivity analysis of the same two variables stratified by age revealed no differences in change in estimated GFR or % change in differential function on renal scan. Conclusions: In the two kidney model, ischemia does not appear to affect long-term renal function outcomes after PN. These data provide evidence that ON-PN is perfectly acceptable in the appropriately selected patient with two kidneys.