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WCE 2018: Effects of Warm Ischemia Time on Kidney Function after Partial Nephrectomy

Paris, France (UroToday.com) Concerns regarding the decline in renal function following partial nephrectomy have given rise to a variety of surgical techniques and maneuvers that intend to reduce kidney damage. These, among others, include early unclamping of the renal artery, off-clamp tumor resection, and cold ischemia. A group of urologists and interventional radiologists from Norway sought to decrease warm ischemia time using preoperative selective embolization of tumor vessels (PSET). The decline in eGFR in a group of patients undergoing PSET followed by laparoscopic partial nephrectomy was compared to that of patients undergoing robotic partial nephrectomy without PSET.

In this small pilot study, 5 patients were treated with PSET followed by laparoscopic partial nephrectomy, and were compared to 16 patients undergoing robotic partial nephrectomy with standard renal artery clamping. R.E.N.A.L. nephrometry scores were comparable in both groups. Preoperatively, metallic coils were used to occlude arteries supplying the renal tumor (at the level of third division of the main renal artery). It was found that for patients who had PSET, ischemia time was significantly shorter (8 v. 21 minutes) and in fact, in 3/5 patients tumor resection was achieved off-clamp. There was also a significant difference between the groups in early postoperative decline in eGFR (5 vs. 21 mL/min/1.73m2). The threshold of warm ischemia time for detectable decline in eGFR was 6 minutes, and a strong linear correlation between ischemia time and eGFR was observed. According to Dr. Lauridsen, the metallic coils were distant enough from the tumor margins and did not interfere with tumor resection.

There are several limitation to this study. These include a small number of patients and comparison of two different procedures (laparoscopic and robotic partial nephrectomy). Despite similar R.E.N.A.L. nephrometry scores, other variables can account for the change in ischemia time and decrease in eGFR. Lastly, postoperative renal function is better evaluated using a DMSA scan rather than eGFR (based on creatinine level) as the overall renal function is compensated by the contralateral kidney. Nevertheless, this technique offers an attempt to preserve renal function in selected patients with kidney tumors.

Presented by: Dr. Jacob Midtlid Lauridsen 

Written by: Dr. Shlomi Tapiero, Department of Urology, University of California-Irvine, medical writer for UroToday.com. at  the 36th World Congress of Endourology (WCE) and SWL - September 20-23, 2018 Paris, France