Induction of cold ischemia in patients with solitary kidney using retrograde intrarenal cooling: 2-year functional outcomes

Purpose: Renal hypothermia is commonly utilized during nephron sparing surgery to minimize ischemic tissue damage. We propose a method to induce renal hypothermia using continuous retrograde irrigation of iced saline via dual-lumen ureteral catheter. We will report results in an ex vivo porcine model followed by clinical outcomes in a series of patients with solitary kidney undergoing robotic-assisted laparoscopic partial nephrectomy (RALPN). Materials and methods: First, we performed temperature measurements during retrograde renal cooling in a porcine model before investigating the technique in humans. In porcine experiments, renal cortical temperature measurements (n = 270) were recorded during retrograde infusion of ice-cold saline via a 10-Fr dual-lumen ureteral catheter placed in ureter. Subsequently, a series of patients (n = 10) undergoing RALPN with a solitary kidney had concomitant intra-operative retrograde renal cooling. A 10-Fr dual-lumen ureteral catheter was placed at initiation of anesthesia and cold saline initiated prior to renal artery clamping. Results: Porcine cortical temperature reached the target temperature (≤20 C) within an average of 203 s of retrograde irrigation. In the clinical series, patients' mean preoperative creatinine was 1.16 mg/dL (GFR = 60). At a median follow-up of 10 months (range 1-27 months), postoperative creatinine was 1.50 mg/dL (GFR = 41.28). Average clamp time was 19.4 min. All patients had negative surgical margins. Conclusions: Retrograde irrigation is a technically feasible method to induce cold ischemia, which may provide an additional protective effect of renal function in patients who have a solitary kidney undergoing surgery via a minimally invasive approach.