Transureteral Saline Perfusion to Obtain Renal Hypothermia: Potential Application in Laparoscopic Partial Nephrectomy

BACKGROUND: Partial nephrectomy for resection of renal tumors often requires renal artery clamping and external renal cooling using ice-slush. Laparoscopic surgery precludes traditional ice-slush cooling. To facilitate renal cooling during laparoscopic partial nephrectomy, we investigated a method of intrarenal cooling by retrograde transureteral iced saline perfusion. METHODS: Open laparotomy was performed in 6 pigs. After atraumatic renal artery clamping, one kidney was cooled externally by using standard ice-slush; the other was cooled transureterally. For transureteral cooling, the ureter was cannulated with a double lumen 12 Fr catheter. Chilled saline (4°C) irrigation was flushed through the catheter into the renal pelvis (16.7 mL/min) and allowed to drain via the second lumen of the catheter. Using a 30-gauge hypodermic thermometer, kidney temperatures were measured at 5-minute intervals for 30 minutes at 3 locations and 2 depths (0.5 cm and 1.5 cm). The animals were euthanized, and the kidneys were harvested for histologic examination. RESULTS: Renal cooling was achieved with both external and transureteral cooling. However, lower (5.0 versus 26.1°C, P<0.001) parenchymal temperatures were achieved more rapidly with external renal cooling. During transureteral cooling, medullary (1.5 cm) temperatures were lower than cortical (0.5 cm) temperatures were; this difference did not reach statistical significance. CONCLUSIONS: Although renal hypothermia can be achieved by transureteral iced saline infusion, external cooling by using ice-slush appears to be more efficient in the porcine model. With refinement of the technique, intrarenal cooling via a transureteral approach may allow more effective cooling of the renal medulla, and limit warm ischemia during laparoscopic partial nephrectomy.