*Purpose: Second warm ischemia time (SWIT) of a renal allograft during anastomosis increases rates of delayed graft function and premature graft failure. In the setting of complex anatomy SWIT can be protracted, and in the context of minimally invasive surgery the time required, particularly in the presence of a significant learning curve, increase anastomosis time and kidney rewarming, resulting in an average SWIT of 40-73 min and limiting its use to a few sites. Furthermore, the difficulty of transplanting obese patients, and their associated complication rates, have prevented patients from qualifying for kidney transplantation. An intra-operative facilitation device with an incorporated method of temperature regulation was developed to address this clinical need.

*Methods: ASTS surgeons (n=185) and organ preservation specialists were surveyed and interviewed to develop the needs-criteria for an intraoperative allograft cooling device. A single use device without tubing applied externally to the donor kidney prior to anastomosis was developed using a combination of hydrogel and a phase-change material to absorb heat from the kidney. Adult porcine kidneys (n=9) were used to test the device in a validated retroperitoneal-cavity model at 37^oC (98.6^oF). Surface, cortex, and medulla temperatures were monitored using implanted temperature probes.

*Results: A standalone device that facilitates the vascular anastomosis while preventing warming and eliminating second warm ischemia was developed. Porcine kidney temperatures remained at 4^oC +/- 2^oC (35.6-42.8^oF) for 60 minutes, whereas control kidney temperatures exceeded the minimum threshold of necrosis 15^oC (59^oF) at 10 minutes and plateaued at 34^oC (93.2^oF) at 60 minutes. The needs criteria were appropriately met by the device design.

*Conclusions: Warming of the renal allograft during anastomosis is independently associated with increased rates of delayed graft function and premature graft failure. An intracorporeal cooling device without tubing or wires has been developed to effectively eliminate SWIT and address these challenges. Tested kidneys remained well below the thermal threshold of necrosis for the duration of 95% of anastomoses.

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