Presentation Authors: Thomas Skinner*, Ottawa, Canada, Ali Dergham, Kingston, Canada, Luke Witherspoon, Ottawa, Canada
Introduction: In renal transplantation, warm ischemia time (WIT) describes the period of ischemia beginning with removal of the organ from ice and concluding at reperfusion. WIT is associated with delayed graft function, and adverse patient and graft long-term survival. Metabolic activity in cooled kidneys is minimal at 5Â°C and resumes above 15Â°C, a temperature reached after only 15 min of WIT. This is of clinical significance because WIT in renal transplantation is often > 40 min. The solution lies not in rushing the anastomosis but maintaining renal hypothermia during the process. Although various devices have been proposed, most suffer from being too bulky, inefficient, expensive, or prone to puncture. We set out to develop a novel, inexpensive device to maintain allograft temperatures â‰¤ 5Â°C, thereby limiting ischemic damage.
Methods: 3/16&[Prime] aluminum tubing was organized in a serpentine pattern to create a malleable, form-fitting cooling jacket. Coolant comprised 4°C saline solution flowing at 240 mL/min. Adult porcine kidneys (n = 4) (175 g, 13x7x3 cm LxWxH) were used to test the device. Kidneys were placed at 24Â°C; surface and core temperatures were monitored using implanted thermocouples. Device usability was tested by anastomosing porcine kidney vessels to GORE-TEXÂ® vascular grafts with the cooling jacket in place in a simulated ex-vivo operative field.
Results: Our cooling jacket costs less than $3.00 to produce and is mouldable to any size kidney. The device resulted in mean surface and core temperatures at 60 min of (mean Â± standard deviation (SD)) 5.8Â±0.6Â°C and 5.4Â±0.5Â°C respectively, significantly less than those of the control; 16.6Â±1.4Â°C and 16.6Â±1.2Â°C, respectively (p < 0.00001 for both). Moreover, our device mitigated surface temperature increases (2.4Â±1.3Â°C vs. 12.9Â±0.9Â°C) and core temperature increases (2.8Â±1.7Â°C vs. 14.1Â±1.5Â°C) at 60 min (p < 0.00001). Surface and core temperatures were significantly lower in cooled kidneys compared to controls within 5 minutes of removal from ice (p < 0.05). Ex-vivo anastomotic testing was not inhibited or delayed by our device during testing by expert transplant surgeons.
Conclusions: WIT is associated with many adverse outcomes. We developed a novel inexpensive, and easy-to-use aluminum cooling jacket that mitigated temperature increase, and maintained renal temperatures below metabolically-active levels.