*Purpose: Traumatic brain injury patients benefit from mild to moderate hypothermia (32-35 °C); and in patients with cardiac arrest, stroke, and asphyxia, hypothermia is and greatly reduces ischemia-related toxicity on neuronal function. Due to organ viability being better preserved in hypothermic patients, deceased donors who receive the hypothermia protocol have been postulated to present an advantage.. While prior studies expose hypothermia as a crucial component in organ viability, they overlook important variables such as BMI, age, gender, and smoking status. Furthermore, the majority of studies have solely focused on kidney graft function while liver allograft function post-hypothermia has not been studied. This study aims to unify these important variables to examine the effect of donor hypothermia on kidney and liver allograft function.

*Methods: This study used data from the United Network for Organ Sharing (UNOS.) Donors with and without a history of hypothermia protocol were extracted from the database. Within these two cohorts, acute (6 months post-transplant) and chronic rejection (1 year post-transplant) was analyzed. Non-cooled (euthermic) donors were concurrently explored as a controls. Donor organs that had acute(AR) or chronic allograft rejection(CR) were further stratified on the basis of age and BMI. This was done to assess if high BMI and age, two significant contributors to allograft failure, could be mitigated by donor hypothermia

*Results: Of the 4,297 liver donors, 2,090 patients received the hypothermia protocol and 2,207 did not. Of the 21,306 kidney donors, 10,487 received the hypothermia protocol and 10,819 did not. In liver transplant patients, median graft lifespan for hypothermic organs was 731 days. AR percentages between hypothermic and euthermic donors was 12.4% vs. 11.8% and 15.3% vs. 13.8% for CR, respectively. In kidney transplant patients, median graft lifespan for hypothermic and euthermic organs was 816 days and 1,240 days, respectively. AR percentages between hypothermic and euthermic donors was 9.1% vs. 9.5% and 10.5% vs. 11.6% When stratifying for donor characteristics such as age (>65) and BMI (>25), high risk hypothermic donors had similar outcomes to their euthermic counterparts.

*Conclusions: While hypothermia remains a life saving procedure, its’ benefit on liver allograft survival is limited There is an increase in chronic and acute rejection among liver recipients with donor hypothermia. Hypothermic kidney donors have shorter survival but slightly lower rates of chronic and acute rejection. The similarities seen in high risk donors across both hypothermic and euthermic cohorts suggest that perceived benefits of hypothermia do not necessarily increase functioning of the allograft in a high risk donor population. The apparent decline in graft survival is minimal but should be further explored to accurately assess the outcome of hypothermia in transplanted organs.

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