Ex vivo evaluation of organ function after cold ischemia

An ex vivo perfusion of kidneys was performed at 34 degrees C after cold is chemia of 24, 48, 72, and 96 hours to evaluate organ function prospectively . The prospective evaluation of organ function followed static hypothermic storage of the kidneys in a solution representative of clinical organ prese rvation. The warm perfusion was performed with an acellular solution that s upports oxidative metabolism of sufficient magnitude to restore urine flow ex vivo. The parameters of organ function evaluated included oxygen consump tion, vascular resistance, urine flow, and glomerular filtration rates, whi ch were correlated with the histologic findings. The results of this study suggest that kidneys exposed to 24 and 48 hours of cold ischemia demonstrat ed oxygen consumption rates and vascular dynamics similar to control kidney s without exposure to cold ischemia, indicating cell viability. When the co ld ischemic period was increased beyond 48 hours of preservation, substanti ally reduced rates of oxygen consumption and increased vascular resistances were observed, representing a loss of viability confirmed histologically. However, organ function was found to be impaired after exposure to cold isc hemia at every time point. These results suggest that cold ischemic exposur e had a negative impact on immediate renal function once oxidative metaboli sm was restored, which was excerbated as the cold ischemic period was exten ded. Furthermore, these findings suggest that although the renal cells were viable after cold ischemic exposure, the viability status did not result i n immediate function. Therefore, assessment of an organ based solely on cel l viability may falsely indicate a functional organ. It will be necessary t o identify parameters of organ function that can distinguish reversibility from nonreversibility of cellular impairment to distinguish permanent funct ional disturbances. The ability to predict organ function prospectively wil l be an important aspect of any effective future expansion of the organ don or pool.