Identification of kidneys subjected to preretrieval warm ischemic injury by simultaneous monitoring of glomerular filtration and perfusate flow during hypothermic perfusion preservation

Background. Historically, ex vivo physiological evaluation of cadaveric ren al allografts has been limited to assessing perfusate flow (PF) during hypo thermic perfusion preservation (HPP), Using a small animal model, we have p reviously described a method for continuous monitoring of glomerular filtra tion rate (GFR) during HPP, Our study was undertaken to determine if monito ring GFR and PF during HPP distinguished kidneys subjected to preretrieval warm ischemic (WI) injury more reliably than PF alone, Methods, In situ WI was induced in Lewis rats (n=10) by extrinsic occlusion of the suprarenal aorta for 30 min, After in situ cold perfusion and retri eval, the left kidney underwent 16 hr of HPP. Nonischemic (NI) control kidn eys (n=10) were retrieved in the absence of suprarenal aortic occlusion. Lo ngitudinal changes in PF, GFR, and filtration fraction (FF) during HPP were compared in WI versus NI kidneys (FF=GFR/PF x 100%). Results. PF remained the same in both cohorts throughout HPP. GFR, however, increased to a significantly greater degree in WI versus NI kidneys during the first 4 hr of HPP (713+/-401 vs. 26+/-23%, respectively) (P<0.05). The increase in FF at 4 hr was 1203+/-696% in the WI kidneys versus 83+/-46% i n the NI controls (P<0.05). Conclusions. In contrast to PF alone, measurement of both PF and GFR distin guished kidneys subjected to pre-WI from NI controls. The data provide a me ans to determine if monitoring of both GFR and PF during HPP will predict s hort- and long-term renal allograft function more reliably than PF alone.