Microdialysis for Detection of Renal Ischemia After Experimental Renal Transplantation

PURPOSE: We designed an experimental renal transplantation model and evaluated microdialysis as a detector of induced postoperative ischemia, a feared complication that when caused by vascular thrombosis most often causes renal graft loss. MATERIALS AND METHODS: Two microdialysis catheters were placed in the left kidney in 16 pigs, including 1 superficially in the renal cortex and 1 fixed on the renal capsule. Two-hour baseline measurements were made at steady state, after which the kidney was removed and subjected to warm and cold ischemia. It was subsequently re-anastomosed end to end in situ and reperfused for 5 hours. Pigs were then randomized into a total renal artery occlusion and a control group. RESULTS: At baseline there were no changes in local metabolites (glucose, glutamate, glycerol and lactate) and no significant difference between the groups. Glycerol increased 4-fold in each group during cold ischemia but there were no pivotal alterations in other metabolites. After kidney reperfusion glycerol decreased and all metabolites were in steady state after 1 hour. At 30 minutes after postoperative ischemia was introduced there were significant increases in all kidneys in ischemia vs steady state reperfusion levels of cortical lactate, glutamate, glycerol and the lactate-to-glucose ratio (each rank sum test p <0.001). No metabolic changes were seen in controls. CONCLUSIONS: Microdialysis detected significant metabolic changes after postoperative ischemia in pigs with experimental renal transplantation, while no metabolic changes were observed in controls. In the future microdialysis may become a valuable tool for postoperative observation of transplanted kidneys, most probably with major impact on early graft survival.