Detection of renal ischemia by in situ microdialysis – an experimental study

Abstract

Purpose Postoperative ischemia in the transplanted kidney is a dangerous condition that might cause loss of the renal graft. Microdialysis is a new promising technique for continuously in vivo measuring of local metabolism. Microdialysis has previously proven valuable for postoperative monitoring of the free flap after reconstructive surgical procedures. The aim of this study was to investigate if microdialysis could be a reliable detector of ischemia in a healthy porcine kidney after occlusion of the renal artery or vein. Material and methods 15 healthy pigs weighing 37 kg were used. (n=7 subjected to arterial occlusion, n=8 subjected to venous occlusion) After removal of the contralateral kidney one microdialysis catheter (CMA 60) was inserted superficially in the renal cortex and one catheter was placed just outside the renal capsule. After baseline measurements ischemia was introduced by occlusion of the renal artery or vein. The microdialysis was analysed for glucose, lactate, glutamate and glycerol. Results Glucose, lactate, glutamate and glycerol measured by microdialysis remained stable in and outside the kidney for a baseline period of 2 hours. 30 minutes after occlusion of the renal artery or vein there was a significant increase in lactate and glutamate. After one hour there was a significant increase in glycerol and decrease of glucose measured by microdialysis, indicating anaerobic metabolism had started in the tissue due to ischemia. The concentrations of glucose and lactate in the systemic blood remained stable. Conclusions Microdialysis seems a reliable tool for early detection of ischemia in a previously normal kidney. Postoperative ischemia in the transplanted kidney is a dangerous condition that might cause loss of the renal graft. Microdialysis is a new promising technique for continuously in vivo measuring of local metabolism. Microdialysis has previously proven valuable for postoperative monitoring of the free flap after reconstructive surgical procedures. The aim of this study was to investigate if microdialysis could be a reliable detector of ischemia in a healthy porcine kidney after occlusion of the renal artery or vein. 15 healthy pigs weighing 37 kg were used. (n=7 subjected to arterial occlusion, n=8 subjected to venous occlusion) After removal of the contralateral kidney one microdialysis catheter (CMA 60) was inserted superficially in the renal cortex and one catheter was placed just outside the renal capsule. After baseline measurements ischemia was introduced by occlusion of the renal artery or vein. The microdialysis was analysed for glucose, lactate, glutamate and glycerol. Glucose, lactate, glutamate and glycerol measured by microdialysis remained stable in and outside the kidney for a baseline period of 2 hours. 30 minutes after occlusion of the renal artery or vein there was a significant increase in lactate and glutamate. After one hour there was a significant increase in glycerol and decrease of glucose measured by microdialysis, indicating anaerobic metabolism had started in the tissue due to ischemia. The concentrations of glucose and lactate in the systemic blood remained stable. Microdialysis seems a reliable tool for early detection of ischemia in a previously normal kidney.