Early detection of renal ischemia by in situ microdialysis: an experimental study

Acute vascular thrombosis of the renal artery or vein is a feared and devastating complication after renal operations, especially transplantation. We evaluated microdialysis as a possible new tool for the rapid and reliable detection of renal ischemia in a porcine model.

A total of 20 healthy anesthetized pigs were randomized to experiments on the left or right kidney and into 3 groups, including arterial ischemia in 8, venous ischemia in 8 and 4 controls. One microdialysis catheter was inserted superficially in the renal cortex and 1 was placed outside on the renal capsule. The contralateral kidney was removed. After 2 hours of baseline measurements ischemia was introduced by clamping the renal artery or vein in the first 2 groups. Microdialysis samples were taken every 30 minutes during baseline and the following 5 hours. The samples were analyzed for glucose, lactate, glutamate and glycerol. The mean change from baseline was analyzed for each metabolite in all groups.

At 30 minutes after the introduction of arterial or venous ischemia there was a significant increased mean change from baseline of glutamate, glycerol and lactate in the cortex and of glutamate extracapsularly. The mean change from baseline of glucose in the cortex decreased significantly 60 minutes after venous ischemia and 90 minutes after arterial ischemia. In controls these metabolites did not change significantly from baseline with time.

Microdialysis from just outside the renal capsule is a reliable tool for the early detection of acute renal ischemia. It may be used to detect acute vascular complications in the first days after renal transplantation.