Tourniquet-induced ischemia and reperfusion in human skeletal muscle

Microdialysis conceivably enables longitudinal and simultaneous investigation of several metabolites by repeated measurements in skeletal muscle. We used and evaluated microdialysis as an in vivo method to characterize the time-course and relative kinetics of pyruvate, glucose, lactate, glycerol, hypoxanthine, uric acid, and urea, in skeletal muscles, exposed to ischemia and reperfusion, in eight patients having arthroscopic-assisted anterior cruciate ligament reconstruction. A dialysis probe was implanted before surgery in the rectus femoris muscle. Dialysate samples were collected at 10-minute intervals at a flow rate of 1 microL/minute until 2 hours after tourniquet deflation. Ninety minutes of ischemia resulted in accumulation of lactate (234% +/- 38%), hypoxanthine (582% +/- 166%), and glycerol (146% +/- 46%), consumption of glucose (54% +/- 9%) and pyruvate (16% +/- 44%), and a slight decrease of urea (78% +/- 11%) compared with baseline (100%). Uric acid was unchanged (95% +/- 12%). Within 90 minutes after tourniquet deflation the concentrations were virtually normalized for all measured metabolites, suggesting that the duration of ischemia was well tolerated by the patients. The results indicate that the use of microdialysis for monitoring energy metabolic events during orthopaedic surgery that requires ischemia and reperfusion is feasible and safe.