Glucose, lactate, and pyruvate response in an experimental model of microvascular flap ischemia and reperfusion: a microdialysis study.

Early diagnosis of postoperative perfusion failure is essential in microsurgical tissue transfer. In order to determine if microdialysis could be used in diagnosing flap ischemia, we tested this method in an experimental pig model. Sixty-six flaps (34 myocutaneous and 29 cutaneous) were created in 18 anesthetized pigs. During the experiment, secondary ischemia was induced for 5 h by selective clamping of the artery (20 flaps) or vein (21 flaps). Glucose, lactate, and pyruvate concentrations were measured hourly from the muscular and dermal layers. We found that decreasing glucose levels and increasing lactate concentrations were associated with arterial and venous occlusions from the first hour of ischemia. In venous ischemia, lactate concentrations remained lower than those in arterial ischemia. The increase in lactate-to-pyruvate and lactate-to-glucose ratios was related to ischemia and also discriminated arterial occlusion from venous occlusion. In conclusion, microdialysis can be used to facilitate early detection of ischemia.