Glucose and lactate metabolism in well-perfused and compromised microvascular flaps

The success in microvascular flap transfer depends on the maintenance of optimal perfusion postoperatively. In addition to anastomosis thrombosis, other perfusion failures such as venous congestion, spasms, and kinks may appear. As perforator flaps become more frequent, it must be remembered that perforating vessels are more fragile and susceptible for trauma and mechanical compression. Sometimes, a flap is doing not well even though its anastomosis is patent. The flap perfusion can be measured using different tools in addition to clinical surveillance. We have used microdialysis in monitoring 268 microsurgical flaps and compared the metabolic data of normally perfused flaps to those that suffered from relative or absolute perfusion failure. We found that tissue glucose and lactate concentrations and especially their relation (lactate-to-glucose ratio) can show the presence of ischemia and aid in decision making, whether to reoperate or not. High lactate-to-glucose ratio may also predict total or partial flap necrosis.