Predictors, management and prognosis of initial hyperemia of free flap

In free flap operation, temporary hyperemia of the transferred flaps can often be encountered in the early postoperative period, appearing reddish and rapid capillary refilling time, which mimics venous congestion. This study aimed to investigate the factors associated with the development of hyperemia and evaluate clinical course. Consecutive patients who underwent free flap-based reconstruction between December 2019 and October 2021 were reviewed. Independent risk factors associated with its development were assessed. Flap showing initial hyperemic features were assessed using flap blood glucose measurement (BGM). If it showed over 60 mg/dL, they were closely observed without management. Their clinical outcomes were evaluated. In total, 204 cases were analyzed, of which 35 (17.2%) showed initial hyperemia. Multivariable analyses showed that using thoracodorsal artery perforator flaps and muscle containing flaps (musculocutaneous/muscle-chimeric flaps) and conducting end-to-end arterial anastomosis (vs. end-to-side) were independent predictors. All cases with initial hyperemia showed over 60 mg/dL in BGM. The phenomenon resolved spontaneously within 6.9 h averagely. Overall perfusion-related complications developed in 10 (4.9%) cases, which rate did not differ between the two groups. Several factors might be associated with the development of initial hyperemia after free flap surgery. With proper assessment, this condition can be successfully managed without unnecessary intervention.