Ratio of Blood Glucose Level Change Measurement for Flap Monitoring.

Background: In a setting of flap congestion, early detection and rapid reexploration are important. Some studies described the efficacy of blood glucose measurement for flap monitoring.1 However, the sensitivity and specificity of this method were not high enough to determine whether reexploration should be done or not. The purpose of this study was to evaluate and establish a method using the ratio of blood glucose level change (RBGC) measurement for detecting venous thrombosis and to propose an algorithm for flap salvage after congestion.

Methods: Blood glucose level was measured in 36 free tissue transfers over time postoperatively and RBGC was calculated. When flap congestion was suspected, frequent blood glucose measurement and some countermeasures were performed complying with an algorithm. If the venous thrombus was suspected, the reexploration was performed. The RBGCs at the points in time when the venous thrombosis was detected were compared with those at the points in time when the flap demonstrated no venous thrombosis.

Results: Of the 36 flaps, 30 flaps demonstrated no venous thrombosis and 6 flaps demonstrated venous thrombosis. Four flaps demonstrated signs of congestion but improved after the reexploration. The mean RBGCs at the points in time when the venous thrombosis was detected was -7.61 mg/dl h and those at times when the flap demonstrated no venous thrombosis was 0.10 mg/dl h, the former being significantly lower than the latter.

Conclusion: Using the flap monitoring method using RBGC measurement, we could salvage some flaps from the congestion due to the venous thrombosis without unnecessary reexploration.