Selective Application of Blood Glucose Monitoring After Free Flap Surgery: Potential Indications in Real-World Practice

Background For free-flap monitoring, physical examination still serves as the criterion standard. Blood glucose measurement (BGM) has been suggested to be useful in identifying flap perfusion status. Nonetheless, its routine use may not be cost-effective in real-world settings. This study aimed to share the experiences of using BGM for flap monitoring and suggest its potential indications. Methods Of cases of free flap reconstruction conducted between March 2017 and May 2021, those using BGM for flap monitoring were reviewed. Blood glucose measurement was selectively conducted for the following specific situations, which included encountering a flap showing a reddish discoloration and/or rapid capillary refilling time in the immediate postoperative period, monitoring discolored flaps after conducting a salvage operation, and conducting bloodletting therapy for salvaging congestive flaps. The clinical course and outcomes were evaluated. Results Of a total of 203 cases, 35 used BGM for flap monitoring in addition to clinical examination. In 29 cases, BGM was performed to distinguish early hyperemia from true venous insufficiency. All flaps showed BGM greater than 60 mg/dL with a mean value of 115.42, suggesting early hyperemia, and had uneventful postoperative courses. In 3 cases with already discolored flaps after a salvage operation, BGM was conducted 4 times serially every 3 hours and showed a mean value of 81.6 mg/dL with increasing trends. The flaps recovered completely. In the other 3 cases requiring bloodletting therapy, BGM was conducted an average of 11 times at a median interval of 7 hours. The bloodletting therapy was terminated with reference to the value of BGM when it showed greater than 60 mg/dL while the therapy was on hold. All flaps were successfully salvaged except one showing partial necrosis. Conclusions Blood glucose measurement may be helpful in assessing flap perfusion and decision making in certain clinical situations and may be useful as an ancillary tool for flap monitoring. Selective application of BGM may contribute to achieving optimal outcomes.