Clinical Value of Transcutaneous PCO₂ in Free Flap Blood Supply

Background: Transcutaneous PCO₂ (TcPCO₂) effectively represents the partial pressure of carbon dioxide in deep tissues, providing us with more accurate information regarding deep tissue perfusion and oxygen metabolism. Based on this, we aimed to explore the clinical value of TcPCO₂ in assessing free flap blood supply during oral cancer surgery. Methods: A total of 27 patients undergoing oral cancer reconstruction with free flap reconstruction were enrolled. For enrolled patients, continuous monitoring was conducted before, during, and after free flap transplantation surgery. Results: A total of 121 measurements were taken, comprising 93 instances in the normal flap group and 28 instances in the insufficient flap group. The TcPCO₂ levels were significantly higher and transcutaneous PO₂ (TcPO₂) levels were lower in the insufficient group (p < 0.001). The cutoff values for TcPCO₂ and TcPO₂, calculated using the Youden index, were 66 mmHg and 16 mmHg, respectively. TcPCO₂ exhibits high specificity in monitoring the blood supply of free flaps. The area under the ROC curve (AUC) for TcPCO₂ in predicting insufficient flap perfusion was calculated to be 0.912. Conclusions: TcPCO₂ demonstrates high specificity in assessing blood supply in free flaps for patients undergoing oral cancer surgery and has diagnostic significance for early identification of insufficient flap.