# Clinical Value of Transcutaneous PCO2 in Free Flap Blood Supply

## TL;DR

This study shows that transcutaneous PCO2 (TcPCO2) is a reliable method for monitoring blood supply in free flaps during oral cancer surgery.

## Contribution

The study demonstrates the high specificity of TcPCO2 in early detection of insufficient flap perfusion during oral cancer surgery.

## Key findings

- TcPCO2 levels were significantly higher in the insufficient flap group compared to the normal flap group.
- The cutoff value for TcPCO2 was 66 mmHg, with an AUC of 0.912 for predicting insufficient flap perfusion.
- TcPCO2 shows high specificity for monitoring free flap blood supply during oral cancer surgery.

## Abstract

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.