Efficiency of Infrared Sensors in Free Flap Monitoring- An Observational Study

Abstract

Introduction: Free flap reconstruction is crucial in maxillofacial surgery for restoring form and function following trauma or oncological resection. Vascular compromise within the first 48 hours postoperatively poses the greatest threat to flap viability. Early detection is critical to improving salvage rates. Conventional monitoring techniques—clinical observation, Doppler ultrasound, and tissue oximetry—are limited by subjectivity, cost, invasiveness, or intermittent assessment.

Objective: This observational study evaluated the effectiveness of a novel, non-invasive, near-infrared (NIR) sensor system for real-time free flap monitoring using a compact ESP8266-based wireless module.

Materials and Methods: Following ethical approval, the sensor was tested on five healthy individuals using radial artery occlusion simulated with a blood pressure cuff. Data were collected before, during, and after induced ischemia. Readings were analyzed to determine sensitivity, specificity, and accuracy in detecting vascular compromise.

Results: Out of 20 total test instances, the sensor achieved a sensitivity of 90%, specificity of 70%, and overall accuracy of 80%. The average time to detect a change post-occlusion was 57 seconds. The F1 score was 81.8%, with a diagnostic odds ratio of 21. These results demonstrate the system’s potential in accurately identifying circulatory changes in a controlled setting.

Conclusion: This NIR-based prototype offers a promising, objective, and low-cost tool for continuous flap monitoring. While early results are encouraging, further validation in clinical settings and diverse patient populations is necessary. Integration into post-surgical workflows could enhance flap salvage rates by enabling timely intervention.