Detection of Microvascular Failure Using Bioimpedance and Sensor-derived Clinical Indicators: A Preliminary Study

Early detection of flap failure is critical for successful salvage surgery outcomes. Delays in diagnosis can lead to additional surgical intervention, tissue necrosis, or even flap loss. Current monitoring methods rely heavily on intermittent clinical evaluations, which are subjective and time-consuming and may miss early signs of failure. A continuous, objective monitoring system could significantly improve detection accuracy and response times. This study explores a multisensory strategy to identify early physiological changes associated with flap failure.

Using a rat hindlimb model, flap failure was simulated via femoral vein or artery clamping (n = 5 per group). Physiological responses-including temperature, skin color, and bioimpedance-were recorded continuously for 2 hours postclamping with sensors. Statistical significance was set at a P value less than 0.05 using a 1-sample t test. Distinct failure patterns were compared against nonclamped controls.

Clear physiological trends emerged in failure groups. We preliminarily validated a multisensor approach for free flap monitoring in a rat model using temperature, bioimpedance, and color sensing. Each modality provided distinct and complementary insights into perfusion changes: color sensing detected changes fastest but was more variable, temperature changes were moderate and potentially influenced by external heating, and bioimpedance showed the most consistent trends over time, highlighting the value of a combined sensing strategy for reliable tissue viability assessment.

This multisensory approach demonstrates strong potential for early, noninvasive flap failure detection through continuous monitoring of temperature, color, and bioimpedance. These findings support further development of real-time sensing systems to enhance surgical outcomes and patient safety in flap-based procedures.