SRS323 - Feasibility of Photoplethysmography in monitoring free flap perfusion disturbance

Abstract Aim Vascular compromise is a critical complication in free flap surgery, and effective postoperative monitoring is essential for early detection and intervention. However, current flap monitoring methods are labor-intensive, subjective, and often inconsistent. Although several objective techniques have been proposed, no gold standard has yet been established. In this study, we investigated the potential of photoplethysmography (PPG) as a continuous, real-time method for detecting vascular compromise in free flaps. Methods We developed a flap phantom model consisting of silicone-based arteries and veins (3–4 mm in diameter) embedded within a silicone block to mimic the mechanical properties of soft tissue. An experimental circulation system was constructed to simulate three hemodynamic states: hypertension, normotension, and hypotension. Within each state, arterial and venous occlusion was induced using vascular clamps to replicate ischemia and congestion, respectively. Results PPG signals were recorded from the phantom under each condition. Distinct waveform changes were observed that enabled clear differentiation among ischemic, normal, and congested states across all pressure conditions. Conclusions This experimental model provides foundational evidence that PPG can detect characteristic hemodynamic changes associated with flap compromise. These findings support the future development of PPG-based monitoring systems for the early detection of vascular complications in clinical free flap surgery.