Free flap pulse oximetry utilizing reflectance photoplethysmography

The successful salvage of a free flap is dependent on the continuous monitoring of perfusion. To date there is no widely accepted and readily available post-operative monitoring technique to reliably assess the viability of free flaps by continuously monitoring free flap blood oxygen saturation. In an attempt to overcome the limitations of the current techniques a reflectance photoplethysmographic (PPG) processing system has been developed with the capability of real-time estimation of arterial oxygen saturation (SpO₂) levels implemented in LabVIEW. This system was evaluated in clinical measurements on five patients undergoing breast reconstruction using Deep Inferior Epigastric Perforator (DIEP) flap. Good quality PPG signals were obtained from the flaps and fingers simultaneously. The estimated free flap SpO₂ values were in broad agreement with the oxygen saturation readings from the commercial pulse oximeter. The results suggest that reflectance free flap photoplethysmography can be used as a continuous monitoring technique to non-invasively monitor the perfusion of free flaps.