Development of a reflectance photoplethysmographic sensor used for the assessment of free flap perfusion

Monitoring of free flap perfusion and early identification of flap failure is an indispensable prerequisite for flap salvage. Although many methods of free flap monitoring are available, there is still no single reliable continuous non-invasive perfusion monitoring technique which will also assist in the early recognition of flap failure. In order to overcome the current technological limitations, we have developed a multi-wavelength photoplethysmographic (PPG) sensor and processing system to systematically investigate the perfusion mechanism in flaps used in reconstructive plastic microsurgery. The new prototype reflectance photoplethysmographic sensor was evaluated on three anaesthetized patients undergoing elective breast reconstructive (Deep Inferior Epigastric Perforator Flap) surgery. PPG signals were successfully obtained pre-operatively, intra-operatively and post-operatively. These preliminary results suggest that a PPG sensor may be a suitable method for evaluating the perfusion of free flap.