Remote photoplethysmography (rPPG) for intaoperative perfusion monitoring of free microvascular anastomosed fasciocutaneous flaps

Abstract

In reconstructive surgery, monitoring of microvascular flaps is critical for early detection of perfusion problems. Since existing monitoring methods are subject to a variety of limitations, there is a need for an objective and practical method to safely assess flap perfusion. Remote photoplethysmography (rPPG) is a camera-based monitoring technique that provides objective information on physiological parameters in various medical applications such as tissue perfusion measurements. The aim of this study is to analyze whether the use of rPPG for intraoperative monitoring of flap perfusion in patients undergoing reconstruction with free fasciocutaneous flaps (FFCL) compares favorably with clinical assessment. Twenty-five oncology patients from a university head and neck tumor center were included in the evaluation between May 2021 and October 2022. After defect reconstruction with an FFCL, the radial artery and accompanying veins were microvascularly anastomosed to the neck vessels. Reperfusion of the implanted FFCL via the anastomosed radial artery was documented with a high-resolution, all-digital surgical microscope. The rPPG signal was extracted and analyzed from the recorded RGB-videos. In 24 of the 25 patients, successful reperfusion of the implanted FFCL was quantified based on the extracted rPPG signal in each case. In one FFCL, no characteristic features could be derived intraoperatively from the rPPG signal; in the postoperative course, this FFCL became necrotic. Intraoperative monitoring of flap perfusion in patients after reconstruction with FFCL using rPPG signal analysis provides objective and reproducible results. Further clinical studies to establish the method for postoperative monitoring of flap perfusion are needed.