Measuring Flap Oxygen Using Electron Paramagnetic Resonance Oximetry

Objectives/Hypothesis To determine if electron paramagnetic resonance (EPR) oximetry is a viable technology to aid in flap monitoring. Study Design Prospective cohort. Methods This was a cohort study assessing accuracy and speed of EPR oximetry in detecting ischemia of a saphenous artery–based flap in a rat model, using transcutaneous oximetry as a control. Measurements were obtained under both resting and ischemic conditions for nine Sprague Dawley rats (18 flaps), for 3 postoperative days following flap elevation. Results The mean partial pressure of oxygen prior to tourniquet application was 66.9 ± 8.9 mm Hg with EPR oximetry and 64.7 ± 5.2 mm Hg with transcutaneous oximetry ( P = .45). Mean partial pressures of oxygen during tourniquet application were 8.9 ± 3.2 mm Hg and 8.5 ± 2.9 mm Hg for EPR oximetry and transcutaneous oximetry, respectively ( P = .48), and 67.2 ± 6.9 mm Hg and 65.3 ± 6.1 mm Hg after tourniquet release for EPR oximetry and transcutaneous oximetry, respectively ( P = .44). The mean ischemia detection time of EPR oximetry was 49 ± 21 seconds. Conclusions Offering timely, accurate, and noninvasive tissue oxygen measurements, EPR oximetry is a promising adjunct in flap monitoring. Level of Evidence NA Laryngoscope , 129:E415–E419, 2019