Transcutaneous oxygen measurement in humans using a paramagnetic skin adhesive film

Abstract

Transcutaneous oxygen tension (TcpO2 ) provides information about blood perfusion in the tissue immediately below the skin. These data are valuable in assessing wound healing problems, diagnosing peripheral vascular/arterial insufficiency, and predicting disease progression or the response to therapy. Currently, TcpO2 is primarily measured using electrochemical skin sensors, which consume oxygen and are prone to calibration errors. The goal of the present study was to develop a reliable method for TcpO2 measurement in human subjects. We have developed a novel TcpO2 oximetry method based on electron paramagnetic resonance (EPR) principles with an oxygen-sensing skin adhesive film, named the superficial perfusion oxygen tension (SPOT) chip. The SPOT chip is a 3-mm diameter, 60-μm thick circular film composed of a stable paramagnetic oxygen sensor. The chip is covered with an oxygen-barrier material on one side and secured on the skin by a medical adhesive transfer tape to ensure that only the oxygen that diffuses through the skin surface is measured. The method quantifies TcpO2 through the linewidth of the EPR spectrum. Repeated measurements using a cohort of 10 healthy human subjects showed that the TcpO2 measurements were robust, reliable, and reproducible. The TcpO2 values ranged from 7.8±0.8 to 22.0±1.0mmHg in the volar forearm skin (N=29) and 8.1±0.3 to 23.4±1.3mmHg in the foot (N=86). The results demonstrated that the SPOT chip can measure TcpO2 reliably and repeatedly under ambient conditions. The SPOT chip method could potentially be used to monitor TcpO2 in the clinic.