Transcutaneous oxygen measurement in humans using a paramagnetic skin adhesive film

Purpose: Transcutaneous oxygen tension (TcpO(2)) 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, TcpO(2) 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 TcpO(2) measurement in human subjects. Methods: We have developed a novel TcpO(2) 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-mu m 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 TcpO(2) through the linewidth of the EPR spectrum. Results: Repeated measurements using a cohort of 10 healthy human subjects showed that the TcpO(2) measurements were robust, reliable, and reproducible. The TcpO(2) values ranged from 7.8 +/- 0.8 to 22.0 +/- 1.0 mmHg in the volar forearm skin (N = 29) and 8.1 +/- 0.3 to 23.4 +/- 1.3 mmHg in the foot (N = 86). Conclusions: The results demonstrated that the SPOT chip can measure TcpO(2) reliably and repeatedly under ambient conditions. The SPOT chip method could potentially be used to monitor TcpO(2) in the clinic.