Wearable Pulse Oximetry Measurements on the Torso, Arms, and Legs: A Proof of Concept

Abstract

For decades pulse oximeters designed for use on the head, hands, or feet have provided invaluable estimates of oxygen saturation to medical personal attending to combat casualties. However, traditional placement sites are not ideal for the relatively new paradigm of continuous battlefield telemonitoring. To assess the feasibility of oximetry on nontraditional body sites, 42 healthy volunteers were enrolled, consented, and underwent an industry standard induced-hypoxia study. During the study volunteers used prototype wearable oximeters, designed for the torso, arms, and legs. Subsets (size n) of the volunteers had the wearables placed at the following body sites, and achieved accuracies (A_RMS, root-mean-square difference) of the following: calf 1.7% (n = 26); bicep 3.1% (n = 12); forearm 3.4% (n = 11); pectoral 2.9% (n = 42); sternum 2.9% (n = 13). In keeping with regulatory guidance calibrations with an A_RMS of less than 3.5% are acceptable for potential future development. Additionally, a new method was developed to enable accurate reporting of respiration rate from the pectoral oximeter, A_RMS of 1.1 breaths per minute (n = 10). This study demonstrates the feasibility of monitoring oxygen saturation and respiration rate from nontraditional sites via a wearable pulse oximeter.