Pulse oximetry in the neck - a proof of concept

Oxygen saturation levels are routinely monitored in clinical settings. Pulse oximetry, in transmittance operation mode, is the most common method of estimating oxygen saturation (SpO₂). This is inexpensive and non-invasive and thus allows for long-term monitoring. However, it suffers from issues such as signal integrity, reliability and patient comfortability. As a result, there is an interest in exploring other locations on the body where oxygen saturation can be measured reliably. In this paper, a wearable device has been designed to study the feasibility of extracting photoplethysmogram (PPG) signals at the neck in reflectance pulse oximetry mode. It explores the signal integrity and strength compared to other locations as well as the presence of motion artefacts in that location. The results demonstrate that the PPG signals acquired at the neck show a very strong correlation (r=0.82) with the SpO₂ values obtained using a commercial device. Further, the SpO₂ values are calculated with an accuracy of 98.6%.