Continuous SpO2 Monitoring Using Reflectance Pulse Oximetry at the Wrist and Upper Arm During Overnight Sleep Apnea Recordings

TL;DR

This study evaluates the accuracy of wearable reflectance pulse oximetry at the wrist and upper arm for continuous SpO2 monitoring during sleep, demonstrating its potential for sleep apnea diagnosis.

Contribution

It introduces a wearable reflectance pulse oximetry method for overnight SpO2 monitoring, comparing its accuracy at different body locations during sleep apnea recordings.

Findings

Upper arm measurement achieved 1.9% RMSE accuracy.

Wrist measurement had 3.2% RMSE accuracy.

Upper arm data rejection rate was 3.1%, lower than wrist at 30.4%.

Abstract

Sleep apnea (SA) is a chronic sleep-related disorder consisting of repetitive pauses or restrictions in airflow during sleep and is known to be a risk factor for cerebro- and cardiovascular disease. It is generally diagnosed using polysomnography (PSG) recorded overnight in an in-lab setting at the hospital. This includes the measurement of blood oxygen saturation (SpO2), which exhibits fluctuations caused by SA events. In this paper, we investigate the accuracy and utility of reflectance pulse oximetry from a wearable device as a means to continuously monitor SpO2 during sleep. To this end, we analyzed data from a cohort of 134 patients with suspected SA undergoing overnight PSG and wearing the watch-like device at two measurement locations (upper arm and wrist). Our data show that standard requirements for pulse oximetry measurements are met at both measurement locations, with an accuracy (root mean squared error) of 1.9% at the upper arm and 3.2% at the wrist. With a rejection rate of 3.1%, the upper arm yielded better results in terms of data quality when compared to the wrist location which had 30.4% of data rejected.