Respiratory and cardiac monitoring at night using a wrist wearable optical system

TL;DR

This paper introduces a non-intrusive wrist wearable system that uses optical sensors to reliably monitor respiratory and cardiac signals during sleep, offering a practical alternative to traditional polysomnography.

Contribution

It presents a novel wearable device that accurately estimates vital signs during sleep using photoplethysmography, validated against standard polysomnography.

Findings

Mean absolute error of 17.4 ms for beat-to-beat intervals

Pulse rate estimation with 0.13 bpm error

Breath rate estimation with 0.9 bpm error

Abstract

Sleep monitoring provides valuable insights into the general health of an individual and helps in the diagnostic of sleep-derived illnesses. Polysomnography, is considered the gold standard for such task. However, it is very unwieldy and therefore not suitable for long-term analysis. Here, we present a non-intrusive wearable system that, by using photoplethysmography, it can estimate beat-to-beat intervals, pulse rate, and breathing rate reliably during the night. The performance of the proposed approach was evaluated empirically in the Department of Psychology at the University of Fribourg. Each participant was wearing two smart-bracelets from Ava as well as a complete polysomnographic setup as reference. The resulting mean absolute errors are 17.4 ms (MAPE 1.8%) for the beat-to-beat intervals, 0.13 beats-per-minute (MAPE 0.20%) for the pulse rate, and 0.9 breaths-per-minute (MAPE 6.7%) for the breath rate.