Accepted for/Published in: JMIR Biomedical Engineering
Date Submitted: Jan 20, 2022
Date Accepted: Jul 23, 2022
Non-contact longitudinal respiratory rate measurements in healthy adults using radar-based sleep monitor (Somnofy®): a validation study
ABSTRACT
Background:
Respiratory rates are arguably the most important vital sign to measure in hospital wards but is rarely measured elsewhere, most likely because an easy and accurate measuring method is lacking. Change in respiratory rate can for example be associated with onset or deterioration of different diseases, opioid overdose, intense workouts, or mood.
Objective:
To validate the radar-based sleep monitor Somnofy for measuring respiratory rates and investigate whether events affecting the respiratory rate should be detectable from personalized baselines calculated from nightly averages.
Methods:
Respiratory rates from Somnofy for 37 healthy adults during full nights of sleep were first extensively validated against respiratory inductance plethysmography. Then the night-to-night consistency of respiratory rates were analysed for six healthy participants that used Somnofy at home for three months.
Results:
Somnofy measured respiratory rate 89% of the seconds with a mean absolute error of 0.18 respirations per minute. Disregarding periods with Somnofy-defined rapid eye movement sleep and movement, the Bland-Altman 95% limits of agreement adjusted for repeated measurements ranged from -0.55 to 0.43. The results were independent of age, sex, and body mass index, but dependent on supine sleeping position for some radar orientations. For nightly averages, the 95% limits of agreement ranged from -0.04 to -0.07 respirations per minute. In the longitudinal part of the study the nightly average were consistent from night to night and all substantial deviations coincided with self-reported illnesses.
Conclusions:
Respiratory rates from Somnofy were more accurate than any other alternative suitable for longitudinal measurements. Moreover, nightly averages were consistent from night to night. Thus, several factors affecting the respiratory rate should be detectable as anomalies from personalised baselines, enabling a range of applications. More research is necessary to investigate the potential in children, elderly, or in a clinical setting.
Citation
Request queued. Please wait while the file is being generated. It may take some time.
Copyright
© The authors. All rights reserved. This is a privileged document currently under peer-review/community review (or an accepted/rejected manuscript). Authors have provided JMIR Publications with an exclusive license to publish this preprint on it's website for review and ahead-of-print citation purposes only. While the final peer-reviewed paper may be licensed under a cc-by license on publication, at this stage authors and publisher expressively prohibit redistribution of this draft paper other than for review purposes.