Continuous respiratory rate monitoring using photoplethysmography technology in patients with Obstructive Sleep Apnea

Purpose Respiratory rate is an important physiological parameter whose abnormality could be, in the presence of other suggestive symptoms, supportive of a diagnose of various serious illnesses. Photoplethysmography (PPG) in wearable sensors potentially plays an important role in early disease detection by making respiratory rate measurements more accessible. We investigated the accuracy of a new non-invasive, continuous, wrist-worn and wireless monitoring PPG device (Corsano CardioWatch 287) in measuring respiratory rate (RR) and heart rate (HR) at rest. Methods Subjects with and without diagnosed Obstructive Sleep Apnea (OSA) underwent simultaneous, continuous PPG and home sleep apnea testing (HSAT) for one night. We assessed the PPG sensor’s measurement accuracy by calculating root-mean-square accuracy (A rms ) and by performing Bland Altman and correlation analysis. Subgroups were defined based on skin type, hair density, age, BMI, gender and OSA severity. Results In 26 participants a total of 31083 RR and 38693 HR measurement pairs were obtained. For RR measurements, A rms was 0.60 breaths per minute (brpm). Correlation was high (r = 0.964 (95%CI 0.963 - 0.965)) and 95% Limits of Agreement (LoA) were −1.28 to 1.71 brpm (mean bias −0.14 brpm). For HR measurements, A rms was 0.95 beats per minute (bpm). Correlation was similarly high (r = 0.996 (95%CI 0.996 - 0.996) and 95% LoA were – 2.09 to 1.17 bpm (mean bias −0.46 bpm). Results were comparable across all subgroups, without significant difference in RR accuracy between subjects with and without diagnosed OSA. In free-living conditions, A rms was 2.43 brpm and 95% LoA were −5.00 to 4.47 brpm (mean bias −0.27 brpm). Conclusion We showed that the Corsano Cardiowatch 287 using PPG technology can monitor continuous RR and HR with high accuracy in healthy subjects as well as in patients diagnosed with OSA. We conclude that wearable devices like these enable new and more accessible ways to measure health, ultimately improving healthcare delivery. The trial was registered in the ISCRTN registry under reference ISRCTN13965929 .