Validation of a New System Using Tracheal Body Sound and Movement Data for Automated Apnea-Hypopnea Index Estimation

Abstract

Study Objectives: The current gold standard for assessment of obstructive sleep apnea is the in-laboratory polysomnography. This approach has high costs and inconveniences the patient, whereas alternative ambulatory systems are limited by reduced diagnostic abilities (type 4 monitors, 1 or 2 channels) or extensive setup (type 3 monitors, at least 4 channels). The current study therefore aims to validate a simplified automated type 4 monitoring system using tracheal body sound and movement data. Methods: Data from 60 subjects were recorded at the University Hospital Ulm. All subjects have been regular patients referred to the sleep center with suspicion of sleep-related breathing disorders. Four recordings were excluded because of faulty data. The study was of prospective design. Subjects underwent a full-night screening using diagnostic in-laboratory polysomnography and the new monitoring system concurrently. The apnea-hypopnea index (AHI) was scored blindly by a medical technician using in-laboratory polysomnography (AHIPSG). A unique algorithm was developed to estimate the apneahypopnea index (AHIest) using the new sleep monitor. Results: AHIest strongly correlates with AHIPSG (r 2 = .9871). A mean ± 1.96 standard deviation difference between AHIest and AHIPSG of 1.2 ± 5.14 was achieved. In terms of classifying subjects into groups of mild, moderate, and severe sleep apnea, the evaluated new sleep monitor shows a strong correlation with the results obtained by polysomnography (Cohen kappa > 0.81). These results outperform previously introduced similar approaches. Conclusions:The proposed sleep monitor accurately estimates AHI and diagnoses sleep apnea and its severity. This minimalistic approach may address the need for a simple yet reliable diagnosis of sleep apnea in an ambulatory setting. Clinical Trial Registration: Trial name: Validation of a new method for ambulant diagnosis of sleep related breathing disorders using body sound; URL: https://drks-neu.uniklinik-freiburg.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00011195; Identifier: DRKS00011195 Keywords: monitoring, movement analysis, respiratory sounds, sleep apnea Citation: Kalkbrenner C, Eichenlaub M, Rüdiger S, Kropf-Sanchen C, Brucher R, Rottbauer W. Validation of a new system using tracheal body sound and movement data for automated apnea-hypopnea index estimation. J Clin Sleep Med. 2017;13(10):1123-1130. I NTRO DUCTI O NWith a prevalence of 4% in adult men and 2% in women, obstructive sleep apnea (OSA) is one of the most common sleeprelated breathing disorders.1 Additionally, more than 75% of people suffering from moderate OSA are either undiagnosed or untreated.2 OSA is characterized by multiple breathing cessations during the night due to different possible causes. If untreated, this disorder can lead to extensive daytime sleepiness 3 and an elevated risk for cardiovascular disease. [4][5][6] The main criteria used to indicate the severity of OSA is the apneahypopnea index (AHI), which describes the mean number of breathing pa...

Automated sleep stage classification based on tracheal body sound and actigraphy

“…4) . A Cohen’s Kappa >0.61 was reached for all groups, which is considered as substantial agreement [ 19 ]. The according ROC curves were created and are shown in Figure 6 (Fig.…”

“…It can therefore be assumed that the new sleep monitor can be used for simple sleep monitoring and preliminary screening at home. Additionally, previous research proved that the new sleep monitor is also able to diagnose one of the most common sleep disorders OSA [ 19 ], [ 20 ]. Using sleep staging, it is suggested that the monitor can now also be used to diagnose other sleep disorders, such as insomnia, or for a preliminary screening to decide whether a PSG is necessary or not.…”

“…Recordings only include so-called diagnostic nights without the presence of any therapeutic measures. Data recorded here was also used in another study to validate the ability of the new monitoring device to screen for OSA [ 19 ]. The study was approved by the ethics committee of Ulm University, and all subjects gave written informed consent.…”

“…A novel type-4 monitoring system has previously been developed by Kalkbrenner et al [ 17 ], [ 18 ]. This monitor utilizes tracheal body sound and actigraphy to screen for OSA [ 19 ], [ 20 ]. This allows simple setup and high comfort, minimizing the effect on sleep quality while outperforming similar existing ambulatory diagnostic.…”

Joint Apnea and Body Position Analysis for Home Sleep Studies Using a Wireless Audio and Motion Sensor

“…A similar system has been recently described by Saha et al in a paper, where a sensor combined of microphone and accelerometer was used [16]; however, the accelerometer was used for respiratory related movements detection (to validate apneic and hypopneic events detected with audio analysis), not to combine audio with body position for positional OSA analysis. Also, Kalkbrenner et al used a tracheal microphone connected with an accelerometer, but here the accelerometer was separately mounted on the chest, and not in a single wireless sensor [17]. Both studies used accelerometry signals and acoustic recordings to detect breathing episodes, apneas, and hypopneas.…”