Measurement of snoring and stertor using the Sonomat to assess effectiveness of upper airway surgery in children.

STUDY OBJECTIVES: The success of surgical treatment for pediatric sleep-disordered breathing is typically assessed using the mixed and obstructive apnea-hypopnea index (MOAHI). Although an important metric, previous work has shown that snoring and stertor are also associated with sleep disruption. Our aim was to assess the efficacy of surgery using the Sonomat (Sonomedical Pty Ltd), a noncontact sleep assessment system, that accurately records complete and partial upper airway obstruction. METHODS: Forty children (< 18 years) had a Sonomat study, in their own beds, before and after surgery. As an MOAHI ≥ 1 event/h is considered abnormal, the same threshold was applied to snore/stertor runs. Median (interquartile range) values are reported. RESULTS: Respiratory event-induced movements decreased from 12.0 (8.7-19.0) to 0.5 (0.1-3.2) events/h (P < .01), with no significant change in spontaneous movements: 12.8 (9.8-17.9) to 16.5 (13.7-26.1) events/h (P = .07). The MOAHI decreased from 4.5 (1.9-8.6) to 0.0 (0.0-0.4) events/h (P < .01). Snoring and/or stertor runs decreased from 32.8 (23.4-44.4) to 3.0 (0.2-14.6) events/h (P < .01). Thirty-four children had an MOAHI < 1 event/h following surgery; however, 20 had snore and/or stertor runs ≥ 1 event/h and 11 had snore and/or stertor runs ≥ 5 events/h. Only 14 (35%) children had a postsurgery MOAHI < 1 event/h combined with snoring and/or stertor < 1 runs/h. CONCLUSIONS: Although surgery is effective in improving breathing, success rates are overestimated using the MOAHI. Our results indicate that snoring and/or stertor are still present at levels that may disrupt sleep despite a normalization of the MOAHI and that when obstructed breathing was objectively measured, there was a large variation in its response to surgery. CITATION: Norman MB, Harrison HC, Sullivan CE, Milross MA. Measurement of snoring and stertor using the Sonomat to assess effectiveness of upper airway surgery in children. J Clin Sleep Med. 2022;18(6):1649-1656.

Snoring and stertor are associated with more sleep disturbance than apneas and hypopneas in pediatric SDB.

PURPOSE: Polysomnography is not recommended for children at home and does not adequately capture partial upper airway obstruction (snoring and stertor), the dominant pathology in pediatric sleep-disordered breathing. New methods are required for assessment. Aims were to assess sleep disruption linked to partial upper airway obstruction and to evaluate unattended Sonomat use in a large group of children at home. METHODS: Children with suspected obstructive sleep apnea (OSA) had a single home-based Sonomat recording (n = 231). Quantification of breath sound recordings allowed identification of snoring, stertor, and apneas/hypopneas. Movement signals were used to measure quiescent (sleep) time and sleep disruption. RESULTS: Successful recordings occurred in 213 (92%) and 113 (53%) had no OSA whereas only 11 (5%) had no partial obstruction. Snore/stertor occurred more frequently (15.3 [5.4, 30.1] events/h) and for a longer total duration (69.9 min [15.7, 140.9]) than obstructive/mixed apneas and hypopneas (0.8 [0.0, 4.7] events/h, 1.2 min [0.0, 8.5]); both p < 0.0001. Many non-OSA children had more partial obstruction than those with OSA. Most intervals between snore and stertor runs were < 60 s (79% and 61% respectively), indicating that they occur in clusters. Of 14,145 respiratory-induced movement arousals, 70% were preceded by runs of snore/stertor with the remainder associated with apneas/hypopneas. CONCLUSIONS: Runs of snoring and stertor occur much more frequently than obstructive apneas/hypopneas and are associated with a greater degree of sleep disruption. Children with and without OSA are frequently indistinguishable regarding the amount, frequency, and the degree of sleep disturbance caused by snoring and stertor.

Validation of the Sonomat Against PSG and Quantitative Measurement of Partial Upper Airway Obstruction in Children With Sleep-Disordered Breathing.

Study Objectives: To validate the Sonomat against polysomnography (PSG) metrics in children and to objectively measure snoring and stertor to produce a quantitative indicator of partial upper airway obstruction that accurately reflects the pathology of pediatric sleep-disordered breathing (SDB). Methods: Simultaneous PSG and Sonomat recordings were performed in 76 children (46 male, age 5.8 ± 2.8, BMI = 18.5 ± 3.8 kg/m2). Sleep time, individual respiratory events and the apnea/hypopnea index (AHI) were compared. Obstructed breathing sounds were measured from the unobtrusive non-contact experimental device. Results: There was no significant difference in total sleep time (TST), respiratory events or AHI values, the latter over-estimated by 0.3 events hr-1 by the Sonomat. Poor signal quality was minimal and gender, BMI, and body position did not adversely influence event detection. Obstructive and central events were classified correctly. The number of runs and duration of snoring (13 399 events, 20% TST) and stertor (5748 events, 24% TST) were an order of magnitude greater than respiratory events (1367 events, 1% TST). Many children defined as normal by PSG had just as many or more runs of snoring and stertor as those with mild, moderate and severe obstructive sleep apnea (OSA). Conclusions: The Sonomat accurately diagnoses SDB in children using current metrics. In addition, it permits quantification of partial airway obstruction that can be used to better describe pediatric SDB. Its non-contact design makes it ideal for use in children.

Validation of the Sonomat: a contactless monitoring system used for the diagnosis of sleep disordered breathing.

STUDY OBJECTIVES: To evaluate the ability of the Sonomat to diagnose obstructive sleep apnea (OSA). DESIGN: Prospective and randomized. SETTING: Sleep laboratory and home. PARTICIPANTS: 62 subjects; 54 with a clinical history of OSA and 8 normal control subjects. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Simultaneous PSG and Sonomat recordings were made in 62 subjects; 2 were excluded due to a poor nasal flow recording in PSG. There were positive correlations between the two devices for measures of sleep time, respiratory events, and the AHI (all correlations > 0.89). Bland-Altman analysis of the AHI showed positive agreement between devices, particularly at levels around common diagnostic thresholds. The mean difference in AHI values was 1.4 events per hour, and at a diagnostic threshold of 15 events per hour, sensitivity and specificity were 88% and 91%. More than 93% of PSG defined respiratory events were identified by the Sonomat and the absence of respiratory events was correctly identified in 91% of occasions. Gender, obesity, and body position did not influence the accuracy of the Sonomat. PSG snore sensors differed in how much snoring was detected when compared to the Sonomat. CONCLUSION: These data indicate that the Sonomat was reliable and accurate for the diagnosis of OSA. The provision of audible breath sound/snoring replay permits more accurate quantification of snoring. It requires no patient attachment and can be performed in the home with minimal training.

The use of epochs to stage sleep results in incorrect computer-generated AHI values.

OBJECTIVE: The objective of this study was to determine what impact the omission of respiratory events scored during wake epochs has on the generation of the apnea/hypopnea index (AHI) using computerised polysomnography (PSG). MATERIALS AND METHODS: Sixty diagnostic PSG recordings were scored using the recommended method of sleep staging with epochs. In addition, absolute sleep scoring criteria was used to calculate the total sleep time (TST). The TST, respiratory events and AHI generated from both scoring methods were compared. RESULTS: The AHI from epoch scoring (AHI(EP)) was significantly less than that derived from absolute sleep staging (AHI(ABS)) [AHI(EP) = 15.8 events/hour (7.3, 38.2), AHI(ABS) = 18.8 events/hour (8.7, 40.2); p < 0.0001]. From a total of 8,820 legitimately scored respiratory events ≥10 s duration, 723 (8%) were excluded from the AHI(EP) calculation as they were identified as having occurred during wake, but 400 of these (57%) started in an epoch of wake and continued into epoch(s) of sleep. These omitted events were not trivial [median 16.6 s (13.0, 24.0)] and were frequently associated with oxygen desaturation events [median 4% (3.0, 7.0)] with a range of 3% to 39%. CONCLUSION: The use of arbitrarily defined epochs for sleep staging has a direct impact on legitimately scored respiratory events resulting in the systematically incorrect reporting of the AHI. This artefact is due to computerised data reduction excluding all respiratory events that are contained within an epoch(s) of wake as well as those that start in an epoch scored as wake.