Quantitative assessment of nocturnal neural respiratory drive in children with and without obstructive sleep apnoea utilising surface EMG.

NEW FINDINGS: What is the central question of this study? Recent studies have suggested potential utility of non-normalised respiratory muscle electromyogram as an index of neural respiratory drive (NRD). Whether NRD measured using non-normalised surface electromyogram of the lateral chest wall overlying diaphragm (sEMGcw) recorded during nocturnal clinical polysomnography can differentiate children with and without obstructive sleep apnoea (OSA) is not known. What is the main finding and its importance? Non-normalised sEMGcw was increased in children with OSA and an additional group of snoring children without OSA but subjectively increased respiratory effort compared to primary snorers. sEMGcw has potential clinical utility in the evaluation of children with sleep-disordered breathing as an objective, non-invasive, and non-volitional marker of NRD.

ABSTRACT: Objectives To investigate whether neural respiratory drive (NRD) measured by non-normalised surface electromyogram recorded from the chest wall overlying diaphragm (sEMGcw) differentiates children with and without obstructive sleep apnoea (OSA). Methods Polysomnography data of children aged 0-18 years were divided into three groups: 1) primary snorers (PS); 2) snoring children without OSA but increased work of breathing (incWOB, subjective physician report of increased respiratory effort during sleep); and 3) children with OSA (obstructive apnoea hypopnoea index (OAHI) > 1/hour). Excerpts of sEMGcw obtained during tidal unobstructed breathing from light, deep, and rapid eye movement sleep were exported for quantitative analysis. Results Overnight polysomnography data from 45 PS (median age 4.4 years (IQR 3.0-7.7), OAHI 0/h (0.0-0.2)), 19 children with incWOB (age 2.8 years (2.4-5.7), OAHI 0.1/h (0.0-0.4)) and 27 children with OSA (age 3.6 years (2.6-6.2), OAHI 3.7/h (2.3-6.9)) were analyzed. sEMGcw was higher in those with OSA (8.47 μV (5.98 - 13.07) p < 0.0001) and incWOB (8.97 μV (5.94 - 13.43; p < 0.001)) compared with PS (4.633 μV (2.98-6.76)). There was no significant difference in the sEMGcw between children with incWOB and OSA (p = 0.78). Log sEMGcw remained greater in children with OSA and incWOB compared to PS after age, BMI centiles, sleep stages and sleep positions were included in the mixed linear models (p < 0.0001). Correlation between sEMGcw and OAHI in children without OSA was small (rs  = 0.254, p = 0.04). Conclusion sEMGcw is increased in children with OSA and incWOB compared to PS. This article is protected by copyright. All rights reserved.