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Microarousals in patients with sleep apnoea/hypopnoea syndrome
S E Martin1, H M Engleman, R N Kingshott
1Department of Medicine, The University of Edinburgh, RIE, UK.
Abstract:
Upper airway obstructions during sleep cause recurrent brief awakenings or microarousals. Standard criteria exist for sleep and respiratory event scoring, however, there are different definitions currently used to score microarousals. We therefore compared three definitions of microarousal (ranging from 1.5-3 s in duration) and one of awakening (>15 s). We examined their occurrence at the termination of apnoeas and hypopnoeas and their correlation with daytime sleepiness in patients with sleep apnoea/hypopnoea syndrome (SAHS). Sixty-three patients (aged 49, SD 10) had overnight polysomnography, multiple sleep latency tests (MSLT) and Epworth Sleepiness Scales (ESS). There were significantly more microarousals by any definition than there were awakenings (P<0.001) and there were more 1.5 s than 3 s microarousals (P<0.001). Significantly more apnoeas and hypopnoeas were terminated by 1.5 s microarousals (83% and 81%) than by 3 s microarousals (75%) (all P<0.001). Apnoea/ hypopnoea index (AHI) correlated significantly with objective daytime sleepiness (rho=-0.30, P<0.01). There were weakly significant relationships between all three microarousal definitions (-0.24
Insights
Different microarousal scoring definitions for sleep fragmentation show similar correlations with daytime sleepiness in patients with sleep apnea/hypopnea syndrome (SAHS). Any definition can be used for visual assessment.
Area of Science:
- Sleep Medicine
- Respiratory Physiology
- Neuroscience
Background:
- Upper airway obstructions during sleep lead to brief awakenings or microarousals.
- Standardized scoring criteria for respiratory events exist, but microarousal definitions vary.
- Sleep fragmentation significantly impacts patient quality of life and health outcomes.
Purpose of the Study:
- To compare three microarousal definitions (1.5-3s) and one awakening definition (>15s).
- To examine microarousal occurrence at the termination of apneas and hypopneas.
- To correlate microarousal scoring with objective and subjective daytime sleepiness in patients with sleep apnea/hypopnea syndrome (SAHS).
Main Methods:
- Overnight polysomnography was performed on 63 patients with SAHS.
- Multiple sleep latency tests (MSLT) assessed objective daytime sleepiness.
- Epworth Sleepiness Scales (ESS) measured subjective sleepiness.
- Three microarousal definitions (1.5s, 3s) and one awakening definition (>15s) were analyzed.
Main Results:
- Microarousals were significantly more frequent than awakenings, and 1.5s microarousals were more frequent than 3s microarousals.
- 1.5s microarousals terminated a higher percentage of apneas/hypopneas (83%) compared to 3s microarousals (75%).
- Apnea/hypopnea index correlated with objective daytime sleepiness; all microarousal definitions showed weak correlations with objective sleepiness but not subjective scores (ESS).
Conclusions:
- While 1.5s microarousals are associated with more respiratory events, the relationship between 1.5s and 3s microarousal definitions and daytime sleepiness is similar.
- Current microarousal scoring definitions are comparable in their correlation with objective daytime sleepiness.
- Any of the three microarousal definitions can be reliably used for visual assessment of sleep fragmentation in SAHS patients.