Sound level intensity severely disrupts sleep in ventilated ICU patients throughout a 24-h period: a preliminary 24-h study of sleep stages and associated sound levels

Maxime Elbaz,Benoit Champigneulle,Jean Paul Mira,Christian Guilleminault,Fabien Sauvet,Damien Léger,Mounir Chennaoui,Stéphane Rio,Mélanie Strauss

doi:10.1186/s13613-017-0248-7

Abstract

BackgroundIt is well recognized that sleep is severely disturbed in patients in intensive care units (ICU) and that this can compromise their rehabilitation potential. However, it is still difficult to objectively assess sleep quantity and quality and the determinants of sleep disturbance remain unclear. The aim of this study was therefore to evaluate carefully the impact of ICU sound intensity levels and their sources on ICU patients’ sleep over a 24-h period.MethodsSleep and sound levels were recorded in 11 ICU intubated patients who met the criteria. Sleep was recorded using a miniaturized multi-channel ambulatory recording device. Sound intensity levels and their sources were recorded with the Nox-T3 monitor. A 30-s epoch-by-epoch analysis of sleep stages and sound data was carried out. Multinomial and binomial logistic regressions were used to associate sleep stages, wakefulness and sleep–wake transitions with sound levels and their sources.ResultsThe subjects slept a median of 502.2 [283.2–718.9] min per 24 h; 356.9 [188.6–590.9] min at night (22.00–08.00) and 168.5 [142.5–243.3] during daytime (8 am–10 pm). Median sound intensity level reached 70.2 [65.1–80.3] dBC at night. Sound thresholds leading to disturbed sleep were 63 dBC during the day and 59 dBC during the night. With levels above 77 dBC, the incidence of arousals (OR 3.9, 95% CI 3.0–5.0) and sleep-to-wake transitions (OR 7.6, 95% CI 4.1–14) increased. The most disturbing noises sources were monitor alarms (OR 4.5, 95% CI 3.5–5.6) and ventilator alarms (OR 4.2, 95% CI 2.9–6.1).ConclusionsWe have shown, in a small group of 11 non-severe ICU patients, that sound level intensity, a major disturbance factor of sleep continuity, should be strictly controlled on a 24-h profile.

Highlights

It is well recognized that sleep is severely disturbed in patients in intensive care units (ICU) and that this can compromise their rehabilitation potential
ICU This study identifies that these particular ICU sound levels are above the limit recommended by the WHO and result in a higher incidence of disturbance of sleep patterns
Sleep recordings (Table 2) The quality of sleep recording was excellent for all 11 subjects, and no data were excluded based on reciprocal analysis of sleep signal quality with a final analysis of 95 040 polysomnographic sleep recording (PSG) epochs of 30 s

Summary

Introduction

It is well recognized that sleep is severely disturbed in patients in intensive care units (ICU) and that this can compromise their rehabilitation potential. The aim of this study was to evaluate carefully the impact of ICU sound intensity levels and their sources on ICU patients’ sleep over a 24-h period. Increasing evidence shows that sleeping too little impacts severely on health with an increasing risk of morbidity [5] and even mortality [6] across many groups. It may affect memory and immunity, and can jeopardize safety [7, 8]. Acute sleep deprivation (defined as sleeping 25–50% of a normal 8 h night’s sleep) contributes to increased inflammation and disturbs the immunological response [11]

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