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

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.

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“…Other groups have observed similar trends (15,37,38). It has been known for over 20 years that high noise levels are present in the ICU and that they adversely affect sleep (15,39,40). There is a clear link between sleep deprivation and delirium, which is related to poor outcomes in ICU patients (11).…”

“…While there is evidence that circadian rhythms are disrupted in the critically ill, the etiology is complex and multifaceted (10). A host of desynchronizing influences are present in critical illness, including poor sleep (11), continuously-administered parenteral nutrition (12)(13)(14), unregulated light/dark cycles and sound levels (15)(16)(17), as well as the influence of pharmacological treatments (18).…”

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“…Exacerbated interruptions of sleep cycles and insomnia can be the result of too much or too little sleep. While there is a debate about the impact of over-stimulation or not enough stimulation, that can complicate the optimal care of neonates 6 or adults 7 who are housed in hospitals, and most particularly within communal units, there is no contesting amongst the medical community about the importance of sleep. "Sleep health" is instrumental toward one's capacity to fight disease, and regular routine sleep habits can increase resilience in maintaining wellness.…”

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“…1). [12][13][14][15] However, with application of traditional PSG scoring criteria, atypical EEG patterns, seen in up to 85% of nighttime recordings in critically ill patients, 3 have no clearly assignable sleep stage. 16,17 For example, sleep spindles, which characterize N2 sleep, can be induced by benzodiazepines, making the distinction between sleep and sedation challenging.…”