Published in:
Open Access 01-04-2013 | Research
Characterisation of sleep in intensive care using 24-hour polysomnography: anobservational study
Published in: Critical Care | Issue 2/2013
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Introduction
Many intensive care patients experience sleep disruption potentially related tonoise, light and treatment interventions. The purpose of this study was tocharacterise, in terms of quantity and quality, the sleep of intensive carepatients, taking into account the impact of environmental factors.
Methods
This observational study was conducted in the adult ICU of a tertiary referralhospital in Australia, enrolling 57 patients. Polysomnography (PSG) was performedover a 24-hour period to assess the quantity (total sleep time: hh:mm) and quality(percentage per stage, duration of sleep episode) of patients' sleep while in ICU.Rechtschaffen and Kales criteria were used to categorise sleep. Interrater checkswere performed. Sound pressure and illuminance levels and care events weresimultaneously recorded. Patients reported on their sleep quality in ICU using theRichards Campbell Sleep Questionnaire and the Sleep in Intensive CareQuestionnaire. Data were summarised using frequencies and proportions or measuresof central tendency and dispersion as appropriate and Cohen's Kappa statistic wasused for interrater reliability of the sleep data analysis.
Results
Patients' median total sleep time was 05:00 (IQR: 02:52 to 07:14). The majority ofsleep was stage 1 and 2 (medians: 19 and 73%) with scant slow wave and REM sleep.The median duration of sleep without waking was 00:03. Sound levels were high(mean Leq 53.95 dB(A) during the day and 50.20 dB(A) at night) and illuminancelevels were appropriate at night (median <2 lux) but low during the day(median: 74.20 lux). There was a median 1.7 care events/h. Patients' meanself-reported sleep quality was poor. Interrater reliability of sleep staging washighest for slow wave sleep and lowest for stage 1 sleep.
Conclusions
The quantity and quality of sleep in intensive care patients are poor and may berelated to noise, critical illness itself and treatment events that disturb sleep.The study highlights the challenge of quantifying sleep in the critical caresetting and the need for alternative methods of measuring sleep. The resultssuggest that a sound reduction program is required and other interventions toimprove clinical practices to promote sleep in intensive care patients.
Trial registration
Australian New Zealand clinical trial registry(http://www.anzctr.org.au/): ACTRN12610000688088.