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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.
Earplugs appear effective at reducing the risk of patients in intensive care units (ICU) developing delirium, a state of confusion in people who are unwell. The effect was seen whether the earplugs were used alone or with other sleep aids like eye masks or soothing music. Earplugs also reduced the duration of confusion by around two days. Patient compliance was high at 86.9%. Cost and cost-effectiveness were not measured, but earplugs are relatively inexpensive.
Around 1 in 5 hospitalised people develop confusion which can extend hospital stays and increase the risk of death. Sleep disturbance can exacerbate the causes of confusion (such as infections) and worsen the patient experience in intensive care. 2010 NICE guidelines recommend sleep disturbance is minimised by keeping night-time medical procedures, medication rounds and noise to a minimum. Clocks and appropriate lighting can also help orientate people to the time of day.
The evidence comes from mixed study types of low quality but suggests earplugs may offer a simple, low-cost option to reduce sleep disturbance without harms.
Why was this study needed?
Prolonged sleep disruption can weaken the immune system, impair cognitive function and raise the risk of delirium – a state of mental confusion in someone who is medically unwell. Such sleep disturbance is common in places like hospital intensive care units, where patients require regular monitoring and care throughout the night.
Around 1 in 5 people admitted to hospital experience a period of delirium often caused by things such as urinary tract or other infections, lack of oxygen, medication and metabolic upset. This increases the time in hospital and risk of death.
This systematic review aimed to evaluate whether simple low-cost ear plugs could reduce sleep disturbance and lower the number of cases of delirium.
What did this study do?
This systematic review included 1,455 patients from nine studies. Six were randomised controlled trials and three were uncontrolled “before and after” studies comparing outcomes before and after the introduction of earplugs but with no separate comparison group (control). All nine studies used ear plugs or noise cancelling headphones. Three studies used earplugs alone, two used earplugs and eye masks, and four combined earplugs, eye masks and other noise reducing approaches including soothing music, sleep inducing medicine melatonin, or changing the environment to minimise noise. The studies were carried out in mixed and specialist intensive care units, and one was in a surgical post-anaesthesia care unit.
This systematic review followed a high-quality methodology but identified studies that were generally small and all had a high risk of bias, because of a lack of blinding and incomplete data. This means we can be relatively confident the review identified the best evidence currently around, but this evidence was itself not very reliable.
What did it find?
- Overall, using earplugs reduced the risk of delirium by around 41% compared to not using them or a control group (relative risk (RR) 0.59, 95% confidence interval [CI] 0.44 to 0.78). This was based on five studies and was similar whether earplugs were used alone or in conjunction with other interventions, such as eye masks.
- Earplugs did not statistically lower the risk of mortality (RR 0.77, 95% CI 0.54 to 1.11).
- Compliance using earplugs was high at 86.9%. Reasons for stopping early included discomfort, earplugs falling out, or clinical need.
- Two studies found that earplugs significantly reduced the time spent in delirium by around two days (3.4 days compared to 1.2 days).
What does current guidance say on this issue?
2010 NICE guidance recommends promoting good sleep patterns and sleep hygiene to prevent delirium in hospitalised people in all ward settings. Key steps to achieve this include avoiding disturbing people’s sleep by only keeping night-time medical procedures, medication rounds and noise to a minimum. Clocks and appropriate lighting can also help orientate people to the time of day.
What are the implications?
Delirium and sleep disturbance can worsen a patient’s health and increase their stay in hospital; therefore prevention is the key.
The best available evidence from nine studies with a high risk of bias, showed earplugs, with and without masks and other noise reducing strategies, were broadly effective at reducing delirium so may offer a simple low-cost prevention strategy. There are also little major harms associated with earplug use and most patients were willing to use them. Cost and cost effectiveness were not assessed but earplugs are low cost interventions. Noise may be a contributing factor to the main causes of confusion, but because the study designs were not ideal, the conclusion may change if better evidence becomes available.
Irrespective of earplug use, NICE recommends avoiding night-time disturbances and maintaining normal sleep patterns in ICU patients wherever possible.
Citation and Funding
Litton E, Carnegie V, Elliott R, Webb SA. The Efficacy of Earplugs as a Sleep Hygiene Strategy for Reducing Delirium in the ICU: A Systematic Review and Meta-Analysis. Crit Care Med. 2016. [Epub ahead of print].
No funding information was provided for this study.
Bibliography
NICE. Acute illness in adults in hospital: recognising and responding to deterioration. CG50. London: National Institute for Health and Care Excellence; 2007.
NICE. Delirium: prevention, diagnosis and management. CG103. London: National Institute for Health and Care Excellence; 2010.
NICE. Rehabilitation after critical illness in adults. CG83. London: National Institute for Health and Care Excellence; 2009.
RCPSYCH. Delirium. London: Royal College of Psychiatrists; 2012.
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