NIHR DC Discover

NIHR Signal Earplugs may reduce risk of confusion in patients while in intensive care

Published on 8 March 2016

doi: 10.3310/signal-000209

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.

Share your views on the research.

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.

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.

The Efficacy of Earplugs as a Sleep Hygiene Strategy for Reducing Delirium in the ICU: A Systematic Review and Meta-Analysis

Published on 8 January 2016

Litton, E.,Carnegie, V.,Elliott, R.,Webb, S. A.

Crit Care Med , 2016

OBJECTIVE: A systematic review and meta-analysis to assess the efficacy of earplugs as an ICU strategy for reducing delirium. DATA SOURCES: MEDLINE, EMBASE, and the Cochrane Central Register of controlled trials were searched using the terms "intensive care," "critical care," "earplugs," "sleep," "sleep disorders," and "delirium." STUDY SELECTION: Intervention studies (randomized or nonrandomized) assessing the efficacy of earplugs as a sleep hygiene strategy in patients admitted to a critical care environment were included. Studies were excluded if they included only healthy volunteers, did not report any outcomes of interest, did not contain an intervention group of interest, were crossover studies, or were only published in abstract form. DATA EXTRACTION: Nine studies published between 2009 and 2015, including 1,455 participants, fulfilled the eligibility criteria and were included in the systematic review. Studies included earplugs as an isolated intervention (n = 3), or as part of a bundle with eye shades (n = 2), or earplugs, eye shades, and additional sleep noise abatement strategies (n = 4). The risk of bias was high for all studies. DATA SYNTHESIS: Five studies comprising 832 participants reported incident delirium. Earplug placement was associated with a relative risk of delirium of 0.59 (95% CI, 0.44-0.78) and no significant heterogeneity between the studies (I, 39%; p = 0.16). Hospital mortality was reported in four studies (n = 481) and was associated with a relative risk of 0.77 (95% CI, 0.54-1.11; I, 0%; p < 0.001). Compliance with the placement of earplugs was reported in six studies (n = 681). The mean per-patient noncompliance was 13.1% (95% CI, 7.8-25.4) of those assigned to receive earplugs. CONCLUSIONS: Placement of earplugs in patients admitted to the ICU, either in insolation or as part of a bundle of sleep hygiene improvement, is associated with a significant reduction in risk of delirium. The potential effect of cointerventions and the optimal strategy for improving sleep hygiene and associated effect on patient-centered outcomes remains uncertain.

The Royal College of Psychiatrists says the most common causes of sudden confusion (delirium) are:

  • a lack of oxygen in the blood (hypoxia) – the cause could be anything from a severe asthma attack to a problem with the lungs or heart
  • an infection anywhere in the body, especially in elderly people
  • a stroke or TIA ("mini stroke")
  • a low blood sugar level (hypoglycaemia)
  • diabetic ketoacidosis, a serious complication of diabetes caused by a lack of insulin in the body
  • certain medications, including digoxin, diuretics, steroids, and opiates
  • alcohol poisoning or alcohol withdrawal
  • drug misuse

Expert commentary

Delirium can be a frightening and disturbing disorder. It is associated with a significantly higher mortality, a longer period of mechanical ventilation and an increased length of hospital stay. It can be overlooked/misdiagnosed and its causes remain the subject of debate. The predisposing factors for delirium are thought to be closely associated with a patient’s underlying illness and the drugs used in intensive care. There is no conclusive evidence that sleep deprivation is the cause. However, any measure which improves the sleep pattern and thus reduces one of the possible causes of delirium should be explored. Further research is needed.

Mr Barry Williams, Chairman of Patients and Relatives Group of ICS