Sleep Neurobiology and Critical Care Illness

A Systematic Review of Risk Factors for Sleep Disruption in Critically Ill Adults

OBJECTIVES

Numerous risk factors for sleep disruption in critically ill adults have been described. We performed a systematic review of all risk factors associated with sleep disruption in the ICU setting.

DATA SOURCES

PubMed, EMBASE, CINAHL, Web of Science, Cochrane Central Register for Controlled Trials, and Cochrane Database of Systematic Reviews.

STUDY SELECTION

English-language studies of any design published between 1990 and April 2018 that evaluated sleep in greater than or equal to 10 critically ill adults (> 18 yr old) and investigated greater than or equal to 1 potential risk factor for sleep disruption during ICU stay. We assessed study quality using Newcastle-Ottawa Scale or Cochrane Risk of Bias tool.

DATA EXTRACTION

We abstracted all data independently and in duplicate. Potential ICU sleep disruption risk factors were categorized into three categories based on how data were reported: 1) patient-reported reasons for sleep disruption, 2) patient-reported ratings of potential factors affecting sleep quality, and 3) studies reporting a statistical or temporal association between potential risk factors and disrupted sleep.

DATA SYNTHESIS

Of 5,148 citations, we included 62 studies. Pain, discomfort, anxiety/fear, noise, light, and ICU care-related activities are the most common and widely studied patient-reported factors causing sleep disruption. Patients rated noise and light as the most sleep-disruptive factors. Higher number of comorbidities, poor home sleep quality, home sleep aid use, and delirium were factors associated with sleep disruption identified in available studies.

CONCLUSIONS

This systematic review summarizes all premorbid, illness-related, and ICU-related factors associated with sleep disruption in the ICU. These findings will inform sleep promotion efforts in the ICU and guide further research in this field.

The effectiveness of noise interventions in the ICU

PURPOSE OF REVIEW

Excessive noise has direct adverse physiological and psychological effects, and may also have indirect negative health consequences by reducing sleep quality and quantity. This review presents a synthesis of the epidemiology of noise in the ICU, and the potential interventions designed to attenuate noise and protect patients.

RECENT FINDINGS

Noise increases cortisol release, oxygen consumption, and vasoconstriction. ICU noise levels are excessive throughout the 24-h cycle, irrespective of level of intervention or whether the patient is in a side room or open ward. Direct measurement suggests that noise is a substantial contributor to poor sleep quantity and quality in the ICU and is frequently recalled by survivors of critical illness as a negative experience of ICU admission. Noise abatement, environmental masking and pharmacological interventions may all reduce the impact of noise on patients. However, the sustainability of behavioural interventions remains uncertain and high-quality evidence demonstrating the benefit of any intervention on patient-centered outcomes is lacking.

SUMMARY

Noise levels in the ICU are consistently reported to reach levels likely to have both direct and indirect adverse health consequences for both patients and staff. Noise reduction, abating the transmission of noise and pharmacological modulation of the adverse neural effects of noise are all potentially beneficial strategies, although definitive evidence of improved patient-centered outcomes is lacking.

Association between death and loss of stage N2 sleep features among critically Ill patients with delirium

PURPOSE

Critically ill patients experience significant sleep disruption. In this study of ICU patients with delirium, we evaluated associations between the loss of stage N2 features (K-complexes, sleep spindles), grade of encephalopathy based on electroencephalography (EEG), and intensive care unit (ICU) outcomes. We hypothesized that loss of stage N2 features is associated with more severe grades of encephalopathy and worse ICU outcomes including death.

MATERIALS AND METHODS

This was an observational cohort study of 93 medical ICU patients without primary acute brain injury who underwent continuous EEG. Type and severity of critical illness, sedative-hypnotic use, length of stay, modified Rankin Scale at hospital discharge, and death during hospitalization were abstracted from the medical record. EEG was evaluated for grade of encephalopathy and sleep features.

RESULTS

Patients without K-complexes or without sleep spindles had more severe encephalopathy and higher odds of death. The odds ratio for patients without K-complexes was 18.8 (p = .046). The odds ratio for patients without sleep spindles was 6.3 (p = .036).

CONCLUSIONS

Loss of stage N2 features is common and associated with more severe encephalopathy and higher odds of death. The absence of either Stage N2 feature, K complexes or sleep spindles, may have important prognostic value.

Repeated sleep-quality assessment and use of sleep-promoting interventions in ICU

To describe sleep quality using repeated subjective assessment and the ongoing use of sleep-promoting interventions in intensive care. It is well known that the critically ill experience sleep disruption while receiving treatment in the intensive care unit. Both the measurement and promotion of sleep is challenging in the complex environment of intensive care unit. Repeated subjective assessment of patients' sleep in the intensive care unit and use of sleep-promoting interventions has not been widely reported. An observational study was conducted in a 58-bed adult intensive care unit. Sleep quality was assessed using the Richards-Campbell Sleep Questionnaire (RCSQ) each morning. intensive care unit audit sleep-promoting intervention data were compared to data obtained prior to the implementation of a sleep guideline. Patients answered open-ended questions about the facilitators and deterrents of their sleep in intensive care unit. The sample (n = 50) was predominately male (76%) with a mean age: 62.6±16.9 years. Sleep quality was assessed on 2 days or more for 21 patients. The majority of patients (98%) received sleep-promoting interventions. Sleep quality had not improved significantly since the guideline was first implemented. The mean Richards-Campbell Sleep Questionnaire score was 47.9±24.1 mm. The main sleep deterrents were discomfort and noise. Frequently cited facilitators were nothing (i.e. nothing helped) and analgesia. The Richards-Campbell Sleep Questionnaire was used on repeated occasions, and sleep-promoting interventions were used extensively. There was no evidence of improvement in sleep quality since the implementation of a sleep guideline. The use of the Richards-Campbell Sleep Questionnaire for the subjective self-assessment of sleep quality in intensive care unit patients and the implementation of simple-promoting interventions by intensive care unit clinicians is both feasible and may be the most practical way to assess sleep in the intensive care unit context.