Sleep, circadian rhythms, and critical illness

Circadian disruption dysregulates lung gene expression associated with inflammatory lung injury

Rationale

Circadian systems drive the expression of multiple genes in nearly all cells and coordinate cellular-, tissue-, and system-level processes that are critical to innate immunity regulation.

Objective

We examined the effects of circadian rhythm disorganization, produced by light shift exposure, on innate immunity-mediated inflammatory lung responses including vascular permeability and gene expression in a C57BL/6J murine model of inflammatory lung injury.

Methods

A total of 32 C57BL/6J mice were assigned to circadian phase shifting (CPS) with intratracheal phosphate-buffered saline (PBS), CPS with intratracheal lipopolysaccharide (LPS), control (normal lighting) condition with intratracheal PBS, and control condition with intratracheal LPS. Bronchoalveolar lavage (BAL) protein, cell counts, tissue immunostaining, and differentially expressed genes (DEGs) were measured in lung tissues at 2 and 10 weeks.

Measurements and results

In mice exposed to both CPS and intratracheal LPS, both BAL protein and cell counts were increased at both 2 and 10 weeks compared to mice exposed to LPS alone. Multiple DEGs were identified in CPS-LPS-exposed lung tissues compared to LPS alone and were involved in transcriptional pathways associated with circadian rhythm disruption, regulation of lung permeability, inflammation with Rap1 signaling, and regulation of actin cytoskeleton. The most dysregulated pathways included myosin light chain kinase, MAP kinase, profilin 2, fibroblast growth factor receptor, integrin b4, and p21-activated kinase.

Conclusion

Circadian rhythm disruption results in exacerbated immune response and dysregulated expression of cytoskeletal genes involved in the regulation of epithelial and vascular barrier integrity-the mechanistic underpinnings of acute lung injury. Further studies need to explore circadian disorganization as a druggable target.

Psychometric evaluation of the Freedman questionnaire to assess sleep in critical patients

AIM

A study was made of the psychometric characteristics of the modified Freedman questionnaire to assess sleep in critical patients.

DESIGN

A psychometric study was carried out, with content validity being explored by a group of experts, and internal consistency based on Cronbach's alpha coefficient. Factor analysis was performed to explore construct validity, and stability was assessed by test-retest analysis.

SETTING

The Department of Intensive Care Medicine of a reference hospital.

PARTICIPANTS

Patients admitted between 23 February 2016 and 20 December 2017.

INTERVENTIONS

Questionnaire administration.

VARIABLES

Items of the modified Freedman questionnaire.

RESULTS

Item relevance and definition yielded scores >3 (Likert scale maximum=4). Cronbach's alpha showed a global value of 0.933. The intraclass correlation index was >0.75 for most of the items of the questionnaire. Factor analysis allowed the detection of specific associations between the studied variables and the four factors.

CONCLUSIONS

The modified Freedman questionnaire showed good psychometric characteristics. It may be a reliable instrument for assessing the quality of sleep in critically ill patients, as well as the environmental factors.

The effect of chronotherapy on delirium in critical care - a systematic review

BACKGROUND

Delirium is highly prevalent within critical care and is linked to adverse clinical outcomes, increased mortality and impaired quality of life. Development of delirium is thought to be caused by multiple risk factors, including disruption of the circadian rhythm. Chronotherapeutic interventions, such as light therapy, music and use of eye shades, have been suggested as an option to improve circadian rhythm within intensive care units.

AIM

This review aims to answer the question: Can chronotherapy reduce the prevalence of delirium in adult patients in critical care?

DESIGN

This study is a systematic review of quantitative studies.

RESEARCH METHOD

Six major electronic databases were searched, and a hand search was undertaken using selected key search terms. Research quality was assessed using the critical appraisal skills programme tools. The studies were critically appraised by both authors independently, and data were extracted. Four themes addressing the research question were identified and critically evaluated.

FINDINGS

Six primary research articles that investigated different methods of chronotherapy were identified, and the results suggest that multi-component non-pharmacological interventions are the most effective for reducing the prevalence of delirium in critical care. The melatonergic agonist Ramelteon demonstrated statistically significant reductions in delirium; however, the reliability of the results in answering the review question was limited by the research design. The use of bright light therapy (BLT) and dynamic light application had mixed results, with issues with the research design and outcomes measured limiting the validity of the findings.

CONCLUSION

Multi-component non-pharmacological interventions, such as noise and light control, can reduce delirium in critical care, whereas other interventions, such as BLT, have mixed outcomes. Melatonin, as a drug, may be a useful alternative to sedative-hypnotics.

RELEVANCE TO CLINICAL PRACTICE

Chronotherapy can reduce the incidence of delirium within critical care, although further research is warranted. Staff education is essential in the implementation of chronotherapy.