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

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.

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

This study is a systematic review of quantitative studies.

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.

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.

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.

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