Delirium in critical illness represents a considerable burden for individual patients, their family members, health-care services, and society. In the past decade, a number of initiatives have been launched with some success in the UK and internationally, with the aim of educating and challenging clinicians to improve sedation practice.1, 2 Less sedation results in lower delirium prevalence, and lower prevalence of delirium is associated with better patient outcomes.3, 4 The Pan American and Iberian Federation of Critical Medicine and Intensive Therapy, German, and US sedation guidelines all recommend mechanically ventilated patients are kept awake or easily aroused, with effective pain control.
Sedation of critically ill patients requiring mechanical ventilation is a complex health-care intervention and patient distress is an understandable concern for clinicians. Progress has been made regarding recognition of the importance of sedation assessment, routine delirium screening, and improving sedation practice. However, in a 2019 sedation reduction trial, only 52–57% of all patients were lightly sedated (defined as at least briefly awoken by voice) in the first 48 h after intensive care unit (ICU) admission.5 In the context of a research trial, it is difficult to achieve the correct level of sedation, thus, how much more difficult is it to achieve in day-to-day clinical practice? Difficulty in achieving optimum levels of sedation combined with the challenges and clinical course of COVID-19 infection creates a difficult scenario for clinicians.6
The cohort study in The Lancet Respiratory Medicine by Brenda Pun and colleagues7 is unique and large in size and breadth.7 A diverse group of clinicians were able to mobilise in a short period of time to do the study, which bodes well for the future of ICU delirium management and research. The authors aimed to identify the risk factors for delirium in patients admitted to the ICU with COVID-19, and to investigate the provision of an evidence-based standard of care bundle. The risk factors identified are similar to those reported in previous studies. An important finding was that patient interaction with family, even if delivered virtually, which has become standard practice during the COVID-19 pandemic, lowered the risk of development of delirium (odds ratio 0·73 [95% CI 0·63–0·84], p<0·0001).
Another key finding was that ICU patients with COVID-19 were kept in a coma for prolonged periods—a median of 10 days (IQR 6–15) compared with 1 day (IQR 1–2) reported for patients without COVID-19.8 The authors identified factors that were likely to have contributed to the use of deep sedation. The study raises many questions and process evaluation is needed to understand the reasons for the rapid changes in sedation practice adopted after the onset of the COVID-19 pandemic. For example, what was the extent of proning patients or use of muscle relaxants, both of which require deep sedation? What was the impact of a reduction in trained staff? 30% of ICUs had a shortage of personal protective equipment for care providers, which alone might have influenced the decision not to reduce a patient's sedation.
This study also provides evidence to explain why over-sedation was commonly observed, since the prevalence of more agitated delirium was high in patients with COVID-19. Before the COVID-19 pandemic, the reported incidence of new agitated delirium was up to 13%, with an overall prevalence of up to 20%, in adults with critical illness.9 In this cohort study, more than 50% of patients had hyperactive delirium. Similarly, Helms and colleagues reviewed 58 consecutive ICU patients with COVID-19, of whom 40 (69%) became agitated following cessation of muscle relaxation and sedation.10 Agitation on emergence from sedation combined with a shortage of resources might partly explain the shift in practice observed from minimal sedation to maintenance of deep sedation. These results also suggest that encephalopathy resulting from COVID-19 infection, when it manifests as delirium, is different because it results in symptoms of hyperactive rather than hypoactive delirium.
Perhaps it is unrealistic to expect that clinicians will be able to safely maintain light sedation in at least half of patients in the prolonged acute stage of COVID-19. The optimal approach to sedation in COVID-19 remains uncertain, although available evidence-based practice outside the context of COVID-19 should form the basis of the approach to delirium management. As the severity of COVID-19 illness is modified with reduced viral load, reduction in risk factors, and earlier presentation, and more is understood about encephalopathy caused by COVID-19, clinicians might be able to safely manage the majority of these patients without the use of deep sedation.
© 2021 Science Photo Library
Acknowledgments
I declare no competing interests.
References
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