Section 1: Introduction (from DOI: 10.1186/s13054-020-02882-x)
From publication: "COVID-19: ICU delirium management during SARS-CoV-2 pandemic" published as Crit Care; 2020 04 28 ; 24 (1) 176. DOI: https://doi.org/10.1186/s13054-020-02882-x
Section 1: Introduction
In patients with COVID-19, delirium may be a manifestation of direct central nervous system (CNS) invasion, induction of CNS inflammatory mediators, a secondary effect of other organ system failure, an effect of sedative strategies, prolonged mechanical ventilation time, or environmental factors, including social isolation. Drawing from experience with other closely related viruses from the coronaviridae family, direct CNS invasion appears to occur rarely and late in the disease course but may be associated with seizures, impairments in consciousness or signs of increased intracranial pressure. Such symptoms may require specialized neuro-intensivist management. Immunologic responses to coronaviridae appear to be mediated by acute cytolytic T cell activation. This response could, if dysregulated, cause an autoimmune encephalopathy. Secondary effects include cerebral hypoxia or metabolic dysregulation in association with failure of pulmonary or other organ systems, such as can be seen in a variety of other types of delirium. Environmental and iatrogenic factors such as prolonged mechanical ventilation, sedatives (especially benzodiazepines), and immobility also contribute heavily to the risk of ICU delirium and can contribute to its development in the context of acute COVID-19 infection.
In an early retrospective report from Wuhan, Mao et al. reported that only 7.5% had any chart documentation of "impaired consciousness," which was the only term approximating delirium. Underreporting of delirium is extremely common in retrospective chart reviews, and under 1 in 10 with delirium is likely a gross underestimation. The literature is very consistent that ~ 75% of occurrences of delirium are missed in patients unless objective delirium monitoring is being employed to detect this form of acute brain dysfunction. In addition, in COVID-19, the risk of complications such as acquired dementia and ICU-acquired weakness (ICU-AW) as well as depression and PTSD, the defining illnesses of post-intensive care syndrome (PICS), and PICS in family members (PICS-F) will be greatly exacerbated if we allow patients to suffer unmitigated delirium.
This article will discuss how ICU professionals (e.g., physicians, nurses, physiotherapists, pharmacologists) can use our knowledge and resources to limit the burden of delirium on patients by reducing modifiable risk factors despite the imposed heavy workload and difficult clinical challenges posed by the pandemic. For example, others have already stressed reasonable analgesia and sedation use with special attention to monitoring and mitigating delirium.
The novel coronavirus, SARS-CoV-2-causing Coronavirus Disease 19 (COVID-19), emerged as a public health threat in December 2019 and was declared a pandemic by the World Health Organization in March 2020. Many hospitalized patients with COVID-19 will develop delirium, and given early insights into the pathobiology of this virus indicating invasion into the brain stem, as well as the emerging interventions utilized to treat these critically ill patients, delirium prevention and management may prove exceedingly challenging, especially in the intensive care unit (ICU). In addition to the neurobiology of COVID-19 and typical deliriogenic factors omnipresent in the ICU, this pandemic has created circumstances of extreme isolation and distancing from human contact whenever possible, including loved ones, plus the inability to freely ambulate, which essentially create a "delirium factory" that must be explicitly addressed to maximize human dignity and respect during care.
In patients with COVID-19, delirium may be a manifestation of direct central nervous system (CNS) invasion, induction of CNS inflammatory mediators, a secondary effect of other organ system failure, an effect of sedative strategies, prolonged mechanical ventilation time, or environmental factors, including social isolation. Drawing from experience with other closely related viruses from the coronaviridae family, direct CNS invasion appears to occur rarely and late in the disease course but may be associated with seizures, impairments in consciousness or signs of increased intracranial pressure. Such symptoms may require specialized neuro-intensivist management. Immunologic responses to coronaviridae appear to be mediated by acute cytolytic T cell activation. This response could, if dysregulated, cause an autoimmune encephalopathy. Secondary effects include cerebral hypoxia or metabolic dysregulation in association with failure of pulmonary or other organ systems, such as can be seen in a variety of other types of delirium. Environmental and iatrogenic factors such as prolonged mechanical ventilation, sedatives (especially benzodiazepines), and immobility also contribute heavily to the risk of ICU delirium and can contribute to its development in the context of acute COVID-19 infection.
In an early retrospective report from Wuhan, Mao et al. reported that only 7.5% had any chart documentation of "impaired consciousness," which was the only term approximating delirium. Underreporting of delirium is extremely common in retrospective chart reviews, and under 1 in 10 with delirium is likely a gross underestimation. The literature is very consistent that ~ 75% of occurrences of delirium are missed in patients unless objective delirium monitoring is being employed to detect this form of acute brain dysfunction. In addition, in COVID-19, the risk of complications such as acquired dementia and ICU-acquired weakness (ICU-AW) as well as depression and PTSD, the defining illnesses of post-intensive care syndrome (PICS), and PICS in family members (PICS-F) will be greatly exacerbated if we allow patients to suffer unmitigated delirium.
This article will discuss how ICU professionals (e.g., physicians, nurses, physiotherapists, pharmacologists) can use our knowledge and resources to limit the burden of delirium on patients by reducing modifiable risk factors despite the imposed heavy workload and difficult clinical challenges posed by the pandemic. For example, others have already stressed reasonable analgesia and sedation use with special attention to monitoring and mitigating delirium.
