The Effect of Sedation with Inhaled Anesthetics on Cognitive and Psychiatric Outcomes in Critically Ill Adults: A Systematic Review

ABSTRACT

Rationale The COVID-19 pandemic has renewed interest in the use of inhaled anesthetics for sedation of ventilated critically ill patients. Compared to intravenous sedatives, inhaled anesthetics reduce lung inflammation, time to extubation, and ICU length of stay. However, their impact on cognitive and psychiatric outcomes is less clear. In this systematic review we summarize the impact of inhaled sedatives on cognitive and psychiatric outcomes in ventilated critically ill patients. Methods: We searched MEDLINE, EMBASE, and PsychINFO for studies from 1970 - 2021 that assessed cognitive and psychiatric outcomes in critically ill adult patients sedated with inhaled anesthetics. We included case series, observational, cohort, and randomized controlled trials. Outcome(s) of interest included cognition, anxiety, depression, hallucinations, psychomotor recovery, and PTSD, as well as instruments for assessing these outcomes. Results: We identified a total of twelve studies that examined at least one of our outcomes of interest (16 total outcomes). Four studies were in post cardiac arrest survivors, three in post-operative (non-cardiac) patients, two in post-operative cardiac patients, and three more in mixed medical-surgical patients. Seven studies reported incidence of delirium, two assessed neurologic recovery post cardiac-arrest, and two examined ICU memories. One study reported on each of anxiety, depression, hallucinations, PTSD, psychomotor recovery, and long-term cognitive dysfunction more than 3 months following ICU discharge. Of the seven studies reporting on delirium, only one reported an increase in delirium for those sedated with intravenous sedation compared to volatile. The remaining studies did not report any difference in delirium incidence between modes of sedation. Similarly, no difference between sedation methods were observed for neurologic recovery following cardiac arrest, anxiety, depression, hallucinations, PTSD, psychomotor recovery, or long-term cognitive dysfunction. The most commonly used tool used was the CAM-ICU tool (delirium outcome;3 studies). Five studies used subjective chart review to assess their outcome of interest, or did not report their method of assessment. Conclusions: Few studies examined cognitive and psychiatric outcomes in critically ill adults sedated with volatile anesthetics. As volatile anesthetics offer a promising alternative mode of sedation in the ICU, future studies should incorporate assessment of these important patientcentered outcomes using validated objective tools during and following hospital stay.