Authors: Rodrigues, Antenor et al.
Anesthesiology, August 5, 2025. DOI: 10.1097/ALN.0000000000005696
This prospective cohort study examined how sedation alters brain activity patterns in mechanically ventilated patients with early acute hypoxemic respiratory failure (AHRF). The researchers used the Odds Ratio Product (ORP), an EEG-derived index that quantifies the continuum between wakefulness and sleep, to differentiate normal sleep physiology from sedation-induced states. They identified and characterized abnormal EEG patterns—termed EEGUps—that are rarely or never seen during natural sleep and hypothesized that these represent sedation-related brain activity.
The study included 23 patients with AHRF (median age 58 years, 87% male) who underwent continuous EEG monitoring for up to seven days while receiving varying combinations and doses of sedatives and opioids. Across 1,832 total hours of EEG data, EEGUps represented 42% of total recording time, often exceeding 50% under specific sedation-opioid combinations. These patterns were more frequent with higher sedation doses, deeper clinical sedation scores, and the use of multiple sedatives. Importantly, EEGUps were inversely associated with physiological features of natural sleep, such as brief wake intrusions, and were independently correlated with increased ICU mortality (P<0.001).
The findings suggest that continuous intravenous sedation produces distinct, nonphysiologic EEG patterns that differ fundamentally from normal sleep. The prevalence of EEGUps appears to reflect both the intensity of sedation and its potential adverse impact on clinical outcomes, raising questions about how sedative regimens may impair neural recovery and sleep homeostasis in critically ill patients.
What You Should Know:
EEGUps—abnormal EEG features induced by sedatives—represent a measurable, dose-dependent marker of altered brain activity in mechanically ventilated patients. These patterns differ from natural sleep, correlate with sedation depth, and are linked to worse outcomes. Incorporating EEG-based monitoring may help optimize sedation strategies and mitigate neurophysiologic harm in the ICU.
Thank you to Anesthesiology for publishing this groundbreaking investigation illuminating how sedation disrupts brain activity and its potential implications for critical care management.