Brainstem response patterns in deeply-sedated critically-ill patients predict 28-day mortality.

Area of Science:

• Critical Care Medicine
• Neuroscience
• Clinical Neurology

Background:

• Deep sedation is linked to acute brain dysfunction and higher mortality rates.
• Previous research indicated that early brainstem reflex assessment may predict outcomes in deeply sedated patients.

Purpose of the Study:

• To determine if specific patterns of brainstem reflexes can predict mortality in deeply sedated patients.
• To develop a predictive score for mortality in this patient population.

Main Methods:

• An observational prospective multicenter cohort study included 148 non-brain-injured deeply sedated patients (Richmond Agitation-Sedation Scale [RASS] ≤ -3).
• Brainstem reflexes and Glasgow Coma Scale were assessed within 24 hours of sedation using latent class analysis.
• The Full Outline of Unresponsiveness (FOUR) score and a novel Brainstem Responses Assessment Sedation Score (BRASS) were evaluated against 28-day mortality.

Main Results:

• Two sub-phenotypes were identified: homogeneous (54.6%) and heterogeneous (45.4%) brainstem reactivity.
• Heterogeneous brainstem reactivity, characterized by loss of response to nociceptive stimuli and varied reflex depression, predicted increased 28-day mortality (OR=6.44 with SAPS-II; OR=5.02 with SOFA), even after adjustment for RASS.
• The BRASS score demonstrated predictive value for 28-day mortality (c-index=0.69).

Conclusions:

• Approximately half of deeply sedated critically ill patients exhibit an early neurological sub-phenotype.
• This sub-phenotype, particularly heterogeneous brainstem reactivity, is a significant predictor of 28-day mortality.
• These findings suggest a potential brainstem dysfunction underlying mortality risk in deeply sedated patients.