Early Bispectral Index and Sedation Requirements During Therapeutic Hypothermia Predict Neurologic Recovery Following Cardiac Arrest*

Abstract

Objective To test the hypothesis that low bispectral index (BIS) scores and low sedative requirements during therapeutic hypothermia predict poor neurologic outcome. Design, Setting, and Patients Observational study of a prospectively collected cohort of 160 consecutive cardiac arrest patients treated with therapeutic hypothermia. Interventions None Measurements and Results Eighty-four (60%) of the 141 subjects that survived hypothermia induction were discharged from the ICU with poor neurologic outcome, defined as a cerebral performance category (CPC) score of 3, 4, or 5. These subjects had lower BIS (p<0.001) and sedative requirements (p<0.001) during hypothermia compared to the 57 subjects discharged with good outcome. Early prediction of neurologic recovery was best seven hours after ICU admission, and median BIS scores at that time were 31 points lower in subjects discharged with poor outcome [11 (IQR 4 to 29) vs. 42 (37 to 49), p<0.001]. Median sedation requirements decreased by 17% (IQR −50% to 0%) seven hours after ICU admission in subjects with poor outcome but increased by 50% (95% CI 0% to 142%) in subjects with good outcome (p<0.001). Each 10-point decrease in BIS was independently associated with a 59% increase in the odds of poor outcome (95% CI: 32% to 76%, p<0.001). The model including BIS and sedative requirement correctly reclassified 15% of subjects from good to poor outcome and 1% of subjects from poor to good outcome. The model incorrectly reclassified 1% of subjects from poor to good outcome but did not incorrectly reclassify any from good to poor outcome. Conclusions BIS scores and sedative requirements early in the course of therapeutic hypothermia improve the identification of patients who will not recover from brain anoxia. The ability to accurately predict non-recovery after cardiac arrest could facilitate discussions with families, reduce patient suffering, and limit use of ICU resources in futile cases.

Bispectral Index to Predict Neurological Outcome Early After Cardiac Arrest

“…28 Using a different approach, we found similar results, strengthening the assumption that BIS monitoring can be an early prognostic indicator in cardiac arrest patients.…”

The role and limitations of EEG‐based depth of anaesthesia monitoring in theatres and intensive care

“…Bispectral index values fall following cardiac arrest as a consequence of global ischaemia . Mean BIS values in the first 24 h after resuscitation are higher in patients with good outcomes compared with those with poor outcomes .…”

Recorded time periods of bispectral index values equal to zero predict neurological outcome after out-of-hospital cardiac arrest

“…Still, most of these robust outcome predictors are labour-intensive, expensive, not continuous and above all require trained specialists for correct interpretation. Recently, the prognostic performance of simple bispectral index (BIS) monitoring has been investigated thoroughly in the post-cardiac arrest (CA) setting [ 8 – 15 ]. This monitoring option, originally designed to monitor the degree of awareness during anaesthesia, converts raw sampled frontal EEG signals into a simple and real-time BIS index that ranges from 0 (iso-electric EEG) to 100 (normal electrical activity in awake subjects).…”