Presence of electroencephalogram burst suppression in sedated, critically ill patients is associated with increased mortality

Abstract

Objectives This study investigates the possibility of a relationship between oversedation and mortality in mechanically ventilated patients. The presence of burst suppression, a pattern of severely decreased brain wave activity on the electroencephalogram, may be unintentionally induced by heavy doses of sedatives. Burst suppression has never been studied as a potential risk factor for death in patients without a known neurologic disorder or injury. Design: Post hoc analysis of a prospectively observational cohort study. Setting Medical intensive care units of a tertiary care, university-based medical center. Patients A total of 125 mechanically ventilated, adult, critically ill patients. Measurements and Main Results A validated arousal scale (Richmond Agitation-Sedation Scale) was used to measure sedation level, and the bispectral index monitor was used to capture electroencephalogram data. Burst suppression occurred in 49 of 125 patients (39%). For analysis, the patients were divided into those with burst suppression (49 of 125, 39%) and those without burst suppression (76 of 125, 61%). All baseline variables were similar between the two groups, with the overall cohort demonstrating a high severity of illness (Acute Physiology and Chronic Health Evaluation II scores of 27.4 ± 8.2) and 98% receiving sedation. Of those with burst suppression, 29 of 49 (59%) died within 6 months compared with 25 of 76 (33%) who did not demonstrate burst suppression. Using time-dependent Cox regression to adjust for clinically important covariates (age, Charlson comorbidity score, baseline dementia, Acute Physiology and Chronic Health Evaluation II, Sequential Organ Failure Assessment, coma, and delirium), patients who experienced burst suppression were found to have a statistically significant higher 6-month mortality [Hazard’s ratio = 2.04, 95% confidence interval, 1.12–3.70, p = 0.02]. Conclusion The presence of burst suppression, which was unexpectedly high in this medical intensive care unit population, was an independent predictor of increased risk of death at 6 months. This association should be studied prospectively on a larger scale in mechanically ventilated, critically ill patients.

Burst Suppression on Processed Electroencephalography as a Predictor of Postcoma Delirium in Mechanically Ventilated ICU Patients

“…Whereas burst suppression is sometimes a therapeutic goal in the treatment of refractory status epilepticus, burst suppression resulting from deep sedation or metabolic derangements during critical illness is nearly always inadvertent and has been shown to be an independent predictor of death [36, 37]. Thus, avoiding burst suppression via EEG monitoring may improve outcomes for deeply sedated ICU patients.…”

Intraoperative Electroencephalogram Suppression Predicts Postoperative Delirium

“…During general anesthesia with ether-derived volatile agents, the EEG often shows a dominance of delta waves (0-4 Hz) coupled with theta waves (4-8 Hz) and/or alpha (8-12 Hz) and low-beta (12)(13)(14)(15)(16) oscillations. 7 Patients with increased low-frequency EEG activity during the rewarming phase of cardiac surgery are at increased risk for postoperative complications, including delirium.…”

Decrease in bispectral index prior to cardiovascular collapse during Caesarean sections

“…SR can appear when there is cerebral hypoxaemia or when anaesthesia is too deep. Watson et al observed that the presence of SR was related to increased mortality in critically ill patients and emphasized the prognostic significance of SR. 14 Although BIS monitoring is limited to the unilateral frontal cortex and values are affected by variety of clinical situation, 15 it may give the chance to detect critical changes of cerebral perfusion. 16 For a better monitoring of cerebral perfusion in high-risk cases, the full EEG monitoring during surgery might be the best.…”