Prognostic value of continuous EEG monitoring during therapeutic hypothermia after cardiac arrest

Andrea O Rossetti,Luis A Urbano,Mauro Oddo,Peter W Kaplan,Frederik Delodder

doi:10.1186/cc9276

Abstract

IntroductionContinuous EEG (cEEG) is increasingly used to monitor brain function in neuro-ICU patients. However, its value in patients with coma after cardiac arrest (CA), particularly in the setting of therapeutic hypothermia (TH), is only beginning to be elucidated. The aim of this study was to examine whether cEEG performed during TH may predict outcome.MethodsFrom April 2009 to April 2010, we prospectively studied 34 consecutive comatose patients treated with TH after CA who were monitored with cEEG, initiated during hypothermia and maintained after rewarming. EEG background reactivity to painful stimulation was tested. We analyzed the association between cEEG findings and neurologic outcome, assessed at 2 months with the Glasgow-Pittsburgh Cerebral Performance Categories (CPC).ResultsContinuous EEG recording was started 12 ± 6 hours after CA and lasted 30 ± 11 hours. Nonreactive cEEG background (12 of 15 (75%) among nonsurvivors versus none of 19 (0) survivors; P < 0.001) and prolonged discontinuous "burst-suppression" activity (11 of 15 (73%) versus none of 19; P < 0.001) were significantly associated with mortality. EEG seizures with absent background reactivity also differed significantly (seven of 15 (47%) versus none of 12 (0); P = 0.001). In patients with nonreactive background or seizures/epileptiform discharges on cEEG, no improvement was seen after TH. Nonreactive cEEG background during TH had a positive predictive value of 100% (95% confidence interval (CI), 74 to 100%) and a false-positive rate of 0 (95% CI, 0 to 18%) for mortality. All survivors had cEEG background reactivity, and the majority of them (14 (74%) of 19) had a favorable outcome (CPC 1 or 2).ConclusionsContinuous EEG monitoring showing a nonreactive or discontinuous background during TH is strongly associated with unfavorable outcome in patients with coma after CA. These data warrant larger studies to confirm the value of continuous EEG monitoring in predicting prognosis after CA and TH.

Highlights

Continuous EEG is increasingly used to monitor brain function in neuro-intensive care unit (ICU) patients
Patients We studied 34 comatose cardiac arrest (CA) survivors treated with therapeutic hypothermia (TH) for 24 hours and monitored with Continuous EEG (cEEG) during TH
Continuous EEG background abnormalities during TH seem to be strongly associated with outcome after CA and appear to yield excellent point estimates for positive predictive values and false-positive rates for mortality

Summary

Introduction

Continuous EEG (cEEG) is increasingly used to monitor brain function in neuro-ICU patients. We and others recently demonstrated that, compared with previous studies performed before the introduction of TH [5], neurologic examination performed at 72 hours may be Continuous EEG monitoring (cEEG) provides important information regarding brain function, in comatose patients [8,9], and is increasingly used to monitor early on-line changes of cerebral electrophysiology at the bedside in critically ill patients. The exact prognostic value of cEEG findings during TH in patients with postanoxic coma has not been investigated In this prospective study, we sought to examine the relation between cEEG findings during TH and outcome in comatose survivors of CA. We primarily tested the hypothesis that the type and reactivity of cEEG background during TH may reliably predict patient prognosis

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