Yield of intermittent versus continuous EEG in comatose survivors of cardiac arrest treated with hypothermia

Abstract

IntroductionElectroencephalography (EEG) has a central role in the outcome prognostication in subjects with anoxic/hypoxic encephalopathy following a cardiac arrest (CA). Continuous EEG monitoring (cEEG) has been consistently developed and studied; however, its yield as compared to repeated standard EEG (sEEG) is unknown.MethodsWe studied a prospective cohort of comatose adults treated with therapeutic hypothermia (TH) after a CA. cEEG data regarding background activity and epileptiform components were compared to two 20-minute sEEGs extracted from the cEEG recording (one during TH, and one in early normothermia).ResultsThirty-four recordings were studied. During TH, the agreement between cEEG and sEEG was 97.1% (95% CI: 84.6 to 99.9%) for background discontinuity and reactivity evaluation, while it was 94.1% (95% CI 80.3 to 99.2%) regarding epileptiform activity. In early normothermia, we did not find any discrepancies. Thus, concordance results were very good during TH (kappa 0.83), and optimal during normothermia (kappa = 1). The median delay between CA and the first EEG reactivity testing was 18 hours (range: 4.75 to 25) for patients with perfect agreement and 10 hours (range: 5.75 to 10.5) for the three patients with discordant findings (P = 0.02, Wilcoxon).ConclusionsStandard intermittent EEG has comparable performance with continuous EEG both for variables important for outcome prognostication (EEG reactivity) and identification of epileptiform transients in this relatively small sample of comatose survivors of CA. This finding has an important practical implication, especially for centers where EEG resources are limited.

Continuous Electroencephalography Monitoring in Adults in the Intensive Care Unit

“…Thirty-minute serial EEGs have been demonstrated to have similar yield to cEEG in adult postcardiac arrest patients undergoing hypothermia [21]. Additional studies need to draw definitive data on this topic.…”

Targeted temperature management and neuroprognostication after cardiac arrest: A survey in Belgium

“…These issues should be explored both in the early and late phase after arrest, which means that EEG monitoring should be started as soon as possible after hospital admission, even during the cooling phase. It remains still unclear whether continuous EEG monitoring would provide a better predictive performance than standard intermittent and repeated EEG in these patients [31].…”

EEG as an Indicator of Cerebral Functioning in Postanoxic Coma

“…It has recently been claimed that EEG patterns in TH have similar value to normothermia (Crepeau et al, 2015), but one should be cautious with early recordings which may overestimate brain dysfunction (Alvarez et al, 2013): it seems therefore reasonable to wait at least 9-12 hours after CA before starting the recordings.…”

“…However a reduced montage does not allow an adequate evaluation of reactivity and may miss important information, such as more focal seizures (admittedly a relatively rare issue in this sort of patient), or when muscular or electrical artifacts are present. Recently, the usefulness of cEEG in postanoxic patients has been challenged, as it seems that routine recordings performed during mid-TH and after rewarming bear a comparable amount of information for clinicians, do not alter patients' prognosis, and are much less expensive (Alvarez et al, 2013;Crepeau et al, 2014).…”