Does continuous EEG influence prognosis in patients after cardiac arrest?

doi:10.1016/j.resuscitation.2018.08.023

Resuscitation

Volume 132, November 2018, Pages 29-32

https://doi.org/10.1016/j.resuscitation.2018.08.023 Get rights and content

Abstract

Aim

Electroencephalography (EEG) is a key modality for assessment of prognosis following cardiac arrest (CA); however, whether continuous EEG (cEEG) is superior to routine intermittent EEG (rEEG) remains debated. We examined the impact of cEEG (>18 h) vs. rEEG (<30 min) on outcome in comatose CA patients as part of multimodal prognostication.

Methods

We analysed a large prospective registry of comatose post-CA adults (n = 497; 2009–2018), stratified based on whether they received cEEG (n = 62) or rEEG (n = 435), including standardized reactivity testing at two time-points. The primary endpoint was the impact of cEEG vs. rEEG on Glasgow-Pittsburgh Cerebral Performance Categories (CPC) at three months; we also assessed impact on time to death.

Results

Main patients’ baseline clinical characteristics and CPC scores were comparable between the EEG groups. By multivariable analysis age, non-shockable rhythm, presence of early myoclonus, absent EEG background reactivity, absent somato-sensory evoked potentials, and serum NSE were independently associated with poor neurological outcome (CPC 3–5), while the EEG approach had no impact on patient prognosis and time to death.

Conclusions

Our data suggest that cEEG does not confer any advantage over intermittent rEEG regarding outcome in patients with CA, and does not influence the time to death.

Introduction

Cardiac arrest (CA) is one of the main causes of death and severe disability. Outcome depends on several factors, such as age, initial cardiac rhythm and longer time to resuscitation [1], history of cardiac disease, and seizures, especially with myoclonus [2]. Early prognostication of comatose CA patients relies on a multimodal approach, where EEG is very frequently applied [3] as it allows a non-invasive bedside measure of brain function [4]. Nevertheless, its optimal duration is debated: some advocate continuous EEG monitoring in order to observe EEG evolution [5,6], while others suggest that prolonged recordings are not related to better outcome [7], and repetitive routine EEG might provide sufficient prognostic information [8,9].

Since previous studies did not take into account prognostication relying on several complementary features, the aim of the present analysis was to explore a cohort of post-CA patients assessing the impact of continuous EEG on outcome and latency to death, considering a multimodal assessment.

Section snippets

Study population

This is a retrospective cohort study, investigating a large prospective registry (approved by our Ethic Commission) of consecutive, comatose adult (>16 years old) post-CA patients referred to our multidisciplinary intensive care unit (ICU) from April 2009 to January 2018. The registry does not consider patients dying within the first 24 h after CA.

Patient assessment

This has been described earlier [10,11]. Briefly, the vast majority of patients were treated for the first 24 h with a targeted temperature

Results

We examined 497 patients: 435 in the rEEG group and 62 in the cEEG group, after excluding two patients for missing clinical data. While virtually all rEEG lasted 20 min, cEEG had a length between 18–87.5 h (median: 27 h). Table 1 illustrates variables stratified by type of EEG recording; demographic and clinical characteristics were comparable in the two groups, as were outcome at three months and latency to death; only early reactivity testing of the first EEG recording was performed somewhat

Discussion

This study, which to the best of our knowledge is the first exploring the impact of EEG recording length in the set of early multimodal prognostic investigation of a large cohort of post-CA patients, shows the lack of impact of continuous EEG on clinical outcome and latency to death.

The essential role of the multimodal assessment of post-CA patients (in terms of clinical and neurophysiological examination and biomarkers detection) has been extensively emphasized [10,11,[15], [16], [17]], in

Conclusion

We did not find evidence of an association between continuous EEG and outcomes or time to death after cardiac arrest. It seems therefore that rEEG, at least for some resource-limited settings, may bear equivalent prognostic information and impact as compared to cEEG, especially if performed at defined time-spots during and after TTM, including video recording and standardized stimulations.

Conflicts of interest

None of the authors has any conflict of interest to disclose.

Acknowledgments

We thank Christine Stähli, RN, and ChristianPfeiffer, PhD, for help in data management.

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The current EEG role for prognostication after cardiac arrest (CA) essentially aims at reliably identifying patients with poor prognosis (”highly malignant” patterns, defined by Westhall et al. in 2014). Conversely, “benign EEGs”, defined by the absence of elements of “highly malignant” and “malignant” categories, has limited sensitivity in detecting good prognosis. We postulate that a less stringent “benign EEG” definition would improve sensitivity to detect patients with favorable outcomes.
Retrospectively assessing our registry of unconscious adults after CA (1.2018–8.2021), we scored EEGs within 72 h after CA using a modified “benign EEG” classification (allowing discontinuity, low-voltage, or reversed anterio-posterior amplitude development), versus Westhall’s “benign EEG” classification (not allowing the former items). We compared predictive performances towards good outcome (Cerebral Performance Category 1–2 at 3 months), using 2x2 tables (and binomial 95% confidence intervals) and proportions comparisons.
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Citation Excerpt :
Furthermore, the optimal duration of EEG recordings in post CA setting still appears unclear. Several experts recommend cEEG to optimally follow the evolution of background activity in the first few days after CA,8,10,20–23 while others point out that cEEG may not be related to improved outcome24,25 nor more informative about prognosis.26 The impact of cEEG versus repeated rEEG on clinical outcome has been assessed in a recent multicenter randomized controlled trial (Continuous EEG Randomized Trial in Adults (CERTA); NCT03129438) in adults with acute consciousness impairment of different etiologies 16: it showed no difference between groups regarding mortality and functional outcomes at 6 months.
Electroencephalography (EEG) is essential to assess prognosis in patients after cardiac arrest (CA). Use of continuous EEG (cEEG) is increasing in critically-ill patients, but it is more resource-consuming than routine EEG (rEEG). Observational studies did not show a major impact of cEEG versus rEEG on outcome, but randomized studies are lacking.
We analyzed data of the CERTA trial (NCT03129438), including comatose adults after CA undergoing cEEG (30–48 hours) or two rEEG (20–30 minutes each). We explored correlations between recording EEG type and mortality (primary outcome), or Cerebral Performance Categories (CPC, secondary outcome), assessed blindly at 6 months, using uni- and multivariable analyses (adjusting for other prognostic variables showing some imbalance across groups).
We analyzed 112 adults (52 underwent rEEG, 60 cEEG,); 31 (27.7%) were women; 68 (60.7%) patients died. In univariate analysis, mortality (rEEG 59%, cEEG 65%, p = 0.318) and good outcome (CPC 1–2; rEEG 33%, cEEG 27%, p = 0.247) were comparable across EEG groups. This did not change after multiple logistic regressions, adjusting for shockable rhythm, time to return of spontaneous circulation, serum neuron-specific enolase, EEG background reactivity, regarding mortality (cEEG vs rEEG: OR 1.60, 95% CI 0.43–5.83, p = 0.477), and good outcome (OR 0.51, 95% CI 0.14–1.90, p = 0.318).
This analysis suggests that cEEG or repeated rEEG are related to comparable outcomes of comatose patients after CA. Pending a prospective, large randomized trial, this finding does not support the routine use of cEEG for prognostication in this setting.
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The review was created and intended for medical staff in the intensive care units and emphasizes EEG patterns and timing which portend both favorable and poor prognoses. Also, the review addresses the overall quality of the existing studies and discusses future directions to address the knowledge gaps in this field.
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SSEPs may be depressed by barbiturate coma but are preserved with other sedative drugs such as propofol and midazolam.357 A bilateral absence of the short-latency N20-potentials over the sensory cortex is a reliable sign of a poor prognosis after cardiac arrest with high specificity and limited sensitivity both early and late after cardiac arrest.201,202,302,310,331,335,337,338,340,342,343,350,352,358–366 Occasional false positive predictions were reported.367
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Short paperDoes continuous EEG influence prognosis in patients after cardiac arrest?

Abstract

Aim

Methods

Results

Conclusions

Introduction

Section snippets

Study population

Patient assessment

Results

Discussion

Conclusion

Conflicts of interest

Acknowledgments

Resuscitation

Resuscitation

Resuscitation

Lancet Neurol

J Am Coll Cardiol

Temporal trends in sudden cardiac arrest: a 25-year emergency medical services perspective

Circulation

European resuscitation council and European society of intensive care medicine 2015 guidelines for post-resuscitation care

Intensive Care Med

Continuous electroencephalography monitoring for early prediction of neurological outcome in postanoxic patients after cardiac arrest: a prospective cohort study

Crit Care Med

The prognostic value of 48-h continuous EEG during therapeutic hypothermia after cardiac arrest

Neurocrit Care

A comparison of continuous video-EEG monitoring and 30-minute EEG in an ICU

Epileptic Disord

Short paper
Does continuous EEG influence prognosis in patients after cardiac arrest?