Simplified frontal EEG in adults under veno-arterial extracorporeal membrane oxygenation

Abstract

Abstract Background EEG-based prognostication studies in intensive care units often rely on a standard 21-electrode montage ( std EEG) requiring substantial human, technical, and financial resources. We here evaluate whether a simplified 4-frontal electrode montage ( 4-front EEG) can detect EEG patterns associated with poor outcomes in adult patients under veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Methods We conducted a reanalysis of EEG data from a prospective cohort on 118 adult patients under VA-ECMO, in whom EEG was performed on admission to intensive care. EEG patterns of interest included background rhythm, discontinuity, reactivity, and the Synek’s score. They were all reassessed by an intensivist on a 4-front EEG montage, whose analysis was then compared to an expert’s interpretation made on std EEG recordings. The main outcome measure was the degree of correlation between 4-front EEG and std EEG montages to identify EEG patterns of interest. The performance of the Synek scores calculated on 4-front EEG and std EEG montage to predict outcomes (i.e., 28-day mortality and 90-day Rankin score $${\ge {4}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>≥</mml:mo> <mml:mn>4</mml:mn> </mml:mrow> </mml:math> ) was investigated in a secondary exploratory analysis. Results The detection of EEG patterns using 4-front EEG was statistically similar to that of std EEG for background rhythm (Spearman rank test, ρ = 0.66, p &lt; 0.001), discontinuity (Cohen’s kappa, $$\kappa$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>κ</mml:mi> </mml:math> = 0.955), reactivity ( $$\kappa$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>κ</mml:mi> </mml:math> = 0.739) and the Synek’s score ( ρ = 0.794, p &lt; 0.001). Using the Synek classification, we found similar performances between 4-front EEG and std EEG montages in predicting 28-day mortality (AUC 4-front EEG 0.71, AUC std EEG 0.68) and for 90-day poor neurologic outcome (AUC 4-front EEG 0.71, AUC std EEG 0.66). An exploratory analysis confirmed that the Synek scores determined by 4 or 21 electrodes were independently associated with 28-day mortality and poor 90-day functional outcome. Conclusion In adult patients under VA-ECMO, a simplified 4-frontal electrode EEG montage interpreted by an intensivist, detected common EEG patterns associated with poor outcomes, with a performance similar to that of a standard EEG montage interpreted by expert neurophysiologists. This simplified montage could be implemented as part of a multimodal evaluation for bedside prognostication.