Clinical sedation assessment versus EEG-based monitoring during deep sedation in VV-ECMO patients: A prospective blinded observational study

Severe ARDS patients on VV-ECMO often require deep sedation, where behavioural assessments may fail to quantify cortical suppression. We evaluated this suppression burden and its relation to routine sedation assessment using blinded EEG.

In this prospective observational study, adult VV-ECMO patients with severe ARDS underwent 24-h blinded Conox EEG monitoring. Burst suppression ratio (BSR) and Quantium Consciousness Index (qCON) were paired with hourly Richmond Agitation-Sedation Scale (RASS) assessments (target -4). Linear mixed-effects models with patient as a random effect tested whether hourly RASS predicted BSR and qCON.

Twenty patients yielded 467 paired RASS-EEG observations. Burst suppression occurred in all patients. Median time-weighted average BSR was 7.3% (IQR 2.1-30.8), maximum BSR was 27.9% (IQR 6.2-71.2), and median time with BSR ≥ 5% was 37.7% (IQR 12.5-96.9). A 1-point RASS increase was associated with a 3.31% decrease in BSR (95% CI - 5.60 to -1.01; p =  0.005). At RASS -4, BSR was ≥5% in 64.5% and ≥10% in 51.7% of observations. Lower qCON values were associated with greater burst suppression burden, with BSR approaching zero above qCON ≈40.

Processed EEG revealed a substantial burden of burst suppression during deep VV-ECMO sedation despite uniform behavioural targets. Within this deep sedation range, RASS had limited resolution for quantifying cortical suppression.