Pitfalls and possibilities of using Root SedLine for continuous assessment of EEG waveforms-based metrics in intensive care research.

Abstract

The Root SedLine Device is used for continuous electroencephalography (cEEG) based sedation monitoring in intensive care patients. The cEEG traces can be collected for further processing and calculation of relevant metrics not already provided. Depending on the device settings during acquisition, the acquired traces may be distorted by max/min values cropping or high digitization error. We aimed to systematically assess the impact of those distortions on metrics used for clinical research in the field of neuromonitoring.
Approach: A 16h cEEG acquired using the Root SedLine Device at the optimal screen settings was analyzed. Cropping and digitization error effects were simulated by consecutive reduction of the maximum cEEG amplitude by 2µV or by reducing the vertical resolution. Metrics were calculated within ICM+ using minute-by-minute data including total power, alpha delta ratio, and 95% spectral edge frequency. Data were analyzed by creating violin-plots or box-plots.
Main Results: Cropping led to a continuous reduction in total and band power leading to corresponding changes in variability thereof. Relative power and alpha delta ratio were less affected. Changes in resolution led to relevant changes. While total power and power of low frequencies were rather stable, power of higher frequencies increased with reducing resolution. 
Significance: Care must be taken when acquiring and analyzing cEEG waveforms from Root SedLine for clinical research. In order to retrieve good quality metrics, the screen settings must be kept within the central vertical scale while pre-processing techniques must be applied to exclude unacceptable periods.
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