Electroencephalographic changes related to cortico-subcortical decoupling during propofol-induced loss of...

Cortico-subcortical decoupling has been observed in functional magnetic resonance imaging (fMRI) during slow propofol-induced loss of consciousness (LOC). However, corresponding electroencephalography (EEG) free of the cardioballistic and fMRI artifacts is essential for translating decoupling observations to clinical monitoring.

To describe artifact-corrected EEG changes corresponding to cortico-subcortical decoupling at LOC.

Secondary analysis of a prospective observational study.

Tertiary-care hospital, data collection from June 2017 to January 2019.

Nineteen healthy volunteers receiving a targeted propofol infusion.

Frontal EEG was recorded synchronously with clinical signs and fMRI. Gradient artifact correction was based on iterative peak detection. Cardioballistic artifact correction was accomplished with a recently described algorithmic method based on peak detection combined with temporal constraints.

The qCON index and frontal EEG before and after decoupling at LOC.

Algorithm-filtered EEG tracings were suitable for analysis in 16 subjects. Propofol-induced LOC was achieved at a median (IQR) target plasma concentration of 4.5 (3.91 to 4.61) μg/mL and an effect-site concentration of 4.0 (2.94 to 4.31) μg/mL. The qCON index remained over 80 before decoupling and gradually decreased to values below 60 afterwards. Frontal alpha band power increased significantly from a median of 0.07 (0.03 to 0.15) 30 s before decoupling to 0.48 (0.08 to 0.58) 30 s after decoupling (p < 0.001).

Cortico-subcortical decoupling related to propofol-induced LOC coincides with a gradual decrease in the qCON index and an increase in frontal alpha power. These results help translate fMRI findings to bedside settings. Registered at EudraCT (reference 2016-004833-25). Principal Investigator: Juan L. Fernández-Candil. Date of registration: January 4, 2017. Start Date: June 13, 2017.