The presence of a respiratory-related cortical activity during tidal breathing is abnormal and a hallmark of respiratory difficulties, but its detection requires superior discrimination and temporal resolution. The aim of this study was to validate a computational method using EEG covariance (or connectivity) matrices to detect a change in brain activity related to breathing. In 17 healthy subjects, EEG was recorded during resting unloaded breathing (RB), voluntary sniffs and breathing against an inspiratory threshold load (ITL). EEG were analyzed by the specially developed covariance-based classifier, event-related potentials and time-frequency (T-F) distributions. Nine subjects repeated the protocol. The classifier could accurately detect ITL and sniffs compared to the reference period of RB. For ITL, EEG-based detection was superior to airflow-based detection (p<0.05). A coincident improvement in EEG-airflow correlation in ITL compared to RB (p<0.05) confirmed that EEG-detection relates to breathing. Premotor potential incidence was significantly higher prior to inspiration in sniffs and ITL compared to RB (p<0.05), but T-F distributions revealed a significant difference between sniffs and RB only (p<0.05). Intraclass correlation values ranged from poor (-0.2) to excellent (1.0). Thus, as for conventional event-related potential analysis, the covariance-based classifier can accurately predict a change in brain state related to a change in respiratory state and given its capacity for near "real-time" detection, it is suitable to monitor respiratory state in respiratory- and critically-ill in patients in the development of a brain-ventilator interface.
- voluntary movement
- mechanical ventilation
- Copyright © 2015, Journal of Neurophysiology