Ketamine induces EEG oscillations that may aid anesthetic state but not dissociation monitoring
Shubham Chamadia, Jacob Gitlin, Jennifer Mekonnen, Breanna R. Ethridge, R. Ibala, Katia Colon, J. Qu, Oluwaseun Akeju
Clinical Neurophysiology October 1, 2021 DOI: 10.1016/j.clinph.2021.08.021 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Open-label study Peer reviewed |
|---|---|
| Sample size | 15 |
| Population | Human subjects receiving ketamine anesthesia |
| Interventions | Ketamine Midazolam |
| Dose | 2 mg/kg |
| Topics | Esketamine Ketamine |
| Key points | Ketamine-induced electroencephalogram power and global coherence signatures track anesthetic state but not dissociation, as only midazolam, not electroencephalogram features, predicted dissociation scores. |
Abstract
Objective: Ketamine is an anesthetic drug associated with dissociation. Decreased electroencephalogram alpha (8 to 13 Hz) and low-beta (13 to 20 Hz) oscillation power have been associated with ketamine-induced dissociation. We aimed to characterize surface electroencephalogram signatures that may serve as biomarkers for dissociation.
Methods: We analyzed data from a single-site, open-label, high-density surface electroencephalogram study of ketamine anesthesia (2mg/kg, n = 15). We assessed dissociation longitudinally using the Clinician Administered Dissociation States Scale (CADSS) and administered midazolam to attenuate dissociation and enable causal inference. We analyzed spectral power and global coherence with multitaper spectral methods. Mixed effects models were used to assess whether electroencephalogram power and global coherence signatures of ketamine could be developed into dissociation-specific biomarkers.
Results: Compared to baseline, ketamine unresponsiveness was associated with increased frontal power between 0.5 to 9.3 Hz, 12.2 to 16.6 Hz, and 24.4 to 50 Hz. As subjects transitioned into a responsive but dissociated state (mean CADSS ± SD, 22.1 ± 17), there was a decrease in power between 0.5 to 10.3 Hz and 11.7 to 50 Hz. Midazolam reduced dissociation scores (14.3 ± 11.6) and decreased power between 4.4 to 11.7 Hz and an increase in power between 14.2 to 50 Hz. Our mixed-effects model demonstrated a quadratic relationship between time and CADSS scores. When models (frontal power, occipital power, global coherence) were reanalyzed with midazolam and electroencephalogram features as covariates, only midazolam was retained.
Conclusions: Ketamine is associated with structured electroencephalogram power and global coherence signatures that may enable principled anesthetic state but not dissociation monitoring.
Significance: A neurophysiological biomarker for dissociation may lead to a better understanding of neuropsychiatric disorders.