Electroencephalogram signatures of ketamine anesthesia-induced unconsciousness

Oluwaseun Akeju; Andrew H Song; Allison E Hamilos; Kara J Pavone; Francisco J Flores; Emery N Brown; Patrick L Purdon

doi:10.1016/j.clinph.2016.03.005

Electroencephalogram signatures of ketamine anesthesia-induced unconsciousness

Clin Neurophysiol. 2016 Jun;127(6):2414-22. doi: 10.1016/j.clinph.2016.03.005. Epub 2016 Mar 16.

Authors

Oluwaseun Akeju¹, Andrew H Song², Allison E Hamilos³, Kara J Pavone⁴, Francisco J Flores⁵, Emery N Brown⁶, Patrick L Purdon⁵

Affiliations

¹ Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA. Electronic address: [email protected].
² Department of Brain and Cognitive Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
³ Harvard Medical School, Boston, MA, USA; Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA; Institute for Medical Engineering and Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
⁴ Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA.
⁵ Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA; Department of Brain and Cognitive Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
⁶ Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA; Department of Brain and Cognitive Science, Massachusetts Institute of Technology, Cambridge, MA, USA; Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA; Institute for Medical Engineering and Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.

Abstract

Objectives: Ketamine is an N-methyl-d-aspartate (NMDA) receptor antagonist commonly administered as a general anesthetic. However, neural circuit mechanisms to explain ketamine anesthesia-induced unconsciousness in humans are yet to be clearly defined. Disruption of frontal-parietal network connectivity has been proposed as a mechanism to explain this brain state. However, this mechanism was recently demonstrated at subanesthetic doses of ketamine in awake-patients. Therefore, we investigated whether there is an electroencephalogram (EEG) signature specific for ketamine anesthesia-induced unconsciousness.

Methods: We retrospectively studied the EEG in 12 patients who received ketamine for the induction of general anesthesia. We analyzed the EEG dynamics using power spectral and coherence methods.

Results: Following the administration of a bolus dose of ketamine to induce unconsciousness, we observed a "gamma burst" EEG pattern that consisted of alternating slow-delta (0.1-4Hz) and gamma (∼27-40Hz) oscillations. This pattern was also associated with increased theta oscillations (∼4-8Hz) and decreased alpha/beta oscillations (∼10-24Hz).

Conclusions: Ketamine anesthesia-induced unconsciousness is associated with a gamma burst EEG pattern.

Significance: The EEG signature of ketamine anesthesia-induced unconsciousness may offer new insights into NMDA circuit mechanisms for unconsciousness.

Keywords: Anesthesia; EEG; Gamma oscillations; Ketamine; Slow oscillations; Unconsciousness.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Adult
Anesthetics, General / pharmacology*
Brain / drug effects*
Brain / physiology
Female
Gamma Rhythm*
Humans
Ketamine / pharmacology*
Male
Middle Aged

Substances

Anesthetics, General
Ketamine

Abstract

Publication types

MeSH terms

Substances

Grants and funding