title: A comparison of propofol- and dexmedetomidine-induced electroencephalogram dynamics using spectral and coherence analysis.
abstract: BACKGROUND
  Electroencephalogram patterns observed during sedation with dexmedetomidine appear similar to those observed during general anesthesia with propofol. This is evident with the occurrence of slow (0.1 to 1 Hz), delta (1 to 4 Hz), propofol-induced alpha (8 to 12 Hz), and dexmedetomidine-induced spindle (12 to 16 Hz) oscillations. However, these drugs have different molecular mechanisms and behavioral properties and are likely accompanied by distinguishing neural circuit dynamics.
  
  
  METHODS
  The authors measured 64-channel electroencephalogram under dexmedetomidine (n = 9) and propofol (n = 8) in healthy volunteers, 18 to 36 yr of age. The authors administered dexmedetomidine with a 1-µg/kg loading bolus over 10 min, followed by a 0.7 µg kg h infusion. For propofol, the authors used a computer-controlled infusion to target the effect-site concentration gradually from 0 to 5 μg/ml. Volunteers listened to auditory stimuli and responded by button press to determine unconsciousness. The authors analyzed the electroencephalogram using multitaper spectral and coherence analysis.
  
  
  RESULTS
  Dexmedetomidine was characterized by spindles with maximum power and coherence at approximately 13 Hz (mean ± SD; power, -10.8 ± 3.6 dB; coherence, 0.8 ± 0.08), whereas propofol was characterized with frontal alpha oscillations with peak frequency at approximately 11 Hz (power, 1.1 ± 4.5 dB; coherence, 0.9 ± 0.05). Notably, slow oscillation power during a general anesthetic state under propofol (power, 13.2 ± 2.4 dB) was much larger than during sedative states under both propofol (power, -2.5 ± 3.5 dB) and dexmedetomidine (power, -0.4 ± 3.1 dB).
  
  
  CONCLUSIONS
  The results indicate that dexmedetomidine and propofol place patients into different brain states and suggest that propofol enables a deeper state of unconsciousness by inducing large-amplitude slow oscillations that produce prolonged states of neuronal silence.
authors.affiliation: From the Department of Anesthesia, Critical Care, and Pain Medicine (O.A., K.J.P., R.V., M.J.P., P.G.H., K.E.H., J.R., A.L.S., G.L., E.T.P., J.L.W., E.N.B., P.L.P.) and Department of Neurology (M.B.W.), Massachusetts General Hospital, Boston, Massachusetts; Clinical Research Center, Massachusetts General Hospital, Boston, Massachusetts (K.H.); Harvard Medical School, Boston, Massachusetts (O.A., M.B.W., R.V., M.J.P., P.G.H., J.R., G.L., E.T.P., J.L.W., E.N.B., P.L.P.); Department of Brain and Cognitive Science, Massachusetts Institute of Technology, Cambridge, Massachusetts (E.N.B., P.L.P.); Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts (E.N.B.); and Institute for Medical Engineering and Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts (E.N.B.).
authors.forename: Oluwaseun
authors.initials: O
authors.lastname: Akeju
authors.forename: Kara J
authors.initials: KJ
authors.lastname: Pavone
authors.forename: M Brandon
authors.initials: MB
authors.lastname: Westover
authors.forename: Rafael
authors.initials: R
authors.lastname: Vazquez
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Prerau
authors.forename: Priscilla G
authors.initials: PG
authors.lastname: Harrell
authors.forename: Katharine E
authors.initials: KE
authors.lastname: Hartnack
authors.forename: James
authors.initials: J
authors.lastname: Rhee
authors.forename: Aaron L
authors.initials: AL
authors.lastname: Sampson
authors.forename: Kathleen
authors.initials: K
authors.lastname: Habeeb
authors.forename: Lei
authors.initials: L
authors.lastname: Gao
authors.forename: Gao
authors.initials: G
authors.lastname: Lei
authors.forename: Eric T
authors.initials: ET
authors.lastname: Pierce
authors.forename: John L
authors.initials: JL
authors.lastname: Walsh
authors.forename: Emery N
authors.initials: EN
authors.lastname: Brown
authors.forename: Patrick L
authors.initials: PL
authors.lastname: Purdon
mesh_terms: D000293:Adolescent; D000328:Adult; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D001519:Behavior / Q000187:drug effects; D003627:Data Interpretation, Statistical; D020927:Dexmedetomidine / Q000494:pharmacology*; D004569:Electroencephalography / Q000187:drug effects* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D008297:Male; D015742:Propofol / Q000494:pharmacology*; D014474:Unconsciousness / Q000139:chemically induced / Q000503:physiopathology; D055815:Young Adult
chemical_list: D018686:Anesthetics, Intravenous; D006993:Hypnotics and Sedatives; D020927:Dexmedetomidine; D015742:Propofol