title: The effects of dexmedetomidine/remifentanil and midazolam/remifentanil on auditory-evoked potentials and electroencephalogram at light-to-moderate sedation levels in healthy subjects.
abstract: Avoidance of excessively deep sedation levels is problematic in intensive care patients. Electrophysiologic monitoring may offer an approach to solving this problem. Since electroencephalogram (EEG) responses to different sedation regimens vary, we assessed electrophysiologic responses to two sedative drug regimens in 10 healthy volunteers. Dexmedetomidine/remifentanil (dex/remi group) and midazolam/remifentanil (mida/remi group) were infused 7 days apart. Each combination of medications was given at stepwise intervals to reach Ramsay scores (RS) 2, 3, and 4. Resting EEG, bispectral index (BIS), and the N100 amplitudes of long-latency auditory-evoked potentials (ERP) were recorded at each level of sedation. During dex/remi, resting EEG was characterized by a recurrent high-power low-frequency pattern which became more pronounced at deeper levels of sedation. BIS Index decreased uniformly in only the dex/remi group (from 94 +/- 3 at baseline to 58 +/- 14 at RS 4) compared to the mida/remi group (from 94 +/- 2 to 76 +/- 10; P = 0.029 between groups). The ERP amplitudes decreased from 5.3 +/- 1.3 at baseline to 0.4 +/- 1.1 at RS 4 (P = 0.003) in only the mida/remi group. We conclude that ERPs in volunteers sedated with dex/remi, in contrast to mida/remi, indicate a cortical response to acoustic stimuli, even when sedation reaches deeper levels. Consequently, ERP can monitor sedation with midazolam but not with dexmedetomidine. The reverse is true for BIS.
authors.affiliation: Department of Intensive Care Medicine, University Hospital of Bern, Bern, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Haenggi
authors.forename: Heidi
authors.initials: H
authors.lastname: Ypparila
authors.forename: Kathrin
authors.initials: K
authors.lastname: Hauser
authors.forename: Claudio
authors.initials: C
authors.lastname: Caviezel
authors.forename: Ilkka
authors.initials: I
authors.lastname: Korhonen
authors.forename: Jukka
authors.initials: J
authors.lastname: Takala
authors.forename: Stephan M
authors.initials: SM
authors.lastname: Jakob
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D020927:Dexmedetomidine / Q000008:administration & dosage*; D004338:Drug Combinations; D004569:Electroencephalography / Q000187:drug effects* / Q000379:methods; D005072:Evoked Potentials, Auditory / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage*; D008297:Male; D008874:Midazolam / Q000008:administration & dosage*; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods; D010880:Piperidines / Q000008:administration & dosage*; D000077208:Remifentanil
chemical_list: D004338:Drug Combinations; D006993:Hypnotics and Sedatives; D010880:Piperidines; D020927:Dexmedetomidine; D000077208:Remifentanil; D008874:Midazolam