Document Detail

Electroencephalogram bispectral analysis predicts the depth of midazolam-induced sedation.
MedLine Citation:
PMID:  8572355     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The electroencephalogram (EEG) has been used to study the effects of anesthetic and analgesic drugs on central nervous system function. A prospective study was designed to evaluate the accuracy of various EEG parameters for assessing midazolam-induced sedation during regional anesthesia. METHODS: Twenty-six consenting adult patients were administered 4.5-20 mg intravenous midazolam (in increments of 0.5-1 mg bolus doses every 6-10 min) until they became unresponsive to tactile stimulation (i.e., mild prodding or shaking). The EEG was continuously recorded from a bifrontal montage (FP1-Cz and FP2-Cz) to obtain the bispectral index (BI), 95% spectral edge frequency (SEF), median frequency (MF), and delta, theta, alpha, and beta power bands. Sedation was assessed clinically at 6-10-min intervals using the Observers' Assessment of Alertness/Sedation (OAA/S) scale, with 1 = no response (unconsciousness) to tactile stimulation to 5 = wide awake. The EEG parameters were correlated with the OAA/S scores using nonparametric Spearman's rank-correlation analysis. Kruskal-Wallis analysis of variance was used to determine significant changes in EEG parameters during the onset of and recovery from midazolam-induced sedation. RESULTS: Of the EEG parameters studied, the BI exhibited the best correlation with OAA/S scores during both the onset (Spearman's Rho = 0.815) and recovery (Spearman's Rho = 0.596) phases. With increasing sedation, there was a progressive decrease in the BI (OAA/S score of 5: BI = 95.4 +/- 2.3; 4: 90.3 +/- 4.5; 3:86.6 +/- 4.6; 2:75.6 +/- 9.7; 1:69.2 +/- 13.9). A similar pattern was found for the 95% SEF as the OAA/S score decreased from 4 to 1. Similarly, EEG-BI increased with recovery from the sedative effects of midazolam (OAA/S score = 2:BI = 75.2 +/- 10.2; 3:82.3 +/- 7.3; 4:90.8 +/- 6). However, no consistent changes were found with the other EEG parameters. The mean EEG values between OAA/S scores 3 and 2 and between OAA/S scores 2 and 1 during the onset and recovery phases from midazolam-induced sedation, defined as EEG50 values for response to verbal command (EEG50-VC) and to shaking of the head (EEG50-SH), were 79.3 +/- 8 and 70.8 +/- 14.3, respectively, for EEG-BI. The EEG-BI displayed the smallest coefficients of variation for the EEG50-VC and EEG50-SH values. CONCLUSIONS: The EEG-BI appears to be a useful parameter for assessing midazolam-induced sedation and can predict the likelihood of a patient responding to verbal commands or to shaking of the head during midazolam-induced sedation.
J Liu; H Singh; P F White
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Anesthesiology     Volume:  84     ISSN:  0003-3022     ISO Abbreviation:  Anesthesiology     Publication Date:  1996 Jan 
Date Detail:
Created Date:  1996-03-04     Completed Date:  1996-03-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  1300217     Medline TA:  Anesthesiology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  64-9     Citation Subset:  AIM; IM    
Department of Anesthesiology and Pain Management, University of Texas Southwestern Medical Center, Dallas 75235-9068, USA.
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MeSH Terms
Anesthesia, Conduction
Electroencephalography / drug effects*,  methods*
Hypnotics and Sedatives / therapeutic use*
Midazolam / therapeutic use*
Middle Aged
Prospective Studies
Reg. No./Substance:
0/Hypnotics and Sedatives; 59467-70-8/Midazolam

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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