Intravenous anesthesia

Abstract

Anesthesia and Pain Medicine. 2002 Sept. 6(3): 142-147
ⓒ Korean Society for Intravenous Anesthesia
  
 
 
Time Sequence Changes of BIS and 95% SEF during I.V. Anesthetic Induction
Il Woo Shin, M.D., Hyoung Chan Cho, M.D., Ju Tae Shon, M.D., Heon Keun Lee, M.D., and Young Kyun Chung, M.D.
Department of Anesthesiology, College of Medicine, Gyungsang National University, Jinju, Korea
 

BACKGROUND: Although it is important to predict the probability of awareness during general anesthesia, we do not have an effective monitor to evaluate the level of consciousness. As a result, several neurophysiologic monitors have been introduced in an attempt to provide a measurement of the conscious level. The bispectral index and 95% spectral edge frequency have been proposed as a measurement to evaluate the level of consciousness. We recorded changes of bispectral index and 95% spectral edge frequency after a single bolus infusion with intravenous anesthetics.
METHODS: Forty-five adult patients were randomly allocated to one of the three groups according to induction agents: thiopental sodium group; 4 mg/kg, propofol group; 2 mg/kg, midazolam group; 0.2 mg/kg. Bispectral index and 95% spectral edge frequency were recorded every 15 sec until 5 min after induction and the correlation coefficient between BIS and 95% SEF was checked.
Results: The minimum BIS was achieved at 1 min with thiopental sodium, 1 min with propofol, 2 min 30 sec with midazolam after induction. At each point minimum BIS value was 45.6 +/- 10.9 (SD), 46.2 +/- 16.3 (SD), 60.3 +/- 8.4 (SD) respectively. The correlation coefficient between BIS and 95% SEF was 0.68 at thiopental sodium group, 0.97 at propofol group and no correlation at midazolam group.
CONCLUSIONS: We concluded that the maximum effect of intravenous anesthetic drugs checked by mean BIS was achieved at 1 min with thiopental sodium, 1 min with propofol, 2 min 30 sec with midazolam.
 
Key words : Bispectral index, intravenous induction, midazolam, propofol, thiopental
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