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KMID : 0374920040250010067
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Inje Medical Journal
2004 Volume.25 No. 1 p.67 ~ p.75
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Effect of Epidural Lidocaine on Desflurane Requirement for Adequate Depth of Anesthesia as Measured by the Bispectral Index Monitor
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Choe Young-Kyun
Lee Kun-Moo
Cheong Soon-Ho
Kim Young-Jae
Shin Chee-Mahn
Park Ju-Yeoul
Shin Sang-Wu
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Abstract
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Background: Epidural anesthesia potentiates sedative drug effects and decreases minimum alveolar concentration (MAC) of inhalation anesthetics. The authors hypothesized that epidural anesthesia also decreases the general anesthetic requirements for adequate depth of anesthesia as measured by Bispectral Index(BIS)
Methods: After premedication with 0.02 mg/kg midazolam, 30 patients aged 20-75 yr were randomized in a double-blinded fashion to receive general anesthesia with either intravenous saline placebo or intravenous lidocaine control (1-mg/kg bolus does; 25 ㎕·kg-1·min-1). A matched group was prospectively assigned to receive epidural lidocaine (15 ml; 2%) with intravenous saline placebo. All patients receive 1.5 mg/kg propofol and 1mg/kg rocuronium for tracheal intubation. After 10 min of equilibration period with 3% end-tidal desflurane concentration, BIS was measured at every 30 second. If BIS score was above 50, vaporizer dial was increased by 0.5 vol%. If BIS score was under 45, vaporizer dial was decreased by 0.5 vol%. When BIS score was maintained between 45-50 by 3minutes, we checked the end tidal desflurane concentration and defined as MACBIS50(Minimum alveolar concentration at BIS 50). MACBIS50, BIS score, and mean arterial pressure were recorded.
Results: The MACBIS50 of desflurane (2.5 0.49%) was significantly decreased with lidocaine epidural anesthesia compared with general anesthesia alone (3.1 0.59%) or with intravenous lidocaine (3.0 0.51%)(p<0.05).
Conclusions: Epidural anesthesia reduced by 19% the desflurane required for adequate depth of anesthesia. This effect was not a result of systemic lidocain absorption, but may have been caused by deafferentation by epidural anesthesia or direct rostral spread of local anesthetic within the cerebrospinal fluid. Lower-than-expected concentrations of volatile agents may be sufficient during combined epidural-general anesthesia.
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KEYWORD
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Desflurane, Epidural Anesthesia, Bispectral Index
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