Document Detail

Equi-MAC concentrations of halothane and isoflurane do not produce similar bispectral index values.
MedLine Citation:
PMID:  17413994     Owner:  NLM     Status:  MEDLINE    
Minimum alveolar concentration (MAC) has been traditionally used to measure the potency of an inhalational anesthetic agent. Recently, bispectral index (BIS) derived from the frontal cortical electroencephalogram has been used frequently for quantifying the hypnotic component of anesthesia. The present study was designed to examine the BIS values produced by equi-MAC concentrations of halothane and isoflurane. In 34 patients undergoing spinal surgery, BIS and spectral edge frequency (SEF95) were recorded at 3 different concentrations of halothane and isoflurane--namely 0.5, 0.75, and 1.0 MAC. The measurements were made both during wash-in and wash-out phases of the anesthetic agent. Eighteen patients received halothane and 16 received isoflurane. Heart rate, mean arterial pressure, oxygen saturation, and end tidal carbon dioxide pressure values were not different between the 2 groups at various MAC concentrations of the anesthetic agents. BIS and SEF95 values decreased significantly with increasing concentrations of both the anesthetic agents (P<0.001). At any given MAC concentration of the anesthetic, BIS and SEF(95) values were significantly lower under isoflurane compared with halothane anesthesia both during wash-in and wash-out phases (P<0.001). For a given anesthetic agent, BIS values were comparable at equi-MAC concentrations during wash-in and wash-out phases. In conclusion, BIS values are significantly lower under isoflurane compared with halothane anesthesia at similar MAC concentrations. For a given anesthetic agent and a given MAC concentration, the BIS values are similar during wash-in and wash-out phases of anesthesia.
Ganne S Umamaheswara Rao; Zulfiqar Ali; Madhusudan Ramamoorthy; Jayaprakash Patil
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of neurosurgical anesthesiology     Volume:  19     ISSN:  0898-4921     ISO Abbreviation:  J Neurosurg Anesthesiol     Publication Date:  2007 Apr 
Date Detail:
Created Date:  2007-04-06     Completed Date:  2007-05-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8910749     Medline TA:  J Neurosurg Anesthesiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  93-6     Citation Subset:  IM    
Department of Neuroanaesthesia, National Institute of Mental Health and Neurosciences, Bangalore, India.
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MeSH Terms
Anesthesia, General*
Anesthesia, Inhalation*
Blood Pressure / drug effects
Electroencephalography / drug effects*
Halothane* / administration & dosage,  pharmacokinetics
Heart Rate / drug effects
Isoflurane* / administration & dosage,  pharmacokinetics
Monitoring, Intraoperative
Neurosurgical Procedures
Pulmonary Alveoli / metabolism*
Spine / surgery
Reg. No./Substance:
151-67-7/Halothane; 26675-46-7/Isoflurane

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

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