Document Detail

Increasing isoflurane concentration may cause paradoxical increases in the EEG bispectral index in surgical patients.
MedLine Citation:
PMID:  10740544     Owner:  NLM     Status:  MEDLINE    
We have studied the effects of increases in isoflurane concentration on the EEG bispectral index (BIS) in 70 patients anaesthetized with isoflurane-nitrous oxide-sufentanil for major abdominal surgery. During surgery, baseline BIS was recorded at 0.8% end-tidal isoflurane with nitrous oxide in oxygen (FIO2 0.35). After this, end-tidal isoflurane was increased to 1.6% for 15 min and decreased subsequently to 0.8% for 20 min to assess recovery. In 20 patients, BIS decreased from a mean value of 40 (SD 9) during baseline to 25 (10) at 1.6% isoflurane. In contrast, BIS did not change in 23 patients and increased in 27 patients from 35 (6) to 46 (8) as isoflurane was increased to 1.6%. In all patients, BIS recovered to baseline values at 0.8% isoflurane. The changes in BIS with increasing isoflurane concentration were not related to drugs or differences in physiological variables, which did not differ between groups. Patients with a decrease in BIS were significantly younger (38 (range 18-68) yr) than those with unchanged (55 (26-70) yr) or increased (60 (40-70) yr) BIS values (P < 0.001). It is possible that the paradoxical increase in BIS is related to continuous pre-burst EEG patterns consisting of high-frequency activity. This suggests that the use of BIS as a guide for isoflurane administration may be misleading in some patients undergoing surgical procedures.
O Detsch; G Schneider; E Kochs; G Hapfelmeier; C Werner
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  British journal of anaesthesia     Volume:  84     ISSN:  0007-0912     ISO Abbreviation:  Br J Anaesth     Publication Date:  2000 Jan 
Date Detail:
Created Date:  2000-04-07     Completed Date:  2000-04-07     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0372541     Medline TA:  Br J Anaesth     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  33-7     Citation Subset:  IM    
Klinik für Anaesthesiologie, Klinikum rechts der Isar, Technische Universität München, Germany.
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MeSH Terms
Abdomen / surgery
Anesthetics, Inhalation / administration & dosage,  pharmacology*
Dose-Response Relationship, Drug
Electroencephalography / drug effects*
Hemodynamics / drug effects
Isoflurane / administration & dosage,  pharmacology*
Middle Aged
Monitoring, Intraoperative / methods*
Prospective Studies
Reg. No./Substance:
0/Anesthetics, Inhalation; 26675-46-7/Isoflurane
Comment In:
Br J Anaesth. 2000 Jul;85(1):171-2   [PMID:  10928009 ]

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