title: Relationship between Sevoflurane Plasma Concentration, Clinical Variables and Bispectral Index Values during Cardiopulmonary Bypass.
abstract: BACKGROUND
  Anesthetic administration is increasingly guided by electroencephalography (EEG)-based monitoring, such as the bispectral index (BIS). However, during cardiopulmonary bypass (CPB), factors other than the administered hypnotic agents may influence EEG signals, and their effects on BIS values are unknown.
  
  
  METHODS
  This report is a secondary analysis of data from a prospective, controlled interventional study comparing the effect of sevoflurane administration guided by BIS monitoring (group SevoBIS) and constant administration of sevoflurane (group Sevo1.8Vol%) during CPB. Sevoflurane plasma concentration (SPC) was measured using gas chromatography. The relationships of BIS to SPC, CPB pump flow, arterial pressure, hematocrit, temperature, time on CPB, and patient characteristics were analysed.
  
  
  RESULTS
  No association was observed between BIS values and SPC in group SevoBIS. In group Sevo1.8Vol%, a 40 μg ml-1 increase in SPC, which encompassed the entire range of observed values of the SPC in this analysis, was associated with a decrease of 3.6 (95% confidence interval (CI): 1.1-6.1) in BIS values (p = 0.005). Each increase in CPB time of 10 minutes was associated with an increase in BIS values of 0.25 (95%CI: 0.11-0.39, p<0.001). Path analysis revealed that the BIS values of SevoBIS patients were 5.3 (95%CI: 3.2-7.5) units higher than those of Sevo1.8Vol% patients (p<0.001), which was the strongest effect on BIS values. Path analysis revealed a slope of 0.5 (95%CI: 0.3-0.7) BIS units per 1°C body temperature (p<0.001).
  
  
  CONCLUSIONS
  BIS monitoring is insensitive to clinically relevant changes in SPC in individual patients during CPB.
authors: Department of Anesthesiology, Center of Anesthesiology and Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors: Rainer
authors: R
authors: Nitzschke
authors: Department of Anesthesiology, Center of Anesthesiology and Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors: Joana
authors: J
authors: Wilgusch
authors: Department of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors: Jan Felix
authors: JF
authors: Kersten
authors: Department of Anesthesiology, Center of Anesthesiology and Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors: Matthias Sebastian
authors: MS
authors: Goepfert
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000758:Anesthesia / Q000379:methods*; D018685:Anesthetics, Inhalation / Q000097:blood* / Q000494:pharmacology / Q000627:therapeutic use; D062186:Arterial Pressure; D001831:Body Temperature; D002315:Cardiopulmonary Bypass; D002849:Chromatography, Gas; D056805:Consciousness Monitors; D004569:Electroencephalography; D005260:Female; D006400:Hematocrit; D006801:Humans; D008297:Male; D008738:Methyl Ethers / Q000097:blood* / Q000494:pharmacology / Q000627:therapeutic use; D008875:Middle Aged; D000077149:Sevoflurane; D013997:Time Factors
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane