title: Correlation between bispectral index, observational sedation scale, and lower esophageal sphincter pressure in volunteers using dexmedetomidine or propofol.
abstract: BACKGROUND
  Many anesthetics reduce lower esophageal sphincter pressure (LESP) and consequently the gastro-esophageal pressure gradient (GEPG); thus they may promote gastro-esophageal reflux and contribute to aspiration pneumonia. Our goals were to evaluate the association between LESP and 2 measures of sedation: bispectral index (BIS) and the responsiveness component of the Observer's Assessment of Alertness score (OAA/S).
  
  
  METHODS
  Eleven healthy volunteers were each sedated on 2 separate days. Subjects were given sedative infusions of increasing target plasma concentrations of dexmedetomidine or propofol. LESP and GEPG were recorded after starting each infusion phase. Generalized estimating equation modeling was used to assess the relationship between LESP and, respectively, BIS and OAA/S. The existence of a drug-dependent association was evaluated within these models by testing an interaction term. Wald tests were used to evaluate the relationships within the models.
  
  
  RESULTS
  We found a significant relationship between LESP and BIS (P=0.0043) after adjusting for the main effect of sedative type--a deepening of sedation as measured by a decrease in BIS of 10% was associated with a decrease [Bonferroni-adjusted 95% CI] in LESP of -1.34 [-2.39, -0.29] mmHg. After adjusting for the main effect of sedative drug, LESP significantly declined with declining OAA/S (P=0.001); a unit decrease of OAA/S was associated with a decrease [Bonferroni-adjusted 95% CI] in LESP of -2.01 [-3.20, -0.81] mmHg.
  
  
  CONCLUSIONS
  Deeper sedation, as measured by either BIS or OAA/S, significantly reduces LESP.
authors.affiliation: Department of Outcomes Research, The Cleveland Clinic, Cleveland, OH 44195, USA. alparslanturan@yahoo.com
authors.forename: Alparslan
authors.initials: A
authors.lastname: Turan
authors.forename: Jarrod E
authors.initials: JE
authors.lastname: Dalton
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kasuya
authors.forename: Ozan
authors.initials: O
authors.lastname: Akça
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Sessler
authors.forename: Stefan
authors.initials: S
authors.lastname: Rauch
mesh_terms: D000328:Adult; D016292:Procedural Sedation; D056805:Consciousness Monitors; D020927:Dexmedetomidine / Q000008:administration & dosage / Q000494:pharmacology*; D049630:Esophageal Sphincter, Lower / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000494:pharmacology*; D011312:Pressure; D015742:Propofol / Q000008:administration & dosage / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D006993:Hypnotics and Sedatives; D020927:Dexmedetomidine; D015742:Propofol