title: Prediction of movement at laryngeal mask airway insertion: comparison of auditory evoked potential index, bispectral index, spectral edge frequency and median frequency.
abstract: We have studied 46 patients to compare the efficacy of the auditory evoked potential (AEP) index, bispectral index (BIS), 95% spectral edge frequency (SEF) and median frequency (MF) in predicting movement in response to insertion of the laryngeal mask airway (LMA). Anaesthesia was induced with target-controlled infusions of propofol and alfentanil. After loss of eyelash reflex and adequate jaw relaxation, the LMA was inserted without the assistance of a laryngoscope or neuromuscular blocker. Patients who showed any visible spontaneous muscle movement within 1 min of LMA insertion were defined as movers. Values in movers and non-movers at 30 s before LMA insertion were analysed. Only AEP index discriminated between movers and non-movers with a prediction probability of 0.872. BIS, SEF and MF could not predict movement at LMA insertion. AEP index was the most reliable predictor of movement in response to LMA insertion.
authors.affiliation: Department of Anaesthesia, HCI International Medical Centre, Clydebank, UK.
authors.forename: M
authors.initials: M
authors.lastname: Doi
authors.forename: R J
authors.initials: RJ
authors.lastname: Gajraj
authors.forename: H
authors.initials: H
authors.lastname: Mantzaridis
authors.forename: G N
authors.initials: GN
authors.lastname: Kenny
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General; D004569:Electroencephalography / Q000379:methods*; D005072:Evoked Potentials, Auditory; D005260:Female; D006439:Hemodynamics; D006801:Humans; D017214:Laryngeal Masks; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology