title: Mandibular advancement improves the laryngeal view during direct laryngoscopy performed by inexperienced physicians.
abstract: BACKGROUND
  When oral or nasal fiberoptic laryngoscopy is attempted, mandibular advancement has been reported to improve the laryngeal view. The authors hypothesized that mandibular advancement may also improve the laryngeal view during direct laryngoscopy.
  
  
  METHODS
  Forty patients undergoing elective surgery under general anesthesia were included in this study. After establishment of an adequate level of anesthesia and muscle relaxation, direct laryngoscopy was performed by inexperienced physicians. Four different maneuvers--simple direct laryngoscopy without any assistance (C), simple direct laryngoscopy with mandibular advancement (M), simple direct laryngoscopy with the BURP maneuver (backward, upward, rightward pressure maneuver of the larynx; B), and simple direct laryngoscopy with both mandibular advancement and the BURP maneuver (BM)--were attempted in each subject, and the laryngeal aperture was videotaped with each procedure. An instructor in anesthesiology who was blinded to the procedure evaluated the visualization by reviewing videotape off-line, using the Cormack-Lehane classification system (grades I-IV) and a rating score within each subject (1 = best view; 4 = poorest view). The Friedman test followed by the Student-Newman-Keuls test was performed for statistical comparison. P < 0.05 was considered significant.
  
  
  RESULTS
  The laryngeal view was improved with M and B when compared with C (P < 0.05 by both rating and Cormack-Lehane evaluation). BM was the most effective method to visualize the laryngeal aperture (P < 0.05, vs. B and M by rating evaluation), whereas B and M were the second and the third most effective methods, respectively. No statistical difference was observed between B and M with the Cormack-Lehane classification.
  
  
  CONCLUSIONS
  Mandibular advancement improves the laryngeal view during direct laryngoscopy performed by inexperienced physicians.
authors.affiliation: Department of Anesthesiology, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Tamura
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Rie
authors.initials: R
authors.lastname: Kato
authors.forename: Shiroh
authors.initials: S
authors.lastname: Isono
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishino
mesh_terms: D000368:Aged; D000769:Anesthesia, Inhalation; D005260:Female; D005336:Fiber Optic Technology; D006801:Humans; D007442:Intubation, Intratracheal / Q000379:methods*; D020704:Laryngoscopes; D007828:Laryngoscopy / Q000379:methods*; D007830:Larynx / Q000033:anatomy & histology*; D008297:Male; D008334:Mandible; D008875:Middle Aged; D016343:Monitoring, Intraoperative