title: The influence of head and neck position on the oropharyngeal leak pressure and cuff position of three supraglottic airway devices.
abstract: BACKGROUND
  With supraglottic airway devices, such as the laryngeal tube suction (LTS), ProSeal laryngeal mask airway (PLMA) and Cobra perilaryngeal airway (CobraPLA), oropharyngeal leak pressure or cuff position may vary according to changes in the position of the head and neck. We evaluated oropharyngeal leak pressure and cuff pressure of the PLMA, LTS, and CobraPLA in different head and neck positions.
  
  
  METHODS
  One-hundred-thirty-nine patients (aged 18-70 yr) scheduled for minor surgical procedures were randomly allocated to one of the supraglottic airway devices. Oropharyngeal leak pressure and cuff pressure were evaluated in four head and neck positions: neutral, 45 degrees of flexion, 45 degrees of extension, and 45 degrees of right rotation. Adverse events (i.e., difficulty in ventilation or gastric insufflation) were assessed during the study.
  
  
  RESULTS
  Leak pressures of the PLMA were lowest in the extension (18.5 vs 23.9 and 26.8 cm H(2)O of LTS and CobraPLA, respectively; P < 0.001) and in the rotation position (25.0 vs 29.4 and 28.5 cm H(2)O of LTS and CobraPLA, respectively; P < 0.005). With the CobraPLA, gastric insufflations occurred before the oropharyngeal leak in 37 of 45 patients. There were ventilatory difficulties in seven patients with LTS after neck flexion, which required tracheal intubation.
  
  
  CONCLUSIONS
  The PLMA showed significantly lower oropharyngeal leak pressures than did the LTS or CobraPLA in the neck extension and rotation positions. Caution is warranted when changing the position of the head and neck when using the Cobra-PLA or LTS as gastric insufflation or ventilatory difficulty may occur.
authors.affiliation: Department of Anesthesiology, Seoul National University Bundang Hospital, Seongnam City, Kyeonggi-do, Korea.
authors.forename: Sang-Hyun
authors.initials: SH
authors.lastname: Park
authors.forename: Sung-Hee
authors.initials: SH
authors.lastname: Han
authors.forename: Sang-Hwan
authors.initials: SH
authors.lastname: Do
authors.forename: Jung-Won
authors.initials: JW
authors.lastname: Kim
authors.forename: Jin-Hee
authors.initials: JH
authors.lastname: Kim
mesh_terms: D000328:Adult; D000776:Anesthesiology / Q000295:instrumentation*; D015505:Chest Tubes; D004867:Equipment Design; D005260:Female; D005336:Fiber Optic Technology; D006257:Head; D006801:Humans; D007442:Intubation, Intratracheal / Q000295:instrumentation; D017214:Laryngeal Masks / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D009333:Neck; D009960:Oropharynx / Q000503:physiopathology*; D011187:Posture; D011312:Pressure; D012120:Respiration Disorders / Q000209:etiology; D012399:Rotation