title: Cricoid pressure prevents placement of the laryngeal tube and laryngeal tube-suction II.
abstract: BACKGROUND
  The laryngeal tube has a potential role in patients with a difficult airway, but cricoid pressure is required if the patient is at risk of aspiration. The effect of cricoid pressure on insertion of these devices is unknown.
  
  
  METHODS
  In a randomized cross-over study, the laryngeal tube (25 patients) or the laryngeal tube-suction II (15 patients) was inserted with cricoid pressure applied on one occasion and with sham pressure on the other occasion. Adequacy of ventilation, time to achieve adequate ventilation, and the leak pressure were assessed.
  
  
  RESULTS
  Ventilation was adequate in all patients when sham pressure was applied. Cricoid pressure significantly reduced the rate of adequate ventilation to 6 of 25 patients for the laryngeal tube [P < 0.001; 95% confidence interval (CI) for difference: 59-93%] and to 5 of 15 patients for the laryngeal tube-suction II (P < 0.05; 95% CI for difference: 43-91%). The median time taken to achieve adequate ventilation for the laryngeal tube was 10 s [inter-quartile range (IQR): 8-15] (range 5-26) for sham pressure and 25 s (15-32) (15-33) for cricoid pressure; the median leak pressure was 30 (IQR: 30-30) (range 20-30) cm H2O for sham pressure and 15.5 (14.3-20.5) (12-22) cm H2O for cricoid pressure.
  
  
  CONCLUSIONS
  Continuous cricoid pressure prevents correct placement of the laryngeal tube and the laryngeal tube-suction II such that placement and ventilation via these devices are ineffective. The effect of cricoid pressure on ventilation via these devices, after correct placement, remains unknown.
authors.affiliation: Department of Anesthesiology, Kansai Medical University, Osaka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Asai
authors.forename: R W L
authors.initials: RW
authors.lastname: Goy
authors.forename: E H C
authors.initials: EH
authors.lastname: Liu
mesh_terms: D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000209:etiology*; D003413:Cricoid Cartilage; D018592:Cross-Over Studies; D004867:Equipment Design; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000379:methods; D017214:Laryngeal Masks / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D011015:Pneumonia, Aspiration / Q000517:prevention & control; D011312:Pressure; D013396:Suction