title: Cricoid pressure impedes insertion of, and ventilation through, the ProSeal laryngeal mask airway in anesthetized, paralyzed patients.
abstract: BACKGROUND
  We designed this prospective self-controlled study to assess whether cricoid pressure hampers placement of and ventilation through the ProSeal laryngeal mask airway (ProSeal LMA) in anesthetized, paralyzed adult patients.
  
  
  METHODS
  After induction of anesthesia, the ProSeal LMA was inserted using the introducer tool with cricoid pressure advanced as far as possible, and the cuff pressure was set at 60 cm H2O. Ventilation adequacy and anatomic position were scored using measures previously described for ProSeal LMA assessment. Airway seal pressure was recorded. Cricoid pressure was then released, the ProSeal LMA further advanced and reseated, and the assessment repeated.
  
  
  RESULTS
  Lung ventilation scores, anatomic position scores, and airway seal pressure were significantly better after release of cricoid pressure and reseating of the ProSeal LMA than in the first position, where the ProSeal LMA was seated with cricoid pressure (P < 0.05). Expiratory tidal volume during intermittent positive pressure ventilation was similar with and without cricoid pressure, but peak inspiratory pressure decreased from 28 cm H(2)O with cricoid pressure to 14 cm H(2)O without cricoid pressure (P < 0.05).
  
  
  CONCLUSIONS
  Cricoid pressure applied before insertion hampered proper placement of the ProSeal LMA. Temporary cricoid pressure release during insertion allowed the device to be advanced to the proper position. After correct placement of the ProSeal LMA, application of cricoid pressure did not change tidal volume, but produced a significant increase in peak inspiratory pressure.
authors: Department of Anesthesiology, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shi-Jing-Shan District, Beijing, People's Republic of China.
authors: Cheng W
authors: CW
authors: Li
authors: Fu S
authors: FS
authors: Xue
authors: Ya C
authors: YC
authors: Xu
authors: Yi
authors: Y
authors: Liu
authors: Peng
authors: P
authors: Mao
authors: Kun P
authors: KP
authors: Liu
authors: Quan Y
authors: QY
authors: Yang
authors: Guo H
authors: GH
authors: Zhang
authors: Hai T
authors: HT
authors: Sun
mesh_terms: D000293:Adolescent; D000328:Adult; D000771:Anesthesia, Intravenous / Q000295:instrumentation / Q000379:methods*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000295:instrumentation / Q000379:methods*; D017214:Laryngeal Masks; D008297:Male; D008875:Middle Aged; D010243:Paralysis / Q000139:chemically induced; D011312:Pressure; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000295:instrumentation / Q000379:methods*