title: Cricoid pressure provides incomplete esophageal occlusion associated with lateral deviation: a magnetic resonance imaging study.
abstract: BACKGROUND
  Cricoid pressure is a routine component of rapid sequence induction and is designed to reduce the risk of reflux and its associated morbidity. Recent studies have raised questions regarding the efficacy of cricoid pressure in terms of changes in the pharyngeal and esophageal anatomy.
  
  
  OBJECTIVE
  This current descriptive study was designed to observe the anatomical effect of cricoid pressure on the occlusion of esophageal lumen in conscious volunteers using magnetic resonance imaging (MRI).
  
  
  METHODS
  We quantitatively assessed esophageal patency before and during application of cricoid pressure in 20 awake volunteers utilizing MRI.
  
  
  RESULTS
  Target cricoid pressure was achieved in 16 of 20 individuals, corresponding to a mean percentage reduction in cricovertebral distance of 43% (range 25-80%). Cricoid pressure was applied incorrectly in 4 (20%) individuals as evidenced by no change in the cricovertebral distance. Incomplete esophageal occlusion was seen in 10 of 16, or 62.5% (95% confidence interval 35-85%) of individuals when appropriate cricoid pressure was applied. Incomplete esophageal occlusion was always associated with a lateral deviation of the esophagus. None of the 6 subjects with complete occlusion had esophageal deviation during the appropriate application of cricoid pressure.
  
  
  CONCLUSIONS
  Effective application of cricoid pressure by an experienced operator frequently resulted in lateral deviation of the esophagus and incomplete occlusion of esophageal lumen. Reliance on cricoid pressure for esophageal occlusion requires further evaluation utilizing functional studies.
authors.affiliation: Department of Anesthesia, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Boet
authors.forename: Kaylene
authors.initials: K
authors.lastname: Duttchen
authors.forename: Jean
authors.initials: J
authors.lastname: Chan
authors.forename: An-Wen
authors.initials: AW
authors.lastname: Chan
authors.forename: William
authors.initials: W
authors.lastname: Morrish
authors.forename: Andre
authors.initials: A
authors.lastname: Ferland
authors.forename: Gregory M T
authors.initials: GM
authors.lastname: Hare
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Hong
mesh_terms: D000328:Adult; D003413:Cricoid Cartilage / Q000033:anatomy & histology / Q000502:physiology*; D004947:Esophagus / Q000033:anatomy & histology / Q000502:physiology*; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011312:Pressure; D053120:Respiratory Aspiration / Q000517:prevention & control; D055815:Young Adult