title: The accuracy of locating the cricothyroid membrane by palpation - an intergender study.
abstract: BACKGROUND
  The cricothyroid membrane (CTM) is the recommended site of access to the airway during cricothyrotomy to provide emergency oxygenation. We sought to compare the ability of physicians to correctly identify the CTM in male and female patients.
  
  
  METHODS
  In a prospective observational study, anaesthetists were asked to locate the CTM by palpation which was then identified using ultrasound and the distance between the actual and estimated margin of the CTM was measured. Participants assessed the ease of CTM palpation using a visual analog scale. In a second series, the angulation of the posterior junction of the thyroid laminae was measured using ultrasound.
  
  
  RESULTS
  23 anaesthetists and 44 subjects participated. A total of 36 assessments were carried out in each gender. Incorrect identification of the CTM was more common in females (29/36 vs. 11/36, P < 0.001) and the distance from the CTM in the vertical plane was greater (11.0 [6.5-20.0] vs. 0.0 [0.0-10.0] mm, P < 0.001). In females distance from the CTM correlated positively with neck circumference (P = 0.005) and BMI (P = 0.00005) and negatively with subject height (P = 0.01). Posterior thyroid cartilage angulation was greater in females (118.6 ± 9.4° vs. 95.9 ± 12.9°, P = 0.02) and was lower in patients with correctly identified CTMs (100.0 ± 14.9° vs. 115.6 ± 15.9°, P = 0.02). VRS palpation correlated with decreased posterior thyroid cartilage angulation (P = 0.04).
  
  
  CONCLUSIONS
  CTM localisation is more difficult in female subjects irrespective of body habitus. It may be prudent to localize this structure by additional means (e.g. ultrasound) in advance of any airway manoeuvres or to modify the cricothyrotomy technique in the event that it is necessary in an emergency.
authors.affiliation: Department of Anesthesia, The Rotunda Hospital, Parnell Square, Dublin 1, Ireland.
authors.forename: Mark
authors.initials: M
authors.lastname: Campbell
authors.affiliation: Department of Anesthesia, The Rotunda Hospital, Parnell Square, Dublin 1, Ireland.
authors.forename: Hilary
authors.initials: H
authors.lastname: Shanahan
authors.affiliation: Department of Anesthesia, The Rotunda Hospital, Parnell Square, Dublin 1, Ireland.
authors.forename: Simon
authors.initials: S
authors.lastname: Ash
authors.affiliation: Department of Anesthesia, The Rotunda Hospital, Parnell Square, Dublin 1, Ireland.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Royds
authors.affiliation: Department of Anesthesia, The Rotunda Hospital, Parnell Square, Dublin 1, Ireland.
authors.forename: Viera
authors.initials: V
authors.lastname: Husarova
authors.affiliation: Department of Anesthesia, The Rotunda Hospital, Parnell Square, Dublin 1, Ireland ; Department of Anaesthesia, Mater Misericordiae University Hospital, Dublin, Ireland ; School of Medicine and Medical Sciences, University College Dublin, Dublin, Ireland.
authors.forename: Conan
authors.initials: C
authors.lastname: McCaul
mesh_terms: D000328:Adult; D002983:Clinical Competence / Q000592:standards*; D003413:Cricoid Cartilage / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000379:methods / Q000592:standards; D008297:Male; D008875:Middle Aged; D010173:Palpation / Q000379:methods / Q000592:standards*; D010820:Physicians / Q000592:standards*; D011446:Prospective Studies; D012727:Sex Characteristics; D013957:Thyroid Cartilage / Q000033:anatomy & histology*
keywords: Airway; Anaesthesia – Emergency; Anatomy; Complications – Hypoxia; Complications- Airway Obstruction; Training
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