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Observational Study
. 2014 Nov 22:14:108.
doi: 10.1186/1471-2253-14-108. eCollection 2014.

The accuracy of locating the cricothyroid membrane by palpation - an intergender study

Mark Campbell  1 , Hilary Shanahan  1 , Simon Ash  1 , Jonathan Royds  1 , Viera Husarova  1 , Conan McCaul  2
Affiliations
Observational Study

The accuracy of locating the cricothyroid membrane by palpation - an intergender study

Mark Campbell et al. BMC Anesthesiol. .

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.

Keywords: Airway; Anaesthesia – Emergency; Anatomy; Complications – Hypoxia; Complications- Airway Obstruction; Training.

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Figures

Figure 1
Figure 1
Flow diagram.
Figure 2
Figure 2
Sample image of calculation of the angle of the junction of the thyroid cartilages.
Figure 3
Figure 3
Polar plot. Estimation of the cricothyroid membrane position by participants. Assessment was performed with the head in the neutral position. Cepahalad and caudad markings indicate distance above or below the upper and lower limits of the cricothyroid membrane, respectively. Markings to the left and right of the vertical line indicate distance from midline.
Figure 4
Figure 4
Image of thyroid cartilage using ultrasound in the transverse plane. The subject in panel A is male and is panel B is female.
See this image and copyright information in PMC

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Pre-publication history
    1. The pre-publication history for this paper can be accessed here: http://www.biomedcentral.com/1471-2253/14/108/prepub

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