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

Abstract

BackgroundThe 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.MethodsIn 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.Results23 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).ConclusionsCTM 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.

Localisation of the cricothyroid membrane by digital palpation in the emergency department

“…Identification of landmarks in female patients had been reported to be more difficult irrespective of how high their BMI was found to be at the time of the procedure,10but this was not confirmed in our study. The previous study was done by anaesthesia physicians who had higher level of training in this procedure, while ED clinicians comprise of a more pragmatic population who are likely to encounter the need for securing a surgical airway.…”

Impact of change in head and neck position on ultrasound localisation of the cricothyroid membrane: an observational study

“…Firstly, some authors have recommended marking the cricothyroid membrane (CTM) before induction of general anaesthesia if difficulty is anticipated [2,3], thus avoiding the need to identify the membrane for the first time during an unfolding emergency. Although this seems to make sense, these authors have suggested marking the CTM in the neutral or intubating position.…”

Clinical Audit to Assess Upper Airway Ultrasound Skills in Anaesthesia Trainees

“…Palpation of cricothyroid membrane is limited by factors like thick pad of subcutaneous tissue, obesity and in females due to the relatively less palpable thyroid prominence. Palpation is also limited by distorted anatomy due to previous radiotherapy to neck and tracheal deviation [5]. A computed tomography (CT)-guided study demonstrated that cricothyroid membrane is not necessarily a superficial structure and also the smallest dimensions of the membrane may necessitate the use of smaller than recommended trocar and endotracheal tubes [6].…”