Feasibility of sonographic access to the cricothyroid membrane in the presence of a rigid neck collar in healthy Chinese adults: A prospective cohort study

Abstract

Objectives: (1) To study the dimensions of cricothyroid membranes (CTMs) in healthy Chinese adults in two neck positions, one with rigid neck collar (RNC) and neck extended by ultrasonography (USG). (2) To evaluate how body habitus and neck positions may affect the access time of CTMs, and thus the feasibility for ultrasound-guided cricothyroidotomy. Methods: We scanned 39 adult staff of a local emergency department. Their CTMs were measured by two emergency physicians (EP) separately. The subjects' gender, weight, height, age, neck circumferences and BMI were collected. Image qualities (graded in ‘inadequate, adequate and good’) and image acquisition time of the CTMs were also recorded to ascertain proper CTM measurements. Results: The mean depth of the CTM (neck extended) was 5.6 mm, and the standard deviation (SD) was 1.52. The mean depth (with RNC) was 5.97mm with SD 1.61. The mean length of the CTM (mm ± SD) with the neck extended and with the RNC was 10.5 ± 2.15 and 9.97 ± 2.24, respectively. The median image acquisition time for neck extended was 6.36s with interquartile range (IQR) of 2.32–8.4 s, while for RNC the median time was 5.60 s (IQR = 3.71–7.49; P = 0.539). Image acquisition time between the first and the second sonographers was similar. All subjects’ CTM could be identified readily by USG. Conclusions: The CTM can be located quickly and reliably by bedside USG, even in overweight/obese persons with or without an RNC in place. We recommend that further study on the feasibility of bedside cricothyroidotomy with RNC kept on should be explored.