ORIGINAL ARTICLE: Accuracy of surface landmark identification for cannula cricothyroidotomy

Abstract

SummaryCannula cricothyroidotomy is recommended for emergency transtracheal ventilation by all current airway guidelines. Success with this technique depends on the accurate and rapid identification of percutaneous anatomical landmarks. Six healthy subjects underwent neck ultrasound to delineate the borders of the cricothyroid membrane. The midline and bisecting transverse planes through the membrane were marked with an invisible ink pen which could be revealed with an ultraviolet light. Eighteen anaesthetists were then invited to mark an entry point for cricothyroid membrane puncture. Only 32 (30%) attempts by anaesthetists accurately marked the skin area over the cricothyroid membrane. Of these only 11 (10%) marked over the centre point of the membrane. Entry point accuracy was not significantly affected by subjects' weight, height, body mass index, neck circumference or cricothyroid dimensions. Consultant and registrar anaesthetists were significantly more accurate than senior house officers at correctly identifying the cricothyroid membrane. Accuracy of percutaneously identifying the cricothyroid membrane was poor. Ultrasound may assist in identifying anatomical landmarks for cricothyroidotomy.

Comparing success rates of anesthesia providers versus trauma surgeons in their use of palpation to identify the cricothyroid membrane in female subjects: a prospective observational study

“…Based on an estimated success rate for anesthesia providers of 30%, 13,15,16 this convenience sample of 57 anesthesia providers and 14 surgeons allowed the detection of [ 52% absolute difference in the proportion of successful identification between anesthesia providers and surgeons, with 80% power at a 0.0125 level of significance after justification for multiple comparisons.…”

“…13,15 The subjects were chosen based on anatomic measurements known or hypothesized to affect the accuracy of identifying the CTM location, including body mass index, 13,15,16 neck circumference, 13,15,16 thyromental distance (TMD-i.e., the distance from the mentum to the thyroid notch), 13 sternomental distance (SMD-i.e., the distance from the suprasternal notch to the mentum with the head fully extended and the mouth closed), 13 and pre-tracheal soft tissue. 15,16 Characteristics and anatomic measurements of the subjects were as follows: Subject 1, non-obese female with a small neck circumference; Subject 2, morbidly obese female with a large neck circumference and significant pre-tracheal subcutaneous tissue; Subject 3, tall female with a small neck circumference; and Subject 4, non-obese female with the lowest TMD/SMD ratio of the four subjects. Subjects were positioned in a standardized fashion with the neck optimally extended (as the height of the CTM increases upon neck extension, 20 exposing a larger working area to perform a cricothyrotomy.…”

“…The ultrasonographer marked the superior and inferior borders and the sagittal midline of the CTM with a fine-point invisible ink marker that appeared pink under ultraviolet light. 16 A 10 cm x 12 cm waterproof transparent dressing (Tegaderm™, 3M Health Care, St. Paul, MN, USA) was placed over the markings. Depth from skin to CTM (mm) 5.0 11.0 4.5 4.0 CTM = cricothyroid membrane; TMD = thyromental distance; SMD = sternomental distance Table 2 Characteristics of anesthesia providers and surgeons Variables Anesthesiology (n = 57) Surgery (n = 14)…”

“…7,[13][14][15][16] Results of the "Fourth National Audit Project" revealed that anesthesiologists failed to perform a successful percutaneous emergency surgical airway 64% of the time when attempted in the cannot intubate, cannot oxygenate setting. 7 Conversely, this audit revealed that all three open cricothyrotomies and 29 tracheostomies were performed successfully (presumably by surgeons) as first choice options for emergency surgical airways.…”

“…7 The first step in the performance of an emergency cricothyrotomy is accurate identification of the CTM, which is often not an easy task in both non-emergency and emergency situations. 5,13,[15][16][17] Predictors of difficult cricothyrotomy include difficulty identifying the location of the CTM (Fig. 1) and difficulty accessing the trachea through the anterior neck.…”