Deficiencies in locating the cricothyroid membrane by palpation: We can’t and the surgeons can’t, so what now for the emergency surgical airway?

Abstract

At times, it seems that we were never meant to discover the underlying mysteries of the neck's surface anatomy. The quest first began with the cricoid cartilage and although Sellick's maneuver 1 seemed an acceptable concept, it eventually proved somewhat disappointing in its application. Who knows how often this technique actually hit its target? Now, as Hiller et al. outline in this issue of the Journal, just north of the cricoid cartilage and sorely needed for expeditious emergency surgical airway (ESA), it seems that the cricothyroid membrane (CTM) is also keeping its exact location a closely guarded secret. 2The ESA is infrequently performed by the average anesthesiologist and has had its issues. Historically, in a can't intubate, can't oxygenate (CICO) emergency, practitioners been slow to initiate the procedure. Furthermore, some of the techniques used to execute the ESA have been less than effective, perhaps accounting for the generally poor success rates.3,4 Fortunately, recently published national airway guidelines address these matters with more definitive recommendations for both when and how ESA should occur.5-7 The trouble is, establishing an ESA generally begins with identifying the location of the CTM by external palpation. As it turns out, for the life of us (not to mention that of our patients), it seems that we can't reliably accomplish this task.At least six recently published studies from a variety of countries attest to this conclusion. [8][9][10][11][12][13] These studies used similar methodologies to determine how often physician assessors correctly identified the location of the CTM by external palpation. The assessors' estimations in these studies (and similarly in the present one) were compared with the actual location of the CTM as confirmed by ultrasound. In most studies, the assessor's attempt to localize the CTM was defined as a failure if the estimation was either outside the vertical confines of the CTM or [ 5 mm from the midline. The results are sobering. Correctly identifying the CTM location using external palpation is no better than a 50:50 proposition, give or take, even in nonobese subjects. Most of the studies include scatter plots of the assessors' estimates, and in some cases, localization is off by at least 3 cm above, below, or lateral to the actual CTM location. Not surprisingly, there is a trend towards worse results in females and obese subjects given their less distinct thyroid cartilage anatomy. These findings occurred in the relatively stress-free conditions of a clinical study in volunteer subjects. We can probably expect even worse results when we add the anxiety-related performance degradation in an actual CICO situation.By adding trauma surgeons to the mix, Hiller et al. add fuel to the fire with their study of the accuracy of CTM identification by external palpation in female subjects. 2Notwithstanding their greater experience in performing ESA, the surgeons failed to demonstrate a significantly better success rate at CTM identification than their anesthesia ...

Effect of palpable vs. impalpable cricothyroid membranes in a simulated emergency front‐of‐neck access scenario

“…Correct identification of the cricothyroid membrane is essential for successful cricothyroidotomy, but is not always possible by external palpation [3][4][5]. In such cases, exposure of the cricothyroid membrane via a vertical skin incision and finger dissection is described by the Difficult Airway Society (DAS) 2015 guidelines [1].…”

Obstructing pathology of the upper airway in a post-NAP4 world: time to wake up to its optimal management

“…19 If an emergency cricothyrotomy is a backup plan, the location of the cricothyroid membrane (CTM) should be determined and marked beforehand, recognizing that existing studies indicate poor success at identification of the CTM by palpation alone. [20][21][22] Thus, if time permits, ultrasound should be used to locate the CTM. 23 The surgical safety briefing should include the planned primary and alternative intubation techniques as well as the plan for a CICO situation.…”

“…19 Si une cricothyrotomie d'urgence est le plan de secours, la position de la membrane cricothyroïdienne (MCT) doit être déterminée et marquée sur la peau au préalable, les études existantes indiquant le faible taux de réussite de la localisation de la MCT par palpation seulement. [20][21][22] Ainsi, si le temps le permet, une échographie doit être réalisée pour localiser la MCT. 23 Deux raisons peuvent justifier de renoncer à la sédation d'un patient éveillé présentant des voies aériennes fragilisées.…”

Emergency airway management: What are the roles for surgical cricothyroidotomy and the Ventrain® device?

“…It focuses on attaining and then maintaining proficiency using an invasive technique (i.e., surgical cricothroidotomy) with which many anesthesiologists are not comfortable 4 and do not have an opportunity to practice. It promotes research and quality improvement of one invasive technique to the exclusion of other approaches.…”

“…In the centrepiece (orange), the diameter decreases from the inlet (2) to the jet nozzle (3), resulting in flow acceleration. Oxygen then enters the conically shaped exhaust pipe (4). If the bypass outlet (5), which functions as an on/off switch, is completely covered, active expiration is enabled (right image).…”