Can novice sonographers accurately locate an endotracheal tube with a saline-filled cuff in a cadaver model? A pilot study.

BACKGROUND: No single confirmatory device can accurately distinguish between endotracheal, endobronchial, and esophageal intubation. Bedside ultrasound (US) shows promising potential for endotracheal tube (ETT) verification. Image acquisition depends on the approach used and the experience of the sonographer. Air within the trachea remains a challenge for interpretation of US images. Insufflation of the ETT cuff with saline helps overcome this difficulty and allows easy visualization of the cuff. This novel approach has not been studied in ETT verification among novice sonographers.

OBJECTIVES: The objective was to evaluate the accuracy of novice sonographers in identifying proper ETT location and depth using US visualization of a saline-filled cuff.

METHODS: Eight pediatric emergency medicine (PEM) fellows without prior training in airway bedside US participated in this prospective pilot study. Baseline US knowledge was assessed using a pretraining questionnaire. Fellows received a 20-minute didactic training session focused on airway US, followed by a 30-minute practice session. Using a linear US probe placed at the suprasternal notch, fellows identified the saline-filled cuff of an ETT in both the trachea and the esophagus. Following training, the ETT was placed in either the esophagus or the trachea of the cadaver model by the principal investigator. ETT depth (adequacy) was confirmed by chest radiograph. Each PEM fellow, blinded to the placement of the ETT, used bedside US to determine ETT location and depth. If placement was determined to be tracheal, the fellow was asked to comment on adequacy of tube placement. Adequate placement was defined as complete visualization of the ETT cuff within the trachea at the suprasternal notch. This was used as a surrogate for correct depth. This study sequence was repeated five times for each trainee, following varying placement of the ETT in the trachea or esophagus.

RESULTS: The PEM fellows displayed limited baseline knowledge of US prior to receiving the training module (average score of 50% on pretest questionnaire). None had any prior airway bedside US experience. Following training, PEM fellows correctly identified ETT location in 39 of 40 scans, with a sensitivity of 96% (23 of 24) for identifying tracheal location. The tube depth was correctly identified in 22 of 23 scans identified as tracheal intubations.

CONCLUSIONS: PEM fellows, lacking formal airway bedside US training, were able to identify the location and depth of a saline-filled ETT above or at the suprasternal notch in an adult cadaver model following a 50-minute teaching module. Filling the ETT cuff with saline allowed novice sonographers to accurately visualize the ETT within the trachea.