This post aims to shine a light on a possibly emerging use of bedside ultrasound. While this is far from being recommended as a viable method of intubation during RSI in an Emergency Department, knowledge that ongoing research evaluating the use of ultrasound-guided tracheal intubation (UGTI) exists can only serve to enhance one's understanding of the progression of ultrasound in medicine. While evidence exists to support the use of ultrasound for confirmiting endotracheal tube placement, positioning the endotracheal tube post-intubation, assessing vocal cord movement, and diagnosis endobronchial intubation, first documentation of use of UGTI without laryngoscopy occured in December 2012 by Fiadjoe et al. of the Department of Anesthesiology at the Children's Hospital of Philadelphia.

Fiadjoe et al. "Ultrasound-Guided Tracheal Intubation: A Novel Intubation Technique." Anesthesiology. December 2012.

• This article is a case report of the authors' first use of ultrasound-guided tracheal intubation. A 14 month-old female was being intubated pre-operatively in the operating room. After two unsuccessful attempts to intubate the patient using direct laryngoscopy, the providers asked for a video-assisted laryngoscope. While waiting for the proper equipment to be set up, they attemped tracheal intubation using ultrasound:
• "A malleable stylet... was placed within a 4.0 cuffed tracheal tube... and shaped like a hockey stick. A 15–6 MHZ HFL50x linear array ultrasound probe attached to a Sonosite S-nerve machine (SonoSite Inc., Bothell, WA) was lightly placed transversely on the patient’s neck at the level of the thyrohyoid membrane. The probe was moved caudally until a view of the vocal cords and surrounding hypopharyngeal tissue was obtained. A second provider opened the mouth and performed a jaw thrust while inserting the hockey-stick–shaped styletted tube in the midline of the patient’s pharynx. The tube was inserted in the midline of the pharynx under the operator’s direct vision, it was then advanced slowly along the tongue base at which point it was visualized to the left of the glottis on the ultrasound image. The tube was withdrawn slightly and its trajectory modified to direct it into the glottis; hypoechoic shadowing and widening of the vocal cords was noted as the tube entered the trachea, a characteristic of successful glottic placement of the tube. The stylet was withdrawn and the endotracheal tube advanced into the trachea. The intubation was performed in less than 10 s. The patient underwent an uncomplicated clinical course and was extubated uneventfully at the end of the procedure.
• Benefit: The authors posit that UGTI has the potential benefit in patients where blood/secretions obscure visualization of airway or if there is a limitation to mouth opening.
• Limitations: The authors list some limitations as a need for two providers (one to perform the ultrasound and one to perform the intubation) as well as limitations relating to the quality of ultrasound images obtainable.
• To understand where the idea to use purely ultrasound guidance for tracheal intubation came from read the original article.

 Janik et al. "The Use of Ultasound-Guided Tracheal Intubation in Pediatrics." Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania. 2014.

• Descriptive case series of ultrasound-guided tracheal intubation in 21 patients
• Success Rate: 90%
• Average Time-to-Intubation: 80 seconds
• Average Number of Attempts for Successful Intubation: 1.5 attempts
• Complications: None
• "Excellent" or "Adequate" View: 99%
• Ultrasound-guided tracheal intubation is safe with no complications.
• Most common technical challenge is modifying bend in stylet.
• Two intubation failures occured in patients over 19 years old, suggesting possible limitation of UGTI in patients with mature neck anatomy.
• Wide range of average intubation time, suggesting possible limitation of UGTI in patients requiring RSI.
• All patients had a normal airway, therefore unknown role in UGTI in patients with difficult airways.