Airway POCUS in Children: Are You Ready to Scan?

Debnath Chatterjee, MD, FAAP and Elaina Lin, MD

Original article

Gomes SH, Canelli R, Corradi F, Pêgo JM, Baker MB, Bilotta F. The Use of Ultrasound in Airway Management: Video in Clinical Anesthesia. Anesth Analg. 2024 Oct 1;139(4):887-890. doi: 10.1213/ANE.0000000000007046. Epub 2024 Sep 4. PMID: 39284139.

The journal Anesthesia & Analgesia has added a new series to its repertoire called “Video in Clinical Anesthesia,” which is listed under the Collections tab on the A&A website. In today’s PAAD, we will review a video from this series titled “The use of ultrasound in airway management” by Gomes SH et al.¹

This is an excellent video describing how point-of-care ultrasound (POCUS) can be used as a valuable tool to evaluate and manage the airway. The first section of the video explains how to identify normal sonoanatomy using POCUS. The ultrasound images of normal anatomical structures are labeled nicely, making this a worthy educational exercise. The next section of the video discusses several ultrasound parameters to predict difficult laryngoscopy. These include the skin-to-hyoid bone distance, skin-to-epiglottis distance, hyomental distance ratio, and various tongue measurements, including tongue thickness, area, and volume. The final section of the video focuses on airway POCUS aspects that interest pediatric anesthesiologists the most, such as estimating endotracheal tube (ETT) size, confirming endotracheal intubation, and guiding front-of-neck access.

So, what is the current literature on airway POCUS in children? A few educational reviews have been published recently, highlighting the different uses of ultrasonography in evaluating the pediatric airway. ^2-4

1. Selection of appropriate ETT size: In general, ultrasonography appears to underestimate the appropriate ETT size since it measures the transverse diameter of the airway, which is known to be smaller than the anteroposterior diameter. ^2,3 Interestingly, most pediatric studies that have reported estimating ETT size have acquired the images on an anesthetized child, highlighting the challenges of performing a preoperative ultrasound in an awake or uncooperative child.⁴

2. Confirming ETT placement and depth. As mentioned in the video, following esophageal intubation, the esophagus acquires a dilated and circular shape with a double hyperechoic line representing the ETT. This has been referred to as the double trachea sign.⁵ There is significant data on using ultrasound to visualize the tip of the ETT to assess ETT depth in neonates and young infants. Because they have less ossified chest structures than older children and adults, they have a unique acoustic window that allows us to visualize the tip of the ETT directly. The right pulmonary artery or the aortic arch is usually used as a surrogate landmark for the carina when determining ETT tip positioning, as the carina cannot be clearly visualized on ultrasound.³

3. Front-of-neck access: Ultrasonography can be used to identify the cricothyroid membrane to improve the success rate of emergency cricothyrotomy, although there is little literature on this topic in the pediatric population.^2-4

4. Predicting difficult laryngoscopy: There is minimal data on sonographic predictors of difficult airways in pediatrics,^6,7, with the vast majority of studies including only adults.

In our experience, airway POCUS is one of the easier POCUS applications to learn, and proficiency can be obtained with limited practice. However, scanning our smallest patients can sometimes be challenging from an equipment standpoint, especially in the sagittal plane. The linear transducers are longer than the length of the infant’s neck, and it is difficult to get good contact between the transducer and the skin.

So, what are your thoughts on using airway POCUS in children? Would you pick up an ultrasound probe to confirm endotracheal intubation and depth? Would you use it to identify surgical airway landmarks? Do you see a value in using it to predict direct laryngoscopy in children if there were more pediatric data? Please send your thoughts and comments to Myron who will post in a Friday reader review.

References

1. Gomes, SH, Canelli R, Corradi F, Pêgo JM, Baker M, Bilotta F. The use of ultrasound in airway management. Anesth Analg. 2024;139(4):887-890.

2. Daniel SJ, Bertolizio G, McHugh T. Airway ultrasound: point of care in children- the time is now. Paediatr Anaesth. 2020;30:347-52.

3. Burton L, Bhargava V. A scoping review of ultrasonographic techniques in the evaluation of the pediatric airway. J Ultrasound Med. 2023; 42(11): 2463-79.

4. Adler AC, Siddiqui A, Chandrakantan A, Matava CT. Lung and airway ultrasound in pediatric anesthesia. Paediatr Anaesth. 2022;32:202-8.

5. Boretsky KR. Images in anesthesiology: point-of-care ultrasound to diagnose esophageal intubation: “the double trachea.” Anesthesiology. 2018;129:190.

6. Sever F, Özmert S. Evaluation of the relationship between airway measurements with ultrasonography and laryngoscopy in newborns and infants. Paediatr Anaesth. 2020; 30(11): 1233-29.

7. Zheng Z, Wang X, Du R, et al. Effectiveness of ultrasonic measurement for the hyomental distance and distance from skin to epiglottis in predicting difficult laryngoscopy in children. Eur Radiol. 2023; 33(11): 7849-56.