J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website https://jocmr.elmerjournals.com

Review

Volume 18, Number 8, August 2026, pages 497-514

Airway Ultrasound: Applications in Pediatric Anesthesiology and Critical Care

↓ Figure 1. Ultrasound of the airway can be performed using transverse, sagittal and parasagittal views at multiple levels including the suprahyoid, thyrohyoid, thyroid, cricothyroid, and suprasternal levels, allowing detailed visualization of airway structures. CTM: cricothyroid membrane; ETT: endotracheal tube; POCUS: point-of-care ultrasound.

↓ Figure 2. Sagittal ultrasound view of the airway showing the cricoid cartilage to the left at the top of the airway, the cricothyroid membrane (blue line), and tracheal rings. Air can be seen in the inflated endotracheal tube (ETT) cuff.

↓ Figure 3. Airway ultrasound in children with measurement of the hyo-mental distance (HMD). For this measurement, the probe is placed in the sagittal plane in the submental area.

↓ Figure 4. Oropharyngeal ultrasound in children. Measurement of the distance between the lingual arteries at the base of the tongue (left) and measurement of the width (1) and height (2) of the tongue at its base at the back of the oropharynx (right).

↓ Figure 6. Transverse (left) and sagittal (right) ultrasound views of the area demonstrating the trachea, subglottic area, and cricothyroid membrane.

↓ Figure 7. High-frequency linear probe placed on the anterior neck in the para-sagittal, long-axis plane (left) for airway ultrasonography. The cricoid cartilage and tracheal rings appear as anechoic structures. The anterior row of tracheal cartilages (anechoic structures) in the longitudinal plane is sometimes referred to as a “string of beads.” The air-filled cuff of the endotracheal tube also appears as an anechoic structure deep to the tracheal cartilages in a two-dimensional plane.

↓ Figure 8. Ultrasonographic images of the airway and endotracheal tube (ETT). The cricoid is an anechoic structure to the right and the tracheal rings are numbered (T1 to T4). To enhance visibility on ultrasound, the cuff of the ETT is filled with saline (white arrow). The cephalad aspect of the cuff is positioned at the lower aspect of the cricoid. A linear hyperechoic line (red arrows) on the longitudinal plane of the trachea is formed by reverberation artifacts from the air-mucosa interface within the trachea (red arrows). The walls of the ETT within the trachea are seen as two hyperechoic lines (yellow and green arrows).

↓ **Table 1.** Ultrasound for Airway Evaluation and Management
1. Assessment of the airway
a. Airway assessment and identifying the difficult airway
b. Grading or identification of obstructive sleep apnea
c. Identifying airway abnormalities including subglottic stenosis
2. Endotracheal intubation
a. Choosing endotracheal tube size
b. Confirming endotracheal intubation
i. direct assessment with transtracheal visualization
ii. indirect assessment with lung sliding or diaphragmatic movement
3. Assessing depth of endotracheal tube placement
a. Cuff placement
b. Tip of the endotracheal tube placement
4. Identification of the site for cricothyroidotomy
5. Miscellaneous applications
a. One lung ventilation

↓ Table 1. Ultrasound for Airway Evaluation and Management

1. Assessment of the airway

a. Airway assessment and identifying the difficult airway

b. Grading or identification of obstructive sleep apnea

c. Identifying airway abnormalities including subglottic stenosis

2. Endotracheal intubation

a. Choosing endotracheal tube size

b. Confirming endotracheal intubation

i. direct assessment with transtracheal visualization

ii. indirect assessment with lung sliding or diaphragmatic movement

3. Assessing depth of endotracheal tube placement

a. Cuff placement

b. Tip of the endotracheal tube placement

4. Identification of the site for cricothyroidotomy

5. Miscellaneous applications

a. One lung ventilation

↓ **Table 2.** Key Articles Regarding Airway Ultrasound
First author and reference	Study cohort	Findings
Kundra et al [5]	Review article	Educational review outlining the use of ultrasound (US) in various aspects of airway management including identification of the difficult airway as well as confirmation of endotracheal tube (ETT) placement, prediction of post-extubation stridor, evaluation of soft tissue masses in the neck, and assessment of subglottic diameter for ETT size.
Carsetti et al [15]	Meta-analysis of 15 studies using airway ultrasound to predict difficult intubation.	Airway US index tests are significantly different between patients with easy versus difficult direct laryngoscopy. Distance from the skin to epiglottis (DSE) is the most studied index test in the literature.
Singh et al [35]	Systematic review and meta-analysis of 21 studies in adults (7 airway and 14 non-airway) with 3,339 patients.	Obstructive sleep apnea (moderate-severe) correlated to a moderate degree with the distance between lingual arteries, resting tongue thickness, and tongue base thickness. The non-airway parameter of carotid intimal media thickness had a low to moderate correlation with moderate to severe OSA.
Husein et al [57]	A prospective, double-blinded pediatric study comparing US, video bronchoscopy, and ETT sizing for measurement of subglottic airway diameter.	US measurements correlated with video-bronchoscopy and ETT sizing. However, US underestimated absolute subglottic dimensions. Despite the authors being less enthusiastic about use of US for absolute airway sizing or ETT selection, they opined that it may serve as a useful non-invasive tool for longitudinal monitoring of changes in subglottic caliber over time.
Wani et al [61]	Prospective, non-randomized study of 80 pediatric patients (1–78 months of age).	US used to locate the ETT cuff relative to the cricoid and tracheal rings. The cephalad end of the ETT cuff was found at the level of the cricoid in 16.3% of patients, at the first, second, and third tracheal rings in 27.5%, 23.8%, and 17.5% of patients, respectively, and at or below the 4th tracheal ring in 15% of patients. The authors suggested that this observed inconsistency highlights known variability in pediatric airway anatomy, underscoring the value of real-time US imaging to document cuff position.
Singh et al [68]	Prospective study of 100 pediatric patients (12–60 months of age).	Using US, tracheal diameter was measured as the transverse air column diameter at the cephalad end of the cricoid cartilage. US correlated more strongly with actual ETT size than other formulas (age-based, body length, or finger width).
Marciniak et al [80]	Prospective study of 30 pediatric patients (mean age 48 months).	US imaging was used to visualize passage of the ETT into the airway by visualization and identification of the trachea, tracheal rings, and the vocal cords. The authors noted widening of glottis as the ETT passed through the airway and correctly positioned the ETT by using lung sliding. A single case of esophageal intubation was readily recognized by visualization of the ETT in the esophagus in the left paratracheal space.
Kerrey et al [82]	Lung US versus chest radiography in 127 intubated pediatric patients.	Chest radiography identified the ETT in the mainstem bronchus in 24 patients, while there were no esophageal intubations. US and chest radiography agreed on ETT placement in 106 patients (94 tracheal and 12 mainstem), for an overall agreement of 0.83. Although diaphragmatic US was not equivalent to chest radiography for ETT placement within the airway, the results were timelier, detected more misplacements than standard clinical confirmation alone, and were highly reproducible.
Walsh et al [84]	Prospective study of 22 pediatric patients.	The cricothyroid membrane (CTM) was accurately identified by US in all cases. Height of the CTM correlated with height measured by MRI.
Moharir et al [97]	Prospective, blinded study comparing US with auscultation during one-lung ventilation (OLV) in patients 0–20 years of age.	Lung US demonstrated a diagnostic accuracy of 95%, significantly higher than auscultation (68%, P < 0.001). Although US required a slightly longer assessment time, it provided substantially greater diagnostic reliability, supporting its role as a superior adjunct to auscultation to document effective lung isolation.

↓ Table 2. Key Articles Regarding Airway Ultrasound

First author and reference

Study cohort

Findings

Kundra et al [5]

Review article

Educational review outlining the use of ultrasound (US) in various aspects of airway management including identification of the difficult airway as well as confirmation of endotracheal tube (ETT) placement, prediction of post-extubation stridor, evaluation of soft tissue masses in the neck, and assessment of subglottic diameter for ETT size.

Carsetti et al [15]

Meta-analysis of 15 studies using airway ultrasound to predict difficult intubation.

Airway US index tests are significantly different between patients with easy versus difficult direct laryngoscopy. Distance from the skin to epiglottis (DSE) is the most studied index test in the literature.

Singh et al [35]

Systematic review and meta-analysis of 21 studies in adults (7 airway and 14 non-airway) with 3,339 patients.

Obstructive sleep apnea (moderate-severe) correlated to a moderate degree with the distance between lingual arteries, resting tongue thickness, and tongue base thickness. The non-airway parameter of carotid intimal media thickness had a low to moderate correlation with moderate to severe OSA.

Husein et al [57]

A prospective, double-blinded pediatric study comparing US, video bronchoscopy, and ETT sizing for measurement of subglottic airway diameter.

US measurements correlated with video-bronchoscopy and ETT sizing. However, US underestimated absolute subglottic dimensions. Despite the authors being less enthusiastic about use of US for absolute airway sizing or ETT selection, they opined that it may serve as a useful non-invasive tool for longitudinal monitoring of changes in subglottic caliber over time.

Wani et al [61]

Prospective, non-randomized study of 80 pediatric patients (1–78 months of age).

US used to locate the ETT cuff relative to the cricoid and tracheal rings. The cephalad end of the ETT cuff was found at the level of the cricoid in 16.3% of patients, at the first, second, and third tracheal rings in 27.5%, 23.8%, and 17.5% of patients, respectively, and at or below the 4th tracheal ring in 15% of patients. The authors suggested that this observed inconsistency highlights known variability in pediatric airway anatomy, underscoring the value of real-time US imaging to document cuff position.

Singh et al [68]

Prospective study of 100 pediatric patients (12–60 months of age).

Using US, tracheal diameter was measured as the transverse air column diameter at the cephalad end of the cricoid cartilage. US correlated more strongly with actual ETT size than other formulas (age-based, body length, or finger width).

Marciniak et al [80]

Prospective study of 30 pediatric patients (mean age 48 months).

US imaging was used to visualize passage of the ETT into the airway by visualization and identification of the trachea, tracheal rings, and the vocal cords. The authors noted widening of glottis as the ETT passed through the airway and correctly positioned the ETT by using lung sliding. A single case of esophageal intubation was readily recognized by visualization of the ETT in the esophagus in the left paratracheal space.

Kerrey et al [82]

Lung US versus chest radiography in 127 intubated pediatric patients.

Chest radiography identified the ETT in the mainstem bronchus in 24 patients, while there were no esophageal intubations. US and chest radiography agreed on ETT placement in 106 patients (94 tracheal and 12 mainstem), for an overall agreement of 0.83. Although diaphragmatic US was not equivalent to chest radiography for ETT placement within the airway, the results were timelier, detected more misplacements than standard clinical confirmation alone, and were highly reproducible.

Walsh et al [84]

Prospective study of 22 pediatric patients.

The cricothyroid membrane (CTM) was accurately identified by US in all cases. Height of the CTM correlated with height measured by MRI.

Moharir et al [97]

Prospective, blinded study comparing US with auscultation during one-lung ventilation (OLV) in patients 0–20 years of age.

Lung US demonstrated a diagnostic accuracy of 95%, significantly higher than auscultation (68%, P < 0.001). Although US required a slightly longer assessment time, it provided substantially greater diagnostic reliability, supporting its role as a superior adjunct to auscultation to document effective lung isolation.