Airway ultrasound for beginners

1. Applications of airway
Ultrasound in RICU
Maiada Kamal El-Din Hashem
Chest dept - Assiut university

2. Objectives
What is airway ultrasound?
What and how to see?
Clinical applications
How to learn airway US?

4. What and How to see?
Position:
• Supine position with a pillow under the occiput to
achieve optimum head extension
Orientation:
• Sagittal
• Parasagittal
• transverse

6. What and How to see? (cont.)

7. What and How to see? (cont.)
Hyoid bone:
 On the transverse view the hyoid bone is visible as a
hyperechoic, inverted U–shaped structure with
posterior acoustic shadowing.
 On the sagittal and parasagittal views, the hyoid bone
is visible in cross section as a narrow, hyperechoic,
curved structure that casts an acoustic shadow.

8. What and How to see? (cont.)
Thyroid cartilage:
 Thyroid cartilage is visible on sagittal and parasagittal
views as a linear hypoechoic structure highlighted by
the bright A-M interface at its posterior surface.
 On the transverse view, it had an inverted V shape,
within which the true and false vocal cords were
visible.

10. What and How to see? (cont.)
Vocal cords:
 Thyroid cartilage provides the best window to view the
vocal cords.
 Vocal cords are seen forming a triangle with a central
tracheal shadow.
 Vocal cords are delineated medially by the hyperechoic
vocal ligaments.
 During phonation, the true cords oscillate and move
towards the midline.

12. What and How to see? (cont.)
Cricoid Cartilage and Cricothyroid Membrane:
 In the parasagittal view the cricoid cartilage has an oval
hypoechoic appearance.
 In the transverse view seen as a hump.
 The posterior surface is delineated by a bright A–M
interface and reverberation artefacts.
 The cricothyroid membrane is seen as a hyperechoic
band linking the hypoechoic thyroid and cricoid
cartilages.

14. What and How to see? (cont.)
Thyroid gland:
 At the level of the suprasternal notch in the transverse
view, the two lobes and isthmus of the thyroid gland
can be visualized anterolateral to the trachea.

15. What and How to see? (cont.)
Trachea:
 In the midline of the neck with the cricoid cartilage
marks the superior limit of the trachea.
 In the parasagittal and sagittal view the tracheal rings
are hypoechoic, and they resemble a “string of beads” .
 In the transverse view, they resemble an inverted U
highlighted by a hyperechoic air-mucosa interface and
by reverberation artifact posteriorly.

18. What and How to see? (cont.)
Esophagus:
 The cervical esophagus is visible posterolateral to the
trachea on the left side at the level of the suprasternal
notch.
 The concentric layers of esophagus result in a
characteristic “bull’s-eye” appearance.
 The esophagus can be seen to compress and expand
with swallowing, and this feature can be used for
accurate identification.

21. Clinical applications:
Identification of endotracheal tube placement:
• Easy , fast and useful
• How ?
Linear array
Lateral
esophagus

29. Clinical applications: (cont.)
Prediction of difficult intubation:
An abundance of pretracheal soft tissue at the level of the
vocal cords by ultrasound is a good predictor of difficult
laryngoscopy.

30. Clinical applications: (cont.)
Prediction of the appropriate diameter of endotracheal,
endobronchial or tracheostomy tube:
• Ultrasound measurements of the outer diameter of the
trachea just above the sternoclavicular joint in the
transverse section
• The ratio between left main-stem bronchus diameter on and
outer tracheal diameter measured with US is 0.68

31. Clinical applications: (cont.)
Guidance of percutaneous tracheostomy and
cricothyroidotomy:
• By localization of the cricothyroid membrane.
• Identification the anterior tracheal wall, thyroid and
cricoid cartilages, tracheal rings, and pretracheal
tissues, including the relationship of the thyroid gland
and the vascular structures of the neck to the trachea.

33. Clinical applications: (cont.)
Guidance of retrograde intubation:

34. Clinical applications: (cont.)
Prediction of post-extubation stridor:
• AC shape
• ACW ratio
• ACW difference

36. Clinical applications: (cont.)
Prediction of subglottic and tracheal stenosis:
• Diameter and air column
• Mucosal lining
• filling

39. How to learn airway US
After 8.5 h of focused training comprising a didactic
course, which included essential views of normal and
pathologic conditions and three hands-on sessions of 2 h,
physicians without previous knowledge of US can
competently perform basic general ultrasonic
examinations.*
*Chalumeau-Lemoine L, Baudel JL, Das V, Arrivé L, Noblinski B, Guidet B, Offenstadt G, Maury E. Results of short-term
training of naïve physicians in focused general ultrasonography in an intensive-care unit. Intensive Care Med 2009;35:
1767–71.

40. Take home message
 US has many advantages for imaging the airway: It is safe, quick,
repeatable, portable, widely available, and gives real-time dynamic
images relevant for several aspects of management of the airway.
 US must be used dynamically for maximum benefit in airway
management and in direct conjunction with the airway management:
Immediately before, during, and after, airway interventions.
 US can be used for direct observation of whether the tube enters the
trachea or the esophagus by placing the ultrasound probe
transversely on the neck at the level of the suprasternal notch during
intubation, thus confirming intubation without the need for
ventilation or circulation.
 US can be used for detection of post-extubation stridor and decrease
rate of reintubation by evaluating air column width.