Chapter 102: Trachea and Bronchi

Question 1

The trachea splits into principal bronchi (2) - then splits into…?

Answer 1

.. splits into lobar bronchi (one to each lung), segmental bronchi branch, subsegmental bronchi and bronchioles

Question 2

How many tracheal rings do dogs have?

Answer 2

35 (can range up to 46)

Question 3

At what point does the trachea have the thinnest cartilage and smallest CSA?

Answer 3

Thoracic inlet

Question 4

What is the major blood supply to the trachea?

Answer 4

Segmental blood supply from cranial and caudal thyroid arteries

At the carina, blood supply shifts primarily to bronchoesophageal arteries

Question 5

Name the venous and lymph drainage and innervation of the trachea?

Answer 5

Thyroid, internal jugular and bronchoesophageal veins

Lymph drainage - deep cervical, cranial mediastinal, medial retropharyngeal and tracheobronchial nodes

Right vagus and recurrent laryngeal nerve

Question 6

What is a normal mucociliary flow rate in a dog?

Answer 6

10-15mm/min - speed and efficiency are hindered by increasing particle size and mucous viscosity

Question 7

Left vagus results in only what % of contraction achieved by maximal stimulation of the right vagus nerve?

Answer 7

28.5%

Question 8

What makes up the trachea?

Answer 8

• Hyaline cartilage rings
• Trachealis muscle
• Annular ligaments

Question 9

How many cartilage rings are present in the right and left mainstem bronchi?

Answer 9

Left = 3
Right = 1

Question 10

What are the three functions of the trachea?

Answer 10

Conduit for gases to and from the lungs
Warming and humidification to air
Mucociliary escalator

Question 11

What is the maximum length of the incision for a transverse temporary tracheostomy?

What is the maximum recommended diameter of the tracheostomy tube?

Answer 11

Maximum incision 50% width of trachea

Maximum tube size 75% of tracheal diameter

Question 12

What muscle needs to be separated on the approach to the cervical trachea?

Answer 12

Sternohyoideus

Question 13

True or False: Tracheal size does not increase proportionally with the size of the dog?

Answer 13

True.
English bulldogs have smaller proportional to even other brachycephalics which are smaller than expected for body size.

Question 14

What is the only way to diagnose bronchomalacia?

Answer 14

Tracheobronchoscopy

Question 15

What are 3 methods for reducing tension at a tracheal anastomosis site?

Answer 15

Tension relieving sutures placed several rings proximal and distal
- Fixed ventroflexion of the neck
- Release of the annular ligament with preservation of the mucosa

Question 16

How does age effect the strength of the trachea?

Answer 16

Juvenile trachea can only withstand 60% of the force of the adult trachea (higher water content with less collagen) so you can’t resect as much.

Question 17

What breeds are predisposed to tracheal collapse?
What % may be affected by 6mo?

Answer 17

• Yorkies, min poodles, pomeranians, chihuahua, pug
• As many as 25%

Question 18

What is the grading system for tracheal collapse?

Answer 18

• Grade I - 25% collapse (laxity of dorsal tracheal membrane)
• Grade II: 50% collapse
• Grade III - 75% collapse
• Grade IV - 100% collapse

Question 19

Up to 50% of people who have ciliary dyskinesia also have situs inversus. The combination of situs, chronic rhinosinusitis, and bronchiectasis is called what?

Answer 19

Kartagener syndrome.