Trachea and Bronchi Flashcards
What makes up the trachea?
- Hyaline cartilage rings
- Trachealis muscle
- Annular ligaments
How many tracheal rings do dogs have?
35 (can range up to 46)
How many cartilage rings are present in the right and left mainstem bronchi?
- Left = 3
- Right = 1
What is the major blood supply to the trachea?
- Segmental blood supply from cranial and caudal thyroid arteries
- At the carina, blood supply shifts primarily to bronchoesophageal arteries
List the functions of the trachea
- Conduit for gases to and from the lungs
- Warming and humidification to air
- Mucociliary escalator
What is a normal mucociliary flow rate in a dog?
10-15mm/min - speed and efficiency are hindered by increasing particle size and mucous viscosity
What nerve supplies smooth muscle control to the trachea?
Vagus
- Right branch assumed to be dominant in dogs
What is the expected tracheal diameter to thoracic inlet in normal dogs? Brachycephalics? English Bulldogs?
- Normal: 0.2 +/- 0.03
- Brachy: 0.16 +/- 0.03
- Eng. Bulldog: 0.13 +/- 0.38
What are the options for a temporary tracheostomy?
- Cuffed or uncuffed tube
- Single or double lumen
- Silicon tracheal stoma stent
What muscle needs to be seperated on the approach to the cervical trachea?
Sternohyoideus
What is the maximum length of the transverse temp trach incision?
What is the maximum recommended diameter of the trach tube?
- Maximum incision 50%
- Maximum tube size 75% of tracheal diameter
What is the recommended time for application of a suction device?
- No more than 10-12 seconds at a time and then releases
- Uninterrupted suctioning can lead to severe atelectasis and hypoxia
What options are there to provide adequate humidification for a temp trach patient?
- 0.2ml/kg sterile saline through trach tube every 1-4hr
- Nebulisation
How can you assess the suitability of trach tube removal?
Occlude with occlusive dressing for 15-20min
What are the reported complications with a temp trach tube?
Acute complications in up to 50%
- Plugging of the tube 18-25%
- Inadvertent tube removal
- SQ emphysema
- Pneumomediastinum
- Pneumothorax
- Infection
- Resp distress
Cats: 87% complications, 40% life threatening
- 91% with benign disease discharged from hospital
What is the most significant long term complications of temp trach tubes?
Stenosis. Associated with larger tubes and inflated cuffs
- Can occur at stoma or level of cuff/tip of tibe
- Average loss of 18-24.7% luminal area
- High-vol, low pressure cuffs have reduced incidence
What is the overall complication rate and survival for temp tracheostomies in dogs and cats?
Dogs
- Overall complications 86%
- Successfully managed in 81%
- However, only 60% survived to discharge
Cats:
- 43% survived to discharge
List the three options for a temp trach incision
- Transverse
- Tracheal flap
- Vertical
What is the recommended size of the tracheal incision for a permanent tracheostomy?
- Ventral half of 3-4 tracheal rings
Why should a permanent tracheostomy not be performed in the distal trachea?
- Higher mortality rates (57%) when the tracheostomy is performed below the 12th tracheal ring
What happens to the tracheal epithelium after a tracheostomy?
Undergoes squamous metaplasia causing excessive mucous production for the first 4-6 weeks
List reported complications of permanent tracheostomy
- Mucous plugs
- Aspiration pneumonia
- Requiring revision surgery
- Acute death following discharge 26%
- Stenosis up to 60%
- MST cats 20.5 - 42 days
- Major complications in 10 of 20 dogs, MST 328d
If pre-existing collapse, should be reinforced with extraluminal rings
How does a tracheotomy/bronchotomy incision heal?
- Epithelialise within 2-8hr
- 48hr - transitional epithelium
- From 96hr - transformation into ciliated and goblet cells can begin