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Tobias ECVS Exam Prep > Ch 102 - Trachea and Bronchi > Flashcards

Ch 102 - Trachea and Bronchi Flashcards

1
Q

What makes up the trachea?

A
  • Hyaline cartilage rings
  • Trachealis muscle
  • Annular ligaments
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2
Q

How many tracheal rings do dogs have?

A

35 (can range up to 46)

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3
Q

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

A
  • Left = 3
  • Right = 1
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4
Q

What is the major blood supply to the trachea?

A
  • Segmental blood supply from cranial and caudal thyroid arteries
  • At the carina, blood supply shifts primarily to bronchoesophageal arteries
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5
Q

List the functions of the trachea

A
  • Conduit for gases to and from the lungs
  • Warming and humidification to air
  • Mucociliary escalator
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6
Q

What is a normal mucociliary flow rate in a dog?

A

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

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7
Q

What nerve supplies smooth muscle control to the trachea?

A

Vagus
- Right branch assumed to be dominant in dogs

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8
Q

What is the expected tracheal diameter to thoracic inlet in normal dogs? Brachycephalics? English Bulldogs?

A
  • Normal: 0.2 +/- 0.03
  • Brachy: 0.16 +/- 0.03
  • Eng. Bulldog: 0.13 +/- 0.38
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9
Q

What are the options for a temporary tracheostomy?

A
  • Cuffed or uncuffed tube
  • Single or double lumen
  • Silicon tracheal stoma stent
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10
Q

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

A

Sternohyoideus

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11
Q

What is the maximum length of the transverse temp trach incision?
What is the maximum recommended diameter of the trach tube?

A
  • Maximum incision 50%
  • Maximum tube size 75% of tracheal diameter
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12
Q

What is the recommended time for application of a suction device?

A
  • No more than 10-12 seconds at a time and then releases
  • Uninterrupted suctioning can lead to severe atelectasis and hypoxia
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13
Q

What options are there to provide adequate humidification for a temp trach patient?

A
  • 0.2ml/kg sterile saline through trach tube every 1-4hr
  • Nebulisation
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14
Q

How can you assess the suitability of trach tube removal?

A

Provided that air can flow around the trach tube, occlude with occlusive dressing for 15-20min while CLOSELY monitoring patient

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15
Q

What are the reported complications with a temp trach tube?

A

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

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16
Q

What is the most significant long term complications of temporary tracheostomy?

A

Stenosis. Associated with larger tubes and inflated cuffs
- Can occur at stoma or level of cuff or tip of tube
- Average loss of 18-24.7% luminal area
- High-vol, low pressure cuffs have reduced incidence of this complication

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17
Q

What is the overall complication rate and survival for temp tracheostomies in dogs and cats?

A

Dogs
- Overall complications 86%
- Successfully managed in 81%
- However, only 60% survived to discharge

Cats:
- 43% survived to discharge

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18
Q

List the three options for a temp trach incision

A
  • Transverse
  • Tracheal flap
  • Vertical
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19
Q

What is the recommended size of the tracheal incision for a permanent tracheostomy?

A
  • Ventral half of 3-4 tracheal rings
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20
Q

Why should a permanent tracheostomy not be performed in the distal trachea?

A
  • Higher mortality rates (57%) when the tracheostomy is performed below the 12th tracheal ring
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21
Q

What happens to the tracheal epithelium after a tracheostomy?

A

Undergoes squamous metaplasia causing excessive mucous production for the first 4-6 weeks

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22
Q

List reported complications of permanent tracheostomy

A
  • 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

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23
Q

How does a tracheotomy/bronchotomy incision heal?

A
  • Epithelialise within 2-8hr
  • 48hr - transitional epithelium
  • From 96hr - transformation into ciliated and goblet cells can begin
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24
Q

How long does it lake a 1x1cm defect of the trachea to heal?

A

15-20 days

25
Q

What degree of tension produced tracheal stenosis?

A
  • 750g of tension will invariably produce stenosis
  • 1500g causes circumferential strictures

Stenosis of 50-75% is required to cause clinical signs

26
Q

List some methods for reducing tension at a tracheal anastomosis site

A
  • Tension-relieveing sutures placed several rings proximal and distal (can negate pressure over 2000g)
  • Fixed ventroflexion of the neck
  • Release of the annular ligament wth preservation of the mucosa
27
Q

How does suture closure of the trachea compare to native tracheal strength?

A
  • Continuous suture closure nearly as strong as native trachea immediately
  • By 1-2 weeks, suture repair is stronger then native trachea, regardless of interrupted vs continuous
28
Q

How does age effect the strength of the trachea?

A
  • Adult trachea can withstand forces of 1700g at the anastomosis site which correspons to removal of 50-58% of the tracheal length
  • Juvenile trachea can only withstand 60% of the force of the adult trachea, and therefore can only resect 20-25% of the trachea (higher water content with less collagen)
29
Q

What complication is associated with nonabsorbable suture material?

A

Granuloma formation and stricture

30
Q

List anastomotic options for the trachea

A

Split cartilage technique
- Less DV luminal stenosis
- More precise alignment
- May be stronger as heals with fibrocartilage

Annular ligament cartilage technique

31
Q

What is the recommended approach to the intra-thoracic trachea?

A

Right-sided 3rd-5th IC thoracotomy
Azygous vein ligated and transected
Vagus, phrenic and recurrent laryngeal nerve protected

32
Q

What options are there for augmentation/reconstruction of a tracheal anastomosis?

A
  • Omentum
  • Hyaluronic acid
  • Fibrin tissue adhesive
  • Auricular cartilage struts
33
Q

What is the effect on mucociliary clearance after a resection and anastomosis?

A

Reduced atleast 3 fold, reestablished over the following month

34
Q

What is the effect of tesion on tracheal anastomosis healing?

A
  • Cartialge seperation beginning laterally and spreading ventrally
  • Any gaps will heal by second intention and increase the degree of stricture
  • Severity of stenosis appears to correlate with amount of traches resected
35
Q

What % of cats with tracheal rupture have SQ emphysema?

A

100%

36
Q

What is the recommended treatment for tracheal rupture?

A
  • Medical management (cage rest, O2, sedatives). SQ emphysema take approx 2 weeks to resolve
  • Surgery if worsening dyspnoea, lack of response to O2, worsening emphysema
37
Q

Where have all reported tracheal ruptures occured?

A

At the junction of the tracheal ring and the trachealis muscle

38
Q

Where does tracheal avulsion tend to occur?
What is the likely cause?

A
  • Occurs at the weakest part of the trachea 1-4cm proximal to bifurcation
  • Caused by blunt trauma while in hyperextension of the neck
39
Q

What is usually seen on imaging for tracheal avulsion?

A
  • Pneumomediastinum
  • Pseudoairway (more chronic)
40
Q

What is the accuracy of radiographs in the diagnosis for a tracheal FB?

A

66%
Absence of finding in 14.8%

41
Q

List primary tumours of the trachea

A
  • Osteochondroma
  • Osteosarcoma
  • Chondroma
  • Chondrosarcoma
  • Ecchondroma
  • Leiomyoma
  • etc
42
Q

What is the treatment of choice for tracheal neoplasia?
What is the exception?

A
  • Surgical resection and anastomosis
  • NOT for lymphoma
43
Q

List some benign masses of the trachea

A
  • Granulomatous
  • Abberant Cuterebra larvae
  • Nodular amyloidosis
  • Broncholithiasis
  • Tracheal intussusception
44
Q

What lesion is often seen in association with bronchoesophageal fistulae?

A

Oesophageal diverticula

45
Q

What are the reported histological changes of the tracheal rings with tracheal collapse?

A
  • Hypocellular with reduction in glycoprotein and glycosaminoglycans leading to decreased water retention
  • Increased complicance and decreased rigidity
  • Decreased chondroitin sulphate and calcium may allow replacement of hyaline cartilage with collagen and fibrocartilage
46
Q

List DDx for tracheal masses

A

Neoplastic:
- Osteochondroma, OSA, Chondroma, chondrosarcoma, ecchondroma, leiomyoma, etc

Benign
- Granulomatous disease
- Aberrant curerebra larvae
- Haemorrhage
- Nodular amyloidosis
- Brocholithiasis
- Tracheal intussusception

47
Q

What condition is often assoc with bronchoesopageal fistula?

A

Oesophageal diverticulum (potentially predisposing to FB)

48
Q

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

A
  • Yorkies, min poodles, pom, chihuahua, pug
  • As many as 25%
49
Q

Which imaging technique gives the most valuable diagnostic information regarding tracheal collapse?

A

Tracheoscopy

50
Q

What is the grading system for tracheal collapse?

A
  • Grade I - 25% collapse (laxity of dorsal tracheal membrane)
  • Grade II: 50% collapse
  • Grade III - 75% collapse
  • Grade IV - 100% collapse
51
Q

What is the rate of severe, life-threatening complications with intra/extraluminal tracheal stenting for tracheal collapse?

A

10% - only recommended if they have failed medical therapy

52
Q

What are the main complications of extraluminal polypropylene rings?

A
  • Laryngeal paralysis 11-30%
  • Tracheal necrosis
  • Pneumothorax
  • Collapse beyond rings
  • Migration
  • 91% survival to discharge, 88% survived over 6m
  • 65% no longer required medical management
53
Q

What is the recommended sizing for intraluminal stents?

A
  • Tracheal diameter measured on radigraphs with cuffed ET tube at larynx and positive-pressure ventilation at 20cmH2O
  • Stend diameter should exceed widest diameter by 10-20%
  • Should span entire trachea from 1cm caudal to cricoid to 1cm cranial to carina
54
Q

List potential complications of intraluminal stents

A
  • Stent fracture (persistant coughing)
  • Stent migration (inaccurate measurements)
  • Inflammatory tissue (motion, Ix, coughing)
    .
    .
    .
  • Immediate improvement 95.8%
  • 83-89% improve for over 1yr
  • MST significantly shorter than extraluminal (365vs1460d) but dogs were significantly older…
  • 43% complication rate (vs 42% extraluminal)
55
Q

What % of dogs with tracheal collapse will also have bronchial collapse?

A

71-83%

56
Q

What breed is overrespresented for congenital lobar emphysema?
What is it?
What lobe is most commonly effected

A
  • Pekingese
  • Congenital bronchial cartilage abnormalities or absense allowing lungs to inflate but then become trapped
  • Right middle lung lobe most common
57
Q

What is Kartagener syndrome?

A
  • Situs invertus
  • Chronic rhinosinusitis
  • Bronchiectasia
58
Q

What conditions are commonly seen in dogs with ciliary dyskinesia?

A
  • Bronchopneumonia
  • Hydrocephalus
  • Thickening of typanum due to obstruction of ciliated auditory tube
  • Situs invertus
59
Q

What are the reported complications with a temp trach tube?

A

Acute complications in up to 50%
- Plugging of the tube 18-25%
- Inadvertent tube removal
- SQ emphysema
- Pneumomediastinum
- Pneumothorax
- Infection
- Resp distress

Overall complications in up to 86%
- successfully managed in 81%
- Only 60% survived to discharfe

Cats: 87% complications, 40% life threatening
- 91% with benign disease discharged from hospital

Tobias ECVS Exam Prep (110 decks)

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