Ch 102 Trachea and bronchi Flashcards
(79 cards)
1
Q
anatomy
A
- trachea: cricoid cartilage of the larynx to the base of the heart, where it terminates at the carina
- trachea bifurcates into the principal (mainstem) bronchi, one to each hemithorax
- series of parallel, incomplete (e.g., C-shaped) hyaline cartilage rings
- tracheal wall consists of an inner mucosa and submucosa surrounded by a fibrocartilaginous layer. The outermost layer is considered adventitia in the cervical trachea and serosa in the intrathoracic trachea
- trachealis muscle is composed primarily of transversely oriented smooth muscle fibers
- narrowest point at the thoracic inlet
- trachea and principal bronchi are lined by pseudostratified columnar epithelium
2
Q
What makes up the trachea?
A
Hyaline cartilage rings
Trachealis muscle
Annular ligaments
3
Q
How many tracheal rings do dogs have?
A
35 (can range up to 46)
4
Q
How many cartilage rings are present in the right and left mainstem bronchi?
A
Left = 3
Right = 1
5
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
6
Q
List the functions of the trachea (3)
A
- Conduit for gases to and from the lungs
- Warming and humidification to air
- Mucociliary escalator (particulate matter entrapped within mucous secretions transported to the larynx via coordinated ciliary action.)
7
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
8
Q
What nerve supplies smooth muscle control to the trachea?
A
Vagus
- Right branch assumed to be dominant in dogs
9
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
10
Q
imaging
A
Radiography and Fluoroscopy
- lumen of the trachea should remain uniform in all phases of respiration
- obstruction proximal trachea: under-aerated lungs, a high and domed diaphragm, possibly pulmonary edema, and tracheal narrowing
- distal tracheal obstruction: overexpanded lungs, a flattened diaphragm, and prominent pulmonary vasculature
- Fluoroscopy is particularly helpful when evaluating dynamic changes
CT
- most obvious disadvantage of CT is the need for general anesthesia
- used for radiation planning for tracheal tumors and establishing the location of tracheal rupture
Tracheobronchoscopy
- diagnosis of functional lesions,
- biopsy of mechanical lesions,
- removal of foreign bodies,
- documentation of disease progression
- diagnosing and grading airway collapse
- Bronchoalveolar lavage through a bronchoscope
11
Q
What are tube options for a temporary tracheostomy?
A
Cuffed or uncuffed tube
Single or double lumen
Silicon tracheal stoma stent
12
Q
What muscle needs to be seperated on the approach to the cervical trachea?
A
Sternohyoideus
13
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
14
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
15
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
16
Q
How can you assess the suitability of trach tube removal?
A
Occlude with occlusive dressing for 15-20min
17
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
18
Q
What is the most significant long term complications of temp trach tubes?
A
tenosis. 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
19
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
20
Q
List the three options for a temp trach incision
A
Transverse
Tracheal flap
Vertical
21
Q
What is the recommended size of the tracheal incision for a permanent tracheostomy?
A
Ventral half of 3-4 tracheal rings
22
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
23
Q
What happens to the tracheal epithelium after a tracheostomy?
A
Undergoes squamous metaplasia causing excessive mucous production for the first 4-6 weeks
24
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
25
How does a tracheotomy/bronchotomy incision heal?
Epithelialise within 2-8hr
48hr - transitional epithelium
From 96hr - transformation into ciliated and goblet cells can begin
26
How long does it lake a 1x1cm defect of the trachea to heal?
15-20 days
27
Resection and Anastomosis
indications: masses, traumatized tracheal segments, stenosis, and avulsion.
considerations
- Sterile endotracheal tubes and anesthetic circuits > intraoperative transincisional
- Injectable anesthetics may also be considered
- tension is considered to be the limiting factor for extensive tracheal resections
- tension distracts the anastomotic site, resulting in healing via granulation tissue formation rather than primary epithelialization
- increased incidence of stenosis with increasing tension
- affect of age
- suture pattern: in dogs, luminal stenosis was significantly less severe when an interrupted pattern was used
- microcirculation was found to remain static after tracheal transection but was significantly decreased after continuous anastomosis
- exact apposition of tracheal ends paramount
- anastomotic options: split or annular
28
what % stenosis cause clinical signs?
Stenosis of 50-75% is required to cause clinical signs
29
List some methods for reducing tension at a tracheal anastomosis site
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
*site closed with a continuous pattern is nearly as strong as native trachea immediately after surgery and by 1 to 2 weeks is stronger than native trachea*
| may not be necessary
30
How does age effect the strength of the trachea?
Adult trachea can withstand forces of 1700g at the anastomosis site which corresponds 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)
31
What complication is associated with nonabsorbable suture material?
Granuloma formation and stricture
32
List anastomotic options for the trachea
Split cartilage technique (placing the suture around divided tracheal rings)
- Less DV luminal stenosis
- More precise alignment
- May be stronger as heals with fibrocartilage
Annular ligament cartilage technique (placement of the suture around adjacent tracheal rings through the annular ligament)
33
What is the recommended approach to the intra-thoracic trachea?
Right-sided 3rd-5th IC thoracotomy
Azygous vein ligated and transected
Vagus, phrenic and recurrent laryngeal nerve protected
34
surgery
- Care is taken to avoid excessive manipulation of the trachea because manipulation can result in increased leukocytic invasion and increased scar tissue formation
- A sterile endotracheal tube can be temporarily placed by the surgeon into the tracheal distal segment and attached to a sterile circuit to provide adequate oxygenation
- 3-0 or 4-0 monofilament absorbable suture. Sutures are preplaced in the dorsal tracheal membrane first;
- Additional tension-relieving sutures can be placed around rings proximal and distal to the anastomosis to reduce tension in long-segment resections.
- thoracic cavity saline + positive-pressure ventilation applied to 20 cm H2O to leak test
35
What options are there for augmentation/reconstruction of a tracheal anastomosis?
Omentum
Hyaluronic acid
Fibrin tissue adhesive
Auricular cartilage struts
36
complications
1. Leakage (subcutaneous emphysema, pneumomediastinum, or pneumothorax)
2. Infection
3. mucociliary clearance (decreased 3x after resection but reestablishes during the next month)
4. stricture (severity appears to correlate with the amount of trachea resected)
*medical management with balloon dilation or bougienage can be attempted for stenosis or revision sx*
37
What is the effect of tesion on tracheal anastomosis healing?
* 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
38
Tracheal Rupture
Pathophysiology
- Iatrogenic tracheal rupture occurs secondary to endotracheal intubation in cats ( overinflation of the cuff)
- dyspnea, anorexia, lethargy, coughing, and stridor.
- subcutaneous emphysema, Pneumomediastinum, pneumoretroperitoneum, and pneumothorax
Dx
- tracheobronchoscopy (operator dependent)
- computed tomography (CT)
Tx
- 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
complication
- scarring can be a sequela > Tracheal narrowing
avoid: use of supraglottic airway devices
| cuffs incrementally inflated until airway pressure held at 20 cm H2O
39
What % of cats with tracheal rupture have SQ emphysema?
100%
| neumomediastinum in cats, 38% history of endotracheal intubation
40
Where have all reported tracheal ruptures occured?
At the junction of the tracheal ring and the trachealis muscle
41
Tracheal Avulsion
Pathophysiology
- occurs secondary to blunt trauma during which the neck is hyperextended
- stretch causes circumferential rupture at the weakest point of the intrathoracic trachea, 1 to 4 cm proximal to the tracheal bifurcation
- Some severely affected patients with tracheal avulsion die acutely
- others contain the air leakage within the mediastinum > typically present 2 to 3 weeks after with signs of airway obstruction
Dx
- pseudoairway between the segments in more chronic cases
- CT
TX
- Resection with anastomosis
- Follow-up (median, 1.7 years) revealed that eight cats had no further problems after tracheal resection and anastomosis, and one had unilateral laryngeal paralysis.
42
What is usually seen on imaging for tracheal avulsion?
Pneumomediastinum
Pseudoairway (more chronic)
43
What is the accuracy of radiographs in the diagnosis for a tracheal FB?
66%
Absense of findingd in 14.8%
| CT or scope may be required
44
removal of FB
- surgery often reserved for those refractory
- tracheobronchoscopy has been performed,d but this technique can be difficult and time-consuming.
- fluoroscopic guidance
- Foley catheter technique has been described in which the catheter is passed beyond the foreign body
- Postretrieval radiography is recommended to rule out occult tracheal rupture (pneumomediastinum or pneumothorax)
- need for surgical intervention following unsuccessful tracheobronchoscopic retrieval of foreign bodies has been reported to be 12.9% to 19.9%
- tracheotomy > technical challenge of maintaining adequate oxygenation
45
List primary tumours of the trachea
Osteochondroma
Osteosarcoma
Chondroma
Chondrosarcoma
Ecchondroma
Leiomyoma
lymphoma,
fibrosarcoma,
squamous cell carcinoma
| obstruction of 50% tracheal lumen is required to produce clinical signs
46
What is the treatment of choice for tracheal neoplasia?
What is the exception?
Surgical resection and anastomosis
NOT for lymphoma
47
List some benign masses of the trachea
Granulomatous
Abberant Cuterebra larvae
Nodular amyloidosis
Broncholithiasis
Tracheal intussusception
48
Esophagotracheal and Esophagobronchial Fistulae
pathophysiology
- congenital or acquired.
- Most occur secondary to an esophageal foreign body
- esophageal diverticula are often seen, it is theorized that these may predispose to foreign body entrapment, fistula formation, or both
- histo: Congenital fistulae are lined with squamous epithelium
dx
- radiography reveals consolidation of the affected lung lobe
- contrast esophagram can be used to highlight the aberrant connection
tx
- lung lobectomy
49
Tracheal Collapse
- Early affliction is characterized by laxity of the trachealis muscle, which progresses to weakness of the cartilaginous rings.
- The collapse of the cartilage infrastructure ultimately leads to obliteration of the tracheal lumen
- vicious cycle of cough and perpetual inflammation ultimately leads to loss of normal tracheal epithelium > formation of squamous metaplasia, reduction of ciliated cells, and production of increasingly viscous mucous secretion
- Pulmonary hypertension with right ventricular enlargement and cor pulmonale have been reported
- toy- and small-breed dogs
- hypothesized that a congenital component is present
- external factors, such as obesity, environmental allergens, cigarette smoke, and kennel cough, exacerbate clinical signs
50
What are the reported histological changes of the tracheal rings with tracheal collapse?
* 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
51
2 type of collapse
malformation type, traditional type
- MTC = W-shaped cartilage rings
- TTC = dorsal membrane laxity, tracheal ring
52
What breeds are predisposed to tracheal collapse?
What % may be affected by 6mo?
Yorkies, min poodles, pom, chihuahua, pug
As many as 25%
53
diagnosis
RADS
- rule out other cardiorespiratory diseases
- sensitivity is variable (60% to up to 90%)
- false-positive readings have been reported in 25%
Fluoroscopy
- visualization of abnormal tracheal dynamics during all phases of respiration
- noninvasive, and it does not require sedation
- demonstrated to detect more sites of collapse when compared with radiography and bronchoscopy.
- false-positive reports are also possible
Tracheoscopy
- taking measurements for stent placement
54
Which imaging technique gives the most valuable diagnostic information regarding tracheal collapse?
Tracheoscopy
55
What is the grading system for tracheal collapse?
Grade I - 25% collapse (laxity of dorsal tracheal membrane)
Grade II: 50% collapse
Grade III - 75% collapse
Grade IV - 100% collapse
| only accurate when describing tracheobronchoscopic findings
56
Medical Management
- recommend exhausting medical management before intervention
- drug administration, environmental alteration, and obesity management.
- 71% success rate with medical management for longer than 1 year in 100 cases
acute
- sedatives, cough suppressants, and short-acting corticosteroids
- distress, and oxygen should be administered immediately
- Acepromazine as a single agent or combined with an opioid
- ett
chronic
- Weight loss is incredibly important, a
- .5 to 1.0 mg/kg/day per os prednisone
- harness around
- modify exercise
- Airway nebulization or humidification
- bronchodilators
- stanazol (anabolic steriod)
57
What is the rate of severe, life-threatening complications with intra/extraluminla tracheal stenting for tracheal collapse?
10% - only recommende once they have failed medical therapy
58
surgical candidates
- grades II to IV tracheal collapse
- only animals that have failed initial medical management.
- evaluated for laryngeal paralysis or collapse and elongated soft palate
59
Extraluminal Prosthetic Tracheal Rings
- external “skeleton” to support the trachea.
- Polypropylene rings
- rings are placed around the trachea axial (medial) to the recurrent laryngeal nerves and tracheal vessels.
- Rings are secured to the trachea circumferentially with 4-0 monofilament nonabsorbable suture material
- restricted to dogs solely with collapse in the cervical and thoracic inlet regions
- In one study, 91% of dogs survived to discharge and 88% of dogs survived >6 months
- 65% no longer required medical management
60
What are the main complications of extraluminal polypropylene rings?
Laryngeal paralysis 11-30%
Tracheal necrosis (due to disruption of blood supply required to place stent/skeletonisation > tunnel is made only where the ring is passed around the trachea.)
Pneumothorax
Collapse beyond rings
Migration
61
Intraluminal Stents
- simultaneous support of the thoracic and cervical trachea
- superelastic material such as nitinol (resist alterations 10% without plastic deformation, thermal shape memory, radial stress resist migration, recronstrainable and foreshortening)
- Advantages: shortened anesthetic, immediate improvement in clinical signs, place the stent within the cervical or thoracic, noninvasive sx
- Laser-cut stents (not woven) do not foreshorten > unacceptable rate of fracture
62
What is the recommended sizing and position for intraluminal stents?
* Tracheal diameter measured on radigraphs with cuffed ET tube at larynx and positive-pressure ventilation at 20cmH2O
* Stent diameter should exceed widest diameter by 10-20%
* Should span entire trachea from 1cm caudal to cricoid to 1cm cranial to carina
* > prevent encroachment of the laryngeal apparatus or carina, which can result in laryngospasm, laryngeal dysfunction, paroxysmal cough, or entrapment of bronchial secretions
63
Outcome
- Immediate improvement in clinical signs was noted in 95.8%
- 83% to 89% improvement for longer than 1 year
- major complications were similar extraluminal 42% vs intraluminal stents 43%
- MST ignificantly lower intraluminal stent (365 days) versus extraluminal rings (1460 days)
- Complications of endoluminal stenting can be severe
64
complications
stent fracture
- attributed to persistent cough.
- severely symptomatic > new deployed within the fractured stent, extraluminal rings
- fractured and penetrated either the trachea or lung
stent migration (up to 37%)
- inappropriate measurement techniques
- using CT may be more accurate for sizing
inflammator tissue
- stent motion, respiratory infection, or persistent cough
tracheitis (concurrent reported in ~ 60% of patients, need to be managed)
collapse beyond the stented region
obstruction with granulation tissue
tracheal rupture
rectal prolapse
65
What % of dogs with tracheal collapse will also have bronchial collapse?
71-83%
66
What breed is overrespresented for congenital lobar emphysema?
What is it?
What lobe is most commonly effected
Pekingese
Congenital bronchial cartilage abnormalities or absense allowing lungs to inflate but then become trapped
Right middle lung lobe most common
67
What is Kartagener syndrome?
Situs invertus
Chronic rhinosinusitis
Bronchiectasia
68
What conditions are commonly seen in dogs with ciliary dyskinesia?
Bronchopneumonia
Hydrocephalus
Thickening of typanum due to obstruction of ciliated auditory tube
Situs invertus
69
Outcome of temporary tracheostomy
tube-placement following surgery for
brachycephalic obstructive airway
syndrome in 42 dogs
Stordalen 2020
postoperative period following
multi-level airway surgery
Forty-two dogs
Median duration was 2 days (range 1 to 7).
The major complication rate was 83.3%,
minor complication rate was 71.4%,
overall 95.2%. T
he most common
tracheostomy tube obstruction (32/42), cough (25/42) and dislodgement (16/42).
successful in 97.6%.
40 of the 42 dogs included in this study survived to discharge
70
Dumon silicone stents can improve respiratory function in dogs with grade IV tracheal collapse: 12 cases (2019–2023)
Lorenzi 2024
Retrospective. Dumon silicone stents grade IV tracheal collapse: 12 cases
end of the study (41.7%) remained alive
Survival time mean 822.43 days
death dt airway collapse [66.6%] and incoercible cough ([33.4%]).
Complications (75%) > granulation tissue, cough, migration and stent deformation [8.3%]
Disease progression is inevitable, but substantial improvement of respiratory function may be achieved for months to years.
silicone stents, unlike nitinol > removal or replacement is always possible
In our case > remove the newly formed tissue through endoscopy-guided laser surgery.
71
Comparison of short-, intermediate-, and long-term results
between dogs with tracheal collapse that underwent
multimodal medical management alone and those
that underwent tracheal endoluminal stent placement
Congiusta 2021
mulimodal medical management for tracheal collapse vs endoluminal stent
- medical management → short-term improvement in clinical signs → regression/worsening
- MST: medical 3.7y, stent 5.2y
- severe disease: medical 12d; stent 1338d
- early stent placement recommended for high clinical score/more severe dz
The ongoing need for medication regardless of whether tracheal surgery is performed.
stent placement often require higher doses of medications
more frequently than do medically managed dogs > dt stent and the severe manifestation of TC
72
Influence of age on resistance to distraction after tracheal
anastomoses in dogs: An ex vivo study
Nikoletta G. Brisimi 2022
immature tracheas sustained more elongation after anastomosis but failed at lower
loads - ex vivo
73
Bronchial collapse and bronchial stenting in 9 dogs
Darren Kelly 2023
| JVIM
Principal and lobar bronchial collapse is increasingly recognized as an
isolated entity.
Objective: Retrospectively
Bronchial stenting was considered successful in all cases, with all dogs
experiencing improved quality of life (QOL), and decreased functional impairment
grade at 4 weeks post-stenting. Follow-up of >6 months was available for 6 dogs and
of these, 5 were alive at 12 months, 3 were alive at 18 months, and 1 was alive at
24 months. Stent-related complications occurred in 4 dogs, and were resolvable in
3. Two dogs developed pneumothorax, 1 developed recurrent pneumonia, and
1 developed new-onset coughing
74
Retrospective study of feline
tracheal mass lesions
Hideyuki Kanemoto 2023
Retrospective study of feline tracheal mass lesions. 18
diagnosis: FNA and cytology (n = 8), bronchoscopic forceps and histopathology (n = 5)
Lymphoma (n = 15)
Most lymphoma cases received chemotherapy with or without radiation
MST 214 days
75
Endoscopic application of fibrin glue may be a feasible
method of treatment for postintubation tracheal
lacerations in cats
Molly R. Cohen 2023
| AJVR
20 feline cadavers
Following the procedure, the airway of each cat was examined and leak tested.
A complete
seal was attained in 6 of the 9 fresh cadavers when filling the defect with fibrin glue.
76
Long-term outcome of permanent tracheostomy
management in two brachycephalic dogs using
a commercial and a three-dimensional-printed
silicone stent
Janssen 2024
After the tracheostomy had healed, a silicone
stent was inserted to support the stoma and facilitate home care
The insertion of a silicone stent is a simple and cost-effective
method to improve home care of dogs with permanent tracheostomy
77
Risk factors for temporary tracheostomy tube placement
following surgery to alleviate signs of brachycephalic
obstructive airway syndrome in dogs
David B. Worth 2018
Retrospective case-control study.
ANIMALS
122 client-owned
staphylectomy
technique, and mortality rate did not differ significantly between cases
and controls. The odds of postoperative TTTP increased approximately
30% (OR, 1.3) for each 1-year increase in patient age. Postoperative administration
of corticosteroids and presence of pneumonia were also positively
associated with the odds of postoperative TTTP. Median duration of hospitalization
was significantly longer for cases than controls.
**mortality rate did not differ
significantly between dogs that did (cases) and did
not (controls) require postoperative TTTP.**
78
Long-term outcomes of 54 dogs with tracheal collapse treated
with a continuous extraluminal tracheal prosthesis
Suematsu 2019
Retrospective. continuous extraluminal tracheal prosthesis 54 dogs
placed for stage 4 only (100% collapse)
(98%) dogs survived to discharge.
Postoperative complications > laryngeal paralysis (1 dog), DIC (1 dog),
and recurrent tracheal collapse (2 dogs).
outcome: pre-op harsh cough resolved 96%, pre-op goose-honk 96%
Goose honking cough was resolved in 25 of 26 (96%) dogs.
survival rate at 36 months 86%
advantages > decreased damage to the recurrent laryngeal nerve and segmental tracheal vessels, placement to second rib, and flexibility
79
Short-, intermediate-, and long-term results for endoluminal stent placement in dogs with tracheal collapse
Chick Weisse 2019
distribution: 51% malformation type, 49% traditional type
- MTC = W-shaped cartilage rings
- TTC = dorsal membrane laxity, tracheal ring weakness (chondromalacia)
- survival: 70/75 (93%) to discharge → MST 1005d
- male and younger dogs longer survival
- not associated with Yorkies, peri-op pneumonia/tracheitis, additiona stent sx,
type of tracheal collapse
- outcome: improvement in goose-honking/raspy breathing 89%, dyspnoea 84%
- mainstem bronchial collapse not associated
- complications: 33/70 (47%) major requiring additional stent placement
- stent fracture and tissue ingrowth most common
