Small Animal Surgery > Tracheal Surgery > Flashcards

Tracheal Surgery Flashcards

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1
Q

What is tracheal collapse? What is the most common signalment?

A

progressive, degenerative disease of the cartilaginous tracheal rings in which hypocellularity, decreased glycosaminoglycan, and calcium contents lead to dynamic airway collapse (radiographs and scopes can look normal - close mouth, normal position)

older toy breeds - Pomeranian, mini and toy Poodles, Yorkies, Chihuahua, Pug

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2
Q

What are the classical signs of tracheal collapse?

A

intermittent honking cough and exercise intolerance to severe respiratory distress from dynamic airway obstruction

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3
Q

How does the location of the collapse in the trachea affect prognosis?

A

bronchial collapse is more severe compared to laryngeal and tracheal collapse

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4
Q

How does the physiology of breathing compare on inspiration and expiration?

A

INSPIRATION - pull of air into lungs creates negative pressure in the lumen of the CERVICAL trachea and positive pressure opens the tracheal rings of the THORACIC trachea and bronchi

EXPIRATION - thoracic pressure used to push air out results in compression of the THORACIC components, while the air moving out serves to open the CERVICAL trachea

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5
Q

What are the 4 grades of tracheal collapse?

A
  1. tracheal membrane is slightly pendulous, cartilage remains normal, and lumen is reduced 25%
  2. tracheal membrane is widened and pendulous, cartilage is partially flattened, lumen is reduced 50%
  3. tracheal membrane is almost in contact with dorsal trachea, cartilage is nearly flat, lumen is reduced 75%
  4. tracheal membrane is lying on the dorsal cartilage, cartilage is flattened and may invert, lumen is obliterated

does not seem to relate to clinical signs

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6
Q

Grade I tracheal collapse:

A
  • pendulous membrane
  • normal cartilage
  • lumen reduced 25%

flat on top, rounded bottom

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7
Q

Grade II tracheal collapse:

A
  • widened and pendulous membrane
  • partially flattened cartilage
  • lumen reduced 50%
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8
Q

Grade III tracheal collapse:

A
  • membrane almost in contact with dorsal trachea
  • nearly flat cartilage
  • lumen reduced 75%
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9
Q

Grade IV tracheal collapse:

A
  • membrane lying on dorsal cartilage
  • flattened/inverted cartilage
  • lumen obliterated
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10
Q

What are 5 common secondary diseases associated with tracheal collapse?

A
  1. laryngeal collapse
  2. bronchiolar collapse
  3. pulmonary hypertension
  4. right ventricular enlargement
  5. cor pulmonale
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11
Q

What are 5 characteristic histopathological findings with tracheal collapse?

A
  1. hypocellular cartilage
  2. decreased glycoprotein and glycosaminoglycan
  3. decreased water retention - chalky, mineralized
  4. increased compliance
  5. decreased rigidity
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12
Q

What are the 5 most common combinations of medical treatment for collapsed tracheas?

A
  1. antitussives
  2. corticosteroids
  3. antibiotics
  4. bronchodilators
  5. anxiolytics (Trazodone)
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13
Q

What is the most common class of drugs used as antitussive therapy for collapsed trachea? What are 2 examples? What is the goal of this therapy?

A

narcotics

  1. Butorphanol tartrate (Torbutrol)
  2. Hydrocodone (Hycodan, Tussigon)

control the frequency/severity of cough to lessen tracheal damage

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14
Q

What are 2 indications for corticosteroid therapy with collapsed trachea? Which one is most commonly used?

A
  1. acute exacerbations
  2. control complications of edema

Prednisone —> taper

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15
Q

What are 3 common complications to chronic corticosteroid usage?

A
  1. hyperadrenocorticism (Cushing’s)
  2. infectious disease (pneumonia, tracheobronchitis) due to immunosuppression
  3. softened cartilage
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16
Q

When is antibiotic therapy indicated for collapsed trachea?

A

usually not encouraged —> management of confirmed secondary infectious complications

  • aspiration pneumonia
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17
Q

In what patients with collapsed trachea is the use of bronchodilators recommended? Which 2 are most commonly used? Which one needs to be used carefully?

A

those with lower airway disease

  1. Theophylline - enhances mucociliary clearance, reduces diaphragmatic fatigue
  2. Terbutaline - may cause anxiety
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18
Q

What is Lomotil? What 2 effects does it have?

A

diphenoxylate hydrochloride + atropine —> schedule V narcotic

  1. antitussive
  2. antisecretory (atropine) - reduces mucus volume
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19
Q

How can tracheal collapse be controlled outside of medications and surgery?

A
  • limit obesity
  • utilize thoracic harness
  • control concurrent complications, like endocrinopathy or lower airway disease
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20
Q

What are the 2 frames of mind for surgically treating collapsed tracheas?

A
  1. OLD SCHOOL - operate when the animal is about to die due to risky surgery
  2. NEW SCHOOL - early intervention can limit secondary disease, minimally invasive techniques
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21
Q

What are the 2 types of extraluminal repair of collapsed tracheas?

A
  1. Hobson rings - syringe containers are cut into rings and have holes drilled in them for the placement of tack sutures
  2. new generation devices - pre-made rings with notches to tie sutures

placed every centimeter from larynx to the heart base

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22
Q

What are the most common results of extraluminal repair of collapsed tracheas?

A
  • 10-20% survival
  • 11% develop laryngeal paralysis due to damage to the recurrent laryngeal nerves
  • 19% require permanent tracheostomies
  • 23% die of respiratory problems on average 25 months later
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23
Q

How far down are intraluminal stents placed for the repair of a collapsed trachea? How does this technique compare to extraluminal stents?

A

1 cm in front of bifurcation to the end of the larynx

  • clinical improvement in > 90%
  • minor complications
  • 5% mortality rate
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24
Q

What are 3 types of intraluminal stents? What are the 2 characteristics of a proper stent?

A
  1. nitinol mesh
  2. stainless steel mesh
  3. braided nitinol stents

inert and can take a beating from the heart

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25
What is nitinol mesh made out of? How does it compare to stainless steel mesh?
alloy of nickel and titanium (Ni Ti NOL) stainless steel is able to stretch 0.3% and return to its initial shape, while nitinol can stretch over 10%
26
What are the 3 major advantages to the use of intraluminal stents over extraluminal?
1. minimally invasive placement 2. decreased anesthesia time 3. access to the entire cervical and thoracic trachea
27
How are intraluminal stents measures?
- a probe with centimeter markers are slipped down the esophagus - a measurement is taken based on these markers from the larynx at the back of C2 to the tracheal bifurcation for the length - compare the collapsed diameter to the optimal diameter of the trachea, aiming to increase the collapsed segment by 20%
28
How can the correct placement of an intraluminal stent be confirmed?
- post-op radiographs: ensures its actually in trachea, makes sure it runs from the back od C2 to the tracheal bifurcation - fluoroscopy: can ensure the dynamic stability of the stent - tracheostomy: direct visualization to confirm 360 degree contact to avoid trapped infection
29
What are the 3 most common long-term complications associated with intraluminal stent placement? How are they treated?
1. granulation tissue formation 2. stent fracture (if its incorporated in new mucosa, this is rarely a problem) 3. collapse or deformation deployment of a second stent if clinical
30
Granulation tissue formation following intraluminal stent placement:
31
Stent collapse:
32
What is laryngeal collapse? What are the 3 stages?
acquired problem secondary to chronic increased inspiratory effort and cartilage degeneration 1. everted saccules 2. medial deviation of arytenoids into the airways 3. total collapse
33
How are the 3 stages of laryngeal collapse surgically treated?
1. resect saccules 2. partial arytenoidectomy and ventriculocordectomy 3. permanent tracheostomy
34
How are laryngeal saccules removed to treat laryngeal collapse?
excision with scissors or ligasures with healing from second intention
35
Stage II laryngeal collapse treatment:
- unilateral arytenoidectomy (large enough to breath without aspiration - bilateral ventriculocordectomy
36
What is the most common complication associated with arytenoidectomies and ventriculocordectomies? How can it be avoided?
webbing/stricture - mucosa from cut arytenoid migrates to the other side to combine by NOT cutting to the dorsal midline between corniculate processes or ventral midline between vocal folds
37
How are permanent tracheostomies performed? What 2 considerations need to be accounted for?
take out a portion of the trachea and suture remaining mucosa to the skin ---> remains open and must be kept clean 1. hypoplastic trachea 2. loose skin folds
38
What is laryngeal paralysis? How does it compare to laryngeal collapse?
dysfunction of the recurrent laryngeal nerve affects the function of the circoarytenoideus dorsalis muscle, causing the failure of the arytenoids to abduct during inspiration has a better prognosis
39
What is the most common etiology of laryngeal paralysis? What is the most common signalment?
Wallerian degeneration of recurrent laryngeal nerve from unknown cause - medium/large breed, older dogs - hypothyroid dogs
40
In what dog breeds is congenital laryngeal paralysis most common?
- Bouvier des Flandres: autosomal dominant - Rottweilers: laryngeal paralysis-polyneuropathy complex - Siberian Huskies - Dalmatians - Leonbergers - Bullterriers (young)
41
What are 3 causes of acquired laryngeal paralysis?
1. idiopathic* 2. neoplasia, trauma, infection, or surgical complication in the cervical or thoracic region 3. myasthenia gravis
42
What are the characteristic signs of laryngeal paralysis?
- hoarse change to bark - exercise intolerance - gagging and coughing after eating/drinking - stridor - extreme dyspnea, cyanosis, syncope (most commonly secondary to exacerbation in times of weather change)
43
What is idiopathic laryngeal paralysis?
progressive, non-inflammatory, degenerative disease of the recurrent laryngeal nerves causing loss of axons, beading of myeline, and perineural fibrosis - leads to neurogenic atrophy of the cricoarytenoideus dorsalis muscle
44
What 2 concurrent diseases are commonly found with laryngeal paralysis?
1. hypothyroidism 2. megaesophagus ---> increased risk of post-op complications
45
What is the most common age, gender, and breeds affected by idiopathic laryngeal paralysis?
geriatric (9.5-12.2 y/o) male > female large and giant breeds: Labrador, St. Bernard, Irish Setter, Afghan hound
46
How is laryngeal paralysis diagnosed?
- clinical suspicion based on signalment, Hx, radiography, and blood work - direct visualization of arytenoid cartilages by laryngoscopy with patient under LIGHT anesthesia
47
How does bilateral and unilateral laryngeal paralysis compare?
BILATERAL = most common presentation in dogs with inspiratory stridor, voice change, exercise intolerance, coughing while eating or drinking, and respiratory distress UNILATERAL = subtle clinical signs, treatment may not be necessary
48
How are patients with laryngeal paralysis experiencing respiratory emergencies stabilized? What must be done carefully?
- oxygen supplementation by flow by (DON'T FORCE A MASK) - sedation with Acepromazine - control edema and inflammation with Dexamethasone or Prednisolone - cool environment with ice water bath if temp is > 105 F - tracheostomy fluid therapy ---> severe upper respiratory tract obstruction patients develop pulmonary edema
49
What long-term medical management is applied before surgery is necessary for laryngeal paralysis?
- control hypoxia, hyperthermia, excitement, and obesity with oxygen therapy, cooling, exercise restriction, stress avoidance, and caloric restrition - supplement if hypothyroid - corticosteroids
50
What clinical signs are seen in feline laryngeal paralysis? What is the pathology like?
tachypnea, stridor, change in phonation, cough lesser known ---> polyneuropathy
51
What is a common diagnostic plan for laryngeal paralysis?
- thorough PE - neurologic exam (myasthenia gravis) - CBC, serum chem - thoracic radiographs (megaesophagus) - ultrasonography - airway examination by laryngoscopy*, tracheoscopy, and bronchoscopy - ancillary EMG or NCV - thyroid panel
52
How can false negative diagnoses of laryngeal paralysis in patients with paradoxical arytenoid movement be avoided?
- light propofol - assistant indicates the inspiratory phase to the clinician (should abduct with inspiration) - Doxapram can stimulate respiration
53
Laryngeal paralysis, laryngoscopy:
54
What is the best perioperative management of laryngeal paralysis?
- gain control of airway - examine pharynx prior to extubation - recover smoothly but quickly - Metoclopramide to decrease aspiration pneumonia??
55
Why should anesthetics be carefully considered in cases of laryngeal paralysis? What are the preferred choices?
anesthetics will depress laryngeal movement - low dose Propofol IV** - Ace/Torb IM + isoflurane mask (have least effect on laryngeal motion)
56
What 3 anesthetics are not recommended for cases of laryngeal paralysis?
1. ketamine/valium IV 2. ace IM + thiopental IV 3. ace IM + propofol IV (cause more depression of laryngeal motion)
57
What 5 additional tests can be used to rule out causes of laryngeal paralysis?
1. thoracic radiographs - aspiration pneumonia, intrathoracic mass, megaesophagus 2. cervical radiographs - neoplasia (thyroid tumor) 3. serum acetylcholine receptor antibodies - myasthenia gravis 4. thyroid function tests 5. electrophysiology, muscle/nerve biopsies
58
What is the most common surgical treatment for laryngeal paralysis? How is it performed?
tieback lateralization of the arytenoids make an incision in the thyropharyngeus muscle to visualize the thyroid cartilage and muscular portion of the arytenoid, which is tied back onto the cricoid cartilage
59
How are ventriculocordectomies performed? Why are they not commonly done to treat laryngeal paralysis?
long forceps/scissors or biopsy forceps are used to remove the vocal cords, ensuring the most ventral 1/4 is not excised to prevent webbing the collapse is more dorsal, so this is not really aiding in opening the airway
60
How are partial arytenoidectomies performed? How is webbing avoided?
biopsy forceps or rongeurs are used to remove the medial portions of the corniculate processes only done unilaterally
61
How is the modified castellated laryngofissure technique used to treat laryngeal paralysis?
- a step incision is created on the ventral midline of the thyroid cartilage and extended down the cricothyroid ligament - the top and bottom steps are sutured together to widen the cartilage and deform/open up the larynx
62
Laryngeal lateralization:
L = perfect R = unilateral, but too large of an incision = aspiration
63
What is the most common complication associated with laryngeal lateralization? How are the chances of development decreased?
aspiration pneumonia unilateral procedure
64
What are 4 possible causes of failures to correct laryngeal paralysis after lateralization?
1. inadequate lateralization 2. failure to correct associated hypothyroidism 3. misdiagnosis of cause of dyspnea 4. dog has gone swimming or wore neck collars
65
Arytenoid lateralization:
66
What is the goal of laryngeal lateralization to treat laryngeal paralysis?
double the size of the laryngeal aditus to provide enough relife to clinical signs while minimizing risk of complications (aspiration pneumonia)
67
Arytenoid lateralization comparison:
68
What are 2 common findings after laryngeal lateralization?
1. dysphagia - usually resolved within a few days as dogs get used to eating slower 2. aspiration - more common in dogs with neurologic disease
69
What is a common cause of implant failure in laryngeal lateralization? What could persistence of clinical signs point towards?
chronic coughing causes suture to break/tear out or muscular process fractures arytenoids not lateralized enough
70
How do partial arytenoidectomies and ventriculocordectomies compare?
PA = unually unilateral excision of the corniculate process; decreased risk of aspiration and webbing V = bilateral avoiding the commissure; greatest enlargement of laryngeal aditus
71
What are the most common complications associated with partial laryngectomies?
- resection of too much tissue = aspiration pneumonia - resection of too little tissue = no improvement in airway - airway obstruction secondary to web formation of scar tissue - pneumonia
72
How can webbing in ventriculocordectomies be avoided?
- avoid ventral commissure - use of a diode laser to cut the corniculate process and vocal folds can decrease tissue growth
73
What are the most common complications seen with surgical treatment of laryngeal paralysis?
- seroma formation - intramural hematoma - aspiration pneumonia* - persistent cough, gagging, or other respiratory signs - residual stridor - failure due to suture breakage or arytenoid cartilage fragmentation - laryngeal webbing* - GDV
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