Transcript To Breathe or Not to Breathe - Yorkshire Terrier National

Collapsing
Trachea
Mark Bohling, DVM
Diplomate, American College of Veterinary Surgeons
Assistant Professor of Surgery
University of Tennessee
College of Veterinary Medicine
What is Tracheal Collapse?
• Normal airflow dynamics in respiration
• Inspiration
• Expansion of chest by muscles of respiration
• Pressure gradient - chest negative
• Effect on the air conduit:
 Thorax - expansion
 Neck - compression
• Expiration
• Reverse effects
History of Collapsing Trachea in
Veterinary Medicine
• Described as early as
1960
• Review of early
treatments
• Single plastic tube
• Ventral chondrotomy
• Modified ventral
chondrotomy
• Dorsal membrane
plication
Tracheal Collapse in Other
Species
• Tracheal collapse in human beings
• History
• Dates to 1930’s
• Similarities
• Softening of tracheal cartilage
• Lateral collapse (same as dorsoventral in dogs)
• Differences
• Classification
 Primary vs secondary collapse
 Pediatric vs adult collapse
Tracheal Collapse in Other
Species
• Tracheal collapse in large animals
• Horses
• Congenital
• Secondary to laryngeal paralysis
• Cattle
• Acquired neonatal
• Tracheal collapse in birds
• Bordetella avium in turkeys
Tracheal Collapse in the Dog
• Miniature breeds
• Middle aged to older
• Other risk factors
• More pronounced in obese individuals
Levels of Collapse
Normal G1
G2
G3
G4
Levels of Collapse
Clinical Signs
• Chronic, dry nonproductive cough
(honking)
• Intermittent dyspnea
(worsens with excitement)
• Cyanosis & syncope in severe cases
• Inspiratory/ expiratory dyspnea
• Prone to heat stroke
Clinical Signs
Pathophysiology
• Disease causes the trachea rings
to weaken
• Dorsal ligament and trachealis muscle
weaken and stretch
• Trachea changes from oval tube
to a flattened conduit
Etiology
• Congenital
• Nutritional
tracheomalacia
• Obesity
• Bacterial infection
• Neurologic
• Chronic airway
disease
• Idiopathic – “who
knows why”
Diagnosis
• Tracheal palpation
• Radiographs
(inspiratory /
expiratory )
• Fluoroscopy
• Tracheoscopy
Radiographs
Tracheoscopy
Medical Management
• Cough suppression
(Hydrocodone, butorphanol)
• Bronchial dilators
(Aminophylline, terbutaline)
• Sedation
(Acepromazine)
• Weight loss
Medical Management
• Help control symptoms
• Can not be cured
• Disease usually progressive
Surgical Correction
• External stenting with plastic rings
Before
After
Surgical Correction
• External spiral stent
External Stent Complications
• Collapse between rings
External Stent Complications
• Damage to recurrent
laryngeal nerve
External Stent Complications
• Interruption of tracheal blood
supply
Internal Stenting
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What is a stent?
History of stenting
History of tracheal stenting
Modern stents and stent materials
Stents in veterinary medicine
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Ultraflex
Stent
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Radiopaque, self-deployed
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4 - 8 cm length, 10 - 20mm diameter
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Made of nitinol (nickel-titanium alloy)
•
Proximal or distal deployment
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Single strand, open
loop knitted design
(flexible, contourable)
Boston Scientific/ Microvasive.
Ultraflex® Stent
Ultraflex® Stents
SmartStent®
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Nitinol tube
Laser cut
No overlapping wires
Less breakage in
human vascular
applications
• Cordis Endovascular®
Infiniti Stent
• Also nitinol
• Single woven wire
• Only stent produced
exclusively for vet use
• Claims as yet
unproven
Stent Placement
• Stent deployed under
fluoroscopic guidance
• Target – 5mm cranial
to bifurcation
• Placement checked
with tracheoscopy
Stent in Place
Radiographs
Postoperative Care
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Perioperative antibiotics
Corticosteroids for 7 days
Sedation
Cough suppression
24 hours oxygen if needed
Humidification
6 Month Post Implant
Stent Results
• The little girl with the curl syndrome…
• Good outcomes…
• Immediate improvement
• Breathing near normal
• Mild chronic cough
• And the not-so-good outcomes…
Stent Complications
• Stent fracture
• Granulation in stent
• Tracheal exudate
• Additional collapse at ends of stent
Fractured Stent
Fractured Stent
Stent Fracture
• Originally thought to be due to bending
stresses
• All brands/types of nitinol stents can
fracture - there is NO unbreakable stent
• At this time, removal is best option - BUT not for the fainthearted!
Granulation Tissue
Tracheal Mucus
Collapsed at Ends
Stent plus Rings
Stent Advantages
• Preserves tracheal blood supply
• Preserves recurrent laryngeal nerve
• Continuous tracheal support
• Easy deployment
• Multiple, sequential deployment
Rings vs. Stents
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Cost to client (stent more expensive)
Stents are easier and quicker
Complication rate similar
Neither cure, only control symptoms
Stent placement requires expensive
equipment
• Rings require surgical expertise
• Lack of proper size stent
A “typical” case with tracheal
rings
• Day 1: Preop workup (bloodwork, radiographs,
tracheoscopy)
• Day 2: Surgery
• Postop recovery in ICU
• Day 3: Still in ICU
• Day 4: Discharged from hospital
• Home monitoring – continue medical therapy 2 –
4 weeks
• Recheck time variable, depends on outcome
• Long term outcome usually good, but…
A “typical” case with tracheal
stent
• Day 1: Workup as for rings. Order stent from
supplier
• Day 2: Stent arrives (usually). Stent is placed in a
30 minute procedure and patient recovers in ICU
• Day 3-4: Recovery in ICU
• Day 5: Discharge from hospital
• Home care for 2-4 weeks
• Re-check tracheoscopy at one month to check if
stent is embedded
Miss Piggy - Stent disaster case
#1
• Signalment: Miss Piggy
• 6 year old spayed female Yorkie
• Body weight 13 lbs (BCS 8/9!!)
• Grade III/VI heart murmur
• History:
• Coughing for past 2 years, getting worse past yr
• Presented to emergency clinic Saturday night
• Unable to breathe, cyanotic
• Oxygen dependent
Miss Piggy
• Presentation at UT
• Still oxygen dependent
• Tracheoscopy findings:
• Cervical - Grade 3 entire length
• Thoracic - Grade 3-4 entire length
• Left main bronchus Grade 2-3
• Plan: stent entire trachea
• Poor anesthetic risk
• Guarded prognosis given
Miss Piggy
• Stent placement
• Thoracic stent 1 cm cranial to carina
• 5mm overlap at thoracic inlet
• Cervical stent 1 cm caudal to cricoid
Miss Piggy
• Postop first 24 hours
• Doing well in oxygen
• Next day…
• Trial period out of oxygen - - cough and
cyanosis
• Back to oxygen and medical mgmt
• Antitussives
• Bronchodilators
Miss Piggy
• 3rd postop day
• Brief trial out of oxygen - - same result
• Still looks good in oxygen
• 4th postop day
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4am “can’t get comfortable”
7am - 7pm: awake all day
9pm: lung sounds getting “harsh”
11pm: crackles ausculted
Miss Piggy
• 5th day….
• Early am hours - No response to
bronchodilators or diuretics
• Patient very tired, has not slept in 24 hours
• 9am - respiratory failure
Stent disaster #2 - Tuffy
• Signalment:
• 4 year old male castrated Yorkie
• BW 8 lbs, BCS 6/9
• History:
• Started at 2 years old
• Now coughs at slightest exertion
• Cyanotic with mild exercise
Tuffy
• Tracheoscopy:
• Cervical collapse grade 3
• Thoracic collapse also grade 3
• Bronchi both open
• Plan:
• Stent entire trachea
Tuffy
• Immediate postop
• Doing well!
• 3 weeks later…
• “gagging” noticed
• Recheck at UT
• BOTH stents fractured
• Tracheal lumen open
but small
• Lots of exudate
What next?
• Immediate plan
• Stabilize his condition
• Antibiotics
• Some antitussives
• Definitive plan
• Stent removal
• Re-stent over the broken ones
Tuffy – the outcome
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Survived the procedure!
Immediate improvement in breathing
Went home doing well, but some cough
Continued to improve
• Still coughs some
• Overall quality of life – better than before
• Cost to owner: $5K+ total, lots of gray hair!
Future Needs
• Immediate needs:
• Improved surgical treatment options
• Less breakable stents
• Improved rings - can we go intrathoracic?
• Improved medical management options
• Cough suppression with less sedation
• Tracheal cartilage - can malacia be arrested?
Future Needs
• Long-term needs
• Greater understanding of the etiology of this
process
• What is happening at the cellular and molecular
level?
• Identification of molecular/genetic marker(s)
• Creation of a breed registry for this disease
• Apparent genetic cause
• Can we “breed it out”?
Special thanks to:
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Dr DJ Krahwinkel
Sue Schwarten
Danielle Browning
UT photo and media
services
• Linda Hicks and Mr T
Thank you – any questions?