collapsing trachea mark bohling, dvm diplomate, american college of veterinary surgeons assistant...

Collapsing Trachea

Collapsing Trachea

Mark Bohling, DVM

Diplomate, American College of Veterinary Surgeons

Assistant Professor of SurgeryUniversity of Tennessee

College of Veterinary Medicine

What is Tracheal Collapse?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 - expansionNeck - compression

• Expiration• Reverse effects

History of Collapsing Trachea in Veterinary Medicine

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 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 collapsePediatric vs adult collapse

Tracheal Collapse in Other Species

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 DogTracheal Collapse in the Dog

• Miniature breeds• Middle aged to older• Other risk factors

• More pronounced in obese individuals

Levels of CollapseLevels of Collapse

Normal G1 G2 G3 G4

Levels of CollapseLevels of Collapse

Clinical SignsClinical Signs• Chronic, dry nonproductive cough

(honking)

• Intermittent dyspnea (worsens with excitement)

• Cyanosis & syncope in severe cases

• Inspiratory/ expiratory dyspnea

• Prone to heat stroke

Clinical SignsClinical Signs

PathophysiologyPathophysiology

• Disease causes the trachea rings to weaken

• Dorsal ligament and trachealis muscle weaken and stretch

• Trachea changes from oval tube to a flattened conduit

EtiologyEtiology

• Congenital• Nutritional

tracheomalacia• Obesity• Bacterial infection• Neurologic• Chronic airway disease• Idiopathic – “who

knows why”

DiagnosisDiagnosis

• Tracheal palpation

• Radiographs (inspiratory / expiratory )

• Fluoroscopy

• Tracheoscopy

RadiographsRadiographs

TracheoscopyTracheoscopy

Medical ManagementMedical Management

• Cough suppression(Hydrocodone, butorphanol)

• Bronchial dilators(Aminophylline, terbutaline)

• Sedation(Acepromazine)

• Weight loss

Medical ManagementMedical Management

• Help control symptoms

• Can not be cured

• Disease usually progressive

Surgical CorrectionSurgical Correction

• External stenting with plastic rings

BeforeBeforeBeforeBefore AfterAfterAfterAfter

Surgical CorrectionSurgical Correction

• External spiral stent

• Collapse between rings

External Stent ComplicationsExternal Stent Complications

• Damage to recurrent laryngeal nerve

External Stent ComplicationsExternal Stent Complications

External Stent ComplicationsExternal Stent Complications• Interruption of tracheal blood

supply

Internal StentingInternal Stenting

• What is a stent?

• History of stenting

• History of tracheal stenting

• Modern stents and stent materials

• Stents in veterinary medicine

Ultraflex® StentUltraflex® Stent• Radiopaque, self-deployed

• 4 - 8 cm length, 10 - 20mm diameter

• Made of nitinol (nickel-titanium alloy)

• Proximal or distal deployment

• Single strand, open loop knitted design (flexible, contourable)

Boston Scientific/ Microvasive.

Ultraflex® StentUltraflex® Stent

Ultraflex® StentsUltraflex® Stents

SmartStent®SmartStent®

• Nitinol tube• Laser cut• No overlapping wires• Less breakage in

human vascular applications

• Cordis Endovascular®

Infiniti StentInfiniti Stent

• Also nitinol• Single woven wire• Only stent produced

exclusively for vet use• Claims as yet

unproven

Stent PlacementStent Placement

• Stent deployed under fluoroscopic guidance• Target – 5mm cranial

to bifurcation

• Placement checked with tracheoscopy

Stent in PlaceStent in PlaceStent in PlaceStent in Place

RadiographsRadiographs

Postoperative CarePostoperative Care

• Perioperative antibiotics

• Corticosteroids for 7 days

• Sedation

• Cough suppression

• 24 hours oxygen if needed

• Humidification

6 Month Post Implant6 Month Post Implant

Stent ResultsStent 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 ComplicationsStent Complications

• Stent fracture

• Granulation in stent

• Tracheal exudate

• Additional collapse at ends of stent

Fractured StentFractured Stent

Fractured StentFractured Stent

Stent FractureStent 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 TissueGranulation Tissue

Tracheal MucusTracheal Mucus

Collapsed at EndsCollapsed at Ends

Stent plus RingsStent plus Rings

Stent AdvantagesStent Advantages

• Preserves tracheal blood supply

• Preserves recurrent laryngeal nerve

• Continuous tracheal support

• Easy deployment

• Multiple, sequential deployment

Rings vs. StentsRings vs. Stents

• 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

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

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

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 PiggyMiss 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 PiggyMiss Piggy

• Stent placement• Thoracic stent 1 cm cranial to carina• 5mm overlap at thoracic inlet• Cervical stent 1 cm caudal to cricoid

Miss PiggyMiss 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 PiggyMiss Piggy

• 3rd postop day• Brief trial out of oxygen - - same result• Still looks good in oxygen

• 4th postop day• 4am “can’t get comfortable”• 7am - 7pm: awake all day• 9pm: lung sounds getting “harsh”• 11pm: crackles ausculted

Miss PiggyMiss 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 - TuffyStent 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

TuffyTuffy

• Tracheoscopy:• Cervical collapse -

grade 3

• Thoracic collapse - also grade 3

• Bronchi both open

• Plan:• Stent entire trachea

Tuffy 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?What next?

• Immediate plan• Stabilize his condition• Antibiotics• Some antitussives

• Definitive plan• Stent removal• Re-stent over the broken ones

Tuffy – the outcomeTuffy – the outcome

• 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 NeedsFuture 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 NeedsFuture 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:Special thanks to:

• Dr DJ Krahwinkel• Sue Schwarten• Danielle Browning• UT photo and media

services• Linda Hicks and Mr T

Thank you – any questions?Thank you – any questions?