Download What`s New with Tracheal Stenting for Collapsing Trachea

What's New with Tracheal Stenting for Collapsing Trachea
Practice points
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Surgical management is a salvage procedure for tracheal collapse
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65-78% of dogs with tracheal collapse respond to medical therapy
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Tracheal stenting carries an approximate 50% complication rate
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Approximately 90% of owners that have tracheal stenting performed were pleased with
the outcome if they were sufficiently educated beforehand
Tracheal collapse is a progressive, irreversible condition. This collapse is typically in a
dorsoventral fashion and is associated with the classic “goose honk” cough. The collapse can be
very minor to life threatening due to airway obstruction, but progressive. Middle-aged toy and
small breed dogs, especially Pomeranians, Yorkshire Terriers, Miniature Poodles, and Pugs are
the most common breeds affected. In a survey of 100 dogs with tracheal collapse, 24% had
initial clinical signs by approximately 6 months of age. Congenital and acquired components
have been proposed as causes for tracheal cartilage weakness and factors such as obesity,
environmental allergens, cigarette smoke, and kennel cough exacerbate clinical signs.
Histopathologic evaluation of the tracheal cartilage in affected animals is found to be
hypocellular, with a reduction in glycoprotein and glycosaminoglycan that is associated with
decreased water retention within the matrix. The decreased water retention leads to increased
compliance and decreased rigidity of the tracheal cartilage. A vicious cycle of cough and
perpetual inflammation ultimately leads to loss of normal tracheal epithelium and replacement
with a fibrous membrane epithelium, followed by formation of squamous metaplasia and
reduction of ciliated cells with secretion of increasingly viscous mucus.
A grading system is used to classify the degree of tracheal collapse but is only accurate
when describing tracheobronchoscopic findings. Grade I collapse is laxity of the dorsal tracheal
membrane, resulting in 25% luminal collapse. Grade II collapse is loss of cartilage rigidity and
further laxity of the tracheal membrane, resulting in 50% luminal collapse. Grade III collapse is
flattening of the tracheal cartilages, resulting in 75% luminal collapse. Grade IV collapse is 100%
loss of luminal integrity.
Medical management of tracheal collapse is variable but often multimodal approach
yields the best results. The most beneficial therapy for dogs with tracheal collapse is keeping
them at a good body condition score (ideally 4/9). Weight loss is a key component to medical
management. An example of one treatment regimen could be: Cerenia daily for 5 days then
EOD, 1/2 lomotil, doxepin 10mg bid and continue with hydrocodone or butorphanol bid - tid,
and have low dose acepromazine ie 2.5mg bid for stressful days. Cerenia has significant antitussive effects. Doxepin reduces anxiety and has some soothing effects on larynx, lomotil has
opioid effects to reduce cough, and acepromazine helps with anxiety and compliments opioids.
Add in Adequan injections twice a week for 4 weeks then once a month as a maintenance
medication. The Adequan may improve cartilage in trachea due to the decrease in
glycosaminoglycans and water content. Since Cerenia can be expensive one way to make it
more economical is to use the 24 mg tablets and cut them into ¼ - ½ tablets. This is just one
example of medications used to treat tracheal collapse and each patient can respond differently
to different protocols.
Surgical options for tracheal collapse are considered salvage procedures because of high
complication rates and often times the tracheal collapse can continue into the lower airways
where there are no surgical options. Reported surgical techniques to restore airway patency
and reduce airway resistance include tracheal ring chondrotomy, plication of the dorsal tracheal
membrane, prosthetic mesh reconstruction and extralumanial prosthetic supports. All of these
surgeries carry a high complication rate (>50%).
In recent years intraluminal tracheal stenting has been developed using a metallic mesh
stent that retains the preformed shape. These stents are made out of metal alloys usually out of
nitinol (an alloy of nickel and titanium). The intraluminal tracheal stents have gained popularity
due to short anesthetic time, immediate improvement in clinical signs and the ability to
noninvasively place the stent within the cervical or thoracic regions. Even though intraluminal
stenting carries a high complication rate (approximately 50%), stenting has been more
successful than other surgeries. The most common complication is a residual cough (61% of
patients). Other complications include stent fracture, aspiration pneumonia, stent migration,
stent collapse, breakage and deformation of the stent, excessive granulation tissue, coughing,
pneumomediastinum, pneumonia and death. Tracheal stenting can be placed under
fluoroscopy or placed via endoscope. In a recent study 90% of owners with a dog with endstage tracheal collapse that chose to have the procedure performed were pleased with the
outcome if they were sufficiently educated beforehand. Unless having the procedure
performed at a large institution where they can carry a large inventory of stents, the patient has
to undergo two anesthetic episodes. One for the measurement of the stent, the patient has to
be anesthetized to get the appropriate positive pressure tracheal expansion. The second
anesthetic episode is for the placement. Typically the stents can be ordered and delivered
overnight express shipping so the placement of the stent can be performed within 24 hours of
the initial measuring.
In summary tracheal stenting is a salvage procedure that carries a fair prognosis. As
long as the owners are aware of the severity of the disease, if the patient has become refractory
to medical management, and the owners are OK with the expense of the procedure and
stenting, it can be a life saving procedure.