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Tracheal stenting for tracheal collapse


DVM360 MAGAZINE


Outcome


Figure 4: A lateral thoracic and cervical static fluoroscopic image obtained at -15 cm H2O negative pressure ventilation (NPV) demonstrating diffuse tracheal collapse (black arrows) as well as carina and mainstem bronchial collapse (white block arrow) not previously apparent without NPV.
This patient was discharged from the hospital the next day with resolution of the dyspnea. A mild dry cough persisted. Discharge medications included a three-week tapering dose of corticosteroids (prednisone 2.5 mg orally twice daily to start), hydrocodone (2.5 mg orally every six hours) and a 10-day course of enrofloxacin (40 mg compounded orally once daily).


Figure 5: A lateral thoracic and cervical static fluoroscopic image obtained immediately after intraluminal stent placement demonstrating reestablished tracheal lumen patency (arrows).
Follow-up phone calls each week confirmed that the dog continued to do well. A recheck examination four weeks later showed dramatically improved respiration with progressive resolution of the dry cough. Occasional periods of excitement-induced coughing episodes continued but dramatically improved compared with episodes before stent placement. Reexamination at three months, six months and one year demonstrated similar clinical signs. Every-other-day prednisone remained necessary as well as daily hydrocodone therapy.

Discussion


Figure 6: A tracheoscopy performed after stent placement demonstrating tracheal lumen patency. Distal tracheal collapse can be seen beyond the stent at the level of the carina and mainstem bronchi.
Tracheal collapse is a progressive, degenerative disease of the cartilage rings in which hypocellularity and decreased glycosaminoglycan content lead to dynamic tracheal collapse during respiration. More recently, tracheal ring malformations have been found to also contribute to tracheal lumen obstruction and respiratory compromise.

Tracheal collapse predominantly occurs in middle-aged small- and toy-breed dogs that develop a wide and varying range of signs varying from a mild, intermittent honking cough to severe respiratory distress from dynamic upper-airway obstruction. Many of these patients (like the dog in this case) are successfully palliated for years with conservative treatments (e.g., weight loss, management of comorbidities) and medications including anti-inflammatories, cough suppressants and bronchodilators. Once medical management fails to provide an acceptable quality of life, more aggressive interventions are considered.

The two most commonly performed treatment options include extraluminal tracheal rings and intraluminal tracheal stenting. Tracheal ring surgery involves placing extraluminal support rings around the trachea during an open cervical approach and, in one study, had a reported 75 percent to 85 percent overall success rate in 90 dogs for reducing clinical signs.1 This procedure is limited to patients with collapse limited to the cervical trachea (primarily inspiratory dyspnea) and is not without complications. The same study reported that 5 percent of animals died perioperatively, 11 percent developed laryngeal paralysis from the surgery, 19 percent required permanent tracheostomies and about 23 percent died of respiratory problems with a median survival of 25 months.1 More important, only 11 percent of the dogs in this study had intrathoracic tracheal collapse (all dogs had extrathoracic tracheal collapse).

The advantages of intraluminal self-expanding metallic stent (SEMS) placement include minimal invasiveness, shorter anesthesia times and access to the entire cervical and intrathoracic trachea. Disadvantages include misplacement, choosing the inappropriate stent size and an unknown but relatively low risk of stent fracture. Two studies report clinical improvement rates in 75 percent to 90 percent of animals treated with intraluminal SEMS.2,3 Immediate complications were typically minor, although there was a reported perioperative mortality rate of about 10 percent—a rather high figure compared with our experience. Late complications included stent shortening, excessive granulation tissue, progressive tracheal collapse and stent fracture. Complications are often due to inappropriate stent placement or sizing, which is reduced with experience.

For stent placement, the patient is anesthetized, tracheal measurements are made and an appropriately sized stent is placed through an endotracheal tube and deployed during direct visualization using fluoroscopy. A video of the procedure can be viewed at http://amcny.org/node/339#Tracheal_Stenting/. The stenting procedure is fairly short, and patients are typically discharged from the hospital the next day. Medical management with corticosteroids and antitussives continues initially, and most dogs will need continued antitussive medications for life. Those with concurrent low-airway disease will often benefit from continued corticosteroid therapy as well.

For more case studies and to see how interventional radiology and interventional endoscopy can benefit patients, visit http://amcny.org/interventional-radiology-endoscopy/.

Dr. Berent is the director of Interventional Endoscopy Services in the Department of Diagnostic Imaging at The Animal Medical Center in New York City. is the director of Interventional Radiology Services in the Department of Diagnostic Imaging at The Animal Medical Center in New York City.

REFERENCES

1. Buback JL, Boothe HW, Hobson HP. Surgical treatment of tracheal collapse in dogs: 90 cases (1983-1993). J Am Vet Med Assoc 1996;208(3):380-384.

2. Norris JL, Boulay JP, Beck KA, et al. Intraluminal self-expanding stent placement for the treatment of tracheal collapse in dogs (abst), in Proceedings. 10th Annu Mtg Am Coll Vet Surg, 2000.

3. Moritz A, Schneider M, Bauer N. Management of advanced tracheal collapse in dogs using intraluminal self-expanding biliary wallstents. J Vet Intern Med 2004;18(1):31-42.


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