Tracheal stenting for tracheal collapse

When medical management is no longer adequate, patients with tracheal collapse need more aggressive surgical intervention. See how stent placement helped this struggling Yorkie.

Catching a breath: See how interventional radiology helped a Yorkie with increasingly worse breathing problems.

Initial findings

• Signalment: 12-year-old 9-lb (4.1-kg) spayed female Yorkshire terrier

• Presenting complaint: Progressively worsening periods of inspiratory dyspnea accompanied by mild coughing

• Pertinent history: Three-year history of collapsing trachea and mild chronic valvular disease; failed medical management consisting of theophylline ER, butorphanol, diphenhydramine, enrofloxacin and acepromazine

• Medications: Prescription diet w/d (Hill's Pet Nutrition), hydrocodone (2.5 mg orally every six hours), prednisone (2.5 mg orally every 12 hours)

• Physical examination findings: Bright, alert and responsive; body condition score 6/9; Grade 2/6 holosystolic heart murmur; intermittent inspiratory dyspnea with mild cyanosis; inducible cough on tracheal palpation; profound increased inspiratory respiratory effort (suggesting upper airway involvement) with moderately increased expiratory effort as well (suggesting intrathoracic tracheal or bronchial involvement)

Diagnostic evaluation

• Hemoglobin saturation: 94 percent

• Complete blood count: Mild stress leukogram

• Serum chemistry profile: ALT 79, AST 39, ALP 420

• Thoracic and cervical radiographic and fluoroscopic examination: See Figure 1

• Tracheobronchoscopy: See Figure 2

• Cardiology consult: Mild chronic valvular disease

Treatment decisions

This patient had received various medications with little improvement in clinical signs. A historical cardiology consultation reported no need for cardiac medications at that time. At an examination two weeks earlier, a final attempt at medical management included antibiotics, corticosteroids and antitussives. No major improvement in clinical signs led to the consideration of more aggressive interventions.

Figure 1: A lateral thoracic and cervical static fluoroscopic image demonstrating cervical and thoracic inlet tracheal narrowing (black arrows) and open intrathoracic tracheal lumen and carina (white arrows).

Treatment options discussed with the owner included extraluminal tracheal ring placement and intraluminal stent placement. While the primarily inspiratory clinical signs suggested more severe extrathoracic tracheal collapse, physical examination and fluoroscopic evaluation suggested concurrent intrathoracic tracheal and bronchial collapse. Tracheal stenting was chosen to treat both the extrathoracic and intrathoracic tracheal collapse.

Figure 2: A tracheoscopy performed before stent placement demonstrating grade 4 (complete) collapse of the trachea at the level of the intrathoracic trachea.

Stent placement

The patient was anesthetized, and, with fluoroscopic guidance, positive pressure (Figure 3; 20 cm H2O) and negative pressure (Figure 4; -15 cm H2O), ventilation tracheal measurements were made to determine the maximal tracheal diameter and the extent of the tracheal or bronchial collapse. A self-expanding metallic tracheal stent was placed through the endotracheal tube (Figure 5). Tracheoscopy was repeated to confirm precise stent placement (Figure 6). The patient recovered in 40 percent oxygen in the intensive care unit until it was awake and ambulatory.

Figure 3: A lateral thoracic and cervical static fluoroscopic image obtained at 20 cm H2O positive pressure ventilation (PPV) demonstrating maximal tracheal diameter. A marker catheter (black arrows) is in place in the esophagus for measurement purposes. The carina is open (white block arrow). Line 3 is 10 mm and used to calibrate the image in order to determine the diameter of the trachea (Line 4).

Outcome

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 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.

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.

Figure 5: A lateral thoracic and cervical static fluoroscopic image obtained immediately after intraluminal stent placement demonstrating reestablished tracheal lumen patency (arrows).

Discussion

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.

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 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 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 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. Dr. Weisse 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.