Tracheal Stenting: Long-term Expectations and New Insights

Tracheal collapse, or tracheal chondromalacia, is a progressive, degenerative condition of the hyaline cartilage rings that support the tracheal lumen. Weakening of the trachealis muscle contributes to the loss of tracheal lumen during different phases of respiration. The resulting clinical syndrome typically manifests as a “goose honk” cough with varying degrees of dyspnea and is most commonly identified in toy breed dogs. Conservative management techniques and medical management can be useful to palliate clinical signs for years, however more aggressive treatment is often required for those animals that eventually fail these more conventional treatments. Candidates for surgical or interventional therapy are those that have failed aggressive conservative medical management. Various surgical techniques have been described, however the currently recommended surgical therapy is extraluminal polypropylene prosthesis. This technique involves placing extraluminal support rings around the trachea during an open cervical approach and has a reported 75%-85% overall success rate in 90 dogs for reducing clinical signs. This procedure is now without complications however. The same study reported that 5% of animals died peri-operatively, 11% developed laryngeal paralysis from the surgery, 19% required permanent tracheostomies, and ~23% die of respiratory problems with a median survival of 25 months. More importantly, only 11% of the dogs in this study had intra-thoracic tracheal collapse (all dogs had extrathoracic tracheal collapse). The authors advised against this technique in animals with intra-thoracic tracheal collapse as the associated morbidity was unacceptably high. Humans can develop tracheal collapse as children (chondromalacia) or can have tracheal stenosis (following lung transplantation) or tracheal compression from malignancies. The current therapy in humans is intraluminal stenting with a number of FDA-approved tracheobronchial stents available. The advantages of intraluminal tracheal stenting include minimal invasiveness, shorter anesthesia times, and access to the entire intrathoracic trachea. Disadvantages include tracheal irritation and possibly cycling of the metallic stent when crossing a highmotion area such as the thoracic inlet. Two studies report clinical improvement rates in 75%-90% of animals treated with intraluminal SEMS have been reported. Immediate complications were typically minor although there was a reported peri-operative mortality rate of approximately 10%, a rather high figure compared to the author’s experience. Late complications included stent shortening, excessive granulation tissue, progressive tracheal collapse, and stent fracture.