Tracheal collapse frustrating; minimally invasive tehniques promising - DVM
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Tracheal collapse frustrating; minimally invasive tehniques promising

Photo 4: A lateral thoracic radiograph after placement of an intraluminal tracheal stent.
More recently, placement of intraluminal self-expanding nitinol tracheal stents has become an available, efficient, effective and minimally invasive method of preventing tracheal collapse. Stent size is selected by measuring the diameter of the trachea and length of the collapse using fluoroscopy. Patients are generally sedated with acepromazine and butorphanol to decrease anxiety and coughing and then placed under general anesthesia. The delivery system containing the self-expanding stent (Photo 2) is placed through an endotracheal tube to the desired location within the trachea (Photo 3). As the stent is unsheathed, placement can be visualized in real-time using fluoroscopy. Prior to final deployment, the expanded stent can be reconstrained and repositioned, if necessary. Proper placement is essential for optimal results (Photo 4). Stent placement adjacent to the carina could result in occlusion of the mainstem bronchi and placement adjacent to the larynx could result in laryngospasms and excessive post-operative coughing. The intraluminal stents are made of woven nitinol wire. Nitinol is an alloy of nickel and titanium and is a soft metal with excellent memory. It can be deformed (i.e. compressed into the delivery system) and then has the ability to return (i.e. expand) to its original shape.

Migration and fracture concerns

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Post-operative complications include migration and fracture of the stents, collapse of the trachea adjacent to the stents, excessive formation of granulation tissue and decreased mucociliary function. Migration of tracheal stents can be life-threatening if the mainstem bronchi became occluded. If migration does not occlude the carina but is displaced from the site of collapse, additional stents may need to be deployed in the trachea. Tracheal resection and anastomosis has been reported as a successful treatment for a fractured tracheal stent. Additional stents may be placed for collapse proximal to the initial stent, as long as the additional stent does not interfere with the larynx. Excessive granulation tissue may be responsive to corticosteroids.

After stent placement, most dogs show an immediate improvement of clinical signs. Patients may have a transient dry cough secondary to irritation that can be treated by continuing corticosteroids and cough-suppressant therapy. Over time, the corticosteroids and cough suppressants are tapered and discontinued. Some dogs will have mild residual cough and some form of medical therapy may be needed to control and prevent excessive coughing. The reported mortality rate compares favorably to surgical options. Tracheal collapse is a frustrating problem to treat in dogs. In the past, extraluminal prostheses placed surgically have been the standard of care with various success rates and a high rate of perioperative morbidity.

Intraluminal stents have become the preferred method of surgical treatment in the authors' hospital. Overall, intraluminal nitinol tracheal stents are proving to be an efficient, effective and minimally invasive means of treating tracheal collapse when medical management has failed.

Carl Sammarco, BVSc, MRCVS, Dipl. ACVIM (cardiology) joined Red Bank Veterinary Hospital, Tinton Falls, N.J. in 2001. He previously served as a lecturer/assistant clinical professor at the University of Pennsylvania, where he completed a residency in cardiology in 1994 .

Garrett J. Davis, DVM, Dipl. ACVS, earned his veterinary degree from Cornell University, completed an internship at Red Bank Veterinary Hospital and completed a residency in surgery at the University of Pennsylvania. He re-joined Red Bank Veterinary Hospital in 2002.

Tara Britt graduated from the University of Pennsylvania School of Veterinary Medicine in 2002. She completed a rotating internship in small animal medicine and surgery at Red Bank Veterinary Hospital and is current a third-year resident in small animal surgery at the hospital.


Source: DVM360 MAGAZINE,
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