Nasopharyngeal stenosis (NPS) is a pathologic narrowing within the nasopharynx caudal to the choanae resulting in a variable degree of inspiratory stertor. This can occur as a congenital anomaly or be secondary to an inflammatory condition (aspiration rhinitis), surgery, trauma, or a space-occupying lesion. Traditional therapy involves surgery or serial balloon dilatation procedures. Balloon dilatation is minimally invasive and utilizes interventional technique via fluoroscopy and endoscopy, but can result in re-stricture in a few days to a few weeks. We have found that stenting of this nasopharyngeal region allows for a more permanent fixation and results in both dogs and cats have been extremely promising.
Under both fluoroscopic and rhinoscopic guidance a hydrophilic Weasel? guidewire is advanced caudally from the nares through the ventral nasal meatus, through the stenotic opening, and down the esophagus. This is viewed inside the nasopharynx with retroflex rhinoscopy, and from the outside with fluoroscopy. Once the stenotic lesion is identified a percutaneous transluminal angioplasty balloon, preloaded with a metallic stent (balloon expanded metallic stent—BEMS) is advanced over the guidewire and centered over the stenotic lesion. Using both fluoroscopic and endoscopic viewing the balloon is inflated (with a 50:50 mixture of contrast and saline) and the waist of the stenosis is subsequently broken with the balloon.
As the balloon expands, the stent deploys. Once the stenosis is open, the balloon is deflated and removed over the wire, and the stent is left to remain in place. The stent will re-epithelialize in a few weeks (approximately 2-6 weeks). The size (length and width) of the stent and balloon are chosen based on Computed Tomography (CT), which is done prior to the procedure. The patients usually go home the same day as the procedure with antifibrotic doses of gluococorticoids (prednisone 0.5 mg/kg), 2 weeks of antibiotics and tramadol as needed for any discomfort.
Tracheal stenting can per performed for a variety of reasons including tracheal neoplasia, tracheal stenosis, and most commonly tracheal collapse. At the University of Pennsylvania tracheal stenting is classically performed using fluoroscopic guidance alone, without the assistance of endoscopy. There are quite a number of veterinarians who perform tracheal stenting under tracheoscopic guidance making this interventional endoscopic (IE) procedure reasonably common. Tracheal stenting will be discussed for a full session so I will defer to that lecture for further details of this procedure.
Tracheal Foreign Body Retrieval
Tracheal foreign bodies are seemingly uncommon to encounter. When you do, having a fast, safe, and effective approach for retrieval is imperative. Most internists would use an endoscope and grasper or basket. In very small animals this requires extubation and a very small endoscope, which can result in hypoxia, hypercarbia and minimal or no ventilation. Using endoscopy with a retrieval basket, in conjunction with fluoroscopy, helps to guide you to the object and watch the wires entrap the prior to removing the basket. For radiolucent objects this would be done with endoscopy alone, but for radio-opaque material this can be easily done with a retrieval basket and fluoroscopy alone, directly through the endotracheal tube, preserving ventilation (see presentation) and foregoing the need for tracheoscopy.