Brachycephalic airway syndrome (Proceedings) - Veterinary Healthcare
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Brachycephalic airway syndrome (Proceedings)


CVC IN KANSAS CITY PROCEEDINGS


Everted laryngeal saccules

Everted laryngeal saccules are most frequently encountered in brachycephalic breeds, with a prolonged history of upper airway obstruction. Everted laryngeal saccules have been present in 48% of the brachycephalic dogs in a study. The mucosa of the laryngeal saccules evertes in the larynx because of the high negative pressure during inspiration. The prolapse mucosa is edematous and creates a mass in the larynx that contributes to the obstruction of the ventral rima glottidis. Resection of everted saccules is not performed routinely. Correction of other components of the syndrome might result in the reduction of the everted saccules.

A temporary tracheostomy is necessary to ensure an adequate airway during surgery and during postoperative recovery. Temporary tracheostomy allows removal of the endotracheal tube from the surgical site and helps manage the airway after the surgery.

A patient is placed in sternal recumbency with the mouth held open as described for partial laryngectomy. The saccule is grasped with long hemostats or Allis forceps, and rostral traction applied. The saccule is amputated at its base with scissors or a long-handled scalpel. Hemorrhage is minor and controlled by pressure. Avoiding the electroscalpel reduces inflammation.

Resection of everted saccules is associated with edema and swelling of the larynx. Dexamethasone intravenously (1 mg/kg) is used to reduce the amount of edema after surgery. The temporary tracheostomy is maintained for 24 hours after surgery. The patient is challenged before removal of the temporary tracheostomy tube.

Laryngeal collapse

Laryngeal collapse occurs as a result of a loss of the supporting function of the cartilages. It represents a very advance form of the brachycephalic airway syndrome. The cuneiform and corniculate cartilages are drawn medially by the excessive inspiratory negative pressure. Laryngeal collapse is a progressive disease in which the prognosis worsens with time. Collectively, stenotic nares, elongated soft palate and everted laryngeal saccules predispose dogs to abnormal stresses within the larynx that lead to progressive distortion and ultimate collapse of the arytenoid cartilages.

Three stages of laryngeal collapse have been described (stages 1 to 3) stage 3 being the most advance. The first stage in the pathogenesis of laryngeal collapse involves eversion of the laryngeal saccules into the cavity of the glottis. This is caused by an abnormal negative pressure created at the glottis during inspiration. The vacuum that develops in the glottis results from the increased inspiratory effort necessary to ventilate through the stenotic nares or elongated soft palate. Inflammation and edema of the mucosa usually accompany saccule eversion and contribute to the dyspnea. During stage 2, the cuneiform process of each arytenoid cartilage, which normally extends to the caudolateral region of the pharynx during inspiration, loses its rigidity and gradually collapses into the laryngeal lumen. In stage 3, the corniculate process of each arytenoid cartilage, which normally maintains the dorsal arch of the glottis, collapses toward the midline, resulting in complete collapse of the larynx. Loss of laryngeal cartilage rigidity is speculated to contribute to the collapse of the cuneiforme and corniculate process. Dogs with stenotic nares, an elongated soft palate, or everted laryngeal saccules are treated for these conditions first. A dog is allowed to recover, and the clinical response suggests whether further resection is necessary.

Dogs with persistent stage 2 disease, even after resection of the soft palate and nares, may require partial arytenochordectomy to enlarge the laryngeal opening. Dogs with stage 3 laryngeal collapse may not show significant improvement when treated with partial laryngectomy. An alternative treatment for dogs with severe laryngeal collapse that does not improve after resection of the elongated soft palate, stenotic nares, or laryngeal saccules is a permanent tracheostomy.


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Source: CVC IN KANSAS CITY PROCEEDINGS,
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