Cardiorespiratory Medicine and Surgery

Brachycephalic airway syndrome (BAS)

Medical aspects: Brachycephalic syndrome is an upper airway obstructive syndrome characterized by any combination of stenotic nares, elongation of the soft palate, everted laryngeal saccules and laryngeal collapse. Of these conditions, stenotic nares is a primary malformation, soft palate elongation can be primary or secondary, and saccular eversion and laryngeal collapse are sequelae to increased inspiratory effort. Of these conditions, laryngeal collapse is the most severe and debilitating to the patient as surgical correction is difficult. Brachycephalic syndrome occurs most commonly in the English and French bulldog, Pekingese, Pug, and Boston terrier. Persian cats and other brachycephalic breeds are also affected. In the English bulldog, brachycephalic syndrome may be accompanied by hypoplastic trachea, a congenital malformation resulting in a narrowed lumen to the trachea where the ends of the tracheal rings meet or overlap or are V-shaped. Males are affected more often than females and other congenital disorders can be found such as pulmonic or aortic stenosis. In some dogs (particularly Pugs), nasal turbinates protrude from the caudal nasopharynx, causing further obstruction of airflow.
Clinical signs of BAS include stertor, snoring, exercise intolerance, respiratory difficulty and collapse. Some dogs (particularly bulldogs) have concurrent vomiting or regurgitation. Stenotic nares can be visualized on physical examination, and if laryngeal collapse is presence, stridor may be detected on auscultation of the larynx. Cervical and thoracic radiographs are recommended to obtain a complete database, however documentation of laryngeal and palatal lesions requires sedation for direct visualization. Because of anesthetic concerns with brachycephalic breeds, surgical correction should be planned at the time the diagnosis is confirmed. If possible, weight reduction should be obtained prior to surgery. Interestingly, gastrointestinal signs often resolve or lessen following surgery to relieve upper airway obstruction.
Surgical aspects: Stenotic nares are easily correctable. Various surgical techniques are used and all have the same end result, permanent enlargement of the external nares. A #11 scalpel blade is preferred in order to make deep and even cuts in the wing of the nostril.
There is no difference in outcome between a horizontal or vertical wedge resection. Absorbable 3-0 to 4-0 multifilament or monofilament suture in a simple interrupted pattern is used to appose cut surfaces.
A normal soft palate should just touch the tip of the epiglottis. To assess soft palate length appropriately, the tongue should be in a normal position. An elongated soft palate typically extends past the tip of the epiglottis by at least several millimeters. Soft palate resection (staphylectomy) is a relatively simple procedure. The most important aspect of the surgery is to make sure that the palate is not cut too short. The consequences of a short soft palate are nasal regurgitation and rhinitis. The procedure is typically performed with the animal in sternal recumbency. The mouth is suspended in an open position to improve visualization and access to the entire oral cavity. The animal is intubated throughout the procedure. The first step prior to surgery is to place stay sutures on either side of the palate at the level of planned resection. Metzenbaum scissors are used to transect approximately one-third to one-half the width of the palate, starting at the lateral aspect of the palate and moving towards midline. A simple continuous pattern with 4-0 absorbable suture is used to oppose the nasal and oral mucosa over the exposed palatine muscle. Removal of the remainder of the palate is performed and the suture line is continued to the opposite side. Hemorrhage and swelling are usually minimal, but premedication with dexamethasone (0.5mg/kg, IV) is often routine. Soft palate resection may also be performed using surgical laser. [...]