Respiratory emergencies: surgical intervention for respiratory distress (Proceedings)
A number of respiratory emergencies may ultimately require surgical intervention, but the surgical techniques most likely to be indicated on an emergent basis are tube tracheostomy, tracheal resection/anastomosis, tube thoracostomy, and diaphragmatic hernia repair.
Temporary tracheostomy tube placement is performed to bypass upper airway obstructions. The emergent "slash" tracheostomy should be a rare occurrence; usually, there is time to capture the airway with an endotracheal tube and prepare the patient for a controlled surgical approach. Make a ventral midline cervical skin incision just caudal to the larynx for a distance of approximately 4 cm. Separate the sternohyoideus muscles on the midline and incise the interannular ligament between the second and third tracheal rings. This tracheal location is chosen because it is the preferred stomal site for permanent tracheostomy should such be required. Place stay sutures around the second and third tracheal rings, knot the sutures and tag them with hemostats. Use the stay sutures to manipulate the interannular opening while the endotracheal tube is removed and the tracheostomy tube is inserted. [During the postoperative course, the stay sutures can be used for manipulation during re-insertion of a tube that has been inadvertently dislodged or requires changing.] An uncuffed tracheostomy tube (or cuffed tube with the cuff deflated) is used if the objective is merely to bypass an obstruction, whereas a cuffed tube is used if positive pressure ventilation or anesthesia is to be employed. Secure the tracheostomy tube by attaching umbilical tape to the wings and tying the tapes behind the neck. Permanent tracheostomy, a salvage technique for untreatable upper airway obstruction, could be done in lieu of temporary tube tracheostomy; however, on an emergency basis it is rare to determine that the only treatment possibility is to create a permanent tracheal stoma.Tracheal Resection And Anastomosis
Tracheal resection is indicated when an isolated segment of trachea is irreversibly damaged or diseased. Up to 17 tracheal rings have been successfully resected in dogs. [Dogs have 34 to 44 total tracheal rings.] However, it is recommended to remove as few rings as possible to minimize tension and resultant stricture formation. A standard ventral midline cervical approach is performed when the cervical trachea is affected. The intrathoracic trachea is approached through a right third intercostal space thoracotomy.
There are three tracheal anastomosis techniques: (1) the split-cartilage technique, where the most cranial and most caudal rings are bisected such that the two halves are apposed with sutures, (2) the annular ligament-cartilage technique, where the cranial and caudal incisions are in the interannular ligaments and the cranial and caudal segments are apposed with sutures that go around the rings at the anastomotic site, and (3) the interannular technique, where the cranial and caudal incisions are in the interannular ligaments and the cranial and caudal segments are apposed with sutures that incorporate only the interannular ligaments at the anastomotic site. Of these 3 techniques, the split-cartilage technique is preferred because it has been shown to result in the least amount of stenosis and luminal attenuation. Synthetic absorbable (or nonabsorbable) monofilament sutures are preferred for the anastomosis. When a large segment of trachea is excised 2 or 3 tension-relieving sutures are placed to support the primary repair. These sutures are placed from a tracheal ring 2 to 3 rings caudal to the anastomosis to a tracheal ring 2 to 3 rings cranial to the anastomosis and tied such that tension on the primary anastomotic suture line is minimized.