33rd Annual Scientific Meeting proceedings

The immediate post-operative course and final outcome of any surgical intervention on the brachycephalic upper airway is dependent not only on the surgical procedures performed, but also on optimal pre-, intra- and post-operative care.

Evaluation of the airway
An accurate history and upper airway examination is critical to ascertain the issues, their severity, what procedures are indicated and the likelihood of complications. Get a detailed history and consider a standardized upper airway history questionnaire. It also helps when discussing prognosis with owner and managing their expectations. Most of the upper airway examination can be done with a laryngoscope or Weider tongue blade, cotton-tipped applicators and wooden tongue depressors. Loupes (2.5x) with a light source greatly facilitates the exam. Flexible endoscopes have the advantage of being able to assess trachea, mainstem bronchi and nasopharynx with retroflexed view, as well as recording the examination.

All airway structures should be assessed for symmetry, function, mucosal condition, phlegm. Consider using a standardized upper airway examination sheet and remember to perform otic examinations. Additional imaging is extremely useful -an extubated head and neck CT with hanging head gives an evaluation of the nasal turbinates, choanae, nasopharynx, palatal length and thickness, infraglottic lumen and middle ear. Including thorax and abdomen in the scan can assess the trachea, bronchi and lungs as well as the opportunity to assess evidence of chronic gastroesophageal reflux or hiatal hernia.

If we fail to recognize the full extent and severity of upper airway anomalies, then we may not address them appropriately, and thus will be faced with complications or progressive clinical deterioration.

Pre-operative preparation
It works well to have two appointments for most brachycephalics – one for the diagnostics and another for the surgery. The first appointment comprises of getting the history, any required bloodwork, the upper upper airway exam ±CT. Occasionally, in dogs less than a year, especially if CT has been declined, we will do diagnostics and surgery on same day. Similarly, if we have an elderly obese brachycephalic, we may do everything on the same day. The advantages of having a separate diagnostic appointment are:

• The patient is full worked up and the surgical plan be developed and diagnostics reviewed.
• Owner discussion can be targeted to their specific dog, accurate estimate provided and you can go through CT and examination with them.
• If prone to regurgitation, there is time for the patient to be placed on anti-reflux and antacid medications before surgical appointment.
• Recovery from diagnostics can be observed closely and anesthesia protocols modified if necessary.

Pre-operative medications typically consist of an antacid such as omeprazole 10 mg/kg q.12 on an empty stomach (or other proton pump inhibitor), and cisapride 0.5 mg/kg q.8 half an hour before feeding and then before bed. Not all brachycephalics tolerate these drugs, so starting a few weeks before surgery and starting each drug separately is recommended. Other drugs that can be used include famotidine, pantoprazole and sildenafil. Anxious dogs may benefit from trazodone.

Immediate pre-operative preparation
Antireflux & pain medications
If the patient is not already on antacid and antireflux medications, intravenous pantoprazole and maropitant ± ondansetron are administered upon admission. If patient is excited or anxious, then acepromazine 0.02 – 0.03 mg/kg IV can be given. No opioids, and especially not hydromorphone, are given pre-operatively. Sometimes no premedication is administered or if tense, midazolam is given with induction agent. Once anesthetized an intravenous injection of buprenorphine or fentanyl (if other surgical procedure such as gonadectomy or caudectomy is to be performed) may be warranted.

Swelling mitigation
The respiratory tract is extremely prone to edema when subjected to traumatic or surgical disruption.  Most brachycephalics receive intravenous dexamethasone 0.25 mg/kg 30 minutes before surgery (unless contraindicated). A smaller, guarded, lubricated ET tube will be less traumatic to the laryngeal aditus, infraglottic lumen and trachea. Intubation should be very gentle. Laryngotracheal swelling results in exponential resistance to airflow (Poiseuille’s Law) causing significant post-operative stridor and obstruction.

Intra-operatively
Positioning and Analgesia
The patient is slung from the maxilla and the oral cavity and pharynx prepped for surgery with povidone-iodine solution. A palatine block of bupivacaine (2.5 mg) with hub of dexmedetomidine is performed. If tonsillectomy is performed, Nocita (liposome-encapsulated bupivacaine) can be instilled into the tonsillar crypts.

Technique
Binocular loupes (2.5x) with a light source greatly facilitates surgery. Pack the pharynx with saline-moistened gauze before surgery, typically after a stay suture has been placed in the midline of the soft palate. Surgery is undertaken in an atraumatic manner with meticulous hemostasis. The most common palatal procedures are a folded flap palatoplasty for thickened and elongated soft palates, or staphylectomy for elongated soft palates. Judicious use of CO2 laser or needle-tip electrocautery with gentle suction are preferred over larger vessel-sealing devices. We always securely suture the palatal mucosa with a rapidly absorbable monofilament suture. Ventricles and cuneiform cartilages can typically be resected without having to extubate due to the small ET tube. Avoid repeated re-intubations.

Suctioning
After finishing surgical interventions, the pharynx, laryngeal aditus and esophagus are suctioned with a whistle-tip catheter. Avoid suctioning trachea unless blood is present. Esophageal suctioning may be negative, but sometimes yields a significant amount of fluid. Suction until negative.

Mannitol Packing
The laryngeal aditus, pharynx and caudal oral cavity are carefully but firmly packed with mannitol-soaked gauze (typically 10mls of mannitol per 10x10cm sponge, then wrung out) for 45 minutes to minimize immediate post-operative swelling. It is best to unfold the gauze sponge and pack bit-by-bit into the pharynx with Debakey forceps. Always count the sponges in and reconcile the count before extubation! During this time, other procedures such as the nares, or OHE, neuter, caudectomy, can be performed.

Post-operatively
Oxygen
If allowed to recover in a quiet environment without stimulation, the animal generally tolerates the ET tube until fairly conscious. Physically maintain the airway s until the dog will absolutely no longer tolerate the tube; by then it is conscious enough to keep its oropharynx open and protect its airway from aspiration if it regurgitates. All brachycephalic patients are recovered routinely in a climate-controlled 40% oxygen cage for at least 2 hours. We typically quote for 2-12 hrs.

Swelling
If swelling becomes significant and the patient becomes stertorous or stridorous, re-induction, intubation and mannitol pharyngeal packing can be repeated for 45 minutes, with a second injection of dexamethasone. Now is the time to talk with owner about temporary tracheostomy tube placement for 2 – 3 days (they should be prepared from the pre-operative discussions).

Temporary tracheostomy
You and your team need to be familiar and competent at placing and maintaining temporary tracheostomy tubes in brachycephalics. Swelling usually (but not always) resolves within 24 - 48 hours, depending on the size of the airway.

Bleeding
Although rarely observed, any significant post-operative bleeding from the oral cavity or vomiting of blood is an indication for immediate re-anesthesia and examination. The consequences of ignoring this could be aspiration of blood, swallowing of blood followed by regurgitation and aspiration. Suction again.

Follow-up
Brachycephalic breeds are much-loved members of their family. Owners are often extremely nervous in the first days following discharge, especially if some stertor remains or if regurgitation occurs. It takes about a week for all swelling to resolve and many more weeks for the tissues to heal and remodel. It makes a huge difference to owners to know that you are with them on the post-operative journey and are available if issues arise. Checking in at least every other day goes a long way, and is also educational for us as surgeons.

Summary
Any upper airway intervention starts with an in-depth anamnesis, accurate evaluation of the patient and discussion with owners and expectations. Subsequent preparation of the patient for surgery includes drug selection to minimize acidic reflux and regurgitation for several weeks pre-operatively, immediate pre-anesthesia preparation, intra-operative techniques to minimize discomfort, swelling and regurgitation/aspiration. Post-operative protocols can also be performed to mitigate the complications that frequently affect the brachycephalic breeds.