Tracheal Foreign Body in a Cat
A five year old male neutered Domestic Shorthair cat presented on an emergency basis to DoveLewis for having difficulty breathing. He is an indoor-outdoor pet and the owners reported that he was outside (absent) the previous night. The owners noticed his abnormal breathing pattern when the cat returned in the morning and brought him directly to the hospital. He is an otherwise healthy cat, current on vaccinations with no significant medical history.
Upon presentation, the cat’s physical exam was notable for tachypnea (60 bpm) and tachycardia (180 bpm) with mildly increased bronchovesicular sounds in all fields with no crackles heard. He had a slight inspiratory wheeze and occasional open mouth breathing. The remainder of his physical exam was within normal limits. His initial treatments included inhaled albuterol (90mcg), butorphanol intramuscular (1.5 mg) and placement in the oxygen chamber at 40% oxygen.
A single lateral thoracic radiograph demonstrated a radiopaque structure within the trachea at the level of the 4th intercostal space with no evidence of pneumothorax or atelectasis. Extended data base was within normal limits except for a hyperglycemia (260 g/dl).
The owners gave permission to proceed to endoscopy. He was pre-oxygenated with flow-by oxygen and given midazolam (0.2mg/kg IV) and fentanyl (5mcg/kg IV bolus) as premedication via a cephalic catheter. Propofol was used as an induction agent and administered as needed via 0.25ml boluses throughout the procedure to maintain full anesthesia (total 40 mg used). Bronchoscopy (flexible 6mm diameter bronchoscope with 2.2mm working channel and 120° field of view) revealed an irregular shaped rock in the trachea just rostral to the carina. The rock was successfully removed with two pronged grasping forceps and the trachea again inspected. There was mild inflammation (redness, edema) of the trachea for approximately 2 cm rostral to the carina. The cat was intubated following removal of the bronchoscope and maintained on 100% oxygen until recovery and extubation. After a procedural radiograph (lateral thorax), he was recovered in the oxygen cage and received acepromazine (0.02 mg/kg IV). The cat was weaned out of the oxygen cage over a 10 hour period and discharged from the hospital 16 hours after endoscopy. Go home medications included amoxicillin-clavulanate for 7 days (12.5 mg/kg PO BID) and buprenorphine (0.012 mg/kg PO q 8 hours) for 3 days. The owner reports that the cat recovered without incident.
Feline tracheal foreign bodies are an uncommon cause of respiratory distress at this hospital and are sporadically reported. Tracheal or bronchial foreign material can result in acute or chronic respiratory signs ranging from complete or near complete obstruction to chronic cough and respiratory inflammation and infection. Plant material and small rocks (gravel) are the most frequently cited foreign material in the veterinary literature, followed by portions of an endotracheal tube.
Most radiodense foreign material is visible on plain radiographs of the chest of cats, however small pieces of plant material, even when of soft tissue opacity, can be difficult to discern with standard films. Computed tomography has been shown to be a good tool for identifying foreign material and associated pulmonary changes (infiltrates, atelectasis etc.), particularly if the foreign material has migrated into the smaller airways. Bronchoscopy is an excellent modality for identification and retrieval of foreign material within the trachea and mainstem bronchi, but has limited use for foreign bodies which have passed into the parenchyma , into the mediastinum or pleural space. Fluoroscopy has also proved useful in finding and assisting in retrieval of airway foreign bodies, particularly where bronchoscopy has failed.
Most large foreign bodies in cats tend to lodge just rostral to the carina and can be retrieved relatively easily with grasping forceps manipulated under direct visualization with a flexible endoscope. However, if the foreign object is too smooth to grasp or resists collection using a basket forceps, snare, suction or other endoscopic device, an over the wire balloon catheter can be passed beyond the obstruction, the balloon inflated, and the foreign body pulled rostrally for retrieval. The balloon catheter can either be placed using fluoroscopic or bronchoscopic guidance. Ideally, these cats are intubated and the flexible endoscope passed through the endotracheal tube by use of a Y or T adapter attached to the oral end of the tube to allow delivery of oxygen throughout the procedure. More commonly, the size of the cat’s trachea precludes passage of an endotracheal tube large enough to allow passage of a flexible scope that has an instrument channel sized for grasping forceps. As in this case, the patient can be intermittently intubated and extubated to allow for adequate ventilation and oxygenation while also allowing tracheoscopy and bronchoscopy. While the flexible endoscope is within the trachea, a small sterile flexible tube (e.g. red rubber catheter) can be passed through the larynx for supplemental oxygen. Planning for total intravenous anesthesia (TIVA) is essential as all staff involved in the procedure would otherwise be exposed to inhaled anesthetic gas.
Prognosis for cats following uncomplicated retrieval of tracheobronchial foreign bodies is good to excellent. If the foreign body is suspected to be chronic with risk of associated pneumonia, a bronchoalveolar lavage or tracheal wash should be performed following foreign body retrieval to better diagnose and treat bacterial infection.
In the event a tracheal or bronchial foreign body cannot be retrieved with the techniques mentioned above, conversion to thoracotomy or thorocoscopy is required. Complications of tracheobronchial foreign body retrieval in a minimally invasive manner include hypoxia, tracheitis, hemorrhage, pneumothorax/pneumomediastinum and infection. Bronchospasm and coughing are common following any manipulation of the airway lumen. Pre-treatment with a bronchodilator such as terbutaline may be helpful, particularly in patients with a known inflammatory disease. Lidocaine (2% topical solution) can be sprayed at the level of the carina following removal of the foreign body to decrease stimulation and coughing post-procedure. Careful anesthetic technique combined with gentle and thorough endoscopic method carries low risk of serious complications.