Trachea and bronchi Flashcards
In a study by Conguista 2021 in JAVMA, what were the MST for dogs treated medically for tracheal collapse v. endoluminal stenting?
MST for medical management was 3.7 years, and 5.2 years for the stent managed group.
For severe disease the MST for medically managed dogs was only 12 days, as compared to 1338 for stented patients.
In a study by Stordalen 2020 in JSAP, what was the complication rate for tracheostomy tubes placed following BOAS surgery? What were the 3 most common complications?
95% complication rate (although 98% of tubes were ultimately successfully managed).
Three main complications were obstruction, dislodgement, and coughing.
In a study by Suematsu 2019 in Vet Surg, what percentage of dogs survived to discharge following placement of a continuous extraluminal tracheal prosthesis for tracheal collapse? What post-operative complications were reported?
98% of dogs survived to discharge.
Laryngeal paralysis (1/54 dogs), DIC (1 dog), and recurrent tracheal collapse (2 dogs) were reported complications. No dogs developed tracheal necrosis.
Goose honking cough resolved in 96% of dogs.
Survival rate was 86% at 36 months.
What muscle connects the tracheal rings dorsally?
The trachealis muscle (predominantly transversely orientated smooth muscle fibers).
What are the bands of fibrous tissue between the tracheal cartilage rings called?
Annular ligaments
How many tracheal rings do the left and right mainstem bronchi have?
Left: 3
Right: 1
Smaller bronchi have overlapping cartilage plates rather than rings, and loss of these rings denotes the transition to bronchioles.
At what level does the trachea have the smallest cross sectional area?
The thoracic inlet (the widest point is at the cricothyroid junction).
What is the vascular supply to the trachea?
The trachea receives segmental blood supply from the cranial and caudal thyroid arteries. At the level of the carina the blood supply switches to the bronchoesophageal arteries.
Venous drainage is via the thyroid, internal jugular and bronchoesophageal veins.
Where does lymphatic drainage from the trachea flow?
Deep cervical, cranial mediastinal, medial retropharyngeal, tracheobronchial lymph nodes.
What is the main innervation to the trachea and trachealis muscle?
The right vagus and recurrent laryngeal nerve.
What is the ratio of the trachea to thoracic inlet in dogs?
Normal: 0.20
Brachycephalic: 0.16
English Bulldog: 0.13
What are some imaging techniques that can be used in assessment of the trachea?
Radiography: can assess tracheal size, may see pulmonary changes in instances of tracheal obstruction (underinflation with proximal obstructions, overinflation with distal obstructions).
Fluoroscopy: useful for assessment of dynamic conditions and interventional radiology techniques.
CT: more accurate for measurements of tracheal diameter (less underestimation). Also used for radiation planning and detection of location of tracheal rupture.
Tracheobronchoscopy: allows for grading of airway collapse, diagnosis of bronchomalacia, and collection of samples via bronchoalveolar lavage.
What are some contraindications to temporary tracheostomy tube placement?
Obstruction distal to the tracheostomy site, tracheal collapse distal to the tracheostomy site, tracheal stent.
What are the options for temporary tracheostomy tube placement?
Transverse, tracheal flap, vertical.
When performing a transverse temporary tracheostomy, the incision length should not exceed what?
Half the circumference of the trachea.
What size endotracheal tube in relation to tracheal diameter should be used for temporary tracheostomy?
Ideally 75% of the tracheal diameter.
Allows for continued flow around the tube in the case of obstruction, and helps to prevent silent death.
Should the cuff of a temporary tracheostomy endotracheal tube be inflated?
No, not unless positive pressure ventilation or anesthetic gases are required. Inflation causes an increase in airway pressure and can cause mucosal damage.
If inflation of the cuff is necessary it should be deflated every 4-hours and repositioned.
Ideally high-volume, low-pressure cuffs should be used.
What can occur with uninterrupted suction of a temporary tracheostomy tube?
Atelectasis, hypoxia, vagal response.
How often should E-tubes be exchanged when placed in a temporary tracheostomy?
At least twice daily (double lumen tubes allow for exchange of just the inner portion of the tube without whole tube replacement).
What are some acute complications associated with temporary tracheostomy?
Occur in 50% of cases; plugging of the tube, inadvertent removal, gagging, coughing, vomiting, SC emphysema, pneumomediastinum, pneumothorax, infection, respiratory distress.
Cats may experience a higher rate of tube obstruction due to greater mucus production.
What is the most significant long-term complication associated with tracheostomy?
Stenosis (either at the stoma or at the location of the cuff or tube tip). Loss of 18-25% of the tracheal lumen is common.
Use of low pressure cuffs may help to reduce damage.
What are the most common indications for permanent tracheostomy?
Cats: laryngeal masses.
Dogs: laryngeal paralysis or collapse.
Placement of permanent tracheostomies are recommended above which level of the trachea?
12th tracheal ring. Mortality rates of 57% reported below this level due to airway obstruction and excessive kinking.
How long does it take for mucous secretions to reduce following permanent tracheostomy?
1 month (they are initially increased due to squamous metaplasia of the tracheal mucosa which takes 16 weeks to resolve).