Nasopharyngeal, Pharyngeal, & Brachycephalic Airway Diseases Flashcards
What is the function of the nasopharynx? How does it do this?
breathing and swallowing
- closes completely for swallowing to protect nasal airways from aspiration of food or fluids
- opens for nasal breathing
What 3 structures does the nasopharynx connect?
- nasal passage
- eustachian tube
- oral passages
What are the 3 parts of the pharynx?
- nasopharynx - opens into eustachian tubes
- oropharynx - opens into mouth
- laryngopharynx - opens into larynx and esophagus
What are 3 causes of abnormalities of the pharyngeal phase of swallowing?
- pharyngeal weakness due to neuropathies or myopathies
- pharyngeal tumors or foreign bodies
- obstruction of the upper esophageal sphincter secondary to hypertrophy of cricopharyngeus
What is essential to allow passage of food boluses into the esophagus?
synchrony between constriction of the pharyngeal muscles and relaxation of the cricopharyngeus
What are some hereditary and acquired causes of nasopharyngeal disease?
HEREDITARY: stricture, lack of lumen/obstruction, stenosis
ACQUIRED: trauma, masses
What are 7 clinical manifestations of nasopharyngeal disease?
- difficult, noisy, and stertorous breathing
- reverse sneezing
- sneezing
- nasal discharge
- expiratory cheek puff
- retching due to irritation of the back of the throat
- vestibular signs (E tube): head tilt, nystagmus, Horner’s
What diagnostics are used for nasopharyngeal disease?
- X-ray using water-based contrast agents in nares if there is no CT
- CT/MRI
- rhinoscopy
- blind biopsy
- nasal flush/culture
What is classically found with stertor?
upper airway obstruction and serous or mucopurulent nasal discharge
In what animals are nasopharyngeal polyps most common? What causes it?
young cats less than 5 years old
nasopharyngeal mass forms from chronic inflammation, where it begins in the middle ear (on bulla) and passes down the Eustachian tube or back of the throat
What is the classical sign of nasopharyngeal polyps? What else is commonly seen?
inspiratory stridor
- voice change
- nasal discharge and sneezing
- vestibular signs if ear is involved
How are nasopharyngeal polyps treated?
traction method of removal - soft palate is retracted rostrally with a spay hook, the polyp is grasped with curved mosquito, and slow, steady traction is applied until the polyp releases
Inflammatory aural polyp:
How are aural polyps treated?
- external ear canal traction is applied and an otoscopy is performed to identify the polyp location
- otoscope is removed and curved mosquitoes are placed in the ear to blindly grasp the polyp, and steady traction is applied until the polyp releases
What are 5 indications for ventral bulla osteotomy for polyp removal?
- polyp has recurred following manual traction
- polyp was incompletely removed
- client wants the pet to undergo only one procedure with the best possible success rate
- marked radiographic changes have occurred in the bulla
- polyp extends into the external ear canal
(some cats will still respond to traction and medical therapy)
What benign and malignant neoplasias are most common in the nasopharynx?
BENIGN - inflammatory polyps
MALIGNANT - lymphoma
What are the 4 classical anatomies in brachycephalic airway syndrome?
- narrowed nostril
- hypertrophy of the nasal turbinates
- extension and outgrowth of the soft palate
- hypertrophy of the tongue
(+/- hypoplastic trachea in Bulldogs)
What are the 3 sad truths of brachycephalic animals?
- tend to die younger more likely due to upper respiratory disease
- owners have habituated to airway dysfunction
- expensive to own and maintain
BAS/BOAS:
What dogs and cats are at risk of BAS/BOAS? What causes this?
- DOGS: English/French Bulldog, Pug, Boston Terrier, Pekingese, Shih-Tzu, Shar-Pei
- CATS: Persians, Himalayan
purely man-made discrete genetic mutation
What 8 malformations are commonly seen with BAS/BOAS?
- stenosis of nares and vestibulum
- malformed and aberrantly growing turbinates and intranasal contact points obstruct the airways
- caudally growing nasopharyngeal meatus and choanae obstruct nasal exit
- larynx collapse, everted laryngeal saccules, obstruction of rima glottis due to thick vocal folds
- small skull
- reduced lumen and increased collapsibility of nasopharynx
- space-occupying structures in the oropharynx (tonsils, tongue)
- hypoplastic trachea, tracheobronchomalacia
How are Pugs’ and Bulldogs’ larynx contribute to BAS/BOAS?
PUGS - collapses due to laryngomalacia with impairment of arytenoid abduction
PUGS and BULLDOGS - obstruction of rima glottis due to everted laryngeal saccules
What breeds with BAS/BOAS most commonly have space-occupying structures in the oropharynx?
Bulldogs and Boxers - enlarged tongue (macroglossia)
- enlarged tonsils common
How are Bulldogs’ and Pugs’ tracheas affected by BAS/BOAS?
BULLDOGS - hypoplastic trachea
PUGS - tracheobronchomalacia
What abnormalities are commonly concurrent with BOAS? Why?
GI —> negative airway pressure during respiration
- esophagitis
- sliding esophageal hiatal hernia
- chronic gastritis
- pyloric stenosis
- chronic regurgitation
- lower esophageal atony
- gastroesophageal and gastroduodenal reflux
- chronic vomiting
- atony of stomach cardia
- inflammatory GI disease
How can GI signs associated with BAS/BOAS be improved? What changes in blood chemistry can also be seen?
upper airway surgery
elevated liver enzymes, likely due to hypoxia
How is the airway impacted by BAS/BOAS? What does this lead to?
narrowed glottis, airway, and nose* increases airway resistance and turbulence
- increased respiratory effort
- more negative pressure required to inhale
- tissues drawn inward become inflamed
- hyperplasia becomes obstructive
What aspect of brachycephalic breeds promotes airway collapse?
short, thick necks
What are 7 acquired secondary abnormalities seen in brachycephalic dogs?
- tonsillar hypertrophy and eversion
- everted laryngeal saccules
- laryngeal saccules
- chondromalacia of trachea and bronchial supports
- chronic generalized pulmonary vasoconstriction secondary to chronic hypoxia results in right ventricular hypertrophy
- chronic respiratory acidosis from hypoventilation
- low blood oxygen levels
What do all of the factors of BAS/BOAS lead to? What does this result in? How is this a vicious cycle?
functional collapse of the nasopharynx
snoring sounds - sterdor
strong negative pressure causes nasopharyngeal tissue to collapse
What tends to make matters worse in BAS/BOAS?
obesity —> makes it more difficult to breath, increased fat in tissues in airways
What is the function of the alar wing and folds?
during exercise, they are abducted to enlarge the naris
When should stenotic nares be corrected? What is the goal to correction?
- SEVERE = 3-4 months
- MILD = 6 months
lateralize the alar wing and fold to facilitate air passage through the nostril —> early correction = less likely to develop secondary problems
How is the nasal passageway and exit affected by BAS/BOAS?
conchae are malformed and grow aberrantly, causing increased resistance due to obstruction
malformed and caudally growing nasopharyngeal meatus and choanae cause obstruction
Hypertrophic soft palate:
- naturally overlaps epiglottis by 1-2 mm
- occludes nasopharynx while swallowing
- stertor
Elongated soft palate while breathing:
- inspiration = palate is sucked in and obstructs rima glottis
- expiration = palate flutters out
How do brachycephalic breeds typically position themselves to enhance breathing?
closing of the jaw or any ventral pressure in the head or neck region hinders respiration —> jaw thrust, chin lift opens the laryngeal inlet and pharynx, pushes glottis rostrally, lifts tongue
How can brachycephalic patients be positioned to maximize lung volume?
- sternal recumbency (improves lung capacity and dissolved oxygen concentration)
- head up; jaw thrust, chin lift
- minimize passive reflux and aspiration
What 4 impacts does increasing lung volume have for brachycephalic patients?
- decreases pharyngeal collapsibility
- decreases upper airway resistance
- stimulates airway smooth muscle to dilate
- increases airway diameter and flow
Dog larynx:
What are the 2 major malformations of the larynx in brachycephalic dogs? How are Pugs and Bulldogs most commonly affected?
- malfomrations of internal laryngeal structures caused by everted lateral ventricles and vocal folds
- malformations of laryngeal skeleton
PUGS - collapse due to laryngomalacia with impairment of arytenoid abduction, everted saccules, impairment of rima glottis opening
BULLDOGS - everting saccules
Everted saccules:
granuloma forms due to increased size and rubbing
What brachycephalic breeds most commonly have tracheal malformation? What malformation is seen?
Bulldogs —> tracheal hypoplasia where there are apposed or overlapping tracheal cartilages and a shortened or absent dorsal tracheal membrane = narrow, rigid, round tracheal lumen
In what 2 ways does tracheal hypoplasia compare to tracheal collapse?
- luminal diameter is reduced, but does not vary with dynamic pressure changes during respiration
- often presents with pneumonia
Congenital and secondary abnormalities with BAS/BOAS:
What are the most common clinical signs of BAS/BOAS?
- panting, coughing, gagging
- stertor (snoring), stridor (inspiratory)
- cyanosis
- collapse
- exercise intollerance
- hyperthermia
(more severe with excitement, high temperatures, humidity)
What are the major rule-outs for emergency airway distress?
- BOAS
- laryngeal paralysis
- larygneal or tracheal foreign body
- trauma/abscess
- pharyngeal mucocele
- bee sting/obstruction
What are the 4 triggers of a BAS crisis?
- heat
- exercise
- increased respiratory rate and effort against a partially closed airway initiates/potentiates mucosal edema
- edema causes further airway compromise
How should a brachycephalic patient presenting as collapsed and hyperthermic?
- oxygen therapy by flow hood or mask and IV access
- sedation to reduce O2 demand with Acepromazine (vasodilatory, increased heat loss) and Butorphanol 0.2 mg/kg IV or IM
- temperature reduction with fans and ice packs
- SpO2 <92% and increased work of breathing causes rising rectal temperature = Propofol and endotracheal intubation
- rehydration, treat shock
What are 3 indications for temporary tracheostomy treatment for patients in BAS/BOAS crisis? What is the risk if done incorrectly?
- unstable patient with no patent airway
- facilitate extubation/transfer of an emergency BAS requiring emergent intubation
- assist extubation of a post-op BAS while mucosal edema resolves
risk of tracheal stenosis if performed inappropriately
What surgical procedures (sometimes done multiple at once) are done to alleviate BAS/BOAS?
- stenotic nares: wedge resection
- elongated soft palate: partial resection
- edematous tonsils: tonsillectomy
- everted saccules: sacculectomy
- laryngeal collapse: partial arytenoidectomy and ventriculocordectomy
What are the 3 keys to success to surgical treatment of BAS/BOAS?
- correct congenital abnormalities BEFORE secondary changes develop
- smooth anesthetic recovery with correct positioning, avoid excitement, keep ET tube in as long as possible, observe closely for increasing respiratory rate and distress
- recommend weight control
When are elongated palates typically treated? What needs to be considered beforehand?
3-4 months
- determine resection extent prior to intubation
+/- perioperative corticosteroids and ice to reduce swelling
What are the 2 resection landmarks for soft palate reduction?
- naturally overlaps epiglottis by 1-2 mm
- laterally the soft palate should extend to the causal border to the tonsillary crypt
What are 4 advantages to the laser freehand technique for soft palate resections?
- rapid
- virtually no blood loss for excellent visualization
- minimal post-op inflammation
- reduced post-op discomfort
What are the most common acute and chronic complications of a palatectomy?
ACUTE: hemorrhage, inflammation
CHRONIC: undershooting requires a repeat surgery, undershooting leads to nasal reflux and aspiration
What are the 3 most common secondary changes in BAS/BOAS?
- pharyngeal edema
- tonsilitis
- laryngeal collapse
What are the 3 stages of laryngeal collapse? How are each
- everted saccules: resection
- medial deviation of arytenoids: partial arytenoidectomy and ventriculocordectomy
- total collapse: tracheostomy
How are everted laryngeal saccules treated?
excision with scissors heals by second intention
How does feline brachycephalic syndrome compare to canine? What cats are most affected?
stenotic nares only
- Persian
- exotic shorthair
- Himalayan
- Scottish Folds
How does the larynx of the cat compare to the dog?
the arytenoid cartilage lacks cuneiform and corniculate processes and aryepiglottic folds
- connects directly to the cricoid lamina by laryngeal mucosa
