Brachycephalic Airway Syndrome Flashcards
what are the components that make up BOAS
- stenotic nares
- elongated soft palate
- hypoplastic trachea
- everted laryngeal saccules
where are potential sites of obstruction along a brachycephalic airway
nares - stenotic
nasal cavity - compressed turbinates
nasopharynx - nasopharyngeal turbinates
soft palate - elongated/thickened
tongue - macroglossia
pharynx - redundant tissue
larynx - tracheal collapse
trachea - hypoplastic
what site (in normal anatomy) is the majority of total airway resistance during inspiration
nasal cavity
should have two pathways of airflow - one turbulent to the brain (to interact with receptors) and one laminar to the lungs
do brachycephalics have laminar airflow to the lungs
NO - nasal turbinates are compressed causing poor air movement and increased resistance to flow
requires increased inspiratory effort to move air
what is brachycephalic syndrome
abnormal anatomy –> increased airway resistance –> increased negative pressure generated in the lower airways during inspiration –> supraphysiological stress on laryngeal and tracheal cartilage and soft tissues –> tissue edema (swelling), hyperplasia, cartilage weakening
mechanical issues contribute to a functional problem
what are the goals of surgical management of BOAS
improving narrowed airways and reducing airway resistance
what is the best candidate for BOAS surgery
younger animals
waiting until end stage disease to treat yields less success
does BOAS surgery cure the disease
NO - must manage owner expectations that the respiratory difficulty is lifelong and will only improve with surgery, not resolve entirely
what components of BOAS can not be treated surgically
- hypoplastic trachea
- nasopharyngeal turbinates
- macroglossia
- redundant pharyngeal tissue
- dynamic pharyngeal collapse
hypoplastic trachea
-reduced luminal diameter
- overlapping tracheal cartilage
- shortened or absent dorsal tracheal membrane
nasopharyngeal turbinates
turbinates extending past the nasal cavity into the nasopharynx
occurs in 20% of brachycephalics
redundant pharyngeal tissues
excessive tissue folds contributing to a narrowed airway –> increased turbulence and resistance to air flow
dynamic pharyngeal collapse
soft palate pulls upwards during inspiration and collapses the nasopharynx
secondary effect of increased chronic negative airway pressure gradients
macroglossia
overly large and thick tongue
increases difficulty during anesthetic recovery
what components of BOAS can be addressed surgically
- stenotic nares
- elongated soft palate
- elevated laryngeal saccules
what position should BOAS surgery be performed in
sternal or dorsal recumbency
what procedure is used to address stenotic nares
rhinoplasty - alar amputation
amputates the medial aspect of the nostril
- must get the entire alar fold all the way back to improve airflow
what procedure is used to address elongated soft palate
palatoplasty/staphyloplasty
removes excess soft tissue of the palate that extends caudally past the tip of the epiglottis and into the larynx
use the “inverted U” incision to open airway without taking too much
what are everted larygeal saccules
mucosal lining of the lateral ventricles of the larynx (behind the arytenoids) swells and everts
- caused by significant negative airway pressure
FIRST stage of laryngeal collapse
what are the stages of laryngeal collapse
1: laryngeal saccule eversion
2: cuneiform process of the arytenoids moves medially
3: corniculate process of the arytenoids moves medially
what procedure is used to address everted laryngeal saccules
laryngeal sacculectomy
removing the laryngeal saccules
what is laryngeal webbing
complication of laryngeal sacculectomy about 1-4 months after surgery
scar that forms across the laryngeal opening between the arytenoids due to medial contact of “rough edges” after getting cut
what medication should be given prior to BOAS surgery
steroids - want to reduce airway edema
IV dexamethasone SP
prognosis of BOAS
depends on severity of anatomic malformations
requires long term lifestyle management
