Lecture 16/17 10/24/24 Flashcards
What are the functions of the upper airway in horses?
-olfaction
-phonation
-deglutition
-thermoregulation
-filtering
-conditioning inspired air
-protection of lower airway from aspiration
-conduit of airflow to and from lung
What are the anatomical considerations regarding the upper airway of the horse?
-large dead space volume
-high resistance to flow
-tends to collapse in response to neg. pressure generated during inspiration
What is the limiting factor in a horse’s exercise capacity?
upper airway
What is the tidal volume and minute ventilation in a horse at rest?
tidal vol: 5L
minute ventilation: 75 L
How does exercise impact a horse’s tidal volume and minute ventilation?
increases it 20-fold
What is impedance?
-ratio of driving pressure and resulting airflow
-measure of how much airflow is opposed by the respiratory system
What are the characteristics of impedance on inspiration and expiration?
-impedance is 2x as high on inspiration
-sub-atmospheric intraluminal pressures cause airway to narrow on inspiration
-positive intraluminal pressures enlarge airway diameter during exhalation
What is the importance of the Bernoulli effect?
reducing the radius by 1/2 increased resistance by 16 fold
What is a progressive ethmoidal hematoma?
-encapsulated, expansive, distorting, and destructive mass
-usually originates within ethmoid turbinate
Where might a progressive ethmoidal hematoma expand into?
-nasal passages
-pharynx
-paranasal sinuses
What are the clinical signs of a progressive ethmoidal hematoma?
-hemorrhagic or serosanguineous unilateral nasal discharge that is intermittent and not associated with exercise
-respiratory noise
-unequal airflow
-fetid breath
-facial distortion
-coughing/choking
-hematoma at external nares
-possible for horse to be affected bilaterally
What is a cleft palate?
incomplete cleft that can impact the hard and soft palate
What is the most common cleft palate presentation?
incomplete cleft of the soft palate that involves the caudal half to two-thirds of the structure
In which direction do the embryonic palatal folds fuse in a cleft palate?
rostral to caudal
What is aryepiglottic fold entrapment?
aryepiglottic folds become dorsally displaced
-fold covers tip of epiglottis and entraps it
-folds of mucous membrane tissue expand when epiglottis is elevated during deglutination