Chapter 42 - Overview of Upper Airway function Flashcards
What is the maximal oxygen uptake (VO2max) for Thoroughbred and Standardbred racehorses?
160 mL/kg/min
By how much does the oxygen uptake in racehorses increase compared to the value at rest?
40 times
What is the approximate tidal volume (VT) at maximal exercise for a horse?
A) 10-12 L
B) 14-18 L
C) 8-10 L
D) 12-14 L
B) 14-18 L
What is the tidal volume at rest for a horse?
A) 10 L
B) 8 L
C) 5 L
D) 7 L
C) 5 L
What percentage of resistance to airflow is produced by the extrathoracic equine airway?
A) 50%
B) 60%
C) 70%
D) 80%
D) 80%
What is the respiratory frequency at maximal exercise?
A) 120 breaths/min
B) 100 breaths/min
C) 80 breaths/min
D) 140 breaths/min
A) 120 breaths/min
At exercise, the respiratory minute volume (VE) increases by how much?
A) 10-fold
B) 27-fold
C) 35-fold
D) 20-fold
B) 27-fold
What is the respiratory minute volume (VE) at rest for a horse?
A) 67 L/min
B) 70 L/min
C) 80 L/min
D) 65 L/min
A) 67 L/min
What is the peak inspiratory flow at rest?
A) 5 L/s
B) 4 L/s
C) 3.5 L/s
D) 2.5 L/s
C) 3.5 L/s
What is the peak inspiratory flow during exercise?
A) 55-65 L/s
B) 65-75 L/s
C) 45-55 L/s
D) 75-85 L/s
B) 65-75 L/s
What is the peak expiratory flow at rest?
A) 5.7 L/s
B) 6 L/s
C) 4.5 L/s
D) 3.7 L/s
A) 5.7 L/s
What is the peak expiratory flow during exercise?
A) 50-70 L/s
B) 55-75 L/s
C) 60-80 L/s
D) 45-65 L/s
C) 60-80 L/s
What is the peak inspiratory tracheal pressure at maximal exercise?
A) −10 to −20 mm Hg
B) −18 to −37 mm Hg
C) −15 to −30 mm Hg
D) −12 to −25 mm Hg
B) −18 to −37 mm Hg
What is the peak expiratory tracheal pressure at maximal exercise?
A) 6-20 mm Hg
B) 5-18 mm Hg
C) 8-25 mm Hg
D) 10-22 mm Hg
A) 6-20 mm Hg
At what gait are stride and respiratory frequency synchronized in a 1:1 ratio?
A) Walk
B) Trot
C) Canter
C) Canter
How much resistance to airflow is produced by the nasal passages?
A) 12%-30%
B) 20%-50%
C) 26%-76%
D) 30%-60%
C) 26%-76%
What is the impedance of the upper airway during inspiration at exercise in normal adult horses?
A) 0.38-0.46 mm Hg/L/s
B) 0.5-0.6 mm Hg/L/s
C) 0.3-0.4 mm Hg/L/s
D) 0.4-0.5 mm Hg/L/s
A) 0.38-0.46 mm Hg/L/s
What is the impedance of the upper airway during expiration at exercise in normal adult horses?
A) 0.16-0.30 mm Hg/L/s
B) 0.20-0.40 mm Hg/L/s
C) 0.16-0.38 mm Hg/L/s
D) 0.30-0.50 mm Hg/L/s
C) 0.16-0.38 mm Hg/L/s
What percentage of resistance to airflow is produced by the larynx?
A) 15%-35%
B) 12%-30%
C) 10%-20%
D) 5%-15%
B) 12%-30%
What ratio is shorter, expiration or inspiration?
A) Expiration is shorter
B) Inspiration is shorter
C) They are equal
A) Expiration is shorter
What is the expiration to inspiration ratio (E) during maximal exercise?
A) 0.9-1.0
B) 1.1-1.2
C) 0.96-0.99
D) 1.0-1.1
C) 0.96-0.99
What condition in horses causes an expiratory obstruction that increases expiratory impedance?
B) Dorsal displacement of the soft palate (DDSP)
According to the Bernoulli principle, what happens to pressure as airflow increases?
A) Pressure increases
B) Pressure decreases
C) Pressure remains constant
B) Pressure decreases
How much of the total airway resistance is produced by the upper airway during inspiration compared to expiration?
A) 1.5 times more
B) 2 times more
C) 1.2 times more
D) 3 times more
B) 2 times more
What law explains the relationship between airway diameter and airflow resistance?
A) Poiseuille’s Law
B) Boyle’s Law
C) Dalton’s Law
D) Venturi Effect
A) Poiseuille’s Law
What happens to inspiratory pressure as airway cross-section decreases?
A) Pressure increases
B) Pressure decreases
C) Pressure stays constant
A) Pressure increases
How much does the respiratory minute volume (VE) increase from rest to maximal exercise?
A) 10 times
B) 15 times
C) 20 times
D) 27 times
D) 27 times
What is the relationship between stride frequency and respiratory frequency at the canter and gallop?
A) 1:2 ratio
B) 1:1 ratio
C) 2:1 ratio
D) 1:3 ratio
B) 1:1 ratio
How much does respiratory frequency increase from rest to low speed (6 m/s)?
A) 10 times
B) 5 times
C) 8 times
D) 27 times
B) 5 times
At what speed does respiratory frequency cease to increase due to synchronization with stride frequency?
A) 5 m/s
B) 6 m/s
C) 7 m/s
D) 8 m/s
B) 6 m/s
At rest, how many liters per second is the airflow rate in horses during expiration?
A) 3.5 L/s
B) 4.5 L/s
C) 5.7 L/s
D) 6.0 L/s
C) 5.7 L/s
The Bernoulli principle is closely related to which effect?
A) Venturi Effect
B) Poiseuille’s Law
C) Boyle’s Law
D) Dalton’s Law
A) Venturi Effect
What is the driving force behind negative airway pressures in horses during maximal exercise?
A) Nasal dilation
B) Diaphragmatic contraction
C) Laryngeal contraction
D) Capacitance vessel constriction
B) Diaphragmatic contraction
What is the approximate percentage of resistance to airflow produced by the nose during inspiration?
A) 20%-40%
B) 26%-76%
C) 30%-50%
D) 15%-35%
B) 26%-76%
Peak inspiratory tracheal pressure in clinically normal horses at maximal exercise is between which two values?
A) −18 to −37 mm Hg
B) −10 to −25 mm Hg
C) −15 to −30 mm Hg
D) −20 to −40 mm Hg
A) −18 to −37 mm Hg
Peak expiratory tracheal pressure in clinically normal horses at maximal exercise ranges from:
A) 5 to 15 mm Hg
B) 6 to 20 mm Hg
C) 8 to 25 mm Hg
D) 10 to 30 mm Hg
B) 6 to 20 mm Hg
Which muscle is primarily involved in controlling negative pressures within the upper airway during maximal exercise?
A) Respiratory muscles
B) Diaphragm
C) Laryngeal muscles
D) Capacitance muscles
B) Diaphragm
What percentage increase in airflow resistance is produced by a narrowing of the airway lumen?
A) 2x
B) 4x
C) 8x
D) 10x
B) 4x
At maximal exercise, how much greater is the inspiratory upper airway impedance compared to expiratory impedance?
A) 2x greater
B) 1.5x greater
C) 3x greater
D) 4x greater
A) 2x greater
What percentage of total airway resistance is produced by the nasal passages at rest?
A) 50%-60%
B) 40%-50%
C) 26%-76%
D) 20%-30%
C) 26%-76%
What percentage of the sensory receptors within the laryngeal mucosa are pressure receptors in horses?
A) 40%
B) 50%
C) 60%
D) 70%
C) 60%
In Standardbred racing, how is the horse’s head and neck positioned?
A) Neutral
B) Flexed
C) Extended
D) Tilted
C) Extended
What anatomical structures are involved in the dynamic collapse of the laryngeal region?
A) Vocal folds, aryepiglottic folds, and arytenoid cartilages
B) Genioglossus and sternohyoid muscles
C) Nasal passages and trachea
D) External nares and nasal valve
A) Vocal folds, aryepiglottic folds, and arytenoid cartilages
By what percentage is the cross-sectional area of the larynx greater than that of the trachea?
A) 5%
B) 10%
C) 7%
D) 15%
C) 7%
What is the approximate percentage increase in upper airway impedance (ZI) when the horse’s head and neck are flexed?
A) 10%
B) 20%
C) 30%
D) 40%
C) 30%
How many horses were measured for airway mechanics in the study mentioned?
A) Four
B) Six
C) Eight
D) Ten
B) Six
What effect do nasal strips have on inspiratory impedance in exercising horses?
A) Increase
B) Decrease
C) No effect
D) Varies by horse
B) Decrease
What is the primary purpose of the external nares in horses during intense exercise?
A) Close the airway
B) Support upper airway collapse
C) Dilate the airway
D) Filter inspired air
C) Dilate the airway
How are the dilator muscles of the external nares innervated?
A) Vagus nerve
B) Facial nerve
C) Hypoglossal nerve
D) Phrenic nerve
B) Facial nerve
What is the primary role of the nasal turbinate region?
A) Gas exchange
B) Particle deposition and air conditioning
C) Vocalization
D) Thermal regulation
B) Particle deposition and air conditioning
What percentage of airway resistance is produced by the external nares during exercise?
A) 10%-15%
B) 20%-30%
C) 30%-50%
D) 50%-60%
C) 30%-50%
What happens to capacitance vessels during exercise?
A) They dilate
B) They constrict
C) They fill with air
D) They become occluded
B) They constrict
What condition is caused by injury to the sympathetic trunk innervating the nasal region?
A) Nasal occlusion
B) EIPH
C) Upper airway collapse
D) Horner syndrome
D) Horner syndrome
What is the consequence of nasal vascular engorgement during recovery from anesthesia?
A) Increased airflow
B) Nasal occlusion
C) Enhanced performance
D) Decreased exercise tolerance
B) Nasal occlusion
What is the function of the upper airway dilating muscles during intense exercise?
A) To collapse the airway
B) To support upper airway collapse
C) To maintain airway patency
D) To facilitate vocalization
C) To maintain airway patency
What physiological stimulus triggers contraction of upper airway dilating muscles?
A) Dehydration
B) Hypercapnia
C) Hypertension
D) Hypoglycemia
B) Hypercapnia
How many polyester springs are included in a nasal strip?
A) One
B) Two
C) Three
D) Four
C) Three
What happens to the airway diameter when sympathetic tone increases?
A) Decreases
B) Increases
C) Remains unchanged
D) Becomes obstructed
B) Increases
What is the primary reason for using nasal strips in horses?
A) Decrease ZI
B) Increase ZI
C) Enhance endurance
D) Improve vocalization
A) Decrease ZI
During maximal exercise, how does the horse’s airway pressure behave?
A) Remains stable
B) Increases significantly
C) Decreases significantly
D) Fluctuates
C) Decreases significantly
What anatomical region is affected by lesions, significantly impacting performance?
A) Nasopharynx
B) External nares
C) Larynx
D) Trachea
B) External nares
How does exercise influence the sympathetic innervation of the nasal turbinate region?
A) Increases sympathetic tone
B) Decreases sympathetic tone
C) Has no effect
D) Alters airflow dynamics
A) Increases sympathetic tone
What role do upper airway sensory receptors play during exercise?
A) Signal collapse
B) Induce airway obstruction
C) Trigger muscle contraction
D) Increase airway resistance
C) Trigger muscle contraction
What is the approximate size of the laryngeal cross-sectional area compared to the trachea?
A) Equal
B) 7% greater
C) 10% greater
D) 5% greater
B) 7% greater
How much does the nasal strip reduce inspiratory impedance?
A) 10%
B) 20%
C) 30%
D) 40%
C) 30%
What is the most significant physiological change during head and neck flexion in horses?
A) Increased airway pressure
B) Increased upper airway abnormalities
C) Decreased muscle activation
D) Decreased respiratory frequency
B) Increased upper airway abnormalities
What is the position of the horse’s head and neck during dressage?
A) Neutral
B) Flexed
C) Extended
D) Tilted
B) Flexed
What happens to airflow as it transitions from the nasopharynx to the larynx?
A) Pressure rises
B) Pressure drops
C) Airflow stabilizes
D) Airflow ceases
B) Pressure drops
How does nasal strip application affect endoscopic examination of the nasal cavity?
A) Causes blockage
B) Reduces turbulence
C) Dilates the nasal valve region
D) Increases resistance
C) Dilates the nasal valve region
What is a common symptom in horses with facial nerve dysfunction during exercise?
A) Increased performance
B) Inspiratory airway obstruction
C) Decreased heart rate
D) Enhanced endurance
B) Inspiratory airway obstruction
How does the nasal turbinate region assist in inhalation?
A) Filters dust only
B) Facilitates vocalization
C) Thermoregulates and humidifies air
D) Prevents nasal occlusion
Answer: C) Thermoregulates and humidifies
How does the laryngeal cross-sectional area compare to the trachea during normal conditions?
A) Smaller
B) Larger
C) Equal
D) Variable
B) Larger
During exercise, how does the body react to hypercapnia?
A) Decrease muscle activity
B) Increase dilator muscle activity
C) No response
D) Increase airway resistance
B) Increase dilator muscle activity
What is the mechanism by which nasal strips help reduce exercise-induced pulmonary hemorrhage (EIPH)?
A) Enhancing airflow
B) Reducing airway collapse
C) Increasing nasal pressure
D) Decreasing respiratory rate
B) Reducing airway collapse
What effect does head flexion have on ZI in horses?
A) Decreases
B) Increases
C) No effect
D) Stabilizes
B) Increases
Which nerve innervates the pressure receptors in the laryngeal mucosa?
A) Vagus nerve
B) Facial nerve
C) Cranial laryngeal nerve
D) Hypoglossal nerve
C) Cranial laryngeal nerve
Where is the nasal strip applied on the horse?
A) Nasal valve region
B) Nasopharynx
C) Trachea
D) Larynx
A) Nasal valve region
What is the main consequence of facial nerve dysfunction in horses during exercise?
A) Loss of balance
B) Upper airway obstruction
C) Excessive sweating
D) EIPH
B) Upper airway obstruction
What is the approximate location of the nasal valve relative to the nasoincisive notch?
A) Rostral
B) Dorsal
C) Caudal
D) Ventral
A) Rostral
What is a common effect of severe nasal vascular engorgement after anesthesia?
A) Hypoventilation
B) Hyperventilation
C) Increased oxygen saturation
D) EIPH
A) Hypoventilation
What percentage of horses benefit from nasal strips in reducing exercise-induced pulmonary hemorrhage?
A) 20%
B) 30%
C) 50%
D) 100%
C) 50%
What causes the greatest reduction in airway pressure during inhalation?
A) Flexed head position
B) Extended neck position
C) Nasal collapse
D) Neutral head position
C) Nasal collapse
What mechanical function do nasal strips serve during intense exercise?
A) Stabilize airflow in the trachea
B) Support the soft tissue forming the lateral nasal wall
C) Increase airway collapse resistance
D) Strengthen the vocal folds
B) Support the soft tissue forming the lateral nasal wall
What part of the nasal anatomy is responsible for thermoregulation during inhalation?
A) Nasopharynx
B) Nasal valve
C) Capacitance vessels
D) Conchae
D) Conchae
During which activity can the external nares completely close the upper airway in horses?
A) Racing
B) Swimming
C) Jumping
D) Trotting
B) Swimming
What is the direct impact of negative inspiratory pressure during exercise?
A) Increases oxygenation
B) Decreases the size of the airway
C) Stimulates the sympathetic nervous system
D) Reduces airway muscle tone
B) Decreases the size of the airway
What is one treatment used to decrease nasal vascular engorgement after anesthesia?
A) Epinephrine
B) Phenylephrine
C) Adrenaline
D) Cortisone
B) Phenylephrine
In horses with recurrent laryngeal neuropathy, which treatment involves maximal arytenoid abduction?
A) Nasal strip application
B) Laryngoplasty
C) Tracheotomy
D) Endoscopy
B) Laryngoplasty
How do capacitance vessels affect airway size during normal exercise?
A) Increase airway size
B) Decrease airway size
C) Remain unchanged
D) Cause airway obstruction
A) Increase airway size
In Horner syndrome, what is a long-lasting condition associated with unilateral airway obstruction?
A) Nasal congestion
B) Exercise intolerance
C) Tracheal collapse
D) Pulmonary embolism
B) Exercise intolerance
How does head and neck flexion impact the prevalence of upper airway abnormalities?
A) Decreases it
B) Increases it
C) No effect
D) Varies by breed
B) Increases it
What is the primary role of the genioglossus muscle in horses during exercise?
A) Flex the neck
B) Support the tongue
C) Stabilize the airway
D) Assist in swallowing
C) Stabilize the airway
Where does airflow experience the largest pressure drop after the nasopharynx?
A) At the trachea
B) At the larynx
C) At the nostrils
D) At the conchae
B) At the larynx
Where does it run the cranial laryngeal nerve?
runs through the thyroid notch at the dorsorostral aspect of the thyroid cartilage
What dual functions does the nasopharynx participate in?
Swallowing and breathing.
What structure supports the pharynx, root of the tongue, and larynx?
Hyoid apparatus.
What are the bones that make up the hyoid apparatus in horses?
Stylohyoid, ceratohyoid, thyrohyoid, and basihyoid bones.
Which nerve innervates the rostral hyoid muscles?
Hypoglossal nerve.
What is the attachment site of the hyoglossus muscle?
Basihyoid and thyrohyoid bones.
What muscle attaches to the stylohyoid bone?
Styloglossus muscle.
Which muscles are responsible for suspending the larynx from the temporal bone?
Hyoglossus, styloglossus, genioglossus, and geniohyoideus muscles.
Which muscle draws the larynx rostrally and dorsally?
Thyrohyoideus muscle same muscle you cut in tie-forward (innvervated by C1 -Genton paper)
What is a common procedure performed on racehorses to prevent dorsal displacement of the soft palate (DDSP)?
Tying down the tongue to the mandible.
Which two muscles prevent the caudal retraction of the larynx?
Genioglossus and hyoglossus muscles.
What role do the stylopharyngeus muscles play in supporting the dorsal nasopharynx?
They raise, support, and prevent collapse of the dorsal nasopharyngeal wall.
What condition can horses experience during nasal occlusion that affects the nasopharynx?
Dorsal displacement of the soft palate (DDSP).
Which direction do the geniohyoid and genioglossus muscles pull the tongue and larynx?
Rostrally and ventrally.
Which muscles pull the tongue and larynx in a caudal ventral direction?
Sternohyoid and sternothyroid muscles.
What part of the hyoid apparatus does the genioglossus attach to?
Basihyoid and ceratohyoid bones.
Which nerve innervates the thyrohyoideus muscle?
Hypoglossal nerve.
What function must be fully coordinated during exercise to maintain upper airway patency in horses?
Sensory and motor functions.
What happens to the dorsal pharyngeal wall when the stylopharyngeus muscles contract?
he wall raises and expands, preventing collapse.
What message is given to surgeons regarding the upper airway of horses?
The upper airway is a finely tuned instrument easily disturbed by disease or surgery.
What structure attaches the tongue to the hyoid bone?
Genioglossus and hyoglossus muscles.
