Auer Ch 41 42 Upper Airway Function & Diagnosis

Front 1

Minute ventilation:

Back 1

product of tidal volume and respiratory frequency

Front 2

Change in minute ventilation between resting and exercising:

Back 2

resting horse approximately 75L (15 bpm x 5L), but in the exercising horse can increase to 1500L (increase in both frequency and tidal volume

Front 3

How does the upper airway contribute to respiratory resistance?

Back 3

exacerbating decrease in PaO2 and increase in PaCO2. Decreased PaO2 limits oxygen delivery to tissues

Front 4

Primary force for ventilation:

Back 4

diaphragm

Front 5

Expiratory pressure in upper airway:

Back 5

positive, to drive air out against atmospheric pressure

Front 6

Inspiratory pressures in upper airway:

Back 6

negative, creating flow of air from outside to the lungs

Front 7

Impedance:

Back 7

cmH2O/L/second, ratio of driving pressure to airflow, a measure of how much airflow is opposed by the respiratory system

Front 8

Most important determinant of impedance:

Back 8

Airway resistance

Front 9

Most important determinant of airway resistance:

Back 9

airway diameter

Front 10

How does airway diameter affect impedance?

Back 10

decrease in airway diameter increases airway impedance

Front 11

How does expiratory and inspiratory pressure affect impedance?

Back 11

positive pressures during exhalation, impedance lower during this phase, and the negative pressure of inspiration, causes an increase in impedance

Front 12

Location of the nasal valve:

Back 12

just rostral to the nasoincisive notch, bordered medially by the nasal septum, ventrally by the concha, and dorsolaterally by the skin of the nare

Front 13

Affect of the nasal valve on airflow:

Back 13

narrowest region of the upper airway, resulting in large pressure drop and increase in flow velocity, based on Bernoulli’s principle

Front 14

Bernoulii’s principle:

Back 14

velocity increases and pressure decreases, velocity decreases as pressure increases

Front 15

How does increase velocity and decrease pressure affect the narrow regions of the upper airway?

Back 15

decreased wall pressure and increase velocity at transition from nasal passage may cause instability of the soft palate and predispose to DDSP, predisposition of larynx to dynamic collapse (vocal folds, aryepiglottic folds, arytenoid cartilages

Front 16

Distribution of inspiratory airway resistance at rest and exercise:

Back 16

66% is from the upper airway in the resting horse and this increases approximately 75% during exercise, with 50% of upper airway resistance from nasal resistance and 50% from laryngeal resistance

Front 17

How is the airway supported against negative pressures experienced on inspiration?

Back 17

walls must be designed to resist collapse. Much of the upper airway is supported by bone and cartilaginous structures, but in regions where these types of rigid support do not allow the other functions involving the upper airway (i.e. swallowing) the rigid support is from muscular activity

Front 18

Benefit of external nasal strips:

Back 18

support to the nasal valve region can reduce inspiratory impedance and collapse of the nares on inspiration, less negative inspiratory pressures which can also reduce transmural pulmonary capillary pressure, reducing the likelihood of EIPH

Front 19

Benefit of straight head and neck position during exercise:

Back 19

decreases impedance, decreases the work of breathing, provides a more direct route to the lung, and stretches upper airway tissues conferring rigidity.

Front 20

Effect of head and neck flexion on airway:

Back 20

impedance can increase by 50% compared to a horse allowed to work with a straight head and neck position

Front 21

Muscles that dilate the external nares:

Back 21

dilator naris lateralis and the transversus nasi

Front 22

Innervation of dilator naris lateralis and transversus nasi:

Back 22

facial nerve

Front 23

How can the mucosa of the nasal turbinate region affect airflow?

Back 23

highly vascular and change nasal passage diameter by increasing or decreasing engorgement of mucosal vessels. During exercise, with increased sympathetic tone, the vessel constrict, increased passage diameter

Front 24

Function of nasal turbinate mucosa:

Back 24

regulate temperature and humidification of inhaled air

Front 25

Function of nasopharynx:

Back 25

involved in swallowing, protecting the airway from aspiration, as well as dilating during exercise to allow unimpeded airflow

Front 26

Function of geniohyoid and genioglossus muscles:

Back 26

contract to pull the hyoid rostrally and ventrally

Front 27

Function of sternohyoid and sternothyroid muscles:

Back 27

contract to pull the hyoid caudally and ventrally

Front 28

Result of contraction of geniohyoid, genioglossus, sternohyoid, and sternothyroid:

Back 28

contraction of all these muscles results in extension of stylohyoid-ceratohyoid articulation, ventral movement of the hyoid, and nasopharyngeal stabilization and dilation

Front 29

Proposed benefit of transection of the “strap muscles”, sternohyoid and sternothyroid:

Back 29

allowing the epiglottis to move cranially and interact with the soft palate

Front 30

Effect of transection of sternohyoid & sternothyroid:

Back 30

decrease nasopharyngeal stabilization and dilation, encouraging pharyngeal collapse. Studies have shown that upper airway resistance increases in exercising horses

Front 31

Proposed mechanism of the tongue tie to prevent DDSP:

Back 31

pull the hyoid cranially and ventrally to dilate the pharynx, however this has not been shown to occur experimentally

Front 32

How is the pharynx supported dorsally?

Back 32

stylopharyngeus muscle

Front 33

Origin and insertion of stylopharyngeus:

Back 33

originates on the stylohyoid and inserts perpendicularly on the dorsal pharyngeal wall

Front 34

Function of the stylopharyngeus:

Back 34

dorsal wall of the pharynx is raised, which expands the pharynx and prevents collapse

Front 35

Innervation of the stylopharyngeus:

Back 35

cranial nerve 9 (glossopharyngeal nerve)

Front 36

Function of the soft palate:

Back 36

separate the oropharynx from the nasopharynx by forming a tight seal around the larynx during breathing and elevating to protect the nasal passage during swallowing

Front 37

What controls soft palate position:

Back 37

tensor veli palatini, levator veli palatini, palatinus, palatopharyngeus

Front 38

Innervation of tensor veli palatini:

Back 38

mandibular branch of the trigeminal nerve

Front 39

Innervation of levator veli palatini, palatinus, and palatopharyngeus:

Back 39

pharyngeal branch of the vagus nerve

Front 40

Function of tensor veli palatini:

Back 40

depresses the soft palate toward the tongue

Front 41

Effect of dysfunction of tensor veli palatin:

Back 41

bulging of the soft palpate into the nasopharynx and experimental blockage causes DDSP

Front 42

MOA of laryngeal hemiplegia or recurrent laryngeal neuropathy:

Back 42

dysfunction of the left recurrent laryngeal nerve, preventing contraction of the cricoarytenoideus dorsalis muscle during inhalation

Front 43

What exacerbates airway obstruction with RLN?

Back 43

Negative luminal pressures move the paralyzed arytenoid cartilage and associated vocal fold into the airway

Front 44

Function of the epiglottis:

Back 44

moves dorsally and caudally to cover the rima glottis during swallowing

Front 45

Origin and insertion of hyoepiglotticus:

Back 45

originates on the basihyoid and inserts on the base of the epiglottis

Front 46

Function of hyoepiglotticus:

Back 46

pull the epiglottis ventrally toward the tongue

Front 47

Innervation of hyoepiglotticus:

Back 47

hyoglossal nerve (cranial nerve XII)

Front 48

How are airway pressures & impedance measured?

Back 48

multi-hole catheter inserted into the trachea from the nasal passage or through the skin. With airway pressure and flow rates, impedance can be calculated

Front 49

Benefit of measurement of airway function:

Back 49

determines the effect of a condition on flow mechanics and determines the efficacy of surgical intervention

Front 50

What is required for diagnosis of upper airway disease?

Back 50

physical examination, resting endoscopic examination, exercise endoscopic examination and can include complementary diagnostics such as sound analysis, spirometry, and diagnostic imaging techniques

Front 51

What specifics should be included in physical examination for upper respiratory diagnostics?

Back 51

sinus percussion and palpation of the nares, larynx, and surgical scars from laryngoplasty, laryngotomy, or sternothyrohyoideus myectomy

Front 52

Size of endoscope used for upper airway endoscopy:

Back 52

outer diameter of 9.5mm is sufficient for airway endoscopy in adults and most foals, but a smaller diameter, 8.5 mm, may be necessary for neonates or small foals. The different in outer diameter affects the biopsy channel size, decreasing from 2.8mm to 2.2 mm

Front 53

Resting endoscopic light source:

Back 53

300 watts. Videoendoscope usually are capable of this degree of light source but fiberoptic endoscopes are not

Front 54

Grades of resting arytenoid function:

Back 54

grade 1 indicating synchronous movement and abduction/ adduction. Grade 2 indicates symmetric abduction & adduction but asynchronous movement. Grade 3 indicates both asymmetric movement and asynchronous abduction & adduction, with inability to maintain abduction. Grade 4 indicates inability to more 1 arytenoid at all

Front 55

How is arytenoid movement stimulated during resting endoscopy?

Back 55

induction of swallowing by spraying water or induction of inspiration by holding off the nostril

Front 56

Which method of stimulating arytenoid movement during resting endoscopy is most accurate?

Back 56

holding off the nostrils mimics pressures experienced during exercise, it is less accurate in estimating arytenoid dysfunction experienced during exercise than induction of swallowing

Front 57

What conditions are not diagnosed on resting endoscopy?

Back 57

pharyngeal collapse, axial deviation of the aryepiglottic folds, epiglottic retroversion, and intermittent DDSP

Front 58

Advantages of treadmill exercise:

Back 58

better control of exercise intensity and ability to closely monitor respiratory parameters

Front 59

Disadvantages of treadmill exercise:

Back 59

need of a number of trained personnel, equipment expense, and need to train or acclimatize the horse to the treadmill.

Front 60

Overground endoscopy advantages:

Back 60

working the horse in its normal environment, no additional acclimatizing period, and reduced cost of equipment, changes in poll flexion are more possible to determine the effect on flexion on degree of obstruction

Front 61

Disadvantages of overground endoscopy:

Back 61

reluctance to work horse at maximal intensity level, inability to standardize exercise testing, and inability to monitor respiratory parameters

Front 62

Sound analysis advantages:

Back 62

when respiratory noise occurs intermittently or when they are more obvious at maximal exercise can occur in the field and under normal working conditions

Front 63

What information is provided from Review of sound recordings?

Back 63

determination of respiratory rate and consistency, how often the horse swallows, frequency of lead changes, and if there is abnormal noise. Sound recordings can also undergo spectrogram analysis, a plot of frequency, time, and sound intensity

Front 64

Disadvantages of sound analysis:

Back 64

correlation of post-operative noise and residual obstruction is weak, so sound analysis should not be used as a predictor of improvement in function in individuals

Front 65

What is spirometry?

Back 65

ultrasonic flow meters to determine airflow velocity

Front 66

Benefits of ultrasonography?

Back 66

structural and functional abnormalities of the larynx, evaluating the non-luminal aspect of the airway

Front 67

How is ultrasound used to corroborate diagnosis of DDSP?

Back 67

Measurement of the depth of the basihyoid bone at the level of the lingual process is significantly more shallow (ventral) in horses with DDSP

Front 68

How is LH confirmed with ultrasonography?

Back 68

changes in echogenicity of the cricoarytenoideus lateralis due to neurogenic atrophy

Front 69

How does ultrasonography for diagnosis of LH compare with treadmill diagnosis?

Back 69

ultrasonography was more effective at diagnosing LH than resting endoscopy. Ultrasound had a sensitivity of 91% and a specificity of 90% compared with the standard, treadmill endoscopy, which had a sensitivity of 92% and a specificity of 96%

Front 70

How is ultrasound beneficial in the diagnosis of arytenoid chondritis?

Back 70

assesses the abaxial aspect of the cartilage and identifies involvement of adjacent structures, such as the thyroid cartilage or the space between the thyroid and arytenoid cartilages

Front 71

Advantages of CT over radiography:

Back 71

better detail with no overlap of structures and superior discrimination of tissue density

Front 72

Advantages of CT over MRI:

Back 72

can be performed quickly and can be used before planned surgical interventions in the same anesthetic period

Front 73

Advantages of MRI over CT:

Back 73

multiplanar without loss of image quality and has excellent soft tissue and bone imaging

Front 74

Effect of experimental blockade of glossopharyngeal nerve (CN9):

Back 74

dorsal pharyngeal collapse