207 OSA And Chest Wall

Question 1

What is the biggest risk factor for OSA?

Answer 1

Neck circumference

Question 2

What is the Bernoulli effect?

Answer 2

Airflow velocity increases at the site of a stricture but as the velocity increases, pressure on the lateral wall decreases and the airway collapses

Question 3

When would you see OSA in children?

Answer 3

When enlarged tonsils

Question 4

What causes the arousal of a pt with OSA?

Answer 4

Increased arterial PCO2

Question 5

Name 5 risk factors for OSA (including facial deformities)

8 listed

Answer 5

Enlarged tonsils
Obesity
DM2
Large overbite
Micrognathia/retrognathia
HTN
High arched palate
Metabolic syndrome

Question 6

What investigations are performed to diagnose OSA?

Answer 6

Overnight oximetry tracing
Polysomnography
Epworth sleepiness score

Question 7

When is OSA diagnosed?

Answer 7

When hypopnoea/apnoea >15 times per hour

Question 8

What is the treatment of OSA?

Answer 8

Lifestyle changes
Treat underlying causes
CPAP

Question 9

Where is the central control of ventilation?

Answer 9

Medulla

Question 10

What are the 2 areas of the medulla which control ventilation?

Answer 10

Ventral respiratory group

Dorsal respiratory group

Question 11

Where is the pre-Botzinger complex found? What is its function?

Answer 11

In the ventral respiratory group - hypothesized location of central respiratory rhythm pattern generation circuitry.
Pacemaker cells here which initiate spontaneous breathing

Question 12

Which area of the medulla controls inspiration?

Answer 12

Dorsal respiratory group

Question 13

Which area of the medulla controls expiration?

Answer 13

Ventral respiratory group

Question 14

What are the 2 main theories of initiation of ventilation?

Answer 14

Group pacemaker hypothesis

Pre Botzinger complex as initiator of generation of ventilation

Question 15

Which cells regulate the patterning of ventilation in the CNS?

Answer 15

Pontine respiratory group

Question 16

What is the role of the pontine respiratory group?

Answer 16

Antagonises the apneustic centre which inhibits inhalation decreasing tidal volume and regulating breathing. i.e. inhibition of inhibitory neurones

Question 17

What is the outcome of damage to the pontine respiratory group?

Answer 17

Apneusis - deep, gasping inspiration with a pause at full inspiration followed by a brief, insufficient release.

Question 18

What is the pathway for voluntary control of breathing?

Answer 18

From cerebral cortices –> pyramidal tracts –> corticospinal tracts (i.e. bypassing brainstem)

Question 19

What is the Hering breuer reflex?

Answer 19

Reflex which prevents overinflation of the lung mediated by pulmonary stretch receptors which decrease the breathing via vagus nerve

Question 20

What are J receptors?

Answer 20

Receptors in alveoli which are juxtaposed to capillaries and respond to e.g. pulmonary oedema (i.e. fluid) and act via vagus to cause dyspnoea due to decreased oxygenation

Question 21

What is ideal PaCO2?

Answer 21

5.3kPa

Question 22

Where are peripheral chemoreceptors found?

Answer 22

Carotid bodies and aortic sinus

Question 23

Where are central chemoreceptors found?

Answer 23

In medulla close to the respiratory centre

Question 24

Where in the CNS is H+ able to affect the central chemoreceptors?

Answer 24

CSF- brain barrier - i.e. choroid plexus. H+ unable to cross BBB whereas HCo3- is able.