Sleep Apnoea

Question 1

What are the two main pumps that circulate our blood gases?

Answer 1

Heart and respiratory muscles

Question 2

What is the metabolic cost of respiratory muscles at rest?

Answer 2

≤5% of body metabolism

Question 3

What is the definition of eupnea?

Answer 3

Normal breathing i.e. automatic and homeostatically regulated breathing

Question 4

What are the phases of the eupneic breathing pattern?

Answer 4

• Inspiration
• Post-inspiration
• Active expiration

Question 5

What type of receptors modulate neural control of respiration?

Answer 5

Stretch receptors, chemoreceptors, irritant receptors

Question 6

What does hypercapnia refer to?

Answer 6

Elevated arterial PCO2

Question 7

What activates breathing by stimulating central chemoreceptors?

Answer 7

CO2

Question 8

What is the role of peripheral chemoreceptors?

Answer 8

• Sense tension of oxygen
• Sense carbon dioxide
• Sense [H+] in the blood

Question 9

Where are central chemoreceptors primarily located?

Answer 9

Near the surface of the medulla of the brainstem

Question 10

What are the clinical consequences of obstructive sleep apnoea (OSA)?

Answer 10

• Daytime sleepiness
• Impaired performance
• Increased cardio/cerebrovascular morbidity and mortality

Question 11

What is the prevalence of obstructive sleep apnoea in adults?

Answer 11

3-7% in men, 2-5% in women

Question 12

What is a common symptom of obstructive sleep apnoea?

Answer 12

Hypersomnia (excessive daytime sleepiness)

Question 13

What are the mechanisms causing airway collapse in OSA?

Answer 13

• Airway narrowing
• Sleep-related muscle atonia

Question 14

What is the main diagnostic tool for obstructive sleep apnoea?

Answer 14

Polysomnogram

Question 15

True or False: CO2 activates breathing only by stimulating the carotid bodies.

Answer 15

False

Question 16

What happens to breathing during sleep regarding chemoreceptor drive?

Answer 16

Breathing becomes more shallow and less stable

Question 17

What is the impact of CNS hypoxia on breathing?

Answer 17

Depresses the respiratory network

Question 18

What is the role of the Pre-Botzinger complex?

Answer 18

Generates the breathing rhythm

Question 19

What occurs when expiratory neurons fire in the pons?

Answer 19

Termination of inspiration

Question 20

What type of neurons are involved in the central respiratory network?

Answer 20

Acid-activated neurons

Question 21

Fill in the blank: The ventilatory recruitment threshold becomes the _______ during sleep.

Answer 21

Apneic threshold

Question 22

What is a significant risk factor for obstructive sleep apnoea in children?

Answer 22

Large tonsils

Question 23

What is the consequence of repeated hypoxia due to OSA?

Answer 23

Deleterious effects on cognitive function

Question 24

What is the incidence of myocardial infarctions (MIs) in snorers compared to non-snorers?

Answer 24

1.5 to 4 times greater in snorers than non-snorers.

Question 25

What percentage of hypertensive patients have sleep apnea?

Answer 25

Up to 40% of hypertensive patients.

Question 26

What happens to blood pressure if sleep apnea is effectively treated?

Answer 26

BP recovers.

Question 27

What is the effect of heavy snoring on brain blood flow during REM sleep?

Answer 27

50% decreased brain blood flow.

Question 28

What is the increase in incidence of stroke among heavy snorers?

Answer 28

50% increase.

Question 29

What are the deleterious effects of repeated hypoxia?

Answer 29

Decreases cognitive function, produces loss of brain matter, decreases arousal.

Question 30

List the treatments of OSA in order of efficacy.

Answer 30

* CPAP machine * Weight loss if applicable * Elimination of sedatives including alcohol * Favorable sleeping posture * Airway surgery (controversial, rare)

Question 31

What percentage of cases of OSA can be improved with weight loss?

Answer 31

~75% of cases.

Question 32

What improvements can exercise provide in managing OSA?

Answer 32

* Decrease AHI * Reduce daytime sleepiness and BMI * Increase sleep quality and VO2

Question 33

What is Central Sleep Apnoea?

Answer 33

Less common than OSA (<10% patients referred to sleep clinics).

Question 34

What are the symptoms of Central Sleep Apnoea?

Answer 34

* Episodic breathing/pauses * Abrupt awakenings with SOB * Insomnia * Hypersomnia * Chest pain * Mood changes * Headaches * Snoring * Low exercise tolerance

Question 35

What causes Central Sleep Apnoea?

Answer 35

Conditions affecting autonomic respiratory control.

Question 36

What is Congenital Central Hypoventilation Syndrome (Ondine’s Syndrome)?

Answer 36

Respiratory disorder leading to severe apnea during sleep.

Question 37

What gene mutation is associated with Congenital Central Hypoventilation Syndrome?

Answer 37

Mutations in the PHOX2B gene.

Question 38

What is the typical treatment for diagnosed Congenital Central Hypoventilation Syndrome?

Answer 38

Mechanical ventilation or diaphragm pacemaker.

Question 39

What are the types of Central Sleep Apnoea?

Answer 39

* Cheyne-Stokes breathing * Drug-Induced Apnoea * High-altitude periodic breathing * Treatment-emergent CSA * Medical condition-induced CSA * Idiopathic (primary) CSA

Question 40

What is Cheyne-Stokes breathing associated with?

Answer 40

Congestive heart failure or stroke.

Question 41

What are risk factors for Central Sleep Apnoea?

Answer 41

* Gender (males more at risk) * Age (>65 yrs) * Cardiovascular conditions * Brain tumor or brainstem injury * High altitude * Opioid use * CPAP use

Question 42

True or False: Sleep Apnoea may lead to poorer cardiovascular outcomes.

Answer 42

True.

Question 43

What are the factors influencing breathing during sleep?

Answer 43

Chemoreceptors sensing CO2 and O2 levels.