Obstructive sleep apnoea

Question 1

What is sleep apnoea?

Answer 1

Absence of airflow during sleep

Question 2

What are the two types of sleep apnoea?

Answer 2

Central and obstructive.

Question 3

What is obstructive sleep apnoea?

Answer 3

Partial or complete occlusion of pharyngeal airway with paradox breathing followed by arousal from sleep. Defined as cessation of airflow for at least 10 seconds. AKA Pickwickian syndrome.

Question 4

What are the associations of OSA? (x5 (x4 and x3))

Answer 4

• LIFESTYLE: Excessive weight gain, smoking, alcohol or sedative use
• ANATOMICAL NARROWING OF PHARYNX: enlarged tonsils or adenoids, craniofacial abnormalities, macroglossia
• Marfan’s syndrome
• Down’s syndrome
• Hypothyroidism

Question 5

What is the pathophysiology of OSA?

Answer 5

Collapse of soft tissues of the pharynx when tone in the pharyngeal dilators decreases during sleep. On arousal, autonomic sympathetic activation occurs which may result in high HR, dysrhythmias and vasoconstriction (increased cardiovascular disease risk).

Question 6

What is the epidemiology of OSA: How common? Gender prevalence? Age? Ethnicity?

Answer 6

Common. 5-20% of men and 2-5% of women. More common with increasing age. Higher in Black and Asian populations.

Question 7

What are the symptoms of OSA? (x6)

Answer 7

• Excessive daytime sleepiness
• Unrefreshing or restless sleep
• Morning headaches or dry mouth
• Irritability or mood changes
• Snoring
• Retrosternal burning may present due to laryngospasm

Question 8

What are the signs of OSA?

Answer 8

Macroglossia, enlarged tonsils, long/thick uvula, retrognathia (pulled back jaws), large neck circumference, and hypertension is common.

Question 9

What are the investigations for OSA?

Answer 9

• Video recording of episodes
• Sleep study: called polysomnography; monitor airflow, respiratory effort, pulse oximetry and heart rate to determine AHI and diagnosis.
• Bloods: TFTs (hypothyroidism associated with OSA) and ABG

Question 10

What is AHI?

Answer 10

Apnoea Hypopnea Index – sum of the number of apneas (pauses in breathing) plus the number of hypopneas (periods of shallow breathing) occurring, on average, each hour.

Question 11

What AHI score is diagnostic of OSA?

Answer 11

An AHI of more than or equal to 15 is confirmatory, but more than or equal to 5 episodes/hour is sufficient in a symptomatic patient or in a patient with hypertension, ischaemic cardiac disease, history of stroke, excessive daytime sleepiness, insomnia, mood disorder, or cognitive dysfunction.

Question 12

How does AHI grade OSA?

Answer 12

5-15 indicates mild, 15-30 indicates moderate, over 30 indicates severe OSA.

Question 13

What is the respiratory disturbance index?

Answer 13

Same as AHI, but also includes respiratory-effort related arousals (arousals that do not meet the definitions of apneas and hypopneas).