Sleep apnoea

Question 1

What is obstructive sleep apnoea?

Answer 1

A disorder characterised by intermittent closure/collapse of the pharyngeal airway causing apnoeic episodes during sleep, which are terminated by partial/full arousal.

Question 2

What is the prevalence of obstructive sleep apnoea?

Answer 2

1-2%

Question 3

What is the pathophysiology of obstructive sleep apnoea?

Answer 3

https://www.youtube.com/watch?v=f4g7_60u_GA

Apnoeas occur when the airway is sucked shut when breathing in during sleep. When awake, this is overcome by the action of opening muscles of the upper airway, genioglossus and palatal muscles, but these become hypotonic during sleep.

Apnoea leads to hypoxia, hypopnoea, and increasingly strenuous respiratory effort until the resistance is overcome. This normally wakes the patient up (combination of hypoxia and airway obstruction).

Question 4

What are causes of sleep apnoea?

Answer 4

• Encroachment on pharynx – obesity, acromegaly, enlarged tonsils
• Nasal obstruction – nasal deformities, rhinitis, polyps, adenoids
• Respiratory depressant drugs – alcohol, sedatives, strong analgesics.

Question 5

What are symptoms of OSA?

Answer 5

• Loud snoring
• Daytime somnolence
• Poor sleep hygeine
• Morning headache
• Decreased libido
• Decreased cognitive performance
• Nocturnal choking
• Ankle swelling

Question 6

What are complications associated with OSA?

Answer 6

• Pulmonary hypertension
• Type II respiratory failure
• Hypertension

Question 7

Why do patients wake in apnoeic episodes?

Answer 7

Combination of hypoxia and increased respiratory effort to compensate

Question 8

How would wou go about investigating for obstructive sleep apnoea?

Answer 8

• Clinical history and examination
• Epworth Sleepiness Scale Questionnaire
• Polysomnography/Overnight sleep study

Question 9

What is involved in polysomnography?

Answer 9

Monitoring of a variety of variables:

• Oronasal airflow
• Thoracoabdominal movement
• Oximetry
• Body position
• EEG
• Audiovisual recording
• EOG
• EMG (peripheral muscle)
• ECG

Question 10

What is the Epworth Sleepiness Scale?

Answer 10

A screening tool that helps distinguish potential sleep apnoea from simple snoring.

Question 11

How many episodes of desaturation need to occur per hour in the night for a diagnosis of mild OSA?

Answer 11

5-15 per hour

Question 12

How many episodes of desaturation need to occur at night for a diagnosis of moderate OSA?

Answer 12

15-30 apnoeas per hour

Question 13

How many apnoeas per hour for the diagnosis of severe OSA to be made?

Answer 13

>30 per hour

Question 14

How would you manage sleep apnoea?

Answer 14

1. Weight reduction
2. Avoid smoking and alcohol
3. CPAP - moderate to severe disease
4. Surgery
5. Restrict driving - if somnolence severe

Question 15

Why might someone with OSA have ankle swelling?

Answer 15

Due to hypoxic cor pulmonale