Obstructive Sleep Apnoea Syndrome

Question 1

What is obstructive sleep apnoea?

Answer 1

• Recurrent episodes of patrial or complete upper (pharyngeal) airway obstruction during sleep, intermittent hypoxia and sleep fragmentation

Question 2

What is obstructive sleep apnoea syndrome?

Answer 2

• OSA that manifests as excessive daytime sleepiness

Question 3

What is apnoea?

Answer 3

• Reduction in airflow >90% of baseline for at least 10 seconds or 4% oxygen desaturation lasting ≥10 seconds

Question 4

What is hypopnoea?

Answer 4

• Reduction in airflow >30% of baseline for at least 10 seconds, associated with >3% desaturation from pre-event baseline

Question 5

What are the stages of the apnoea-hypopnoea index (AHI)?

Answer 5

• AHI < 5 Normal
• AHI 5-15 Mild
• AHI 16-30 Moderate
• AHI >30 Severe
• ≥15 is diagnostic of OSA
• Calculated by adding apnoeas and hypopnoeas and dividing by total sleep time in hours

Question 6

What is the oxygen desaturation index (ODI)?

Answer 6

• Number of times per hour of sleep that the O2 saturations falls ≥4% from baseline

Question 7

What are respiratory effort related arousals?

Answer 7

• Arousals assocaited with a change in airflow that does not meet criteria for apnoea or hypopnoea

Question 8

What are the symptoms of OSAS?

Answer 8

• Apnoea episodes during sleep (reported by partner)
• Snoring
• Morning headache
• Unrefreshing sleep
• Daytime fatigue
• Choking or gasping during sleep
• Impaired concentration
• Recurrent awakenings from sleep
• Reduced O2 sats during sleep

NB - Always ask about occupation as patients with jobs requiring them to be fully alert require urgent referral (i.e. heavy goods vehicle operators)

Question 9

What factors promote airway collapse?

Answer 9

• Negative pressure on inspiration
• Extraluminal positive pressure
• Fat deposition
• Small mandible

Question 10

What factors promote airway potency?

Answer 10

• Pharyngeal dilator muscle contraction (genioglossus)
• Lung volume (longitudinal traction)

Question 11

What does the limitied polysomnography study used to investigate OSAS involve?

Answer 11

• O2 saturations
• HR
• Flow
• Thoracic and abdominal effort
• Position

Question 12

What does the full polysomnography study used to investigate OSAS add to the limited study?

Answer 12

• EEG (sleep staging)
• Video
• Audio
• Limb leads
• Snore

Question 13

What are the treatment options for OSAS?

Answer 13

• CPAP
• Weight reduction
• Mandibular advancement splints
• Surgery (tracheostomy, bariatric surgery, jaw advancement, palatal surgery)

Question 14

Does OSAS affect your ability to drive?

Answer 14

• Only need to stop if daytime somnolence

Question 15

Management of OSAS

Answer 15

• Referral to ENT specialist of sleep clinic for sleep studies
• Correct reversible factors (i.e. stop drinking alcohol, stop smoking, lose weight)
• CPAP
• Surgery (restructuring of the soft palate and jaw - most common procedure is a uvulopalatopharyngoplasty/UPPP)

Question 16

Risk factors for OSAS

Answer 16

• Middle age
• Male
• Obesity
• Smoking
• Alcohol