Obstructive sleep apnoea

Question 1

What is obstructive sleep apnoea?

Answer 1

Upper airway obstruction during sleep due to pharyngeal airway collapse > apnoeic episodes > excessive daytime sleepiness

Question 2

Risk factors for OSA

Answer 2

• obese
• excessive alcohol
• smoking
• acromegaly
• hypothyroidism
• large tonsils
• Marfan’s syndrome

Question 3

Pathophysiology of OSA

Answer 3

• upper airway patency depends on pharngeal dilator muscle activity
• all muscles relax during sleep, including these
• excessive narrowing can be due to: already small pharyngeal size or excessive narrowing occurring with relaxation during sleep

Question 4

Causes of small pharyngeal size

Answer 4

• fatty infiltration of pharyngeal tissues + external pressure from increased neck fat
• large tonsils
• craniofacial abnormalities
• extra submucosal tissue e.g. myxoedema

Question 5

Causes of excessive narrowing of airway during sleep

Answer 5

• obesity
• increasing age
• muscle relaxants e.g. sedatives, alcohol
• neuromuscular disease with pharyngeal involvement > increased loss of dilator muscle tone e.g. stroke, MND

Question 6

Presentation of OSA

Answer 6

• apnoeic episodes (stops breathing in sleep) reported by partner
• snoring
• morning headache
• excessive daytime sleepiness
• concentration problems
• complaints of unrefreshed sleep

Question 7

What scales are used to help in investigations of obstructive sleep apnoea?

Answer 7

Epworth sleepiness scale
Berlin scale

Question 8

Diagnosis of obstructive sleep apnoea

Answer 8

• overnight oximetry alone
• limited sleep study: oximetry, snoring, body movement, HR, oronasal flow, chest movements, leg movements
• full polysomnography: limited sleep study + EEG + EMG

Question 9

Management of OSA

Answer 9

• consider occupation
• patient to notify DVLA
• weight loss
• adjust sleep position
• smoking cessation + reduce alcohol
  .
  Given based on symptoms/QOL, not severity on investigations
• for snorers + mild OSA: mandibular advancement devices | consider pharyngeal surgery as last resort
• for significant OSA: nasal CPAP, consider gastroplasty/bypass
• for severe OSA + CO2 retention: may require NIV prior to CPAP

Question 10

Outline continuous positive airway pressure CPAP

Answer 10

• usually given via nasal mask
• upper airway splinted open with ~10cm H2O pressure
• preventing airway collapse, sleep fragmentation + daytime sleepiness
• opens collapses alveoli + improves V/Q matching

Question 11

CPAP vs NIV

Answer 11

• CPAP supplies constant positive pressure during inspiration + expiration
• CPAP is NOT a form of ventilatory support
  .
• NIV does provide ventilatory support with two levels of pressure (IPAP + EPAP)