Obstructive sleep apnoea (RESP)

Question 1

Define OSA.

Answer 1

Sleep-related breathing disorder characterised by episodes of complete or partial upper airway obstruction during sleep

Question 2

What is the pathophysiology of OSA?

Answer 2

Sleep –> decreased muscle tone –> upper airway collapse –> apnoea (intermittent hypoxia) –> arousal (fragmented sleep, sleepiness and cognitive dysfunction) –> airway reopens

Question 3

What groups does OSA happen most in? (3)

Answer 3

• M>F
• prevalence increases with age
• classically in overweight middle-aged men

Question 4

How is OSA classified?

Answer 4

• mild (5-15 events/hr)
• moderate (15-30 events/hr)
• severe (>30 events/hr)

Question 5

What are some causes of OSA? (6)

Answer 5

• obesity
• acromegaly (causes macroglossia)
• hypothyroidism (causes macroglossia)
• large tonsils
• alcohol
• smoking

Question 5

What are the clinical features of OSA? (5)

Answer 5

• excessive daytime sleepiness - measured with Epworth sleepiness scale (14 is moderate, 18 severe)
• unrefreshing or restless sleep
• episodes of apnoea and gasping
• chronic loud snoring
• signs of complications - impaired cognitive function, depression, decreased libido, hypertension with increased pulse pressure

Question 6

How is excessive daytime sleepiness measured in OSA?

Answer 6

Epworth sleepiness scale (14 is moderate sleepiness, 18 is severe sleepiness)

Question 7

What are some signs of complications that OSA can present with? (4)

Answer 7

• impaired cognitive function
• depression
• decreased libido
• hypertension with increased pulse pressure

Question 8

What might be seen on examination in OSA? (7)

Answer 8

• macroglossia - large tongue
• enlarged tonsils
• long/thick uvula
• maxillomandibular anomalies e.g. retrognathia (pulled back jaw)
• neck circumference (>42cm male, >40cm female)
• obesity
• hypertension

Question 9

What are the risk factors for OSA? (14)

Answer 9

• increased age
• male
• obesity, weight gain –> more soft tissue in neck
• surgical swelling
• smoking
• alcohol
• hypothyroidism
• sedative use
• enlarged tonsils and adenoids in children
• macroglossia
• Marfan’s syndrome
• post-menopause
• craniofacial abnormalities
• Fx, GORD, Down’s, tooth extractions, motor vehicle accidents

Question 10

What are the 1st-line investigations for OSA? (3)

Answer 10

• polysomnography (PSG)
• portable multichannel sleep tests
• awake fibreoptic endoscopy - excludes hypertrophic lingual tonsils, nasal polyps or tumours

Question 11

What is the definitive (gold-standard) test for OSA?

Answer 11

Polysomnography (PSG)

Question 12

What does polysomnography show us in OSA?

Answer 12

• monitor airflow, respiratory effort, pulse oximetry and HR, and snoring and movement
• occurrence of 15+ episodes of apnoea/hypopnoea during 1h of sleep indicates significant sleep apnoea:
  
  • snoring
  • upper air resistance syndrome
  • mild OSA (5-15 events/hr)
  • moderate OSA (15-30 events/hr)
  • severe OSA (>30 events/hr)

Question 13

What Apnoea-Hypopnoea Index (AHI) do we need on polysomnography to diagnose OSA?

Answer 13

• 15+ episodes/hour
• OR 5+ with symptoms or comorbidities

Question 14

How do we assess risk of OSA?

Answer 14

STOP-BANG score (>3 = do polysomnography)

Question 15

What are some differential diagnoses for OSA? (4)

Answer 15

• central sleep apnoea, Cheyne-stokes respiration (recurrent episodes of apnoea with absence of respiratory effort)
• narcolepsy (higher Epworth Sleepiness scale scores, cataplexy, hypnagogic hallucinations, sleep paralysis)
• insufficient sleep/inadequate sleep hygiene
• hypothyroidism

Question 16

What is the diagnostic criteria for OSA?

Answer 16

• Apnoea-Hypopnoea Index (AHI) or Respiratory Event Index (REI)
• occurrence of 15+ episodes of apnoea/hypopnoea during 1h of sleep indicates significant sleep apnoea:
  
  • snoring
  • upper air resistance syndrome
  • mild OSA (5-15 events/hr)
  • moderate OSA (15-30 events/hr)
  • severe OSA (>30 events/hr)

Question 17

What risk factor needs to be addressed for OSA management?

Answer 17

Weight loss

Question 18

What are some general OSA treatments for all AHI/REI scores? (3)

Answer 18

• with concurrent obesity - weight loss & bariatric surgery
• with persistent hypersomnolence - modafinil/armodafinil/solriamfetol (promotes wakefulness)
• with positional component - positional therapy (non-supine sleep position)

Question 19

What is 1st (and 2nd line) for OSA with AHI/REI>30 per hour?

Answer 19

• 1st line: continuous positive airway pressure (CPAP)
• 2nd line: oral appliance therapy
• 2nd line: implantable hypoglossal neurostimulation
• 2nd line: upper airway surgery

Question 20

What is 1st (and 2nd line) for OSA with AHI/REI 5-30 per hour?

Answer 20

• 1st line: CPAP or oral appliance therapy
• 2nd line: implantable hypoglossal neurostimulation or upper airway surgery

Question 21

What is 1st line for OSA with discrete anatomical lesions?

Answer 21

Upper airway surgery

Question 22

How can we improve CPAP adherence in OSA?

Answer 22

Nasal surgery, intranasal corticosteroid application and non-benzodiazepine soporifics

Question 23

In general, what is 1st line for OSA?

Answer 23

Continuous positive airway pressure (CPAP) at night

Question 24

In OSA, what do we tend to use if CPAP not tolerated?

Answer 24

Intra-oral devices e.g. mandibular advancement

Question 25

In OSA, what do we give if co-existing respiratory failure?

Answer 25

BiPAP (vs CPAP)

Question 26

Who needs to be informed about certain patients with OSA?

Answer 26

DVLA if OSA is causing excessive daytime sleepiness

Question 27

What are some complications of OSA? (6)

Answer 27

• impaired glucose metabolism (due to sleep deprivation)
• cardiovascular disease (MI, dysrhythmias, stroke, hypertension)
• depression
• motor vehicle accidents
• cognitive dysfunction
• increased mortality

Question 28

Describe the prognosis of OSA.

Answer 28

Patients efficiently treated may report improvements in alertness and some improvement in QoL, mood and cognitive function