Obstructive sleep apnoea (RESP) Flashcards

1
Q

Define OSA.

A

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

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2
Q

What is the pathophysiology of OSA?

A

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

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3
Q

What groups does OSA happen most in? (3)

A
  • M>F
  • prevalence increases with age
  • classically in overweight middle-aged men
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4
Q

How is OSA classified?

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

What are some causes of OSA? (6)

A
  • obesity
  • acromegaly (causes macroglossia)
  • hypothyroidism (causes macroglossia)
  • large tonsils
  • alcohol
  • smoking
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5
Q

What are the clinical features of OSA? (5)

A
  • 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
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6
Q

How is excessive daytime sleepiness measured in OSA?

A

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

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7
Q

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

A
  • impaired cognitive function
  • depression
  • decreased libido
  • hypertension with increased pulse pressure
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8
Q

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

A
  • macroglossia - large tongue
  • enlarged tonsils
  • long/thick uvula
  • maxillomandibular anomalies e.g. retrognathia (pulled back jaw)
  • neck circumference (>42cm male, >40cm female)
  • obesity
  • hypertension
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9
Q

What are the risk factors for OSA? (14)

A
  • 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
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10
Q

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

A
  • polysomnography (PSG)
  • portable multichannel sleep tests
  • awake fibreoptic endoscopy - excludes hypertrophic lingual tonsils, nasal polyps or tumours
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11
Q

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

A

Polysomnography (PSG)

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12
Q

What does polysomnography show us in OSA?

A
  • 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)
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13
Q

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

A
  • 15+ episodes/hour
  • OR 5+ with symptoms or comorbidities
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14
Q

How do we assess risk of OSA?

A

STOP-BANG score (>3 = do polysomnography)

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15
Q

What are some differential diagnoses for OSA? (4)

A
  • 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
16
Q

What is the diagnostic criteria for OSA?

A
  • 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)
17
Q

What risk factor needs to be addressed for OSA management?

A

Weight loss

18
Q

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

A
  • with concurrent obesity - weight loss & bariatric surgery
  • with persistent hypersomnolence - modafinil/armodafinil/solriamfetol (promotes wakefulness)
  • with positional component - positional therapy (non-supine sleep position)
19
Q

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

A
  • 1st line: continuous positive airway pressure (CPAP)
  • 2nd line: oral appliance therapy
  • 2nd line: implantable hypoglossal neurostimulation
  • 2nd line: upper airway surgery
20
Q

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

A
  • 1st line: CPAP or oral appliance therapy
  • 2nd line: implantable hypoglossal neurostimulation or upper airway surgery
21
Q

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

A

Upper airway surgery

22
Q

How can we improve CPAP adherence in OSA?

A

Nasal surgery, intranasal corticosteroid application and non-benzodiazepine soporifics

23
Q

In general, what is 1st line for OSA?

A

Continuous positive airway pressure (CPAP) at night

24
In OSA, what do we tend to use if CPAP not tolerated?
Intra-oral devices e.g. mandibular advancement
25
In OSA, what do we give if co-existing respiratory failure?
BiPAP (vs CPAP)
26
Who needs to be informed about certain patients with OSA?
DVLA if OSA is causing excessive daytime sleepiness
27
What are some complications of OSA? (6)
- impaired glucose metabolism (due to sleep deprivation) - cardiovascular disease (MI, dysrhythmias, stroke, hypertension) - depression - motor vehicle accidents - cognitive dysfunction - increased mortality
28
Describe the prognosis of OSA.
Patients efficiently treated may report improvements in alertness and some improvement in QoL, mood and cognitive function