Obstructive sleep apneoa Flashcards

1
Q

What is it?

A

Obstructive sleep apnoea is characterised by recurrent episodes of complete or partial obstruction of the upper airway during sleep, causing apnoea or hypopnoea

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2
Q

Why does this occur?

A

Upper airway patency depends on dilator muscle
activity. All muscles relax during sleep (including
pharyngeal dilators).

Excessive narrowing can be due to either :
- an already small pharyngeal size during awake state which undergoes a normal degree of muscle
relaxation during sleep causing critical narrowing
- OR excessive narrowing occurring with relaxation during sleep

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3
Q

Risk factors?

A
  • Increasing age
  • Male sex
  • Upper body Obesity
  • Collar size >17 inches
  • Alcohol
  • Smoking
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4
Q

Causes of small pharyngeal size?

A
  • Fatty infiltration of pharyngeal tissues and external
    pressure from increased neck fat and/or muscle
    bulk
  • Nasopharyngeal obstruction: large tonsils
  • Craniofacial abnormalities- relatively undersized or set back mandible
  • Extra submucosal tissue, e.g. myxoedema
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5
Q

Causes of excessive narrowing during sleep?

A
  • Obesity may enhance residual muscle dilator
    action
  • Neuromuscular disease with pharyngeal
    involvement may lead to greater loss of dilator
    muscle tone, e.g. stroke, MND, myotonic
    dystrophy
  • Muscle relaxants – sedatives, alcohol
  • Increasing age
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6
Q

Differentials to the symtoms ?

A

Narcolepsy
Hypothyroidism

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7
Q

Symptoms

A
  • excessive daytime sleepiness (daytime somnolence)
  • Recurrent arousals lead to highly fragmented and waking up unrefreshed from sleep
  • Concentration problems
  • excessive snoring
  • Transient arousal required
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8
Q

Signs

A
  • Reduces oxygen saturation during sleep
  • Hypertension
  • Heart failure
  • compensated respiratory acidosis
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9
Q

What do we use to assess Sleepiness ?

A

Epworth Sleepiness Scale- questionnaire completed by patient +/- partner

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10
Q

In the sleepiness scale what do they use to measure it

A
  • Points for following: 0=would never doze, 1=slight chance, 2=moderate chance, 3=high chance
    • Sitting & reading
    • Watching TV
    • Sitting in a public place, e.g. theatre
    • Passenger in a car for an hour
    • Lying down to rest in the afternoon
    • Sitting & talking
    • Sitting quietly after lunch without alcohol
    • In a car, while stopped in traffic
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11
Q

For the sleepiness scale: what score would make OSA likely and need to investigate further

A

> 9

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12
Q

What is the diagnostic test for OSA?

A

Sleep studies- Polysomnography

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13
Q

What are the types of polysomnography? Which one is most common ?

A
  • Overnight oximetry alone
  • Limited sleep study – oximetry, snoring, body
    movement, heart rate, oronasal flow,
    chest/abdominal movements, leg movements –
    usual study of choice
  • Full polysomnography – limited study plus EEG,
    EMG
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14
Q

How many apnoeic episodes is significant?

A
  • Apnoeic episodes ≤ 5 is normal
  • Apnoeic episodes 5-15 mild
  • Apnoeic episodes 15-30 Moderate
  • Apnoeic episodes >30 severe
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15
Q

What is treatment based on?

A

on symptoms/quality of life – NOT on severity seen on sleep study

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16
Q

Correct reversible risk factors in OSA?

A
  • weight loss
  • Avoid/reduce evening alcohol
  • Smoking cessation
  • sleep decubitus rather than supine
17
Q

Treatment for mild OSA

A

Mandibular advancement device
consider pharyngeal surgery as last resort

18
Q

treatment for significant OSA?

A
  • Nasal Continuous positive airway pressure (CPAP)is first line
  • consider gastroplasty/bypass
  • rarely tracheostomy
19
Q

treatment in SEVERE OSA &CO2 retention?

A

May require a period of NIV prior to CPAP if acidotic, but compensated CO2 may reverse with CPAP alone

20
Q

What is CPAP?

A
  • Usually given via nasal mask, but can use
    mouth/nose masks
  • Upper airways splinted open with approximately
    10cm H2O pressure – this prevents airways
    collapse, sleep fragmentation, and ultimately
    daytime somnelence
  • Also opens collapsed alveoli and improves V/Q
    matching
21
Q

Is CPAP a form of ventilatory support like NIV

A

No