OSA (obstructive sleep apnoea) Flashcards

1
Q

What is sleep apnoea?

A

Episodic partial / complete obstruction of upper airways during sleep

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2
Q

Define

  1. Apnoea
  2. Hypopnoea
  3. Hyperpnoea
A
  1. complete airway obstruction lasting 10+ seconds
  2. Reduction in RR/depth of breathing (>50% reduced ventilation)
  3. Increased RR/depth of breathing
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3
Q

Types of sleep apnoea

A
  1. Obstructive = airflow obstruction (reduced/no airflow despite resp. effort)
  2. Central = reduced drive to breath (no airflow – no resp. effort)
  3. Mixed = both
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4
Q

Mechanisms of sleep apnoea

A
  1. Anatomical obstruction due to increased mass of pharyngeal tonsils/tongue/adenoids, maxillomandibular abnormalities, obesity (airway compression) –> reduced pharyngeal inlet
  2. Neuromuscular dysfunction
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5
Q

Normal Δ breathing during sleep

A
  1. Reduced tidal volume
  2. Higher PaCO2
  3. relaxation of pharyngeal muscles (+ glossopharyngeus which extends tongue to prevent airway obstruction)
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6
Q

Pathophysiology of an apnoeas episode → physiological consequences

A

Reduced drive to breathe during sleep + narrowed upper airways

  • -> partial / complete airway obstruction (esp. during inspiration w. loss of positive pressure)
  • -> reduced ventialation
  • -> hypoxia + hypercapnoea
  • -> detected by chemoreceptors
  • -> SNS stimulation –> arousal -
  • > normal breathing (cycle repeats)
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7
Q

Key RF for OSA (9)

A
  • obesity
  • age
  • male (or postmenopausal female)
  • CVD (HTN, etc…)
  • FHx
  • Chronic snoring
  • Large neck circumference
  • anatomical abnormalities (maxillomandibular, tonsils, adenoids, tongue)
  • Metabolic disorders (T2DM, PCOS, hypothyroidism), Down’s syndrome
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8
Q

Other RFs for OSA (4)

A

Smoking
Alcohol
Nasal obstruction
Sex hormone levels (changes ass. w. age)

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9
Q

AIH classification of sleep apnea

A

15+ episodes /h

5+ if additional symptoms / co-morbidities

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10
Q

Clinical Px

  1. Symptoms
  2. Cx
  3. Co-morbidities
A

Important to get a collateral Hx from partner

    • morning headaches
    • night time gasping
    • excessive daytime somnolence
    • restless sleep / insomnia
    • loud snoring
    • dry mouth
    • night sweats
    • heartburn/dyspepsia (laryngospasm)
    • reduced libido / erectile dysfunction
    • depression / mood
    • cognitive impairment
    • MVAs
    • CVD
    • nocturia
    • those listed above
    • CVD
    • GORD
    • Hx tooth extraction due to overcrowding / difficulty intubating for anaesthesia
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11
Q

Ix

A
  1. Polysomongram
    - 15+ episodes a night (5+ in some cases)
    - multi-modal monitoring during a full-night sleep study (EEG, EOG, ECG, capnography, oesphageal manometry, pulse oxymetry)
    - most accepted test
  2. Portable multichannel sleep test
    - fewer parameters
    - not done routinely - avoid if possible
  3. Awake fibre optic endoscopy
    - done to rule out nasal/pharyngeal/laryngeal masses
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12
Q

Possible Cx (7)

A
  • cognitive impairment
  • CVD (e.g. pulmonary HTN, HTN)
  • depression
  • MVAs
  • type II resp. failure
  • impaired glucose metabolism
  • increased mortality
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13
Q

What is OSA an independent RF for?

A

HTN

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14
Q

Rx

A
  1. Weight reduction
  2. smoking cessation, alcohol reduction
  3. change sleep behaviours (sleep on side, tongue/mandibular splint…)
  4. CPAP
  5. Surgery (to repair anatomical defect)
  6. Medication for somnolence (e.g. medafinil)
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15
Q

Screening

A

Screening (e.g. questionnaire) recommended for at-risk populations

  • commercial drivers
  • operators of heavy machinery
  • obesity
  • Other populations at risk from diurnal sleepiness
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