Obstructive sleep apnoea

• What is obstructive sleep apnoea?


  Common sleep disorder

  Characterised by recurrent episodes of partial or complete upper airway obstruction during sleep -> intermittent hypoxia & arousals from sleep
• What is OSA associated with an increased risk of?


  CVD

  Stroke

  Metabolic disorders
• Pathophys of OSA


  In OSAHS → when pt transitions from wake to sleep, reduced muscle tone + negative pressure generated by inspiration → airway collapse → reduction/cessation of airflow despite ongoing respiratory efforts

  Events trigger brief arousals (micro-awakenings) to restore airway patency → fragmented sleep

  Repetitive cycle of hypoxia, reoxygenation & sleep fragmentation → activation of sympathetic NS, oxidative stress & systemic inflammation → long-term complications of OSAHS (HTN, CVD & metabolic disorders)
• What forces promote airway patency?


  Activity of upper airway dilator muscles & lung volume

  During waking, neural input counterbalances negative intra-luminal pressure generated on inspiration -> keeps airway open
• What forces promote airway collapse?


  Negative intraluminal pressure during inspiration

  Weight of neck & pharyngeal tissue

  Loss of muscle tone during sleep
• What are the signs & symptoms of OSA?


  Episodes of apnoea during sleep (reported by partner)

  Snoring

  Morning headache

  Waking up unrefreshed from sleep

  Daytime sleepiness

  Concentration problems

  Reduced O2 sats during sleep
• What are the RFs for OSA?


  Obesity

  Increased age

  Male

  Menopause

  FHx

  Anatomy (conditions that reduce size of upper airway)

  Alcohol & sedatives

  Smoking

  Medical conditions (hypothyroidism, acromegaly & PCOS)
• What are the Inx of OSA?


  Obs (wake & sleep)

  Full Hx

  Epworth Sleepiness Scale

  EEG during sleep

  Resp airflow during sleep
• What are the DDx of OSA?


  Central sleep apnoea

  Narcolepsy

  Insufficient sleep

  Inadequate sleep hygiene

  Periodic limb movement disorder

  Hypersomnia due to drug or substance abuse

  Hypothyroidism

  Laryngospasm due to GORD

  Sleep-related hypoventilation
• What is the treatment of OSA?


  Weight loss

  CPAP (1st line for moderate or severe)

  Intra-oral devices (e.g. mandibular advancement)

  DVLA should be informed if OSA causes excessive daytime sleepiness
• What is the gold standard Inx for OSA?


  polysomnography

  • measures multiple parameters during sleep