What is obstructive sleep apnoea?
- Recurrent episodes of patrial or complete upper (pharyngeal) airway obstruction during sleep, intermittent hypoxia and sleep fragmentation
What is obstructive sleep apnoea syndrome?
- OSA that manifests as excessive daytime sleepiness
What is apnoea?
- Reduction in airflow >90% of baseline for at least 10 seconds or 4% oxygen desaturation lasting ≥10 seconds
What is hypopnoea?
- Reduction in airflow >30% of baseline for at least 10 seconds, associated with >3% desaturation from pre-event baseline
What are the stages of the apnoea-hypopnoea index (AHI)?
- AHI < 5 Normal
- AHI 5-15 Mild
- AHI 16-30 Moderate
- AHI >30 Severe
- ≥15 is diagnostic of OSA
- Calculated by adding apnoeas and hypopnoeas and dividing by total sleep time in hours
What is the oxygen desaturation index (ODI)?
- Number of times per hour of sleep that the O2 saturations falls ≥4% from baseline
What are respiratory effort related arousals?
- Arousals assocaited with a change in airflow that does not meet criteria for apnoea or hypopnoea
What are the symptoms of OSAS?
- Unrefreshing sleep
- Daytime fatigue
- Choking or gasping during sleep
- Impaired concentration
- Recurrent awakenings from sleep
What factors promote airway collapse?
- Negative pressure on inspiration
- Extraluminal positive pressure
- Fat deposition
- Small mandible
What factors promote airway potency?
- Pharyngeal dilator muscle contraction (genioglossus)
- Lung volume (longitudinal traction)
What does the limitied polysomnography study used to investigate OSAS involve?
- O2 saturations
- Thoracic and abdominal effort
What does the full polysomnography study used to investigate OSAS add to the limited study?
- EEG (sleep staging)
- Limb leads
What are the treatment options for OSAS?
- Weight reduction
- Mandibular advancement splints
- Surgery (tracheostomy, bariatric surgery, jaw advancement, palatal surgery)
Does OSAS affect your ability to drive?
- Only need to stop if daytime somnolence