OSA occurs where upper airway obstruction (partial or complete) blocks airflow during sleep (see images below). This is usually due to low muscle tone causing relaxation of the muscles around the tongue and throat, excessive tissue in the upper airway, or anatomical abnormalities. OSA is more common in those with obesity, increased age, hypertension, and atrial fibrillation.
Figure 1: Airflow obstruction in obstructive sleep apnoea
Reproduced with permission from Australian Medical Home Sleep Testing
Common symptoms of OSA may include:
- Loud snoring
- Witnessed apnoeas
- Choking arousals, recurrent wakenings
- Unrefreshing sleep, daytime sleepiness
- Impact on mood, memory or concentration
- Impact on work performance or relationships
- Cardiovascular consequences of OSA
Untreated OSA is associated with significant physiological sequelae. Overnight hypoxaemia and large intra-thoracic pressure swings lead to increased sympathetic activity, systemic hypertension, endothelial dysfunction, oxidative stress, tissue ischaemia, as well as platelet activation and increased coaguability. Ventricular ectopics, brady-arrhythmias and decreased heart rate (HR) variability may also occur. OSA is closely associated with atrial fibrillation (AF).