Respiratory function is significantly altered by sleep
Pts with normal awake breathing can develop significant respiratory compromise in sleep
After sleep onset, central motor neuron output falls
Reduced upper airway dilator muscle function narrows the upper airway
Reduced inspiratory muscle activity causes shallower breathing vs awake state
Complicating factors: Obesity, Enlarged neck circumference, Upper airway obstruction (enlarged tonsils, adenoids, polyps), Kinking of the airway, Retrognathia, Chronic obstructive or restrictive ventilatory defects
Def: any abnormal breathing at night causing sx, sleep disturbance or long-term complications
SDB affects sleep via: Sleep fragmentation, Intermittent hypoxia, Intrathoracic pressure swings, Hypercapnia
Classification
1. Snoring
2. Upper airway resistance syndrome (UARS)
3. Obstructive sleep apnea (OSA)
4. Central sleep apnea (CSA)
5. Complex sleep apnea
6. Obesity hypoventilation syndrome (OHS)
7. Hypercapnic respiratory failure assoc with COPD
8. Hypoventilation due to neuromuscular conditions
9. Rare conditions, e.g. Ondine’s curse (CCHS)
Epidemiology
OSA is the most common type of SDB
At least moderate OSA in up to 23% of middle-aged women and 49% of middle-aged men
OSA rates rising worldwide with obesity epidemic
- Oxford Handbook of Sleep Medicine 2022