The term "sleep-disordered breathing" (SDB) refers to conditions where apneas1 and hypopneas2 are present during sleep.
Approximately one in every five adults3 have SDB.
Both apneas and hypopneas are associated with sleep arousal and/or oxygen desaturations of 3-4% or more. Apneas and hypopneas result from upper airway occlusion, either full or partial, or from a decrease in ventilatory drive. There are three types of apnea.
Obstructive sleep apnea (OSA)
The most common type of sleep apnea occurs when the upper airway occludes (either partially or fully) but efforts to breathe continue.
The primary causes of upper airway obstruction are lack of muscle tone during sleep, excess tissue in the upper airway, and anatomic abnormalities in the upper airway and jaw.
Central sleep apnea (CSA)
Affects only 5-10% of the sleep apnea population
Occurs when both airflow and respiratory effort cease. This cessation of breathing results from a decrease in ventilatory drive
Mixed apnea
Is even less common than CSA
Occurs when there is both a central and obstructive component
Disease severity
Disease severity is usually classified according to the apnea/hypopnea index (AHI).
AHI is measured during a sleep study and refers to the number of apneas and hypopneas per hour.
| AHI | |
|---|---|
| Normal | <5 |
| Mild | 5 - <15 |
| Moderate | 15 - <30 |
| Severe | 30+ |