Sleep-related hypoventilation or hypoxemia disorders

**Definition:** The primary feature of these disorders is insufficient sleep related ventilation, resulting in abnormally elevated arterial partial pressure of carbon dioxide (PaCO2) during sleep. Sleep-related hypoxemia is diagnosed when overnight monitoring reveals sustained (> 5 minutes) decline in oxygen saturation to ≤ 88% in adults (or ≤ 90% in children) for ≥ 5 minutes.

Note: A definitive diagnosis requires objective evidence based on polysomnography as well as carbon dioxide (CO2) monitoring during sleep (by arterial, end-tidal or transcutaneous measures).