Sleep-Related Hypoventilation is characterized by which of the following?

• A. Lung Disease
• B. Sleep-Related Hypoventilation
• C. Central Sleep Apnea
• D. Obesity Hypoventilation Syndrome

Answer: (B)

Sleep-related hypoventilation is defined by reduced ventilation during sleep that leads to elevated carbon dioxide levels in the blood at night. The key feature is nocturnal hypercapnia (PaCO2 typically >45 mmHg during sleep), often with accompanying desaturation, that occurs during sleep and is not explained by other sleep disorders.

This makes sense here because the hallmark of this condition is the breathing pattern during sleep itself, not simply an underlying lung disease, a different sleep-disordered breathing, or a condition like obesity hypoventilation syndrome, which centers on daytime hypercapnia and obesity. Central sleep apnea involves a loss of respiratory drive and pauses in breathing, rather than persistent nocturnal hypoventilation with CO2 retention.