Hypopnea is defined as which of the following?

• A. Complete cessation of breathing
• B. Rapid breathing
• C. Irregular breathing
• D. Shallow or slow breathing

Answer: (D)

Hypopnea means reduced ventilation due to shallow or slow breathing. Airflow is decreased, but breathing does not stop completely. This is different from apnea, which is a complete cessation of breathing, and from irregular breathing, which describes an erratic or uneven breathing rhythm. In practice, hypopneas are partial reductions in airflow that can be accompanied by lowered oxygen levels or arousal from sleep.