Which statement best describes an obstructive apnea?

Which statement best describes an obstructive apnea?

• A. At least 30% reduction in airflow for at least 10 seconds, with at least 3% oxygen desaturation
• B. At least 70% reduction in airflow for at least 10 seconds, with effort throughout the apnea
• C. At least 90% reduction in airflow for at least 10 seconds, with effort throughout the apnea
• D. At least 90% reduction in airflow for at least 10 seconds, with no effort

Answer: (C)

Obstructive apnea is defined by a severe drop in airflow—at least a 90% reduction—for a minimum of 10 seconds—while breathing effort remains present throughout the event. The key characteristic here is the ongoing respiratory effort, which shows that the airway is obstructed but the muscles are still trying to breathe. This distinguishes it from central apnea, where there is no respiratory effort during the event, and from hypopnea, which is a partial reduction in airflow (not the full 90% cutoff) often accompanied by desaturation or arousal. So the statement describing a 90% reduction in airflow for 10 seconds with continued respiratory effort best matches obstructive apnea.

Obstructive apnea is defined by a severe drop in airflow—at least a 90% reduction—for a minimum of 10 seconds—while breathing effort remains present throughout the event. The key characteristic here is the ongoing respiratory effort, which shows that the airway is obstructed but the muscles are still trying to breathe. This distinguishes it from central apnea, where there is no respiratory effort during the event, and from hypopnea, which is a partial reduction in airflow (not the full 90% cutoff) often accompanied by desaturation or arousal. So the statement describing a 90% reduction in airflow for 10 seconds with continued respiratory effort best matches obstructive apnea.