Which statement best describes an obstructive apnea?

Which statement best describes an obstructive apnea?

• A. At least 90% reduction in airflow for at least 10 seconds, with effort throughout the apnea
• B. At least 30% reduction in airflow for at least 10 seconds, with at least 3% oxygen desaturation
• C. At least 70% 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: (A)

Obstructive apneas occur when airflow falls by a very large amount for at least 10 seconds while the person continues to make respiratory effort. The key is both a near-total drop in airflow and the presence of ongoing effort against an obstruction. The described scenario—90% or greater reduction in airflow for 10 seconds or longer with ongoing effort—fits this definition exactly, which is why it is the best description. The other statements don’t fit obstructive apnea: a 30% reduction with desaturation fits a hypopnea, not a full apnea; a 70% reduction is not enough to meet the apnea threshold; and a 90% reduction with no effort would indicate a central apnea, where there is no respiratory effort.

Obstructive apneas occur when airflow falls by a very large amount for at least 10 seconds while the person continues to make respiratory effort. The key is both a near-total drop in airflow and the presence of ongoing effort against an obstruction. The described scenario—90% or greater reduction in airflow for 10 seconds or longer with ongoing effort—fits this definition exactly, which is why it is the best description.

The other statements don’t fit obstructive apnea: a 30% reduction with desaturation fits a hypopnea, not a full apnea; a 70% reduction is not enough to meet the apnea threshold; and a 90% reduction with no effort would indicate a central apnea, where there is no respiratory effort.