What best describes an obstructive apnea?

An obstructive apnea is specifically defined by the presence of complete or near-complete airway obstruction during sleep, occurring along with an effort to breathe. The correct answer highlights that there is a significant reduction in airflow—at least 90%—for a minimum duration of 10 seconds while the patient continues to exert respiratory effort. This distinguishes obstructive apnea from other types of apneas, where airflow may be absent or where the individual's breathing effort is not present.

The rationale behind the 90% reduction in airflow indicates a severe limitation in airflow due to an obstruction, which is the hallmark of obstructive sleep apnea. Additionally, the continued effort to breathe signifies that the respiratory muscles are attempting to overcome the obstruction, thereby demonstrating the obstructive nature of the apnea event.

In contrast, the other options may describe related phenomena but do not capture the essence of obstructive apnea as defined by these criteria. For instance, a 50% reduction in airflow would not represent the severity typically associated with obstructive events, while an absence of breathing for 15 seconds could refer to central apnea, where there is no respiratory effort. A decrease in tidal volume might be indicative of other conditions but does not specifically define an obstructive apnea event. Understanding these parameters is crucial