What is the minimum duration for which the event must last to be classified as a hypopnea?

The minimum duration for an event to be classified as a hypopnea is 10 seconds. This duration is significant because it ensures that the event is pronounced enough to have a measurable impact on the patient's oxygen saturation levels and overall sleep quality. In clinical practice, hypopnea is characterized by a reduction in airflow (typically defined as a decrease of at least 30% from baseline) that occurs alongside an associated desaturation of oxygen or an arousal from sleep. The 10-second threshold helps in standardizing the diagnosis across sleep studies, ensuring that hypopneas are not only transient but also significant enough to warrant clinical attention. Hence, recognizing the importance of duration in the definition aids in accurately assessing and managing sleep disorders.