How long must the nasal pressure signal decrease for an event to be classified as a hypopnea?

A hypopnea is defined as a reduction in airflow that results in a decrease in the nasal pressure signal for a specific duration. The correct classification of a hypopnea requires that the nasal pressure signal decrease for at least 10 seconds. This threshold is critical for ensuring that the event is significant enough to be clinically relevant, as it distinguishes hypopneas from transient fluctuations in airflow that may not necessitate intervention or assessment. This definition aligns with the clinical consensus and standard guidelines used in sleep medicine, ensuring accurate and consistent identification of respiratory events during polysomnography. The emphasis on a 10-second duration helps in determining whether there is enough airflow reduction to potentially impact the patient's oxygen levels or overall sleep quality.