What does the term "hypopnea" refer to in a sleep study?

The term "hypopnea" refers to a reduction in airflow that leads to decreased oxygen saturation during sleep. This condition is characterized by a partial blockage of the upper airway, resulting in shallow breathing that does not completely obstruct airflow but is sufficient to affect the body's oxygen levels. In sleep studies, hypopneas are typically identified when there is a decrease in the amplitude of respiratory airflow, coupled with a drop in blood oxygen saturation percentage.

This definition highlights the critical distinction between hypopnea and other respiratory events. For instance, a complete cessation of airflow, known as apneas, is not what hypopnea describes. Additionally, conditions like excessive snoring or increased heart rate do not directly correlate with the definition of hypopnea, as they pertain to different aspects of sleep physiology. Understanding the nuances of these terms is essential for accurately interpreting sleep study results.