Which metric on a sleep study is used to diagnose obstructive sleep apnea?

Which metric on a sleep study is used to diagnose obstructive sleep apnea?

• A. Forced expiratory volume in 1 second (FEV1)
• B. Body mass index (BMI)
• C. Oxygen saturation nadir
• D. Apnea-hypopnea index (AHI)

Answer: (D)

The metric used to diagnose obstructive sleep apnea is the apnea-hypopnea index. It quantifies how many breathing interruptions occur per hour of sleep, based on polysomnography. An apnea is a complete pause in airflow for at least 10 seconds, and a hypopnea is a partial reduction in airflow accompanied by a drop in oxygen or an arousal. The AHI averages these events per hour and defines diagnosis and severity: generally, an AHI of 5 or more with symptoms or objective impairment confirms OSA, with mild (5–14), moderate (15–29), and severe (≥30) categories. Oxygen saturation nadir shows the lowest oxygen level reached but does not by itself diagnose OSA. Measures like FEV1 and BMI relate to lung function and body habitus but are not the diagnostic sleep-study metric.

The metric used to diagnose obstructive sleep apnea is the apnea-hypopnea index. It quantifies how many breathing interruptions occur per hour of sleep, based on polysomnography. An apnea is a complete pause in airflow for at least 10 seconds, and a hypopnea is a partial reduction in airflow accompanied by a drop in oxygen or an arousal. The AHI averages these events per hour and defines diagnosis and severity: generally, an AHI of 5 or more with symptoms or objective impairment confirms OSA, with mild (5–14), moderate (15–29), and severe (≥30) categories. Oxygen saturation nadir shows the lowest oxygen level reached but does not by itself diagnose OSA. Measures like FEV1 and BMI relate to lung function and body habitus but are not the diagnostic sleep-study metric.