Establishing a physiological normative value of area-based hypoxic burden in obstructive sleep apnea

This study aimed to establish a physiological normative value for area-based hypoxic burden, also known as "hypoxic dip area" (HDA), in obstructive sleep apnea (OSA). HDA is a novel metric that may better characterize intermittent hypoxemia in OSA and predict outcomes. A physiological normative value was necessary for its routine clinical use. Researchers analyzed data from 10 large cohorts, including 14,031 subjects. HDA was defined as the area bounded by SpO2 nadirs with a desaturation of 2% or more. Based on the 97.5th percentile of HDA among asymptomatic subjects, a cutoff of 8.6 %min/h was established. Individuals with HDA equal to or greater than 8.6 %min/h (9,531 subjects) demonstrated worse nocturnal hypoxemia, higher apnea-hypopnea index, and a higher prevalence of cardiovascular disease and hypertension. This physiologically derived threshold for HDA can be useful in clinical practice to distinguish between normal and abnormal physiological profiles.