The importance of classifying central hypopneas: a call to action.

Obstructive and central sleep apnea share pathophysiologic features and often coexist within individual patients. There is general agreement on the criteria for scoring obstructive and central apneas but less guidance and clarity on how and when to classify obstructive and central hypopneas. This paper is an expert panel discussion that examines the importance of accurately classifying obstructive from central hypopneas and the implications of this distinction for both diagnosis and treatment of sleep-disordered breathing. The physiologic and polysomnographic features that allow hypopneas to be classified as either obstructive or central are discussed. When hypopneas are systematically classified, a substantial number of patients are found to have a high proportion of coexisting central disease. The authors discuss how hypopnea classification has growing importance in evaluating patients for neurostimulation and emerging pharmacologic therapies. Finally, the authors outline the need for reproducible approaches to hypopnea classification.