Sleep Disordered Breathing
Obstructive Sleep Apnea is defined as apnea-hypopnea index greater than or equal to five (ie more than 5 events per hour), and has been found to be present in 9% of women and 24% of men (1). Male sex and obesity are strong associations. The term Sleep Disordered Breathing is broader and more general: it includes Central Sleep Apnea (which is not obstuctive), as well as the more minor forms of obstuctive breathing that can occur in sleep, including snoring and Respiratory Effort Related Arousals (RERAs) when ventilation remains adequate but the increased effort of breathing causes sleep disturbance. When the average hourly disturbance rate includes RERAs as well as apneas and hypopneas, some centres now use the term Respiratory Disturbance Index.