Clinical presentation and definitions of sleep-related breathing disorders

The sleep disordered breathing (SDB) patients need to be monitored for sleep and breathing during sleep. However there is no consensus about the definitions of the most common features observed during the night. Although apnea is usually defined as a cessation of airflow lasting more than 10 seconds, the definitions of hypopnea differ in the literature with respect to the amount of reduction of airflow and to the drop in oxygen desaturation. Variations in the technique of monitoring airflow and ventilary effort can cause variation in the detection of SDB events. We discuss in this paper the standard definitions of respiratory events as observed during the night and the elements of diagnosis obtained with the polysomnographic examination for the SDB patients.