[Usefulness of arousals for the detection of sleep breathing disorder]

Because of the difference of sensitivity among measurement techniques, upper airway obstruction events cannot always be scored as apnea or hypopnea. We hypothesized that arousal accompanied with breathing disturbance is a more sensitive index for the diagnosis of sleep breathing disorders than others. We studied 75 patients with sleep breathing disorder by polysomnograph. Breathing disturbance related arousal (B-Ar) was defined as an arousal accompanied with at least one of the following (apnea, hypopnea, more than 4% oxygen desaturation, snoring), and the breathing disturbance indices were compared. There were close relationships between B-ArI and apnea hypopnea index (AHI), oxygen desaturation index (DI), and percent of total sleep time with SpO2 below 90% in all patients (r = 0.93, r = 0.58, r = 0.92, respectively, all p < 0.001). In 25 patients whose AHI was below 20 per hour, no relationship between B-ArI and AHI was found, and B-ArI was significantly greater than AHI. Thus, B-ArI seemed to be more sensitive than AHI. In all 6 patients whose AHI was below 10, B-ArI was lowered decreased by continuous nasal positive airway pressure therapy. These results suggest that B-ArI may be more sensitive in the detection of sleep breathing disorders than the other indices when AHI is below 20 per hour.