Differences in arousal probability and duration after apnea and hypopnea events in adult OSA patients

Objective: In obstructive sleep apnea (OSA) breathing cessations are often followed by arousals leading into sleep fragmentation and thus, impaired sleep quality. Arousals and fragmented sleep are also related to detrimental cardiovascular events. The key index for OSA diagnosis (i.e. apnea-hypopnea index) attributes equal diagnostic value to apneas and hypopneas despite associated arousals and desaturations may be very different. Thus, considering the severity of consequences of apneas and hypopneas could enhance the estimation of OSA severity. In this study, we investigate whether the probability and duration of apnea- and hypopnea-related arousals differ and whether the difference in desaturations severity following apneas and hypopneas is dependent on sleep stage. Approach: Polysomnographic recordings of 348 consecutive OSA patients were included for analysis. Severity of arousals and desaturations related to hypopneas within different sleep stages were compared to those related to apneas. In addition, probability of arousals related to apneas and hypopneas was evaluated within OSA severity categories. Main results: Apneas caused arousals less frequently than hypopneas in N1, N2, and N3 sleep in all OSA severity categories. However, arousals caused by apneas were longer (pSignificance: Desaturations and arousals related to apneas are more severe compared to those related to hypopneas. Therefore, apneas followed by arousal or desaturation should have different diagnostic value than hypopneas when assessing OSA severity and related risk for cardiovascular consequences