The effects of arousal accompanying an apneic event on blood pressure and sympathetic nerve activity in severe obstructive sleep apnea

Purpose Arousal plays an important protective role against life-threatening events by terminating the apneic events. However, arousal might also be considered as a contributor to obstructive sleep apnea (OSA) pathogenesis since ventilatory overshoot due to arousal leads to irregular breathing. Patients with OSA who have greater upper airway compensation, expressed by relatively high proportion of apneic events without arousal, could have less adverse events or consequences. Thus, our hypothesis was that the proportion of apneic events with or without arousal affects daytime systemic blood pressure and nocturnal sympathetic activity. Methods Subjects were consecutive 97 patients who had diagnostic polysomnography (PSG) and showed severe OSA (apnea-hypopnea index ≥ 30). The proportion of apnea-hypopneas with arousal among all apnea-hypopneas was calculated in each patient. Then, the association among the proportion of arousal accompanying apnea-hypopneas and a diagnosis of hypertension or heart rate variability during the PSG were investigated. Results The proportion of apnea-hypopneas with arousal among all apnea-hypopneas was higher in hypertensive patients ( n = 47) than that in normotensive patients ( n = 50) (mean ± standard deviation; 80.0 ± 12.8% vs. 73.7 ± 13.0%, p