Hiroki Uyama1, Motoo Yamauchi2, Yukio Fujita1, Masanori Yoshikawa1, Yoshinobu Ohnishi3, Hiroshi Kimura4. 1. Second Department of Internal Medicine (Department of Respiratory Medicine), Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-8522, Japan. 2. Second Department of Internal Medicine (Department of Respiratory Medicine), Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-8522, Japan. mountain@pastel.ocn.ne.jp. 3. Center for Sleep Disorders, Tenri City Hospital, Tenri, Japan. 4. Department of Advanced Medicine for Pulmonary Circulation and Respiratory Failure, and Department of Pulmonary Medicine, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan.
Abstract
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 < 0.01). However, heart rate variability was not associated with the proportion of apnea-hypopneas with arousal. CONCLUSIONS: Apnea-hypopneas terminated by arousal are more often present in those with current systemic hypertension but independent of sympathetic nerve activity, compared with those whose apnea-hypopnea events do not have as many arousals. One could target an elevation in arousal threshold as a pathway for reducing daytime blood pressure.
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 hypertensivepatients (n = 47) than that in normotensive patients (n = 50) (mean ± standard deviation; 80.0 ± 12.8% vs. 73.7 ± 13.0%, p < 0.01). However, heart rate variability was not associated with the proportion of apnea-hypopneas with arousal. CONCLUSIONS:Apnea-hypopneas terminated by arousal are more often present in those with current systemic hypertension but independent of sympathetic nerve activity, compared with those whose apnea-hypopnea events do not have as many arousals. One could target an elevation in arousal threshold as a pathway for reducing daytime blood pressure.
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