Background-There is increasing evidence that obstructive sleep apnea (OSA) is an independent risk factor for arterial hypertension. Because there are no controlled studies showing a substantial effect of nasal continuous positive airway pressure (nCPAP) therapy on hypertension in OSA, the impact of treatment on cardiovascular sequelae has been questioned altogether. Therefore, we studied the effect of nCPAP on arterial hypertension in patients with OSA. Methods and Results-Sixty consecutive patients with moderate to severe OSA were randomly assigned to either effective or subtherapeutic nCPAP for 9 weeks on average. Nocturnal polysomnography and continuous noninvasive blood pressure recording for 19 hours was performed before and with treatment. Thirty two patients, 16 in each group, completed the study. Apneas and hypopneas were reduced by Ϸ95% and 50% in the therapeutic and subtherapeutic groups, respectively. Mean arterial blood pressure decreased by 9.9Ϯ11.4 mm Hg with effective nCPAP treatment, whereas no relevant change occurred with subtherapeutic nCPAP (Pϭ0.01). Mean, diastolic, and systolic blood pressures all decreased significantly by Ϸ10 mm Hg, both at night and during the day. Conclusions-Effective nCPAP treatment in patients with moderate to severe OSA leads to a substantial reduction in both day and night arterial blood pressure. The fact that a 50% reduction in the apnea-hypopnea index did not result in a decrease in blood pressure emphasizes the importance of highly effective treatment. The drop in mean blood pressure by 10 mm Hg would be predicted to reduce coronary heart disease event risk by 37% and stroke risk by 56%.

The exact influence of sleep-related breathing disorder (SRBD) on blood pressure control remains unknown. We investigated the influence of different degrees of SRBD on daytime blood pressure and its association to documented hypertension by examining 1,190 consecutive patients referred for diagnosis of SRBD. The protocol includes clinical interview, physical examination, office blood pressure measurement, cholesterol, and blood gas analysis. Unattended home monitoring of nocturnal breathing was performed for assessment of SRBD activity (respiratory disturbance index [RDI]). RDI was independently and linearly associated with systolic blood pressure (unstandardized coefficient [B] = 0.07 +/- 0.03, p = 0.03), diastolic blood pressure (B = 0.07 +/- 0.02, p = 0 < 0.001), and heart rate (B = 0.10 +/- 0.02, p < 0.001) at rest. The relative risk for hypertension (blood pressure >/= 160/95 mm Hg) increased with SRBD severity (odds ratio [OR], 4.15 for RDI >/= 40 versus < 5 [95% CI, 2.7 to 6.5]). This relative risk was also elevated in younger ( 50 yr) (OR, 7.15 versus 2.70 for RDI >/= 40 versus < 5). These cross-sectional clinical data suggest a relationship between SRBD severity and systolic blood pressure, diastolic blood pressure, and heart rate after control for confounders such as body mass index (BMI), age, alcohol/nicotine consumption, cholesterol level, and daytime PO(2) and PCO(2). SRBD is an independent risk factor for systemic hypertension with an increased likelihood in subjects

R Ri is sk k o of f t tr ra af ff fi ic c a ac cc ci id de en nt ts s i in n p pa at ti ie en nt ts s w wi it th h s sl le ee ep p--d di is so or rd de er re ed d b br re ea at th h--i in ng g: : r re ed du uc ct ti io on n w wi it th h n na as sa al l C CP PA AP P Fifty nine patients completed the study. The accident rate was significantly decreased from 0.8 per 100,000 km (untreated) to 0.15 per 100,000 km with nCPAP treatment. Variables that were considered to be likely to increase accident risk (sleeping spells, fatigue, vigilance test reaction time, daytime sleep latency) also improved with treatment.We conclude that treatment of sleep-disordered breathing by nasal continuous positive airway pressure is related to reduction in patient motor vehicle accident rates, probably due to the reversal of excessive daytime sleepiness. Eur Respir J., 1996Respir J., , 9, 2606 This study is part of the research project 2.9107: "Sleep related breathing disorders and traffic security", carried out on behalf of the "Bundesanstalt für Straβenwesen".

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