阻塞性睡眠呼吸暂停低通气综合征（OSAHS）是继发性高血压病重要诱因。持续气道正压通气（CPAP）在理论上可通过改善OSAHS而降低血压水平，但大量文献显示CPAP对OSAHS降压作用存在争议。目前尚无资料显示何种OSAHS亚型可从CPAP中获得明显降压效应。据文献报道OSAHS血压变异性(BPV)高低与血压水平密切相关。预实验发现夜间短时BPV高的OSAHS患者，CPAP降压效果明显优于BPV低的患者，且血压下降幅度与干预前后四氢生物蝶呤变化密切相关。我们推测：OSAHS夜间短时BPV的高低对CPAP降压效果有预判作用;CPAP可通过降低夜间短时BPV,减少不规则血流剪切力对血管内皮细胞影响,干预内皮型一氧化氮合酶脱偶联机制，从而达到降压目的。本研究拟通过观察CPAP对BPV不同亚型的OSAHS合并高血压患者的降压疗效及血管内皮损伤机制的差异，为OSAHS合并高血压的精准治疗提供理论依据

Obstructive sleep apnea hypopnea syndrome (OSAHS) is an important inducer of secondary hypertension. Although theoretically continuous positive airway pressure (CPAP) treatment can reduce the level of blood pressure (BP) through improving OSAHS, an accumulative data suggest that it is still controversial about the BP reducing effects by CPAP in OSAHS patients. So far no data can show exactly which subtype of OSAHS patients can be beneficial from the BP reducing efficacy by CPAP. Previous study showed that blood pressure variability (BPV) was closely associated with hypertension. It was detected in our previous study that the BP reducing efficacy of CPAP treatment was more remarkable in those OSAHS patients with a higher nocturnal short-term BPV than those with a lower nocturnal BPV. Moreover, we also found that the BP reducing amplitude was closely associated with the changes of tetrahydrobiopterin (BH4) before and during CPAP treatment. Therefore, we speculate that a) for OSAHS patients with hypertension their nocturnal short-term BPV can be served as a predictor for evaluation of the BP reducing efficacy by CPAP; b) CPAP treatment can achieve its BP reducing efficacy through inhibition of both nocturnal BPV and effects of irregular shear stress on vascular endothelial cells, as well as intervention on endothelial nitric oxide synthase (eNOS) uncoupling mechanism which can reverse declined blood NO level. Through observation on the disparity in CPAP's BP reducing efficacies in different short-term BPV subtypes of OSAHS with hypertension as well as the injury results of vascular endothelium and associated mechanisms, the current study is aimed to provide theoretic basis for precise treatment for OSAHS patients with hypertension.