Purpose: Obstructive sleep apnea (OSA) can induce dramatic nocturnal blood pressure fluctuations (NBPFs) and can be associated with nocturnal hypertension and arterial stiffness. We investigated the effect of short- and long-term continuous positive airway pressure (CPAP) therapy on NBPFs, nocturnal blood pressure (BP), and arterial stiffness in patients with coexisting cardiovascular diseases (CVD) and OSA (CVD/OSA).
Methods: Of 86 patients with CVD, 58 also had OSA, while 28 without OSA served as controls. Nighttime BP was measured continuously using pulse transit time (PTT) and arterial stiffness was measured with pulse wave velocity (PWV). A NBPF was defined as systolic BP elevation > 12 mmHg in a 30 s interval of sleep. All measurements were conducted at baseline, after the first night of CPAP, and after 6 months of CPAP therapy.
Results: In CVD/OSA patients, we observed significantly more frequent NBPFs (p < 0.001) compared with controls. CPAP therapy decreased the frequency of NBPFs (p < 0.001), the maximum systolic BP by 9 mmHg (p = 0.021), and PWV (p < 0.001) even after the first night. After long-term CPAP therapy, there was an additional decrease in average nocturnal systolic BP by 10 mmHg (p = 0.039).
Conclusions: Our findings demonstrate that CPAP therapy reduces NBPFs, nocturnal BP, and arterial stiffness in CVD/OSA patients. This effect was demonstrable after the first night of CPAP and grew more robust after 6 months of CPAP therapy.
Keywords: Arterial stiffness; Cardiovascular disease; Continuous positive airway pressure; Nocturnal blood pressure; Nocturnal blood pressure fluctuations; Obstructive sleep apnea.