Does CPAP treatment improve blood pressure in patients with obstructive sleep apnea and hypertension?

Obstructive sleep apnea (OSA) independent of obesity (OBS) imposes severe cardiovascular risk. To what extent plasma cystine concentration (CySS), a novel pro-oxidative vascular risk factor, is increased in OSA with or without OBS is presently unknown. We therefore studied CySS together with the redox state and precursor amino acids of glutathione (GSH) in peripheral blood mononuclear cells (PBMC) in untreated male patients with OSA (apnea-hypopnea-index (AHI) > 15 h−1, n = 28) compared to healthy male controls (n = 25) stratifying for BMI ≥ or < 30 kg m−2. Fifteen OSA patients were reassessed after 3–5-months CPAP. CySS correlated with cumulative time at an O2-saturation <90% (Tu90%) (r = 0.34, p < 0.05) beside BMI (r = 0.58, p < 0.001) and was higher in subjects with “hypoxic stress” (59.4 ± 2.0 vs. 50.1 ± 2.7 µM, p < 0.01) defined as Tu90% ≥ 15.2 min (corresponding to AHI ≥ 15 h−1). Moreover, CySS significantly correlated with systolic (r = 0.32, p < 0.05) and diastolic (r = 0.31, p < 0.05) blood pressure. CPAP significantly lowered CySS along with blood pressure at unchanged BMI. Unexpectedly, GSH antioxidant capacity in PBMC was increased with OSA and reversed with CPAP. Plasma CySS levels are increased with OSA-related hypoxic stress and associated with higher blood pressure. CPAP decreases both CySS and blood pressure. The role of CySS in OSA-related vascular endpoints and their prevention by CPAP warrants further studies.

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The Worsening of Positional Mild Obstructive Sleep Apnea over Time Is Associated with an Increase in Body Weight: Impact on Blood Pressure and Autonomic Nervous System

Respiration ◽

10.1159/000517031 ◽

2021 ◽

pp. 1-10

Author(s):

Wei-Hsiu Chang ◽

Hsien-Chang Wu ◽

Chou-Chin Lan ◽

Yao-Kuang Wu ◽

Mei-Chen Yang

Keyword(s):

Blood Pressure ◽

Obstructive Sleep Apnea ◽

Nervous System ◽

Autonomic Nervous System ◽

Sleep Apnea ◽

Obstructive Sleep ◽

Mild Obstructive Sleep Apnea ◽

Positional Dependency ◽

Over Time

Background: Most patients with mild obstructive sleep apnea (OSA) are positional dependent. Although mild OSA worsens over time, no study has assessed the natural course of positional mild OSA. Objectives: The aim of this study was to evaluate the natural course of positional mild OSA, its most valuable progression predictor, and its impact on blood pressure (BP) and the autonomic nervous system (ANS). Methods: This retrospective observational cohort study enrolled 86 patients with positional mild OSA and 26 patients with nonpositional mild OSA, with a follow-up duration of 32.0 ± 27.6 months and 37.6 ± 27.8 months, respectively. Polysomnographic variables, BP, and ANS functions were compared between groups at baseline and after follow-up. Results: In patients with positional mild OSA after follow-up, the apnea/hypopnea index (AHI) increased (9.1 ± 3.3/h vs. 22.0 ± 13.2/h, p = 0.000), as did the morning systolic BP (126.4 ± 13.3 mm Hg vs. 130.4 ± 15.9 mm Hg, p = 0.011), and the sympathetic activity (49.4 ± 12.3% vs. 55.3 ± 13.1%, p = 0.000), while the parasympathetic activity decreased (50.6 ± 12.3% vs. 44.7 ± 13.1%, p = 0.000). The body mass index changes were the most important factor associated with AHI changes among patients with positional mild OSA (Beta = 0.259, adjust R2 = 0.056, p = 0.016, 95% confidence interval 0.425 and 3.990). The positional dependency disappeared over time in 66.3% of patients with positional mild OSA while 69.2% of patients with nonpositional mild OSA retained nonpositional. Conclusions: In patients with positional mild OSA, disease severity, BP, and ANS regulation worse over time. Increased weight was the best predictor for its progression and the loss of positional dependency. Better treatments addressing weight control and consistent follow-up are needed for positional mild OSA.

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