[Long-term effects of continuous positive airway pressure treatment on subclinical atherosclerosis in obstructive sleep apnoea syndrome]

Association between obstructive sleep apnea and 24-h urine protein quantification in patients with hypertension

The association between obstructive sleep apnea (OSA) and proteinuria is undetermined, with few studies on hypertension, a high-risk group for renal impairment. Therefore, we aimed to explore whether OSA is an independent risk factor for proteinuria in patients with hypertension. We investigated the cross-sectional association between OSA and proteinuria. Participants were divided into groups by apnea hypopnea index (AHI) category. Multivariable Logistic regression analysis was used to evaluate the association between OSA severity, objectively measured sleep dimensions, and proteinuria which is mainly defined by 24-h urine protein quantification > 300 mg/24 h. Sensitivity analyses were performed by excluding those with comorbidities (primary aldosteronism and homocysteine ≥ 15 μmol/L). Of the 2106 participants, the mean age was 47.57 ± 10.50 years, 67.2% were men, and 75.9% were OSA patients. In total participants, compared with those without OSA, patients with mild OSA, moderate OSA, and severe OSA showed 1.09 (95% CI 0.80-1.40), 1.24 (95% CI 0.89-1.74) and 1.47 (95% CI 1.04-2.08) fold risk for proteinuria with a trend test P trend < 0.05. Each 10-unit increase in the AHI, oxygen desaturation index (ODI), and time spent with oxygen saturation < 90% (T90) was found to be associated with 13%, 10%, and 2% higher likelihood of proteinuria in the crude model, significant in adjusted models. The more severe the OSA is, the higher the risk of proteinuria. AHI and T90 are independently associated with a higher risk of structural renal damage in the population with hypertension.

Cardiovascular Disorders Triggered by Obstructive Sleep Apnea-A Focus on Endothelium and Blood Components

Obstructive sleep apnea (OSA) is known to be an independent cardiovascular risk factor. Among arousal from sleep, increased thoracic pressure and enhanced sympathetic activation, intermittent hypoxia is now considered as one of the most important pathophysiological mechanisms contributing to the development of endothelial dysfunction. Nevertheless, not much is known about blood components, which justifies the current review. This review focuses on molecular mechanisms triggered by sleep apnea. The recurrent periods of hypoxemia followed by reoxygenation promote reactive oxygen species (ROS) overproduction and increase inflammatory response. In this review paper we also intend to summarize the effect of treatment with continuous positive airway pressure (CPAP) on changes in the profile of the endothelial function and its subsequent potential clinical advantage in lowering cardiovascular risk in other comorbidities such as diabetes, atherosclerosis, hypertension, atrial fibrillation. Moreover, this paper is aimed at explaining how the presence of OSA may affect platelet function and exert effects on rheological activity of erythrocytes, which could also be the key to explaining an increased risk of stroke.

TLRs and RAGE are elevated in carotid plaques from patients with moderate-to-severe obstructive sleep apnea syndrome

Background

There is growing evidence that obstructive sleep apnea (OSA) promotes vascular endothelial dysfunction and atherogenesis. Pathways that mediate this pathology may include Toll-like receptors (TLRs) and receptor for advanced glycation end products (RAGE) which play a significant role in proinflammatory processes. The aim of this study was to measure the expression of the above-mentioned receptors in relation to OSA severity in carotid plaques obtained during open endarterectomy.

Methods

This prospective study included patients with a sleep study prior to surgery and a plaque specimen obtained during standard open endarterectomy. Immunohistochemistry of TLR2, TLR4, TLR7, TLR9, RAGE, HMGB1, and NF-κB was performed on atherosclerotic plaques from carotid arteries of patients with and without OSA.

Results

There were 46 patients (22 women, mean age 73.2 ± 1.3 years): 14 control patients, 13 with mild, 11 with moderate, and 8 with severe OSA. The expression of all TLRs and RAGE increased proportionately with increasing OSA severity. The largest differences between patients with severe OSA and no OSA were found for TLR2 (2.88 ± 0.35 vs. 1.27 ± 0.47, p < 0.001), TLR4 (2.88 ± 0.35 vs. 1.64 ± 0.5, p < 0.001), TLR9 (2.38 ± 0.52 vs. 1.45 ± 0.52, p < 0.01), and RAGE (2.5 ± 0.53 vs. 1.82 ± 0.6, p < 0.05).

Conclusion

TLR2, TLR4, TLR9, and RAGE expression was significantly increased in carotid plaques of patients with moderate-to-severe OSA when compared with control patients with no OSA and those with mild OSA. TLR and RAGE-mediated pathways may play a significant role in OSA-dependent atherogenesis.

Effect of continuous positive airway pressure on carotid intima-media thickness in patients with obstructive sleep apnea: A meta-analysis

Objective

Obstructive sleep apnea (OSA) is associated with increased carotid intima-media thickness (IMT), an early marker of atherosclerosis. Continuous positive airway pressure (CPAP) is the first-line treatment for OSA. A meta-analysis was performed to determine whether CPAP therapy could decrease carotid IMT.

Methods

The PubMed, Embase, Web of Science, and Cochrane library were searched before March, 2017. Weighted mean difference (WMD) was calculated to estimate the treatment effects of pre and post-CPAP therapy. Seven studies were examined and the meta-analysis was performed using STATA 12.0.

Results

There was no change of carotid IMT before and after CPAP treatment in OSA patients (WMD = 0.052, 95% confidence interval (CI) = −0.002 to 0.105, z = 1.90, p = 0.057). Meanwhile, meta-analysis of the two RCTs showed that carotid IMT was not changed in CPAP group when compared with control group (WMD = 0.002 95% CI = −0.125 to 0.129, z = 0.03, p = 0.976). Subgroup analyses indicated that carotid IMT was significantly decreased after CPAP use in more severe OSA patients (AHI≥50) (WMD = 0.073, 95% CI = 0.022 to 0.124, z = 2.80, p = 0.005) and patients with therapeutic duration ≥6 months (WMD = 0.121, 95% CI = 0.019 to 0.223, z = 2.32, p = 0.021).

Conclusions

CPAP had no impact on carotid IMT in OSA patients. However, carotid IMT was significantly decreased after CPAP treatment in more severe OSA patients and patients with longer CPAP usage.