Selected routine laboratory tests in the clinical assessment of patients with obstructive sleep apnea.

INTRODUCTION: Obstructive sleep apnea (OSA) is a chronic disease characterized by repetitive complete or partial occlusion of the upper airways during sleep with respiratory muscle effort, which leads to consecutive apneas and hypopneas. Obstruction of the upper airways during sleep leads to repetitive episodes of disrupted airflow and consequent changes in blood oxygenation, resulting in hypoxaemia and hypercapnia. Intermittent hypoxaemia induces the production of pro-inflammatory factors and promotes metabolic dysregulation and platelet aggregation. OBJECTIVE: The main aim of this study was to determine differences, if any, in selected standard parameters in routine laboratory tests often used in GP practice between patients with obstructive sleep apnea, without comorbidities, and a well-defined control group with the absence of this syndrome proven in polygraphic examination. MATERIAL AND METHODS: Of the 192 clinically assessed persons with suspected OSA and admitted to the Internal Medicine Department in Lublin, 85 were qualified for the study after application of exclusion criteria. Demographic and health behaviour-related data, medical history regarding sleep habits and cardiovascular disease, were collected from each patient. RESULTS: Apart from significantly higher MCV and MCH among the cpontrol group, no significant differences were found between patients with obstructive sleep apnea and the control group. CONCLUSIONS: The results can be useful for the holistic assessment of the health status of patients with newly-diagnosed OSA.

The Influence of Dietary Interventions on Arterial Stiffness in Overweight and Obese Subjects.

Arterial stiffness is often increased in overweight/obese subjects before the development of hypertension. It is also one of the earliest indicators of increased cardiovascular disease risk and can be considered a good predictor of the development of subclinical cardiovascular dysfunction. Arterial stiffness is a significant prognostic factor influencing cardiovascular risk, which dietary habits can modify. Obese patients should use the caloric-restricted diet because it augments aortic distensibility, diminishes pulse wave velocity (PWV), and increases the activity of endothelial nitric oxide synthases. High intake of saturated fatty acids (SFA), trans fats, and cholesterol, typical for the Western diet, impairs endothelial function and raises brachial-ankle PWV. The replacement of SFA with monounsaturated (MUFA) or polyunsaturated fatty acids (PUFA) derived from seafood and plants diminishes the risk of arterial stiffness. The dairy product intake (excluding butter) decreases PWV in the general population. The high-sucrose diet causes toxic hyperglycemia and increases arterial stiffness. Complex carbohydrates with a low glycemic index (including isomaltose) should be recommended to keep vascular health. The high sodium intake (>10 g/day), particularly associated with low potassium consumption, has a deleterious effect on arterial stiffness (↑ baPWV). Since vegetables and fruits are good sources of vitamins and phytochemicals, they should be recommended in patients with high PWV. Thus, the dietary recommendation to prevent arterial stiffness should be similar to the Mediterranean diet, which is rich in dairy products, plant oils, and fish, with a minimal red meat intake and five servings of fruits and vegetables daily.

The Impact of Whole-Body Cryotherapy on Endothelium Parameters in Patients with Ankylosing Spondylitis.

BACKGROUND: The aim of the study was to assess the effect of whole-body cryotherapy (WBC) with subsequent exercise training (WBC group) or exercise-only training (ET group) on endothelium inflammation parameters in patients with ankylosing spondylitis (AS). METHODS: The WBC procedure lasted 3 min, and exercise training consisted of one 60 min session a day, which was the same in each group. The ET group was compared to the WBC group. Endothelium (high-sensitivity C-reactive protein (hsCRP), soluble P-Selectin, soluble vascular cell adhesion molecule-1 (sVCAM-1), neopterin), and oxidative stress (lipid hydroperoxide (LHP), protein sulfhydryl (PSH), lipofuscin, paraoxonase-1(PON-1), and albumin) parameters were estimated 1 day before and 1 day after the completion of the study. RESULTS: A significant decrease in hsCRP, sP-Selectin, sVCAM-1, and neopterin concentrations was observed in the WBC group after the treatment. After the treatment, in both groups, LHP and lipofuscin levels and PON-1 activity decreased significantly. The observed drop in these parameters was higher in the WBC group compared to the ET group. Albumin concentration increased in the WBC group after treatment. CONCLUSION: Procedures of WBC have a beneficial effect on endothelium parameters in AS patients; therefore, this method can be applied in the treatment of this group of patients.

Level of Serum Fetuin-A Correlates with Heart Rate in Obstructive Sleep Apnea Patients without Metabolic and Cardiovascular Comorbidities.

Obstructive sleep apnea (OSA) is the most common type of sleep-induced breathing disorder in the adult population and significantly affects the condition of the cardiovascular system. Fetuin-A (Fet-A) is a hepato- and adipokine, which prevents vessel calcification, and its level correlates with atherogenesis and metabolic disorders. The associations of cardiovascular diseases (CVD) both with OSA, which increases CVD risk, and Fet-A, which prevents CVD, justify the question of their mutual interactions in patients with OSA. Therefore, we sought to analyze Fet-A as an early biomarker of CVD risk in OSA patients without metabolic and cardiovascular comorbidities except for properly controlled arterial hypertension. We have found that in these patients, OSA does not appear to directly affect Fet-A levels. However, high Fet-A levels were more common in the group of patients with OSA, and the hypopnea index was significantly higher among subjects with the highest Fet-A levels. The level of Fet-A in OSA patients positively correlates with pulse rate, and it does not correlate with pulse pressure in this group unlike in the control group, where such a relationship exists. To our best knowledge, this is the first study to analyze this relationship in OSA patients without any significant cardiovascular comorbidities.

Prevalence of target organ damage in hypertensive patients with coexisting obstructive sleep apnea.

INTRODUCTION AND OBJECTIVE: Obstructive sleep apnea (OSA) is associated with cardiovascular risk and higher mortality. Assessment of subclinical organ lesions is significant for prevention of clinically manifested complications which might result in death. The aim of the study was to assess the prevalence of subclinical target organ damage in hypertensive patients with OSA, and to establish whether these lesions are dependent on the intensity of sleep-disordered breathing. MATERIAL AND METHODS: The study covered 67 patients with OSA diagnosed on the basis of polygraphy. Depending on the apnea/hypopnea index (AHI), the patients were divided into two groups: G1 (n=32; AHI=5-30) and G2 (n=35; AHI>30). The control group C consisted of 31 hypertensive subjects with OSA risk estimated as low based on the Berlin Questionnaire (BQ). Each patient had the following parameters measured: intima-media thickness (IMT), ankle-brachial index (ABI), left ventricular mass index (LVMI), and estimated glomerular filtration rate (eGFR). RESULTS: The patients with severe OSA had significantly higher LVMI compared to the control group (130.99±44.6 g/m2 versus 106.61±27.86 g/m2; p=0.0332). The G2 group had higher eGFR than C (104.7±17.96 ml/min/1.73m2, 88.85±17.68 ml/min/1.73m2; p=0.0058). Similar results of eGFR were observed between G1 and C (104.35±21.06 ml/min/1.73m2, 88.85±17.68 ml/min/1.73m2; p=0.0081). G1 and G2 did not differ significantly in terms of eGFR. The other measured parameters, such as IMT and ABI, did not differ significantly between OSA and controls. CONCLUSIONS: Patients with severe OSA demonstrate signs of left ventricular hypertrophy, while early atherosclerotic lesions (ABI and IMT) were not more intense than in the control group. High eGFR levels may indicate hyperfiltration, which does not correlate with OSA intensity level.

The Role of Intermittent Energy Restriction Diet on Metabolic Profile and Weight Loss among Obese Adults.

Obesity is a disease defined by an elevated body mass index (BMI), which is the result of excessive or abnormal accumulation of fat. Dietary intervention is fundamental and essential as the first-line treatment for obese patients, and the main rule of every dietary modification is calorie restriction and consequent weight loss. Intermittent energy restriction (IER) is a special type of diet consisting of intermittent pauses in eating. There are many variations of IER diets such as alternate-day fasting (ADF) and time-restricted feeding (TRF). In the literature, the IER diet is known as an effective method for bodyweight reduction. Furthermore, IER diets have a beneficial effect on systolic or diastolic pressure, lipid profile, and glucose homeostasis. In addition, IER diets are presented as being as efficient as a continuous energy restriction diet (CER) in losing weight and improving metabolic parameters. Thus, the IER diet could present an alternative option for those who cannot accept a constant food regimen.

The Role of Obesity-Induced Perivascular Adipose Tissue (PVAT) Dysfunction in Vascular Homeostasis.

Perivascular adipose tissue (PVAT) is an additional special type of adipose tissue surrounding blood vessels. Under physiological conditions, PVAT plays a significant role in regulation of vascular tone, intravascular thermoregulation, and vascular smooth muscle cell (VSMC) proliferation. PVAT is responsible for releasing adipocytes-derived relaxing factors (ADRF) and perivascular-derived relaxing factors (PDRF), which have anticontractile properties. Obesity induces increased oxidative stress, an inflammatory state, and hypoxia, which contribute to PVAT dysfunction. The exact mechanism of vascular dysfunction in obesity is still not well clarified; however, there are some pathways such as renin-angiotensin-aldosterone system (RAAS) disorders and PVAT-derived factor dysregulation, which are involved in hypertension and endothelial dysfunction development. Physical activity has a beneficial effect on PVAT function among obese patients by reducing the oxidative stress and inflammatory state. Diet, which is the second most beneficial non-invasive strategy in obesity treatment, may have a positive impact on PVAT-derived factors and may restore the balance in their concentration.

Oxidative Stress Markers among Obstructive Sleep Apnea Patients.

Obstructive sleep apnea (OSA) is a chronic respiratory disorder, which can be present in up to 50% of the population, depending on the country. OSA is characterized by recurrent episodes of partial or complete obstruction of the upper airways with consistent movement of the respiratory musculature during sleep. Apneas and hypopneas can lead to a decrease in oxygen saturation, an increase in carbon dioxide in the blood, and subsequent arousals and sleep fragmentation caused by repetitive activation of the central nervous system. As a consequence, intermittent hypoxemia and consequent reoxygenation result in the production of reactive oxygen species, leading to systematic oxidative stress, which is postulated to be a key mechanism of endothelial dysfunction and increased risk for cardiovascular disorders in patients with OSA. In this review, various biomarkers of oxidative stress, including high-sensitivity C-reactive protein, pregnancy-associated plasma protein-A, superoxide dismutase, cell-free DNA, 8-hydroxy-2-deoxyguanosine, advanced oxidation protein products, lipid peroxidation products, receptor for advanced glycation end-products, and thioredoxin are discussed. Biomarkers of oxidative stress have the potential to be used to assess disease severity and treatment response. Continuous positive airway pressure (CPAP) is one of the most common noninvasive treatments for OSA; it keeps the upper airways open during sleep. This reduces episodes of intermittent hypoxia, reoxygenation, and arousal at night. CPAP has been shown to have anti-inflammatory properties and decrease oxidative stress. The administration of certain compounds, like vitamins A, C, and E as well as N-acetylcysteine and allopurinol, can decrease oxidative stress markers. However, their role in the treatment of OSA remains unclear.

The Assessment of Endothelial Dysfunction among OSA Patients after CPAP Treatment.

Background and Objectives: Microcirculation dysfunction is present in patients with obstructive sleep apnea (OSA). Intermittent hypoxia generates "oxidative stress", which contributes to chronic inflammation. The secretion of nitric oxide (NO), which is responsible for adequate regulation of the endothelium, is impaired due to a decrease in endothelial nitric oxide synthetase (eNOS) expression and an increase in endogenous eNOS inhibitors. Furthermore, nocturnal awakenings lead to the dysregulation of cortisol release and increased stimulation of the sympathetic nervous system. The non-invasive method of choice in OSA treatment is continuous positive airway pressure (CPAP). Materials and Methods: PubMed, Scopus, and Google Scholar databases were searched, and only papers published in the last 15 years were subsequently analyzed. For this purpose, we searched for keywords in article titles or contents such as "obstructive sleep apnea", "microcirculation", and "CPAP". In our review, we only studied English articles that reported systemic reviews and meta-analyses, clinical studies, and case reports. Results: Endothelial dysfunction can be assessed by methods based on reactive hyperemia, such as flow-mediated dilation (FMD) measured by ultrasonography, laser-Doppler flowmetry (LDF), or capillaroscopy. In invasive techniques, intravenous administration of vasodilator substances takes place. Some surveys detected impaired microcirculation in OSA patients compared with healthy individuals. The level of dysfunction depended on the severity of OSA. CPAP treatment significantly improved endothelial function and microvascular blood flow and lowered the inflammatory mediator level. Conclusions: The first-choice treatment-CPAP-reduces the number of apneas and hypopneas during the night, induces the reversal of hypopnea and the chronic inflammatory state, and enhances activation of the sympathetic nervous system. Changes are visible as improved blood flow in both macro- and microcirculation, increased arterial elasticity, and decreased stiffness. Thus, early implementation of adequate treatment could be essential to reduce high cardiovascular risk in patients with OSA.