Relação da apneia obstrutiva do sono com a função endotelial, estresse oxidativo, biomarcadores inflamatórios, perfil metabólico e atividade simpática em indivíduos obesos

Abstract

Introduction: obstructive sleep apnea (OSA) is considered a risk factor for cardiovascular disease. The mechanisms responsible for the development of atherosclerosis triggered by OSA are not completely known. However, there is evidence that OSA is associated with increased oxidative stress, higher levels of inflammatory mediators, insulin resistance, increased sympathetic nervous system activity, elevated blood pressure (BP) and endothelial dysfunction. Objective: to evaluate the relation of OSA with endothelial function, oxidative stress, inflammatory biomarkers, metabolic profile, body adiposity, sympathetic activity and BP in obese individuals. Methods: cross-sectional study involving 53 obese patients with body mass index (BMI) > 30 and < 40 kg/m2, without distinction of race and gender, aged between 20 and 55 years. The sleep study was performed with the equipment Watch-PAT200® and the diagnosis of OSA was made when apnea-hipopnea index (AHI) &#8805; 5 events/h. All participants underwent evaluation of: body adiposity (weight, % body fat and circumferences of waist, hip and neck); BP; sympathetic nervous system activity (plasma levels of catecholamines); inflammatory biomarkers (high sensible c-reactive protein (hs-CRP) and adiponectin); oxidative stress (malondialdehyde); metabolism of glucose (glucose, insulin and HOMA-IR) and lipids (total cholesterol and fractions and triglycerides); and endothelial function (reactive hyperemia index (RHI) evaluated by Endo-PAT 2000® and cellular adhesion molecules). Statistical analysis was performed with software STATA version 10. Results: of the 53 evaluated patients, 20 were included in the group without OSA (Control group; CG) (AHI: 2.55±0.35 events/h) and 33 in the group with OSA (OSAG) (IAH: 20.16±3.57 events/h). The mean age (39.6±1.48 vs. 32.5±2.09 years) and the percentage of male participants (61% vs. 25%) were significantly higher in OSAG than in CG (p=0.01). The OSAG compared the CG showed significantly higher values of neck circumference (NC) (40.98±0.63 vs. 38.65±0.75 cm, p=0.02), glucose (92.54±1.97 vs. 80.2±1.92 mg/dL, p=0.0001), systolic BP (126.05±1.61 vs. 118.16±1.86 mmHg, p=0.003) and noradrenaline (0.16±0.02 vs. 0.12±0.03 ng/mL, p=0.02). After adjustment for confounders, glucose and hs-CRP were significantly higher in OSAG. Both groups presented similar values of BMI, insulin, HOMA-IR, lipid profile, adiponectin, diastolic BP, adrenaline, dopamine, adhesion cellular molecules and malondialdehyde. Endothelial function evaluated by RHI was also similar in both groups (OSAG: 1.85±0.2 vs. CG: 1.98±0.1, p=0.31). In correlation analysis, considering the whole group of patients, AHI presented a positive and significant association with NC and hs-CRP after adjustments for confounders. The minimum oxygen saturation was associated negatively and significantly with NC, insulin and HOMA-IR even after adjustments for confounders. Conclusions: the present study suggests that in obese individuals, OSA is associated with higher values of glucose and inflammation; higher AHI presents significant association with central adiposity and with inflammation; and lower oxygen saturation is associated with insulin resistance.