Resistant hypertension and obstructive sleep apnea syndrome in therapy with continuous positive airway pressure: evaluation of blood pressure, cardiovascular risk markers and exercise tolerance.

OBJECTIVE: Resistant hypertension (RH) may be associated with Obstructive Sleep Apnea (OSA), determining a remarkable increase in cardiovascular risk. The aim of the study was to assess the effect of six months with continuous positive airway pressure (CPAP) treatment on blood pressure (BP) values, cardiovascular risk markers, and exercise tolerance in patients with RH and OSA. PATIENTS AND METHODS: Twenty-four patients with RH and OSA were recruited and 24-hour ambulatory BP, intima-media thickness (IMT), flow mediated dilation (FMD), renal resistive index (RRI), and endurance cardiopulmonary exercise testing (CPET) were obtained at enrollment and after 6-month treatment. RESULTS: Significant reduction in clinic systolic and diastolic BP, IMT, and RRI (p = 0.003, p = 0.009, p = 0.020, p = 0.04, respectively) and increase in the left ventricular ejection fraction (p = 0.035) were observed after a 6-month therapy with CPAP. Moreover, improvement in all polysomnographic parameters (number of apneas/hypopneas per hour (p < 0.001), number of episodes of night-time hemoglobin desaturation (ODI) (p = 0.010)), an improvement in Epworth Sleepiness Scale (p < 0.001), as well as in endurance time during constant workload CPET (p = 0.017) were observed too. CONCLUSIONS: CPAP treatment for six months reduces BP and improves cardiovascular risk and exercise tolerance in patients with RH and OSA. An extended cardiovascular assessment, including exercise testing, might be helpful in this population, given the possible reversibility of some endothelial dysfunction and atherosclerotic markers with CPAP treatment, as reported in our study.

Intrarenal hemodynamic and oxidative stress in patients with obstructive sleep apnea syndrome.

BACKGROUND: Oxygen desaturation and reoxygenation, related to intermittent hypoxia cycles due to upper airway obstruction, are major pathophysiologic features of obstructive sleep apnea syndrome (OSAS) and are thought to be responsible for an increased risk of cardiovascular diseases. Continuous positive airway pressure (CPAP) is therefore considered the gold standard in the management of OSAS. Further data demonstrated a high prevalence of OSAS in patients with altered renal function despite the underlying pathophysiological mechanisms that have not been clarified. This study aims to provide evidence on the reported high prevalence of endothelial dysfunction and alterations of the intrarenal hemodynamic in patients affected by OSAS. Furthermore, we evaluated the effect of a CPAP therapy on these endpoints. METHODS: Twenty patients were enrolled in a prospective study and underwent ultrasound examination to assess endothelial dysfunction, by collecting brachial flow-mediated dilation (FMD) and intrarenal artery stiffness, pre- and post a 30-day treatment with CPAP. RESULTS: Endothelial dysfunction and intrarenal artery stiffness significantly improved in all patients after a month of CPAP. In particular, we observed a significant reduction in the renal resistance index (RI) (p < 0.001) and systolic/diastolic ratio (S/D) ratio (p < 0.001) and a significant increase of FMD (p < 0.001). The apnea-hypopnea index (AHI) showed a negative correlation with Δ FMD (p < 0.05, r = -0.46). Conversely, a positive correlation exists between Δ RI and the oxygen desaturation index (ODI) (specificare la sigla) (p < 0.05, r = 0.46). CONCLUSIONS: Our study firstly showed a significant effect of CPAP on renal perfusion and endothelial function in OSAS patients without concomitant cardiovascular comorbidities.