Effect of Continuous Positive Airway Pressure (CPAP) Treatment in the Control of Refractory Hypertension

The working hypothesis for the present study is that treatment with CPAP in patients with an sleep apnea (IAH\>15) and AHT-r is capable of producing significant reductions in blood-pressure levels. This hypothesis is supported by four proven findings: 1. -sleep apnea is an independent risk factor for arterial hypertension (1). 2. -The greater the number of RSD, the greater the loss of control over blood-pressure levels (1). 3. -The prevalence of sleep apnea in patients with AHT refractory to treatment is very high (11,12). 4. -Treatment of patients with sleep apnea and AHT-r with CPAP succeeds in significantly reducing blood-pressure levels in the only (small-scale) studies undertaken to date (14,15). 4\. OBJECTIVES Main objective: To evaluate the effect of treatment with CPAP on blood-pressure levels in patients with AHT refractory to medical treatment. Secondary objectives: * To evaluate the effect of treatment with CPAP on the various elements assessed in BP (systolic/diastolic; daytime/nighttime, etc) and the circadian profile (dipper/non-dipper/raiser patterns; variability and homogeneity of blood-pressure levels, etc) obtained during a 24-hour out-patient study (AMPA). * To analyze the related variables or subgroups of patients most affected by treatment with CPAP. * To evaluate the effect of CPAP on the levels of some of the biological variables involved in the pathogenesis of AHT-r (renin, angiotensin, aldosterone, atrial natriuretic factor, etc).