Effect of Continuous Positive Airway Pressure (CPAP) Versus Auto-titrating Continuous Positive Airway Pressure (APAP) on Resistant Hypertension (HTN) and Arterial Stiffness

• Non-invasive measures of arterial stiffness using applanation tonometry. [ Time Frame: 6 weeks and 12 weeks after initial intervention ] [ Designated as safety issue: No ]
• Standard measures of OSA severity, including AHI and measures of nocturnal oxygenation and sleep quality using polysomnography. [ Time Frame: 6 weeks and 12 weeks after initial intervention ] [ Designated as safety issue: No ]
• Blood tests to assess levels of aldosterone, hsCRP, fasting glucose, HbA1c, and plasma insulin. [ Time Frame: 6 weeks and 12 weeks after initial intervention ] [ Designated as safety issue: No ]

The primary objective is to evaluate the relative effectiveness of fixed CPAP in comparison to APAP in reducing arterial blood pressure in patients with resistant hypertension and obstructive sleep apnea (OSA).

The secondary objectives are: a) to evaluate the relative effectiveness of fixed CPAP versus APAP in improving arterial stiffness, sleep-disordered breathing, sleep quality, inflammatory markers and glucose regulation; b) to identify specific characteristic of persons who respond to the two CPAP modalities in order to identify which device is better for each subject.

The confirmatory hypothesis is that subjects with resistant hypertension and OSA will show a greater degree of blood pressure reduction after 6 weeks of treatment with fixed CPAP in comparison to those treated with APAP. Explanatory and exploratory hypotheses are that a greater reduction in arterial stiffness will be noted when compared with the benefit in blood pressure, that reductions in arterial stiffness will be associated with benefits to serum measurements of inflammatory markers and glucose regulation, and that control of sleep apnea and the attendant improvement in sleep quality will be better with fixed CPAP than APAP.

• Resistant Hypertension
• Obstructive Sleep Apnea

• Device: CPAP
  6 weeks treatment with fixed CPAP
  Other Name: Continuous Positive Airway Pressure
• Device: APAP
  6 weeks of treatment with auto-titrating positive airway pressure
  Other Name: auto-titrating airway pressure

• Active Comparator: auto-titrating
  Patients being treated for 6 weeks with auto-titrating continuous airway pressure.
  Intervention: Device: APAP
• Active Comparator: Fixed
  Patients receiving 6 weeks of treatment with fixed continuous positive airway pressure.
  Intervention: Device: CPAP

Inclusion Criteria:

• Resistant Hypertension
• Moderate Obstructive Sleep Apnea

Exclusion Criteria:

• Creatinine >150 μmol/l
• Systolic blood pressure > 170 mmHg
• Diastolic blood pressure > 105 mmHg
• Secondary cause of hypertension other than OSA
• Treatment within the last 3 months or current treatment for sleep-disordered breathing or some other sleep disorder
• Current treatment or recent treatment within the last 3 months for any other medical condition which has resulted or would be expected to result in a change in blood pressure medications