This study aims to learn about the effects of continuous positive airway pressure (CPAP) on people with autonomic failure and high blood pressure when lying down (supine hypertension) to determine if it can be used to treat their high blood pressure during the night. CPAP (a widely used treatment for sleep apnea) involves using a machine that blows air into a tube connected to a mask covering the nose, or nose and mouth, to apply a low air pressure in the airways.
The study includes 3-5 days spent in the Vanderbilt Clinical Research Center (CRC): at least one day of screening tests, followed by up to 3 study days. Subjects may be able to participate in daytime and/or overnight studies. The Daytime study consists of 2 study days: one with active CPAP and one with sham CPAP applied for up to 2 hours. The Overnight study consists of 3 study nights: one with active CPAP, one with sham CPAP, both applied for up to 9 hours and one night sleeping with the bed tilted head-up.
Male and female subjects, age 40-80 years, with autonomic failure including pure autonomic failure, multiple system atrophy and Parkinson disease.
Neurogenic orthostatic hypotension, defined as a ≥20-mmHg decrease in systolic blood pressure within 3 minutes of standing associated with impaired autonomic reflexes determined by autonomic testing in the absence of other identifiable causes.
Nocturnal supine hypertension (nighttime systolic blood pressure ≥140 mmHg) during the overnight screening for supine hypertension.
Patients who are willing and able to provide informed consent
Patients with history of recent facial trauma or surgery or intolerance to CPAP or to the CPAP mask.
Patients who cannot tolerate the medication withdrawal, defined as those who are unable to stand for at least one minute or those with sustained supine blood pressure ≥180/110 mmHg after the medication withdrawal period.
Bedridden patients or those who are unable to stand due to motor impairment or severe orthostatic hypotension.
Smokers, patients who are pregnant, or have clinically unstable coronary artery disease, or major cardiovascular or neurological event in the past 6 months; heart failure; and other factors which in the investigator's opinion would prevent the subject from completing the protocol including clinically significant abnormalities in clinical or laboratory testing.
Crossover
Active CPAP
DeviceContinuous positive airway pressure (CPAP) is applied at 8, 10, or 12 cm H20. The active CPAP level will be determined during a CPAP titration trial
Sham CPAP
DeviceSham continuous positive airway pressure applied at \<4 cm H2O
Sleeping in a head-up tilt (HUT) position
Other interventionSleeping with the whole bed tilted head-up by 10 degrees or with the head elevated by 13-14 inches.
Systolic blood pressure (daytime)
Change from baseline in systolic blood pressure at 2 hours of the intervention
Systolic blood pressure (overnight)
Area under the curve of the change from baseline in systolic blood pressure
Stroke Volume (daytime)
Change from baseline in stroke volume at 1and 2 hours of the intervention
Natriuretic hormone (daytime)
Percent change from baseline in N-terminal-proatrial natriuretic peptide at 2 hours after the intervention
Nocturnal diuresis (overnight)
Urine volume collected during the night
Morning orthostatic tolerance (overnight)
Area under the curve of the upright systolic blood pressure during head-up tilt
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Vanderbilt University Medical Center
Lead sponsor
National Heart, Lung, and Blood Institute (NHLBI)
Collaborator
