Reversibility of Cardiovascular Injury With CPAP Use: Mechanisms Involved

Study Overview
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Brief Summary
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The purpose of this study is to determine the factors that are associated with improved cardiovascular function with the use of CPAP therapy on subjects diagnosed with moderate to severe obstructive sleep apnea.

Detailed Description
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We will monitor non-invasively changes in arterial stiffness, cardiac mass, pulmonary pressures, endothelial function, etc. We will also assess the reversibility of these changes after only 5-7 days of not using the CPAP mask. In a subgroup of subjects we will explore changes in coronary flow response after 12 weeks of CPAP use compared with baseline.

Official Title
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Reversibility of Cardiovascular Injury With Continuous Positive Airway Pressure (CPAP) Use: Mechanisms Involved

Conditions
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Hypoxia, Hypercapnia, Sleep Apnea, Obstructive, Sleep Disorders, Obesity, Hypertension, Coronary Artery Vasospasm, Right Ventricular Overload, Left Ventricular Function Systolic Dysfunction, Ventricular Hypertrophy

Intervention / Treatment
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* Other: Clinically prescribed CPAP therapy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: subjects naïve of CPAP therapy just recently diagnosed with moderate to severe obstructive sleep apnea (OSA). The degree of OSA is defined by results of a comprehensive polysomnogram requiring an apnea hypopnea index (AHI) >15 events/hour and Epworth score >10, or an AHI >20 events/hour either sex any race between 21-50 years old. Exclusion Criteria: Systolic blood pressure >160 mmHg, or diastolic blood pressure >100 mmHg Changes in antihypertensive medications in the last 6 weeks Restless leg syndrome Average overnight oxygen saturation below 80% Current use of beta-blockers History of coronary artery disease History of Stroke Atrial fibrillation Peripheral vascular disease Suspected cardiac valve abnormality Ejection fraction <50% Type I and type II Diabetes Mellitus (DM) Asthma or confirmed Chronic Obstructive Pulmonary Disease Cigarette smoking in the last 6 months Raynaud's disease Pregnancy (the normal hormonal changes that occur in pregnancy affect greatly arterial stiffness parameters) If a subject becomes pregnant we will discontinue data collection. Physically incapable of resting on left lateral decubitus for 40 minutes. Mastectomy with lymph node removal that might preclude us to monitor blood pressures on both arms

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Clinically prescribed CPAP therapy<br>Clinically prescribed CPAP therapy | Other: Clinically prescribed CPAP therapy<br>* CPAP as prescribed by attending physician<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in endothelium mediated response to brachial artery reactivity test between baseline and 4 and 12 weeks after CPAP therapy | Ultrasound based brachial artery reactivity tests will be performed at entry before CPAP therapy and at 4, 12 weeks post CPAP use and 5-7 days after CPAP withdrawal | 14 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in arterial stiffness between baseline and after CPAP treatment | Subjects will undergo pulse wave velocity testing with applanation tonometry. tonometry recordings will be at entry and after 4 and 12 weeks of CPAP use and 5-7- days after withdrawal. | 14 weeks | 
| Changes in coronary artery flow under a cold pressor test | A subset of subjects with abnormal endothelial function determined during the baseline scan and good echocardiographic images will be invited to participate on this portion of the test. We will record the response to a cold pressor test (submerging their hand in ice water for 1.5 minutes) on left anterior descending coronary artery velocities with transthoracic echocardiography at baseline and after 12 weeks of CPAP therapy. | 13 weeks |