Mechanisms of Endothelial Cell Dysfunction in Sleep Apnea

• NTPDase (vascular enzyme) activity in white blood cells [ Time Frame: Day 1 (all subjects) and Day 34 (post treatment - sleep apnea only) ] [ Designated as safety issue: No ]
• Circulating endothelial cells (CECs) [ Time Frame: Day 1 (all subjects) and Day 34 (post treatment - sleep apnea only) ] [ Designated as safety issue: No ]

Sleep apnea is a common sleep disorder characterized by temporary stops in breathing during sleep and has been associated with the development of cardiovascular disease. This research will investigate one potential mechanism leading to the development of cardiovascular disorder, specifically, the blockage of blood vessels called "vascular occlusion", in subjects with sleep apnea. A group of healthy controls will be used for comparison. All subjects will undergo clinical evaluation followed by an overnight sleep study and a morning blood draw. Subjects with sleep apnea will be treated according to standard clinical management and followed under the research protocol for one month. At the end of one month, a repeat blood draw will be performed on the sleep apnea subjects for comparative analysis. If a control subject is found to have any abnormality during this research study, he or she will be referred for further clinical evaluation.

The importance of this project is to investigate mechanisms of vascular disease in sleep apnea and determine pathways for intervention, aiming to prevent the development of cardiovascular disease in these individuals.

This proposed research aims to evaluate both NTPDase activity in lymphocytes and levels of circulating endothelial cells (CECs) in patients with intermittent hypoxemia (IH) due to obstructive sleep apnea (OSA) and healthy controls. This is an original approach to define mechanisms which underlie the high incidence of occlusive vascular events in patients with OSA. The evaluation of such pathophysiological mechanisms will lead to a better understanding of the pathways involved and the development of therapeutic strategies targeting the reduction or avoidance of endothelial injury with the ultimate goal of reducing morbidity and mortality associated with these pathologic events in sleep apnea. The standard of care will be used in this protocol, which involves the use of CPAP (continuous positive airway pressure) for treating sleep apnea.

• Obstructive Sleep Apnea
• Intermittent Hypoxemia

• Active Comparator: Sleep Apnea
  Subjects found to have Obstructive Sleep Apnea (OSA) with Intermittent Hypoxemia (IH). This arm will undergo a pre-treatment blood draw, one month of Continuous Positive Airway Pressure (CPAP) to treat OSA, and a post-treatment blood draw.
  Intervention: Device: Continuous Positive Airway Pressure (CPAP)
• No Intervention: Normal Control
  Subject found to have no evidence of Obstructive Sleep Apnea (OSA) after Nocturnal Polysomnography (NPSG). These subjects will only undergo a blood draw and will not have the Continuous Positive Airway Pressure (CPAP) treatment.

Study Group 1: Sleep Apnea

Inclusion Criteria:

• 21 years or older
• Presence of intermittent hypoxemia (IH) and obstructive sleep apnea (OSA)
• No diagnosis of hypertension, coronary artery disease, diabetes, stroke, or evidence of underlying vascular disease

Exclusion Criteria:

• Smoking
• Pregnancy
• Known cardiovascular disease, stroke, or diabetes
• Current or previous treatment for sleep apnea
• Central or Cheyne-Stokes sleep apnea
• Use of supplemental oxygen at night
• Alcohol abuse
• Regular use of sedatives
• Regular use of aspirin or cholesterol lowering agents

Study Group 2: Normal Controls

Inclusion Criteria:

• 21 years or older
• No diagnosis of intermittent hypoxemia (IH) or obstructive sleep apnea (OSA)
• No diagnosis of hypertension, coronary artery disease, diabetes, stroke, or evidence of underlying vascular disease

Exclusion Criteria:

• Smoking
• Pregnancy
• Known cardiovascular disease, stroke, or diabetes
• Use of supplemental oxygen at night
• Alcohol abuse
• Regular use of sedatives
• Regular use of aspirin or cholesterol lowering agents