Oxidative Stress and Endothelial Dysfunction in Obstructive Sleep Apnea

Exhaled Markers of Oxidative Stress and Endothelium-dependent Vascular Relaxation in Obstructive Sleep Apnea. Effect of Continuous Positive Airway Pressure Therapy.

Patients with sleep apnea syndrome have repeated apneic events that induce periodic hypoxia-reoxygenation, drawing away an overproduction of oxidants. This exaggerated generation of oxidants is associated with a dysfunction of the vascular endothelium that evolves, in its turn, towards cardiovascular diseases such as systemic hypertension, stroke, and myocardial infarction. The major aim of our study is to examine the effect of CPAP treatment on biochemical (markers of oxidative stress) and functional (endothelium-dependent vascular relaxation reactivity) abnormalities at 1 and 4 weeks of treatment.

Subjects will undergo overnight polysomnography in the sleep laboratory (PSG1, D0), which will be immediately preceded and followed by measurements of oxidative stress in exhaled gas and vascular relaxation. Patients included in the OSAS group will be randomly assigned to treatment by either CPAP or Placebo (sham CPAP) for 4 weeks. Measurements of oxidative stress in exhaled gas and vascular reactivity will be repeated immediately before and after PSG2 and PSG3 at D7 and D30, respectively.

Inclusion Criteria:

• No smoking
• 30-70 years old subjects
• being referred for daytime hyper- somnolence and snoring
• apnea hypopnea index >=30/hour and desaturation index>=30/hour

Exclusion Criteria:

• Chronic lung diseases.
• Exposure to occupational contaminants.
• Active smoking within last 2 years.
• Alcoholism.
• Chronic systemic disease other than OSAS.
• Treatment with vasoactive drugs or antioxidants
• Respiratory infection or vaccination during the 6 weeks preceding the PSG1.