title: The effect of continuous positive airway pressure therapy on arterial stiffness and endothelial function in obstructive sleep apnea: a randomized controlled trial in patients without cardiovascular disease.
abstract: BACKGROUND
  Obstructive sleep apnea (OSA) is associated with increased cardiovascular morbidity and mortality which may be mediated by increased arterial stiffness and endothelial dysfunction. Continuous positive airway pressure (CPAP) therapy improves excessive daytime somnolence (EDS), but its effect on vascular function in patients without preexisting cardiovascular disease (CVD) is unclear.
  
  
  METHODS
  Fifty-three patients with OSA defined as an apnea-hypopnea index (AHI) of ⩾15 and without CVD were recruited into a double-blind, randomized, placebo-controlled, crossover trial of 12weeks of CPAP therapy, of whom 43 participants completed the study protocol. Arterial stiffness was assessed by measuring the augmentation index (AIx) and pulse wave velocity (PWV) by applanation tonometry and cardiovascular magnetic resonance imaging to determine aortic distensibility. Endothelial function was assessed by measuring vascular reactivity after administration of salbutamol and glyceryl trinitrate.
  
  
  RESULTS
  CPAP therapy lowered systolic blood pressure (SBP) (126mmHg [standard deviation {SD}, 12] vs 129mmHg [SD, 14]; P=.03), with a trend towards reduced AIx (15.5 [SD, 11.9] vs 16.6 [SD, 11.7]%; P=.08) but did not modify endothelial function. When subjects with (n=24) and without (n=19) EDS were separately examined, no effect of CPAP therapy on vascular function was seen.
  
  
  CONCLUSIONS
  In patients without overt CVD, CPAP therapy had a nonsignificant effect on AIx and did not modify endothelial function.
authors.affiliation: Department of Sleep Medicine, Royal Infirmary of Edinburgh, Edinburgh, UK. Electronic address: annejones2000@hotmail.com.
authors.forename: Anne
authors.initials: A
authors.lastname: Jones
authors.forename: Marjorie
authors.initials: M
authors.lastname: Vennelle
authors.forename: Martin
authors.initials: M
authors.lastname: Connell
authors.forename: Graham
authors.initials: G
authors.lastname: McKillop
authors.forename: David E
authors.initials: DE
authors.lastname: Newby
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Douglas
authors.forename: Renata L
authors.initials: RL
authors.lastname: Riha
mesh_terms: D058666:Adrenergic beta-2 Receptor Agonists; D000328:Adult; D000420:Albuterol; D001011:Aorta / Q000503:physiopathology; D001783:Blood Flow Velocity / Q000502:physiology; D002318:Cardiovascular Diseases / Q000503:physiopathology; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D018592:Cross-Over Studies; D006970:Disorders of Excessive Somnolence / Q000503:physiopathology / Q000628:therapy; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D005996:Nitroglycerin; D015990:Placebo Effect; D017286:Polysomnography; D011673:Pulsatile Flow / Q000502:physiology; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000628:therapy*; D016896:Treatment Outcome; D059289:Vascular Stiffness / Q000502:physiology*; D014665:Vasodilator Agents
chemical_list: D058666:Adrenergic beta-2 Receptor Agonists; D014665:Vasodilator Agents; D005996:Nitroglycerin; D000420:Albuterol
keywords: Aortic distensibility; Arterial stiffness; Augmentation index; Cardiovascular disease; Continuous positive airway pressure (CPAP) therapy; Endothelial function; Obstructive sleep apnea (OSA); Pulse wave velocity