title: Elevated levels of endothelial cell-derived microparticles following short-term withdrawal of continuous positive airway pressure in patients with obstructive sleep apnea: data from a randomized controlled trial.
abstract: BACKGROUND
  Obstructive sleep apnea has been associated with impaired endothelial function; however, the mechanisms underlying this association are not completely understood. Cell-derived microparticles may provide a link between obstructive sleep apnea and endothelial dysfunction.
  
  
  OBJECTIVE
  This randomized controlled trial aimed to examine the effect of a 2-week withdrawal of continuous positive airway pressure (CPAP) therapy on levels of circulating microparticles.
  
  
  METHODS
  Forty-one obstructive sleep apnea patients established on CPAP treatment were randomized to either CPAP withdrawal (subtherapeutic CPAP) or continuing therapeutic CPAP, for 2 weeks. Polysomnography was performed and circulating levels of microparticles were analyzed by flow cytometry at baseline and 2 weeks.
  
  
  RESULTS
  CPAP withdrawal led to a recurrence of obstructive sleep apnea. Levels of CD62E+ endothelium-derived microparticles increased significantly in the CPAP withdrawal group compared to the continuing therapeutic CPAP group (median difference in change +32.4 per µl; 95% CI +7.3 to +64.1 per µl, p = 0.010). CPAP withdrawal was not associated with a statistically significant increase in granulocyte, leukocyte, and platelet-derived microparticles when compared with therapeutic CPAP.
  
  
  CONCLUSIONS
  Short-term withdrawal of CPAP therapy leads to a significant increase in endothelium-derived microparticles, suggesting that microparticle formation may be causally linked to obstructive sleep apnea and may promote endothelial activation.
authors.affiliation: Department of Clinical Immunology, Churchill Hospital, Oxford, UK. lisa.ayers@nhs.net
authors.forename: Lisa
authors.initials: L
authors.lastname: Ayers
authors.forename: Anne-Christin
authors.initials: AC
authors.lastname: Stoewhas
authors.forename: Berne
authors.initials: B
authors.lastname: Ferry
authors.forename: John
authors.initials: J
authors.lastname: Stradling
authors.forename: Malcolm
authors.initials: M
authors.lastname: Kohler
mesh_terms: D000368:Aged; D001773:Blood Cells / Q000502:physiology; D055252:Cell-Derived Microparticles / Q000378:metabolism*; D045422:Continuous Positive Airway Pressure; D042783:Endothelial Cells / Q000502:physiology; D004730:Endothelium, Vascular / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000503:physiopathology / Q000628:therapy; D028761:Withholding Treatment