title: In vivo platelet activation is increased during sleep in patients with obstructive sleep apnea syndrome.
abstract: BACKGROUND
  Patients with obstructive sleep apnea syndrome (OSAS) have an increased risk of cardiovascular events including myocardial infarction and stroke.
  
  
  OBJECTIVE
  To determine whether in vivo platelet activation and the generation of procoagulant platelet-derived microparticles (PMP) are increased during sleep in patients with OSAS.
  
  
  METHODS
  In vivo platelet activation and PMP formation was determined using flow cytometry in 12 patients with untreated OSAS during and after sleep (4 and 7 a.m.). To study the effect of treatment with continuous positive airway pressure (CPAP), the measurements were repeated at the same time points after initiation of CPAP therapy. Healthy volunteers served as controls (n = 6).
  
  
  RESULTS
  Patients with OSAS had an increased percentage of platelets positive for the activation-dependent epitopes CD63 and CD62P during sleep (4 a.m.) compared to controls (4.8 +/- 0.8 vs. 1.9 +/- 0.4% for CD63, p < 0.01, and 2.0 +/- 0.5 vs. 1.1 +/- 0.3% for CD62P, p < 0.05). In OSAS patients, the amount of CD63- and CD62P-positive platelets was significantly elevated at 4 compared to 7 a.m. (4.8 +/- 0.8 vs. 2.6 +/- 0.4% for CD63 and 2.0 +/- 0.5 vs. 1.1 +/- 0.2% for CD62P, p < 0.05), but not in the control group. The levels of PMP were similar in patients with OSAS and controls at 4 and 7 a.m. After 1 night of CPAP therapy, there was a trend to reduced levels of CD63- and CD62P-positive platelets at 4 a.m.
  
  
  CONCLUSIONS
  Patients with OSAS have increased in vivo platelet activation during sleep, which may contribute to the increased incidence of cardiovascular events in patients with OSAS.
authors.affiliation: Department of Pulmonary Medicine, University Hospital, Bern, Switzerland. Thomas.Geiser@insel.ch
authors.forename: Thomas
authors.initials: T
authors.lastname: Geiser
authors.forename: Florian
authors.initials: F
authors.lastname: Buck
authors.forename: Beat J
authors.initials: BJ
authors.lastname: Meyer
authors.forename: Claudio
authors.initials: C
authors.lastname: Bassetti
authors.forename: André
authors.initials: A
authors.lastname: Haeberli
authors.forename: Matthias
authors.initials: M
authors.lastname: Gugger
mesh_terms: D000368:Aged; D015703:Antigens, CD / Q000032:analysis; D000939:Epitopes; D006801:Humans; D008297:Male; D008875:Middle Aged; D019007:P-Selectin / Q000032:analysis; D015539:Platelet Activation; D010980:Platelet Membrane Glycoproteins / Q000032:analysis; D012890:Sleep / Q000502:physiology*; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D060149:Tetraspanin 30
chemical_list: D015703:Antigens, CD; C554586:CD63 protein, human; D000939:Epitopes; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins; D060149:Tetraspanin 30