title: A randomized controlled trial of aspirin and exertional heat stress activation of platelets in firefighters during exertion in thermal protective clothing.
abstract: OBJECTIVE
  Platelet aggregation is enhanced in firefighters following short bouts of work in thermal protective clothing (TPC). We sought to determine if aspirin therapy before and/or following exertion in TPC prevents platelet activation.
  
  
  METHODS
  In a double-blind, placebo-controlled study, 102 firefighters were randomized to receive daily therapy (81 mg aspirin or placebo) for 14 days before and a single dose (325 mg aspirin or placebo) following exercise in TPC resulting in four potential assignments: aspirin before and after exercise (AA), placebo before and after exercise (PP), aspirin before and placebo after exercise (AP), and placebo before and aspirin after exercise (PA). Platelet closure time (PCT) was measured with a platelet function analyzer before the 2-week treatment, after the 2 week treatment period, immediately after exercise, and 30, 60, and 90 minutes later.
  
  
  RESULTS
  Baseline PCT did not differ between groups. PCT changed over time in all four groups (p < 0.001) rising to a median of >300 seconds [IQR 99, 300] in AA and >300 [92, 300] in AP prior to exercise. Following exercise, median PCT decreased to in all groups. Median PCT returned to >300 seconds 30 minutes later in AA and AP and rose to 300 seconds in PA 60 minutes after exercise.
  
  
  CONCLUSIONS
  Daily aspirin therapy blunts platelet activation during exertional heat stress and single-dose aspirin therapy following exertional heat stress reduces platelet activation within 60 minutes.
authors.forename: David
authors.initials: D
authors.lastname: Hostler
authors.forename: Joe
authors.initials: J
authors.lastname: Suyama
authors.forename: Francis X
authors.initials: FX
authors.lastname: Guyette
authors.forename: Charity G
authors.initials: CG
authors.lastname: Moore
authors.forename: Riana R
authors.initials: RR
authors.lastname: Pryor
authors.forename: Priya
authors.initials: P
authors.lastname: Khorana
authors.forename: Serina J
authors.initials: SJ
authors.lastname: McEntire
authors.forename: Diane
authors.initials: D
authors.lastname: Comer
authors.forename: Steven E
authors.initials: SE
authors.lastname: Reis
mesh_terms: D000328:Adult; D001241:Aspirin / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005080:Exercise Test / Q000379:methods; D061388:Firefighters; D006359:Heat Exhaustion / Q000097:blood* / Q000517:prevention & control; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D008297:Male; D005082:Physical Exertion / Q000187:drug effects*; D015539:Platelet Activation / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage; D010979:Platelet Function Tests; D011481:Protective Clothing; D012016:Reference Values; D018570:Risk Assessment; D013997:Time Factors
chemical_list: D010975:Platelet Aggregation Inhibitors; D001241:Aspirin