Enhanced Firefighter Rehab Trial: The Role of Aspirin in Preventing Heat Stress Induced Platelet Activation
Condition: Heat Stress Disorders
MeSH terms: Heat Stress Disorders
Study type: Interventional

Summary: 
      The purpose of this study is to determine if aspirin taken by firefighters prevents platelets
      from becoming sticky when body temperature rises during work in protective clothing.
    

Detailed description: 
      Firefighters have the highest rate of line-of duty death (LODD) in the United States. More
      than half of these LODD are cardiovascular related occurring disproportionately around fire
      suppression activities. In addition, shift work, lifestyle factors, and the exposures
      associated with fire suppression (e.g. smoke, chemicals) may predispose the firefighter to
      earlier onset of heart disease or cause a pro-inflammatory state leading to endothelial
      dysfunction.

      Fire suppression activities exacerbate cardiovascular strain and endothelial dysfunction and
      provide potential triggers for ischemic events (e.g. myocardial infarction, stroke). There is
      a rapid rise in heart rate following the activation of a fire company which may persist for
      as long as 20 minutes. Even in cases where heavy work is not being performed, the repetitive
      upper body exercise associated with tool use raises heart rate disproportionately to oxygen
      consumption.

      Finally, there is a rapid rise in core body temperature from increased physical activity,
      environmental heat and impaired thermoregulation that has been shown to cause
      vasoconstriction and activate coagulation during heat stress (12, 13). This has recently been
      demonstrated in firefighters working in thermal protective clothing. The combination of
      triggers created during fire suppression may result in heart attack or stroke, especially in
      firefighters with risk factors for cardiovascular disease.

      Interventions beyond basic fireground rehab may be required to minimize the effect of these
      triggers and enhance a firefighter's health and wellness. Fireground rehab typically focuses
      on cooling and rehydration of the firefighter following fire suppression or training with the
      assumption that these interventions will correct the underlying pathophysiology. Effective
      fireground rehab must deliver appropriate interventions and monitor the progress of the
      firefighter. While correcting hyperthermia and hypohydration are essential for continued
      performance, it is not clear if these therapies correct alterations in platelet or
      endothelial function or if other interventions are necessary to correct these physiological
      disturbances. Furthermore, the options for monitoring the firefighter beyond simply measuring
      heart and respiratory rate are limited. In our FEMA-funded Fireground Rehab Evaluation (FIRE)
      Trial, we demonstrated that five commercially available thermometers did not reliably measure
      or estimate core temperature following uncompensable heat stress (UHS) making it impossible
      to gauge the effectiveness of rehab interventions.
    

Intervention name(s): Daily aspirin (ASA); Active cooling; Acute aspirin (ASA); Passive cooling; Daily placebo; Acute placebo
Intervention type(s): Drug; Other; Drug; Other; Drug; Drug
Intervention description(s): Two weeks 82 mg aspirin taken orally prior to exercise protocol; Active cooling to remediate heat stress following exercise by placing hands and forearms into cold water; 325 mg chewable aspirin administered immediately following exercise; Removing protective garments for passive cooling following exercise; Placebo comparator for daily aspirin therapy; Placebo comparator for acute aspirin therapy
Intervention MeSH terms: Aspirin
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Prevention
Keywords: firefighter; heat stress; platelet activation; aspirin