Enhanced Firefighter Rehab Trial: The Role of Aspirin in Preventing Heat Stress Induced Platelet Activation

Heat Stress Disorders Clinical Trial

— EFFoRT  

Official title:

Enhanced Firefighter Rehab Trial: Aspirin Versus Placebo

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT01066923
• Other study ID #: EMW-2008-FP-01638
• Status: Completed
• Phase: N/A
• First received: February 5, 2010
• Last updated: October 10, 2017
• Start date: February 2010
• Est. completion date: June 2011

Study information

• Verified date: October 2017
• Source: University of Pittsburgh
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial 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.

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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 124
• Est. completion date: June 2011
• Est. primary completion date: June 2011
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 49 Years

Eligibility

Inclusion Criteria:

1. Apparently healthy males and females aged 18-49 years

Exclusion Criteria:

1. History of heart disease, vascular disease, or sudden death including prior MI, coronary revascularization, congenital heart disease or history of stroke

2. Hypertension during screening: SBP>139 or DBP>89

3. Those who are taking medications that may be expected to blunt the physiologic response to a treadmill exercise test (e.g. beta blockers)

4. Prescription medication with known side effect of impaired thermoregulation

5. Positive pregnancy test at any time during the study

6. Resting ECG with clinical presentation suggesting coronary heart disease (e.g. pathologic Q wave)

7. Known history of gastrointestinal disease or disorder i.e. diverticulitis which creates a theoretical risk of the core temperature capsule becoming lodged in the digestive tract

8. Medications and supplements known to alter endothelial function (e.g. arginine, omega 3 fatty acids, NSAIDS, tobacco products. This exclusion may be disregarded for subjects willing to stop taking the supplement for the duration of the study

9. At the discretion of the study physician for any other medical condition or prescription medication

10. Known history of platelet dysfunction

11. Aspirin allergy or intolerance

Related Conditions & MeSH terms

• Heat Stress Disorders

Intervention

Drug:
• Daily aspirin (ASA)
Two weeks 82 mg aspirin taken orally prior to exercise protocol

Other:
• Active cooling
Active cooling to remediate heat stress following exercise by placing hands and forearms into cold water

Drug:
• Acute aspirin (ASA)
325 mg chewable aspirin administered immediately following exercise

Other:
• Passive cooling
Removing protective garments for passive cooling following exercise

Drug:
• Daily placebo
Placebo comparator for daily aspirin therapy
• Acute placebo
Placebo comparator for acute aspirin therapy

Locations

Country	Name	City	State
United States	University of Pittsburgh, Emergency Responder Human Performance Lab	Pittsburgh	Pennsylvania

Sponsors (3)

Lead Sponsor	Collaborator
Dave Hostler	Eyemarker Systems, Inc, Federal Emergency Management Administration

Country where clinical trial is conducted

United States, 

References & Publications (2)

Hostler D, Suyama J, Guyette FX, Moore CG, Pryor RR, Khorana P, McEntire SJ, Comer D, Reis SE. A randomized controlled trial of aspirin and exertional heat stress activation of platelets in firefighters during exertion in thermal protective clothing. Preh — View Citation

Olafiranye O, Hostler D, Winger DG, Wang L, Reis SE. Effect of aspirin on acute changes in peripheral arterial stiffness and endothelial function following exertional heat stress in firefighters: The factorial group results of the Enhanced Firefighter Reh — View Citation

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Platelet Closure Time		0, 30, 60, and 90 minutes post exercise
Primary	Vascular Function Measured by Peripheral Arterial Tonometry	Reactive Hyperemia Index	Baseline, 30, 60, and 90 minutes post exercise
Secondary	Activation of Coagulation	This measure was not collected. Equipment was not available.	0, 30, 60, and 90 minutes post exercise
Secondary	Hyperthermia and Hemoconcentration Identified by Retinal Imaging	This measure was not collected. Equipment was not available.	0, 30, 60, and 90 minutes post exercise

External Links

•   Emergency Responder Human Performance Lab