Effect of Real-fire Training on Vascular Function

Study Overview
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Brief Summary
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Fire-fighters are at increased risk of death from heart attacks when compared to other emergency service professionals whose jobs involve similar components such as emergency call-outs and shift work. The unique risk to fire-fighters is likely to reflect a combination of factors including extreme physical exertion, mental stress, heat and pollutant exposure. In the largest analysis of cause of death amongst on-duty fire-fighters, fire-fighter deaths were classified according to the duty performed during the onset of symptoms or immediately prior to any sudden death. The majority of deaths due to a cardiovascular cause (i.e. heart attack) occurred during fire-suppression whilst this activity represented a relatively small amount of a fire-fighters professional time. Fire simulation training centers offer a unique opportunity to assess the heart, blood and blood vessel response to fire suppression in a controlled environment. In this study the investigators will assess healthy career fire-fighters on two occasions: following a fire-suppression training exercise in a purpose built real-fire training center, and following a sedentary period as a control. The investigators will take blood samples to measure platelet activity (platelets are the particles in blood that help blood clot) and will examine how blood clots outside of the body. The investigators will then perform studies placing small needles in the arm to assess blood vessel function following fire suppression. By undertaking this comprehensive assessment of blood, blood vessel and heart function we hope to understand the mechanisms whereby the risk of a heart attack is influenced by fire suppression. The investigators hypothesize that following the fire-suppression exercise firefighters blood will clot more readily and their blood vessels will not relax properly which are two of the main processes in the development of a heart attack.

Official Title
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Effect of Real-fire Training on Vascular Function

Conditions
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Vascular Function, Atherothrombosis

Intervention / Treatment
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* Procedure: Forearm Vascular Study
* Procedure: Badimon Chamber Study


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Non-smoking healthy firefighters Exclusion Criteria: Current smoker History of lung or ischaemic heart disease Malignant arrhythmia Systolic blood pressure >190mmHg or <100mmHg Renal or hepatic dysfunction Previous history of blood dyscrasia Unable to tolerate the supine position Blood donation within the last 3 months Recent respiratory tract infection within the past 4 weeks Routine medication including aspirin and NSAIDs

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Real-fire training exercise<br>Subjects will undergo a 20 minute standardised training exercise in a fire simulation facility. | Procedure: Forearm Vascular Study<br>* Forearm venous occlusion plethysmography to measure forearm blood flow during intra-arterial infusion of the vasodilators Verapamil (10-100 µg/min), bradykinin (100-1000 pmol/min), sodium nitroprusside (2-8 µg/min) and Acetylcholine (5-20 µg/min).<br>* Other names: VP;Procedure: Badimon Chamber Study<br>* Ex-vivo assessment of thrombus formation using the Badimon Chamber<br>|
| Sham Comparator: Sedentary training session<br>Subjects will undergo a training exercise where they will remain sedentary for 20 mins in an ambient temperature. | Procedure: Forearm Vascular Study<br>* Forearm venous occlusion plethysmography to measure forearm blood flow during intra-arterial infusion of the vasodilators Verapamil (10-100 µg/min), bradykinin (100-1000 pmol/min), sodium nitroprusside (2-8 µg/min) and Acetylcholine (5-20 µg/min).<br>* Other names: VP;Procedure: Badimon Chamber Study<br>* Ex-vivo assessment of thrombus formation using the Badimon Chamber<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Forearm blood flow measured by venous occlusion plethysmography in response to infused vasodilators |  | 3-6 hours post exposure | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Ex-vivo thrombus formation using the Badimon chamber |  | 2 hours post exposure | 
| Plasma t-PA and PAI concentrations following infusion of bradykinin |  | During forearm study, 3-6 hours post exposure | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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firefighters, fire-simulation training, myocardial infarction, endothelial function, thrombosis