Effect of Woodsmoke on Vascular Function

Study Overview
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Brief Summary
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Exposure to air pollution is a well established risk factor for the development of heart disease. Firefighters are exposed to excess air pollution in the form of wood smoke during the extinguishing of forest or woodland fires. Heart attacks in on-duty firefighters have been linked to specific duties and in particular fire suppression, but the reasons for this increase in risk are not well understood. Exposure to wood smoke may alter blood vessel function and increase blood clot formation to explain the link between fire suppression and heart attacks. The investigators wish to determine the effect of exposure to wood smoke at concentrations found at the perimeter of a woodland fire on blood vessel function and clotting in healthy non-smoking male professional firefighters or volunteers. Volunteers will be studied before and after inhalation of wood smoke or clean air for one hour in a purpose built whole-body exposure chamber. The investigators will perform comprehensive vascular assessments thereafter. Understanding the effects of wood smoke on the blood vessels and clotting will be an important first step in helping to protect firefighters from heart disease. Through research, the investigators hope to identify methods to minimise the risk of heart attacks in firefighters and understand the health effects of a major source of air pollution that is relevant to the general population.

Official Title
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Effect of Woodsmoke on Vascular Function in Healthy Firefighters

Conditions
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Vascular Function

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


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Non-smoking healthy male firefighters or volunteers Exclusion Criteria: Current smoker or regular users of snus 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: 35 Years

Sexes Eligible for Study
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Male

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: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Sham Comparator: Filtered Air Exposure<br>1 hour exposure to filtered air during intermittent exercise | 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: ACh;Procedure: Badimon Chamber<br>* Ex-vivo assessment of thrombus formation using the Badimon Chamber<br>|
| Active Comparator: Woodsmoke Exposure<br>1 hour exposure to dilute woodsmoke at a concentration of 1000µg/m3 during intermittent exercise | 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: ACh;Procedure: Badimon Chamber<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 |  | 4-6 hours after exposure | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Ex-vivo thrombus formation using the Badimon chamber |  | 2 hours after exposure | 
| Plasma t-PA and PAI concentrations following infusion of bradykinin |  | During forearm study, 4-6hours after exposure | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Firefighter, Woodsmoke, Vascular function, Air Pollution, Endothelial function, Thrombosis