Exposure to extreme heat and the physical exertion of a fire increase the cardiovascular risk of firefighters.
Their mission is to save lives. But these perilous interventions put the hearts of firefighters to the test. A study published in Circulation shows that exposure to extreme temperatures and the production of violent physical exertion to fight the fire increases the risk of heart attack in firefighters.
“These very difficult conditions can damage the heart muscle of healthy firefighters,” says Dr Nicholas Mills, cardiologist at the University of Edinburgh (Scotland). This would explain the link between firefighting and the risk of myocardial infarction ”.
The Scottish researchers looked into the subject because the scientific literature, especially American, reports – surprisingly – that cardiovascular pathologies are the main cause of death in firefighters. A French study conducted by the University of Bordeaux and Public Health France rather shows that it is cancer that kills the most firefighters (45%). Pathologies of the circulatory system come second (19%). Until then, no study had been carried out in our country on the mortality of firefighters.
A temperature approaching 400 ° C
To explain the preponderance of heart disease, researchers cited the intense and chronic psychological stress to which firefighters are exposed. They also mentioned exposure to toxic fumes containing in particular carbon monoxide and cyanide, or exposure to extreme conditions during their interventions to extinguish a fire.
And it is this hypothesis that the Scottish researchers wanted to study. For this, they selected 17 volunteer firefighters in good health and non-smokers. The latter agreed to participate in two fire simulations during which they had to withstand a temperature that could climb to 400 ° C and try to save victims weighing on average 79 kg.
Throughout these experiments, and for the next 24 hours, the firefighters’ heart functions were recorded. “Firefighters wore monitors that continuously recorded their heart rate and rhythm, as well as the electrical impulses passing through the heart on either side. We then analyzed them for evidence that the heart tires, which could mean a low blood supply to the heart muscle, ”says Dr Mills.
A profession to watch closely
With the help of these collected data, the cardiologists demonstrated an increase in the mechanism of blood coagulation, which would promote the formation of clots in the vessels. They also observed a drop in blood pressure immediately after the simulated fire. “This drop in blood pressure is surely due to dehydration and the increased supply of blood to the skin to help the body cool down,” explains the Scottish doctor, adding that the more this loss of water is important , especially linked to excessive sweating, the more the blood becomes concentrated in hemoglobin.
In a comment also published in Circulation, Prof. Stefanos Kales of the Harvard School of Public Health believes that these results highlight the need for special monitoring of firefighters. “This study should encourage practitioners to immediately assess and treat firefighters with cardiovascular risks, as well as order additional examinations, such as stress tests, cardiac ultrasounds and coronary artery scans, in order to detect atherosclerosis. or an enlarged heart, ”he wrote.
For their part, Scottish cardiologists suggest that athletes engaging in physical exercise in extreme conditions take precautions to stay hydrated and take time after this effort to rest.
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