This is the second column in a series discussing the number-one cause of firefighter line-of-duty deaths (LODDs): sudden cardiac death. To review the previous column (April 2009), firefighters are at a higher risk of cardiac death than the general public. The most strenuous physical activities, including fire suppression and physical training, have the highest risk of cardiac death. Additionally, responding to and returning from alarms also has a higher risk of cardiac death, while non-emergency duties, EMS and non-fire responses did not have a higher risk of cardiac death. To completely understand this problem, what it is about these activities that put firefighters at such a high risk of cardiac death must be explored.
Anyone who puts on bunker gear and self-contained breathing apparatus (SCBA) and drags a charged line up a flight of stairs knows how physically demanding firefighting is. It has been well documented that firefighting, in particular fire suppression, requires firefighters to operate at maximal levels of exertion. The American Heart Association classifies firefighting as the most intense category. Firefighters must perform at the highest level of cardiovascular function.
Firefighters experience an immediate dramatic increase in heart rate and blood pressure in response to the receipt of an alarm. This is due to the "fight-or-flight response," which is that rush of adrenaline firefighters get when the alarm comes in. A sharp increase in blood pressure could provoke a heart attack, which would explain why firefighters are at a higher risk of cardiac death while responding to or returning from alarms.
It is also well known that physical activity can provoke heart attacks and sudden cardiac death. This helps explain why firefighters are at a higher risk of cardiac death than the general public. The high stress and physical workload that firefighting places on a firefighter's cardiovascular system may precipitate a heart attack. Recent medical research shows that firefighters who died of cardiac deaths had pre-existing cardiovascular disease after review of their medical records in these LODDs. All of the firefighters that died of cardiovascular disease had major modifiable risk factors for cardiovascular disease.
These studies have shown that age greater than 45, smoking, previous diagnosis of cardiovascular disease and high blood pressure are strong risk factors for cardiovascular disease and sudden cardiac death in firefighters. Elevated cholesterol levels were found to be a strong indicator of cardiovascular disease in firefighters, but not of sudden cardiac death.
The majority of firefighters who die of cardiovascular disease are men. This is because men have a higher risk of cardiovascular disease at younger ages, while for reasons that are not clearly understood, women have a lower risk of developing cardiovascular disease until age 55. This would explain why cardiac deaths are seen almost exclusively in male firefighters, since in women the risk of cardiovascular disease increases only after menopause. So the presence of major modifiable cardiac risk factors in firefighters with underlying cardiovascular disease can be used as a predictor of firefighters with the highest risk of cardiac death.
Specific risk factors have been identified in firefighters. Two important risk factors are age and gender. Men have an inherently higher risk of cardiovascular disease than women as discussed above. This is significant, since over 99% of the firefighters in this country are males. Other studies have documented significant proportions of firefighters with high blood pressure, high cholesterol levels and obesity. Also, it has been documented that half of the deceased firefighters in one study had an established diagnosis of cardiovascular disease. This is significant, since it has been shown that the presence of these cardiac risk factors increases the risk of sudden cardiac death in firefighters.
The risk factors for cardiovascular disease are divided into two categories: non-modifiable risk factors and modifiable risk factors. Non-modifiable risk factors are risk factors that cannot be changed such as age or gender. Modifiable risk factors are conditions that can be changed mainly through lifestyle changes or medical therapy.
Non-modifiable risk factors are age, gender, family history of cardiovascular disease, diabetes mellitus and previous diagnosis of cardiovascular disease. Modifiable risk factors are high blood pressure, high cholesterol, cigarette smoking, obesity and sedentary lifestyle.
It should be noted that although a patient cannot change the fact that he or she has diabetes, adequately controlling blood sugars can decrease the progression of cardiovascular disease in diabetics. Additionally, controlling modifiable risk factors can decrease the overall risk of developing cardiovascular disease.
To review the important points of this column:
- It is most likely the high physical intensity of firefighting that places firefighters at a high risk of sudden cardiac death
- Sudden cardiac death is most likely to occur in firefighters with underlying or established cardiovascular disease
- The presence of cardiac risk factors in firefighters can be used to predict which firefighters are at most risk to have underlying cardiovascular disease and are at the most risk for cardiac death
- Significant proportions of firefighters have been shown to have cardiac risk factors that can be used to predict who is at risk of sudden cardiac death
Next: Current medical screening guidelines to identify the firefighters who are most at risk.
DR. RAYMOND BASRI, MD, FACP, is in the private practices of internal medicine and diagnostic cardiology in Middletown, NY. Dr. Basri is a Diplomate of the American Board of Internal Medicine and president of the Mid-Hudson Section. He received the 2008 Laureate Award of the American College of Physicians, of which he is a Fellow. Dr. Basri also is clinical assistant professor of medicine at New York Medical College, attending physician in the Department of Internal Medicine at Orange Regional Medical Center and on the consulting staff in cardiology at The Valley Hospital in Ridgewood, NJ. He is a member of the Excelsior Hook and Ladder Company in Middletown and a deputy fire coordinator for Orange County. Dr. Basri is the senior physician of the Disaster Medical Assistance Team (DMAT NY-4). He is a senior aviation medical examiner for the Federal Aviation Administration (FAA) and chief physician for Health & Safety Specialists in Medicine, which does onsite medical examinations for the fire service and consultant to FirePhysicals.com. ERIC BERGMAN, PA-C, is a physician assistant practicing internal medicine at Hartford Hospital in Hartford, CT. He earned a bachelor of science degree in allied health from the University of Connecticut and a master's degree from Albany Medical College. He is a member of the Killingworth, CT, Volunteer Fire Company; a past company officer and life member of the Avon, CT, Volunteer Fire Department; and a past member of the Shaker Road-Loudonville Fire Department in Colonie, NY.