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Hard on the Heart
Research illuminates the relationship between firefighting and cardiac strain
By Shannon Pieper

By now, you can probably recite in your sleep that “heart attacks are the leading cause of line-of-duty deaths.” But do most firefighters truly understand their increased risk for cardiac events?

I recently asked that question of Professor Denise Smith, who presented “Sudden Cardiac Events: Why Are Firefighters at Risk?” this afternoon at FDIC. “Many firefighters are paramedics, so they understand the pathology behind it—that you can have a cardiac event due to infarction or arrhythmia due to ischemia,” Smiths says. “But when firefighters deploy to a fire, they’re not thinking about the cardiac strain they’re undergoing. Nor do I think most firefighters have thought about reducing cardiac LODDs from a strategic standpoint.”


The Trigger Effect
Smith, who teaches Health and Exercise Sciences at Skidmore College in Saratoga Springs, N.Y., and also works with the Illinois Fire Service Institute, isn’t arguing that firefighting itself causes heart attacks. “Someone who is fit and healthy, and undertakes firefighting activity, is not likely to have a heart attack,” she says. “But, if someone has underlying disease, and it could be silent disease, then firefighting can serve as a trigger for a sudden cardiac event on the fireground.”

While much of Smith’s research is designed to document the physiological strain of firefighting, it’s the recommendations that come out of the research that are so important. “If firefighting is serving as a trigger, there must be something we can do in terms of policies, procedures, technologies, etc. to mitigate against the stress of fire fighting,” she says.

Some of these recommendations you’ve heard before, but they bear repeating because they can save firefighters’ lives. As Smith sees it, there are at least four areas that warrant attention:

1. Physical aptitude testing
“Medical clearance is absolutely essential, because we can assess risk factors and often we can detect early (or silent) indicators of CV disease that raise risk of sudden cardiac events,” Smith says. “The data is absolutely convincing that fitness is critical.” Just as doing a set of 15 pull-ups becomes easier over time for your upper-body muscles, plunging into a fire environment with 50 lbs. of gear, on air, is less stressful to your heart if your heart is used to being exercised at that level. “Fitness improves work performance and cardiac efficiency, it makes it less likely that blot clots will occur, and it increases blood volume, which in turn protects against dehydration,” Smith says.

2. Weight maintenance
“It’s hard to say it without sounding critical, but there is too much overweight and obesity in the fire service,” Smith says. Being overweight or obese is related to high cholesterol and plaque development, and it places a larger burden on the heart. “You’re working harder if you’re heavier,” Smiths says. “It also interferes with thermal balance, so you’re more likely to have heat stress and cardiovascular strain.”

Smith says that data on the body fatness of firefighters reveals that new recruits are getting heavier and heavier. “If you’re overweight coming in, where does that put you in 20 years?” Smith says. “It makes many firefighters vulnerable to sudden cardiac events.” Granted, the upper-body strength required by firefighting operations tends to favor larger frames, but Smith warns not to avoid the obvious: “The truth is, we all know whether we’re overweight, and we can do a great deal about it without a lot of new resources.”

3. Medical monitoring
Technology by which incident commanders will have access to firefighters’ vital signs, core temperature, etc.—is frequently touted as the way to reduce cardiac LODDs. Smith supports on-scene medical monitoring, but she cautions that it won’t be a cure-all: “We don’t have an accurate way to measure core temperature that’s feasible for the fireground,” she says. “In the lab, we ask firefighters to ingest one of those core temperature monitoring pills eight hours before we do testing. We can’t do that in the real world.”

But here’s the interesting thing: Smith says that during most fireground operations—a normal room-and-contents fire in which the firefighter is using one or two air bottles—there’s little evidence that body temperature rises to dangerous levels anyway. “The body has a tremendous ability to maintain homeostasis, and body temperature doesn’t change quickly,” Smith says. “Imagine putting foil over a turkey and putting it in a 45-degree oven for 10 minutes. When you pull it out, the turkey isn’t even hot yet. The outer skin might be warm but the inside is still cold. Similarly, all the data shows small core temperature fluctuations even when the firefighter is experiencing significant physical symptoms of heat stress.” She goes on to point out that even when core temperature is not high enough to be considered dangerous from a thermoregulatory standpoint, the increase in core temperature places additional strain on the cardiovascular system and that may be very significant.

Smith is equally quick to point out that core temperature monitoring may play a significant role in reducing deaths that occur during training. “Of the fatalities in the fire service related to heat stress, most are in training scenarios,” she says. “In training, we have firefighters conduct repeated bouts of firefighting activity, or other strenuous physical activity, and the effects can be cumulative, especially on a hot day. Those firefighters are susceptible to elevations in core temperature, and technology could be used to help us there.”

4. Rehab
Directly related to medical monitoring is rehab, which involves rest, recovery, cooling, fluid replacement, rehydration and nourishment. “On the fireground, you have someone who’s fatigued, dehydrated, and has experienced heat stress. Effective rehab should mitigate all those factors and thereby decrease cardiovascular strain,” Smith says.

Many fire departments still lack formal rehab procedures, however, and I asked Smith why that was the case, if the value of rehab is so obvious. “I think there’s some reluctance related to the culture—the idea of taking a break during a fire doesn’t come naturally to many firefighters,” Smith says. “The other factor that undermines the acceptance of rehab is the cost associated with it. Departments are already struggling to maintain adequate staffing; if you tell them to bring the crews out more often, it places more strain on the staffing.”

Getting Better?
Since Smith spends so much of her time studying sudden cardiac events in the fire service, I wondered about her long-term outlook: Are things getting better or worse when it comes to firefighters and heart attacks? “I’m really conflicted,” she says. “Last year’s LODD number was encouraging, but one year’s data must be viewed cautiously. It comes after many years of increased attention and serious efforts to decrease cardiovascular events, so I’m cautiously optimistic that it’s a positive trend.

“On the other hand, the data that continues to nag at me is the data that suggests firefighters continue to become heavier and are joining the force heavier, and the recognition that we still have a large percentage of fire departments that don’t require any medical screening—this is unacceptable considering that firefighting is one of the most strenuous activities humans will ever encounter.”

You can bet Smith will be watching the numbers, hoping that research like hers continues to drive a positive trend in cardiac LODDs.

Shannon Pieper is deputy editor for FireRescue magazine.