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Preventing Fire Fighter Fatalities from Cardiovascular Events

Posted on by John Howard, MD

Welcome to the first post of the NIOSH Science Blog. We are pleased to inaugurate this new avenue of communication by highlighting a recent NIOSH publication that recommends strategic interventions to prevent deaths from heart attacks and other cardiovascular events among firefighters.

Some 1.1 million firefighters selflessly risk their own safety and health for our safety and the safety of our communities. Last month we saw this heroism first hand as over 7,000 firefighters battled the dangerous wildfires in Southern California. Fortunately, no fire fighters lost their lives but 130 suffered injuries as of November 2, according to media reports. It is an inherently dangerous job, but injuries, illnesses, and deaths should not be viewed or accepted as inevitable occurrences. NIOSH and other safety and fire service agencies work to protect fire fighters and prevent the estimated 100 fire fighter fatalities that occur each year. Through its Fire Fighter Fatality Investigation and Prevention Program, NIOSH investigates the deaths of fire fighters in the line of duty to formulate science-based recommendations for preventing future deaths and injuries.

In June 2007, NIOSH issued an Alert on the most common cause of fire fighter fatalities—sudden cardiac death. The Alert, Preventing Fire Fighter Fatalities Due to Heart Attacks and Other Sudden Cardiovascular Events, incorporates findings from 131 NIOSH investigations, examines the circumstances of these cardiac events, reviews the current fire service standards, provides case reports, and makes recommendations for preventing injury and death to fire fighters from preventable cardiovascular conditions. Thomas Hales, Scott Jackson, and Tommy Baldwin of NIOSH were the principle contributors to the Alert. The document also reflected the assistance of twelve outside reviewers from fire-service, occupational health, and medical organizations and agencies.

Coronary artery disease in fire fighters is due to a combination of personal and workplace factors. The personal factors are well known: age, gender, family history, diabetes mellitus, hypertension, smoking, high blood cholesterol, obesity, and lack of exercise. Not as widely known, however, is that fire fighters have exposures to workplace factors that are associated with adverse cardiovascular outcomes such as exposure to fire smoke (notably carbon monoxide, hydrogen cyanide, and particulates), heat stress, noise, and shift work.

The Alert contains several recommendations for dealing with both the workplace factors and the personal factors in the work setting. Among other steps, these include recommendations for action by fire departments to provide appropriate post-offer, pre-placement medical evaluations for candidates, to develop and encourage participation in comprehensive wellness/fitness programs, to ensure the existence of a smoking cessation program, to reduce exposure to fire smoke, and to ensure that fire stations are non-smoking facilities.

In fire fighting and in regard to work in general, it is important to link worker health and safety protection with work-based health promotion. We call this worklife (see NIOSH WorkLife Initiative). In the past, a concern with focusing on personal health at work was that too much emphasis might be placed on the worker’s individual behavior at the expense of dealing with known workplace hazards. Today’s reality is that we cannot consider each type of risk in a vacuum. As illustrated in the Alert, a firefighter’s compromised physical fitness combined with work-related exposures and physical demands known to trigger sudden cardiac events can have deadly outcomes.

Just as NIOSH recommends that fire departments implement effective prevention programs to address the risk factors for cardiovascular disease, we would like to see every workplace preventing work-related illness, injury, and disability and promoting healthy living and lifestyles to reduce and prevent chronic disease. This is truly a win-win scenario resulting in the optimized health of the U.S. workforce.

If you have examples of successful programs that address both work-related and personal health issues, please post them on the blog. Your experiences can help inform the NIOSH WorkLife initiative.

In good health,

John Howard, MD
Director, National Institute for Occupational Safety and Health

Posted on by John Howard, MD Tags ,

14 comments on “Preventing Fire Fighter Fatalities from Cardiovascular Events”

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

    I am delighted to see this innovative approach to communication appear on the web. This will get the message out about occupational safety and health tools and it will encourage dialogue and discourse among stakeholders. More than just talking, this use of the web will reduce injuries and save manys lives. Thank you NIOSH, I am proud to know that the web has become a tool for this vital life-saving effort thanks to NIOSH.

    As both a practicing occupational physician and an active fire-fighter, I would agree with Mr. Mirer’s comments. It goes without saying that we need to reduce cardiac risk factors in our firefighters by addressing issues such as smkoing, weight, exercise levels and diet. But NIOSH needs to step up and deal with the particulate issues, particularly involving wildland fires. The particulate content of these fires are not adequately addressed even by a N95 respirator. Additional research needs to be done in this area.

    I very much welcome the NIOSH science blog. This responds to the posting about cardiac mortality among fire service personnel.

    This post does not sufficiently emphasize the plausible role of particulates, and therefore the unsustainability of SCBA respiratory protection in fire and fire recovery sites. And, in my opinion, far overemphasizes personal risk factors where NIOSH has much reduced experience and authority.

    The American Heart Association scientific statement of 2004 (available in full text at http://circ.ahajournals.org/cgi/content/full/109/21/2655) notes increased cardiac mortality associated with increases in exposure to PM2.5-and-below at community exposure levels in the range of current NAAQS limits of 15 ug/M3 annual average and 35 ug/M3 24-hour. There is limited data available on particulate levels in fire vicinity and fire recovery sites, but it would be hard to believe these levels are not far exceeded. Further, fire vicinity sites would likely shift particle size distribution to smaller sizes, increasing particle number and surface area beyond those observed in community air monitoring. These consensus findings are uniformly ignored by the occupational health community — like a tree that burned in the forest with no one to smell it.

    Personal observations of community fire interventions suggest that fire service members actually enter smoky buildings without donning SCBA, likely to protect the limited duration air supply for when it is acutely needed, and stand around the fire site for some time during and after the attack on the fire. The fitness of fire service personnel is frequently noted by medical personnel involved in medical care, often phrased “superfit.”

    These new finding about cardiac effects should spur emphasis on causes amenable to successful intervention, such as environmental exposures, rather than the poorly understood causes of health risk behaviors.

    It has been a source of surprise that there has been a silence and lack of response from NIOSH regarding the recent findings related to the “probable” increased cancer risk of firefighters at four organ sites and the “Possible” risk at several others (see LeMasters et al. 2006, JOEM).

    I note that your Blog addresses specifically NIOSH related research. Perhaps a more inclusive approach to NIOSH’s research as well as others might better serve firefighters. The International Agency for Research on Cancer (IARC) examined fire fighters as an occupation with potential cancer risk, in part, based on that article at their recent meeting October, 2007 in Lyon France that evaluated “Fire fighters, Painters and Shift Workers”.

    Thank you to everyone who read the blog and took the time to comment. Regarding concerns about the health effects of fire smoke particulate, we would like to point out that the blog is a summary of the full Alert. The Alert much more comprehensively addressed various factors relating to fire fighters’ risk of heart attacks and other cardiovascular events, including exposures to particulates and other contaminants in smoke. The Alert:

    discussed fire smoke particulate as a chronic and triggering agent and cited the relevant literature,
    highlighted the importance of controlling exposure to fire smoke, and
    highlighted the need for additional research on the health effects of fire smoke on the cardiovascular system.
    Regarding concerns that the blog emphasized personal risk factors over occupational exposures that that could cause heart disease, we would again request that readers refer back to the Alert where both types of risks are represented. Furthermore, it should be noted that it is very difficult to develop engineering controls at the fire ground. Thus, most efforts to protect fire fighters involve administrative controls and the use of personal protective equipment. In addition, the NIOSH fatality investigations and other peer-reviewed articles show that individual modifiable cardiac risk factors are a big problem for fire fighters. As a result numerous fire service organizations (IAFF, NFPA, NVFC, IAFC) have pushed for comprehensive fitness/wellness programs. While health promotion should not come at the expense of health “protection,” both are needed to address the safety and health needs of fire fighters.

    Thomas Hales, M.D., M.P.H., is a Senior Medical Epidemiologist and Team Leader for the NIOSH Fire Fighter Fatality Investigation and Prevention Program, Cardiovascular Component

    Excellent report. There is a critical need to provide more support for translational research to apply current knowledge to solving health related problems of first responders such as innovative health protection programs for the fire fighters, sensor technology to provide the fire-chief with “real-time” health status of firefighters during firefighting, etc. The health knowledge base and sensor technology exist but it has to be adapted for the benefit of the first responders. It can be done but there is a critical need for concerted financial support from appropriate funding agencies.

    Due to adrenalin increase, blood pressure increase, body temp. increase, heart rate increase, stress, and possilble toxic exposure(chemicals unknown). Have you experienced any arhythmic problems in firefighters.

    There are a number of factors that could, and probably do, trigger cardiac arrhythmias in fire fighters. Most of these factors occur during emergency response [adrenalin rush, blood pressure increase, heart rate increase, stress] or during fire suppression [carbon monoxide, or other components of fire smoke]. Cardiac arrhythmias resulting from these exposures would probably be temporary. We are unaware of any studies addressing the question of whether fire fighters have increased rates of cardiac arrhythmias compared to the general population.

    In 2000, NIOSH’s Health Hazard Evaluation program completed a report addressing whether job stressors were associated with EKG changes taken during fire department annual medical evaluations. EKGs were available for 179 of the 196 participants working in a fire station. The NIOSH physician reported that 73% (131 persons) were within normal limits and 27% (48 persons) were abnormal. The NIOSH physician noted several EKG abnormalities; the most common was sinus arrhythmia, occurring in 23 participants. The only other abnormalities noted in more than five participants were sinus bradycardia (11 persons) and conduction delay (10 persons). Due to the small number of participants with any single condition other than sinus arrhythmia, we focused further analysis on this finding. We did not find a meaningful linear relationship (that is, more job stress associated with more sinus arrhythmia) between sinus arrhythmia and any of the job stressors studied. The full report is available at the following website, http://www.cdc.gov/niosh/hhe/reports/pdfs/1994-0390-2822.pdf.

    I am a union safety representative, investigating the death by cardiac arrest of one of our members. He was a male in his 50s who worked in a steel plant, and was undergoing “gas rescue” training in case of a release of carbon monoxide from a blast furnace. He was not a firefighter or EMT; the company requires this training of everyone assigned to work in ironmaking (blast furnace) areas. He had limited SCBA training, but was required to don an SCBA and perform a mock rescue by placing a rescue mannequin on a stretcher in a room filled with theatrical fog. He had several cardiac risk factors, and we believe the medical evaluation was insufficient. It appears that the attack occured while he was bending down, but before he had to handle the mannequin. Most physiological stress would have come from the SCBA itself. The literature I’ve seen on SCBAs is mostly military or from firefighters, where the effect of the SCBA is entangled with the effect of the turnout gear or other PPE, and sometimes with the toxic atmosphere. Can anyone direct me to research on the physiological stress caused by the SCBA itself in light to mederate exercise? In addition, there may have been some phychological stress, since he was unprepared for the drill, and was not told what he would encounter. Is there any research which would help me assess that factor?

    Question 1
    To answer the question of whether the medical screening was appropriate we would need the physiologic requirements of the task.

    Based on the brief description, “gas rescue” seems to involve donning an SCBA (about 30 pounds), searching for the mannequin, and carrying/dragging a 150-200 pound mannequin outside the room. Research has shown that carrying a 143-pound victim requires a MVO2 (maximum rate of oxygen consumed during exercise) of 17.5 ml/kg/min with a mean heart rate of 152 beats per minute. Dragging a 200-pound victim required a MVO2 of 20.0 with a mean heart rate of 148. [Glenhill & Jamnik Can J Spt Sci 1992;17(3):207-213.] Using a 34-pound SCBA ensemble, conducting “light exertion” resulted in a heart rate that was 15 beats per minute higher than a control group doing light exertion without the SCBA [White MK et al. Ergonomics 1989;32(9):1111-1123]. Wearing a SCBA increases oxygen consumption by 0.54 l/min [Loubevaara et al. J Occup Med 1985;27:213-216] and reduces their maximal performance capacity by 20% [Raven et al. J Occup Med 1977;19:802-806].

    Given these numbers, it is reasonable to conclude the task of “gas rescue” would involve moderate physical exertion. Workers engaging in moderate physical exertion should be medically evaluated to ensure the worker is not at increased risk of a cardiac event. The medical evaluation should include a history, physical exam, and, if “at risk” for an coronary event, an exercise stress test.)

    The American College of Cardiology / American Heart Association (ACC/AHA ) [Gibbons Circulation 2002;106:1883-1892] considers the evidence to be in favor of conducting exercise stress tests for those with:

    1. previous history of CAD (e.g. angina, heart attack, angioplasty, bypass, etc),
    2. asymptomatic individuals with diabetes mellitus, but “less well established” (Class IIb)- for:
    3. asymptomatic men older than 45 years, and women older than 55 years who are sedentary and plan to start vigorous exercise;
    4. Asymptomatic men older than 45 years, and women older than 55 years who are involved in occupations in which impairment might jeopardize public safety (e.g., fire fighters);
    5. Asymptomatic men older than 45 years, and women older than 55 years who are at high risk for CAD due to other diseases (e.g., peripheral vascular disease and chronic renal failure)
    6. Those at moderate risk of CAD by the number and severity of their risk factors (e.g. Framingham risk of coronary event of >10% in the next 10 years)[NHLBI http://hp2010.nhlbihin.net/atpiii/calculator.asp?usertype=prof%5D.

    Question 2
    Could the effort of donning the SCBA alone triggered his sudden cardiac arrest?

    The following articles (cited in the NIOSH Fire Fighter Alert) found that moderate to heavy/severe exertion can trigger a cardiac arrest.

    Willich SN, Lewis M, Lowel H, et al. [1993]. Physical exertion as a trigger of acute myocardial infarction. N Eng J Med 329:1684-1690.

    Tofler GH, Muller JE, Stone PH, et al. [1992]. Modifiers of timing and possible triggers of acute myocardial infarction in the Thrombolysis in Myocardial Infarction Phase II (TIMI II) Stiudy Group. J Am Coll Cardiol 20:1049-1055.

    Mittleman MA, Maclure M, Tofler GH, et al. [1993]. Triggering of acute myocardial infarction by heavy physical exertion. N Eng J Med 329:1677-1683.

    Albert CM, Mittleman MA, Chae CU, Lee IM, Hennekens CH, Manson JE [2000]. Triggering of sudden death from cardiac causes by vigorous exertion. N Engl J Med 343:1355-1361.

    Kales SN, Soteriades ES, Christoudias SG, Christiani DC [2003]. Firefighters and on-duty deaths from coronary heart disease: a case control study. Environ health: a global access science source. 2:14. [http://www.ehjournal.net/content/2/1/14]. Date accessed: February 15, 2007.

    Kales SN, Soteriades ES, Christophi CA, Christiani DC [2007]. Emergency duties and deaths from heart disease among fire fighters in the United States. N Eng J Med 356:1207-1215.

    I am a graduate student at ODU in a risk assessment course. After reviewing your article, I agree that many fire fighters are neglecting to take personal responsibility to prevent cardiac occurrences. Departments are equally to blame for not requiring their professional fire fighters to pass regular physical and medical standards, which leads to the majority of cardiac occurrences. However, there is no information related to sleep disturbances and cardiac occurrences. Many professional fire fighters work shift hours and are frequently jolted awake by sirens and alarms. Sudden arousal causes the body to go into the “fight or flight” mode, increasing blood pressure and heart rate. Does NOISH plan to study the relationship between lack of restful sleep and cardiac occurrences? Does NOISH plan to support 12 hour work shifts verses 24 hour shifts in order to promote better overall health and an overall reduction in cardiac occurrences on the job?

    You raise the question of whether sleep disturbances among fire fighters contribute to their risk of CVD.

    One issue relates to the physiologic response to the alarm (while sleeping or while awake). We know from studies in the general population [Albert et al. 2000] and in fire fighters [Kales et al. 2003, 2007] that heavy physical exertion is associated with sudden cardiac events. Presumably, the increase in heart rate and blood pressure are responsible for this association. Studies from Barnard et al. [1975] and Kuorinka et al. [1981], have shown that fire fighter’s heart rate (and presumably blood pressure) increase with the alarm. In addition, the Kales et al. studies found that alarm response was associated with a 1.5-5.5 times risk of a coronary event compared to hanging out at the fire station.

    The second issue relates to shift work and/or fatigue.

    Several studies in working populations (non-fire fighter) suggest a modest association between rotating shifts (e.g., a week of days, a week of evenings, a week of nights, with weekends off) and heart disease [Steenland 2000]. Because most career fire departments work 24-hour shifts and volunteers fire fighters do not work shifts at all, these findings may have limited application to the fire service. However, emergency calls or other tasks might require nighttime awakening during the 24-hour period on-duty which might produce cardiovascular demands similar to rotating shifts. Little empirical data are available comparing regular rotating and 24-hour shifts.

    A 24-hour shift, however, is long, stressful, and fatiguing. The literature does suggests long hours can increase blood pressure and may lead to increased heart disease, independently of other stressful conditions at work [Steenland 2000]. Whether a 24h shift among FF is more fatiguing that a 12h shift is unclear. This is particularly true because of the varying number of emergency calls between fire departments, and fire stations within fire departments. A recently published review of the topic noted the complexity of the issue [Elliot et al. 2007]. In June of 2008, FEMA awarded the Brigham & Women’s Hospital in Boston a $1,000,000 grant to study sleep disturbances among fire fighters as part of the Assistance to Firefighter Grants Program, Fire Prevention and Safety Grants [FEMA 2008].

    Albert CM, Mittleman MA, Chae CU, Lee IM, Hennekens CH, Manson JE [2000]. Triggering of sudden death from cardiac causes by vigorous exertion. N Engl J Med 343:1355– 1361.

    Barnard RJ, Duncan HW [1975]. Heart rate and ECG responses of fire fighters. J Occup Med 17:247–250.

    Elliot DL, Kuehl KS [2007]. Effects of sleep deprivation on fire fighters and EMS responders. International Association of Fire Chiefs. Fairfax, VA.

    FEMA [2008]. Assitance to Firefighters Grants Program. Fire Prevention and Safety Grants 2008. [http://firegrantsupport.com/fps/award/07/] Date accessed: October 8, 2008.

    Kales SN, Soteriades ES, Christoudias SG, Christiani DC [2003]. Firefighters and onduty deaths from coronary heart disease: a case control study. Environ health: a global access science source. 2:14. [http://www. ehjournal.net/content/2/1/14]. Date accessed: February 15, 2007.

    Kales SN, Soteriades ES, Christophi CA, Christiani DC [2007]. Emergency duties and deaths from heart disease among fire fighters in the United States. N Eng J Med 356:1207–1215.

    Kuorinka I, Korhonen O [1981]. Firefighters’ reaction to alarm, an ECG and heart rate study. J Occup Med 23:762–766.

    Steenland K [2000]. Shift work, long hours, and SCD: a review. Research finding linking workplace factors to CVD outcomes. In: Schnall PL, Belkic K, Landsbergis P, Baker D, eds. The workplace and cardiovascular disease. Occupational Medicine State of the Art Reviews 15(1):7–17. Philadelphia, PA: Hanley & Belfus, Inc.

    Can you provide us with information on appropriate heart scanning procedures. How can we best decide whether treadmill based testing, or arterial scans would provide the better predictive tool.

    There are a number screening tests to detect coronary artery disease. The following factors should be used in determining the best screening test for your location.

    1. The quality, expertise, and experience of the staff performing and interpreting the test.
    2. The sensitivity, specificity, predictive value positive, and predictive value negative of the test.
    3. The cost and accuracy of the test.
    4. Effect the test has on clinical decision making.

    Your question mentioned treadmill tests. A broader term would be exercise testing because it encompasses treadmill, bike (cycle ergometer), and step tests. Most validity studies have been conducted on the treadmill type of exercise test. There are a number of treadmill exercise protocols. The Bruce protocol has the most experience and is the one most commonly used. However, protocols using a more gradual increase in workload (e.g. Balke, Gerkin, etc) have advantages for the fire service. In either case, these protocols should not terminate the test at a predetermined heart rate (e.g. 85% of your maximum). Rather, the patient should continue exercising until they cannot go any longer, assuming that they have none of the absolute and relative indications for terminating the test [see reference]. Adding an imaging test after completing the exercise test increases the sensitivity and specificity, but this also at least triples the cost [Gibbons et al. 2002].

    The coronary artery calcium (CAC) scoring tests (also known as electron beam CT scans) are a promising new technology. In 2000 the American College of Cardiology/American Heart Association (ACC/AHA) experts reviewed the topic and determined that “At this time, ….the body of evidence using CAC measurement to predict CHD [coronary heart disease] events was insufficient.” In 2007 the ACC/AHA revisited the issue and concluded that CAC measurements “MAY BE REASONABLE TO CONSIDER” in SOME patients. Specifically, asymptomatic patients with an intermediate risk of CHD. Intermediate risk was defined as between 10% and 20% 10-year risk of estimated coronary events. The expert panel did not recommend its use for asymptomatic low-risk (20% 10-year CHD risk) patients. [Greenland 2007]

    Gibbons RJ, Balady GJ, Bricker JT, Chaitman BR, Fletcher GF, Froelicher VF, Mark DB, McCallister BD, Mooss AN, O’Reilly MG, Winters WL Jr. [2002]. ACC/AHA 2002 guideline update for exercise testing: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 106:1883-1892.

    Greenland P, Bonow RO, Brundage BH, Budoff MJ, Eisenberg MJ, Grundy SM, Lauer MS, Post WS, Raggi P, Redberg RF, Rodgers GP, Shaw LJ, Taylor AJ, Weintraub WS. ACCF/AHA 2007 clinical expert consensus document on coronary artery calcium scoring by computed tomography in global cardiovascular risk assessment and in evaluation of patients with chest pain: a report of the American College of Cardiology Foundation Clinical Expert Consensus Task Force (ACCF/AHA Writing Committee to Update the 2000 Expert Consensus Document on Electron Beam Computed Tomography). J Am Coll Cardiol 2007;49:378 – 402.

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