Firefighting and the Heart
2017; Lippincott Williams & Wilkins; Volume: 135; Issue: 14 Linguagem: Inglês
10.1161/circulationaha.117.027018
ISSN1524-4539
AutoresStefanos N. Kales, Denise L. Smith,
Tópico(s)Traffic and Road Safety
ResumoHomeCirculationVol. 135, No. 14Firefighting and the Heart Free AccessEditorialPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessEditorialPDF/EPUBFirefighting and the HeartImplications for Prevention Stefanos N. Kales, MD, MPH and Denise L. Smith, PhD Stefanos N. KalesStefanos N. Kales From Environmental & Occupational Medicine & Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA (S.N.K.); Occupational Medicine, The Cambridge Health Alliance/Harvard Medical School, Cambridge, MA (S.N.K.); Health and Exercise Sciences, Skidmore College, Saratoga Springs, NY (D.L.S.); and University of Illinois Fire Service Institute, Champaign (D.L.S.). and Denise L. SmithDenise L. Smith From Environmental & Occupational Medicine & Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA (S.N.K.); Occupational Medicine, The Cambridge Health Alliance/Harvard Medical School, Cambridge, MA (S.N.K.); Health and Exercise Sciences, Skidmore College, Saratoga Springs, NY (D.L.S.); and University of Illinois Fire Service Institute, Champaign (D.L.S.). Originally published4 Apr 2017https://doi.org/10.1161/CIRCULATIONAHA.117.027018Circulation. 2017;135:1296–1299Article, see p 1284Firefighting is widely recognized as a hazardous occupation. In particular, fire scenes are unpredictable and dangerous environments characterized by loud noise, high temperatures, flames, smoke with gaseous and particulate toxicants, and potential structural instability of affected buildings, among other hazards. Accordingly, during fire suppression, firefighters are at risk for various injuries, including burns, trauma, and smoke inhalation. Although less intuitive, the strenuous physical activity, emotional stress, and environmental pollutants encountered while fighting a fire place considerable strain on the cardiovascular system, and each of these exposures can act alone or in concert to increase the risk of cardiovascular disease (CVD) events among susceptible individuals.1,2 The investigation of Hunter et al3 in this issue of Circulation solidifies and expands a growing body of science elucidating the pathophysiologic mechanisms1,2,4 through which fire-suppression activities markedly increase the risk of CVD events among firefighters: 10- to >100-fold greater risk compared with nonemergency fire department duties.2,5Cardiovascular Strain of Fire-Suppression ActivitiesWe use the term "fire-suppression activities" broadly here to refer to firefighting with the use of hoses and application of water, as well as to refer to forcible entry, building ventilation, and search and rescue operations at a fire scene, while distinguishing this class of duty from additional jobs performed by firefighters, such as medical and other calls. Structural fire-suppression activities are usually preceded by an alarm response, which produces an adrenergic "fight-or-flight" reaction with prominent sympathetic arousal.1,2,4 The increases in heart rate and blood pressure continue until scene arrival, where suppressing a fire requires significant aerobic effort (stair and ladder climbing), anaerobic power (forcible entry, search and rescue operations), and static exertion (heavy materials handling, cutting and chopping to ventilate the building, and advancing charged hoselines). The use of heavy (>25 kg), encapsulating personal protective equipment and the extreme heat of the fire add further to cardiometabolic demands and can also lead to hyperthermia and dehydration.1,2,4 As confirmed by the present and previous studies, all of these factors can produce further increases in heart rate and blood pressure, which are accompanied by alterations in blood flow, vascular shear stress, and electrolytes; decreased plasma volume; increased blood viscosity; a procoagulatory state3,4; and, as documented in the present study, low-level myocardial injury and ischemia.3 While Hunter et al3 emphasize that this state promotes myocardial infarction, it is crucial to recognize that the same constellation of cardiovascular stressors is also arrhythmogenic (Figure). In fact, the autopsies of firefighters succumbing to on-duty sudden cardiac death (SCD) strongly suggest that most of these fatalities result from arrhythmias.6,7Download figureDownload PowerPointFigure. From left to right, both the average cardiovascular strain of fire duties and individual firefighter susceptibility increase. In the vast majority of cases, even during fires where cardiovascular strain is quite high, firefighters with or without underlying health issues fully recover to their baseline states. Infrequently, however, the cardiovascular strain threshold of a vulnerable firefighter is exceeded, and through 1 or more of the mechanisms depicted, an acute CVD event is triggered. For every death caused by SCD, ≈17 to 25 nonfatal events occur. CV indicates cardiovascular; CVA, cerebrovascular accident; CVD, cardiovascular disease; EMS, emergency medical services; PPE, personal protective equipment; and SCD, sudden cardiac death.CVD Epidemiology in FirefightersOne must look beyond fighting fires to fully understand why SCD is the leading cause of duty-related fatalities among US firefighters, causing ≈45% of all job-related deaths.2,5 Although ≈33% of SCD events occur during fire suppression and the relative risk is highest during fires, >60% of firefighter SCD occurs across a variety of other duties. For example, CVD event risk is increased 5- to 7-fold during the sympathetic arousal of the alarm response.1,2,5 Additionally, the odds of SCD are also increased during physical training activities (including simulated fires, but also simple exercise and other nonfire training drills). Further proof that heavy protective equipment, heat stress, dehydration, and air pollution are not required to trigger CVD events in public safety workers comes from law enforcement, where pursuits of and altercations with suspects increase the relative risk of SCD 30- to 70-fold compared with routine duties.8 Moreover, despite the marked alterations in physiological function that firefighters experience during fire suppression, it is highly unusual to observe a CVD event in a healthy and fit firefighter.2,4 The common denominator of occupational CVD events, including SCD across occupations and different types of duties, is an interaction between individual vulnerability and cardiovascular strain. When a public safety worker with underlying CVD (structural or coronary heart disease) is unable to tolerate a given load of cardiovascular stressors or threshold of cardiovascular strain, pathophysiologic changes precipitate or trigger a CVD event (Figure).Consistent with the previous theoretical framework, case-control studies among firefighters demonstrate that SCD fatalities and CVD retirements have statistically higher burdens of classic CVD risk factors (eg, smoking, hypertension, and obesity) than healthy controls.6,7,9 Furthermore, on-duty CVD events occur almost exclusively in firefighters with previously diagnosed CVD (20% to 30% of all events), firefighters with underlying (often subclinical) structural heart disease, firefighters with a clustering of traditional CVD risk factors and subclinical coronary heart disease, or persons belonging to >1of the 3 previous categories.2,7,9 Autopsies of firefighter SCD victims typically show varying degrees of coronary atherosclerosis usually accompanied by left ventricular hypertrophy/cardiomegaly.6,7 The major role of cardiac enlargement in fire service SCD is highlighted by numerous cases where coronary heart disease is not present or the degree of coronary occlusion is ≤40% to 50% and no evidence of coronary thrombus or plaque rupture is present. Compared with firefighters dying of traumatic causes, the hearts of firefighters dying of SCD are significantly heavier, and cardiomegaly (heart weight >450 g) conveys a 5-fold increase in the risk of SCD.7 Older age also increases the risk of SCD and CVD retirement among public safety workers in a dose-response fashion, and this risk increases sharply beyond 60 years of age.5,8,9 Depending on the duty performed, the risks of job-related SCD among firefighters ≥60 years of age range from ≈4- to 18-fold greater than that of colleagues 40 to 49 years of age.5Clinical research is also informative. Obesity among firefighters is associated with lower aerobic fitness, the clustering of various CVD risk factors, and a higher risk of cardiac enlargement.2,10,11 Firefighters with low physical fitness (≤10 METS) have a significantly and several-fold higher risk of metabolic syndrome, as well as EKG abnormalities and clinically abnormal heart rate recovery associated with maximal treadmill tests, compared with firefighters with excellent fitness (>14 METS).12,13 In the study of Hunter et al, 3 20 minutes of fire simulation training resulted in significant increases in cardiac troponin and more EKG-detected ischemia in carefully selected healthy firefighters. Repeating their experiments in firefighters who smokeand have health problems, low fitness, or even previously diagnosed heart disease would raise safety concerns. Yet it is known that many firefighters who respond on a regular basis to real fires and other stressful emergencies lack recommended fitness levels and have a high prevalence of CVD risk factors.2Implications of Research for Reducing CVD in the Fire ServiceBased on their study, Hunter et al3 suggest measures to decrease the cardiovascular risks of fire simulation training, including limiting the duration of exposure, active cooling, and effective rehydration. Given the confirmation that fire-suppression duties result in prothrombotic changes, more widespread use of low-dose aspirin among middle-age firefighters should also be considered.14 However, such approaches, although reasonable, would do little to reduce the overall burden of CVD in the fire service. Based on all of the established data from physiological, epidemiologic, and clinical studies of representative fire service populations as summarized earlier, we reiterate a series of appropriate preventive measures,15 some of which are gradually being adopted by major US fire organizations. These measures include banning smoking and tobacco products in fire services, commonsense fitness and obesity standards, wellness programs that promote exercise and healthy diets, annual medical evaluations for all firefighters, and considering mandatory retirement from active firefighting (fire-suppression and other strenuous duties) at 60 years of age.Hopefully, the impressive results of Hunter et al3 will persuade clinicians that firefighting is uniquely stressful on the cardiovascular system and encourage practitioners to aggressively evaluate and treat CVD risk factors in these invaluable public servants and, when indicated, perform additional studies (such as exercise stress testing, coronary artery calcium scans, or echocardiography) to detect subclinical atherosclerosis or cardiac enlargement. Finally, given the markedly higher risk (≥15-fold after covariate adjustment) of SCD among firefighters with established coronary heart disease or other structural heart disease, clinicians should consider recommending that patients with such a profile refrain from participating in strenuous emergency duties such as fire suppression and fire simulation.2Sources of FundingThis work was supported in part by US Department of Homeland Security, Federal Emergency Management Agency Assistance to Firefighters grant program awards EMW-2014-FP-00612 and EMW-2013-FP-00749.DisclosuresDr Kales reports serving as a paid expert witness, an independent medical examiner, or both in workers' compensation and disability cases, including cases involving firefighters. Dr Smith reports serving as a consultant in cases involving medical evaluations and firefighter fatalities.FootnotesThe opinions expressed in this article are not necessarily those of the editors or of the American Heart Association.Circulation is available at http://circ.ahajournals.org.Correspondence to: Stefanos N. Kales, MD, MPH, The Cambridge Health Alliance–Occupational Medicine, 1493 Cambridge St, Macht Bldg, Ste 427, Cambridge, MA 02139. E-mail [email protected]References1. Smith DL, Barr DA, Kales SN. Extreme sacrifice: sudden cardiac death in the US Fire Service.Extrem Physiol Med. 2013; 2:6. doi: 10.1186/2046-7648-2-6.CrossrefMedlineGoogle Scholar2. Soteriades ES, Smith DL, Tsismenakis AJ, Baur DM, Kales SN. Cardiovascular disease in US firefighters: a systematic review.Cardiol Rev. 2011; 19:202–215. doi: 10.1097/CRD.0b013e318215c105.CrossrefMedlineGoogle Scholar3. Hunter AL, Shah ASV, Langrish JP, Ratis JB, Lucking AJ, Brittan M, Venkatasubramanian S, Stables CL, Stelzle D, Marshall J, Graveling R, Flapan AD, Newby DE, Mills NL. Fire simulation and cardiovascular health in firefighters.Circulation. 2017; 135:1284–1295. doi: 10.1161/CIRCULATIONAHA.116.025711.LinkGoogle Scholar4. Smith DL, DeBlois JP, Kales SN, Horn GP. Cardiovascular strain of firefighting and the risk of sudden cardiac events.Exerc Sport Sci Rev. 2016; 44:90–97. doi: 10.1249/JES.0000000000000081.CrossrefMedlineGoogle Scholar5. Kales SN, Soteriades ES, Christophi CA, Christiani DC. Emergency duties and deaths from heart disease among firefighters in the United States.N Engl J Med. 2007; 356:1207–1215. doi: 10.1056/NEJMoa060357.CrossrefMedlineGoogle Scholar6. Geibe JR, Holder J, Peeples L, Kinney AM, Burress JW, Kales SN. Predictors of on-duty coronary events in male firefighters in the United States.Am J Cardiol. 2008; 101:585–589. doi: 10.1016/j.amjcard.2007.10.017.CrossrefMedlineGoogle Scholar7. Yang J, Teehan D, Farioli A, Baur DM, Smith D, Kales SN. Sudden cardiac death among firefighters ≤45 years of age in the United States.Am J Cardiol. 2013; 112:1962–1967. doi: 10.1016/j.amjcard.2013.08.029.CrossrefMedlineGoogle Scholar8. Varvarigou V, Farioli A, Korre M, Sato S, Dahabreh IJ, Kales SN. Law enforcement duties and sudden cardiac death among police officers in United States: case distribution study.BMJ. 2014; 349:g6534.CrossrefMedlineGoogle Scholar9. Holder JD, Stallings LA, Peeples L, Burress JW, Kales SN. Firefighter heart presumption retirements in Massachusetts 1997-2004.J Occup Environ Med. 2006; 48:1047–1053. doi: 10.1097/01.jom.0000235909.31632.46.CrossrefMedlineGoogle Scholar10. Korre M, Sampani K, Porto LGG, Farioli A, Yang J, Christiani DC, Christophi CA, Lombardi DA, Kovacs RJ, Mastouri R, Abbasi S, Steigner M, Moffatt S, Smith DL, Kales SN. Cardiac enlargement in US firefighters: prevalence estimates by echocardiography, cardiac magnetic resonance and autopsies.J Clin Exp Cardiolog. 2016; 7:459.CrossrefGoogle Scholar11. Korre M, Porto LG, Farioli A, Yang J, Christiani DC, Christophi CA, Lombardi DA, Kovacs RJ, Mastouri R, Abbasi S, Steigner M, Moffatt S, Smith D, Kales SN. Effect of body mass index on left ventricular mass in career male firefighters.Am J Cardiol. 2016; 118:1769–1773. doi: 10.1016/j.amjcard.2016.08.058.CrossrefMedlineGoogle Scholar12. Baur DM, Christophi CA, Kales SN. Metabolic syndrome is inversely related to cardiorespiratory fitness in male career firefighters.J Strength Cond Res. 2012; 26:2331–2337. doi: 10.1519/JSC.0b013e31823e9b19.CrossrefMedlineGoogle Scholar13. Baur DM, Leiba A, Christophi CA, Kales SN. Low fitness is associated with exercise abnormalities among asymptomatic firefighters.Occup Med (Lond). 2012; 62:566–569. doi: 10.1093/occmed/kqs112.CrossrefMedlineGoogle Scholar14. Smith DL, Horn GP, Woods J, Ploutz-Snyder R, Fernhall B. Effect of aspirin supplementation on hemostatic responses in firefighters aged 40 to 60 years.Am J Cardiol. 2016; 118:275–280. doi: 10.1016/j.amjcard.2016.04.032.CrossrefMedlineGoogle Scholar15. Kales SN, Smith DL. Sudden cardiac death in the fire service.Occup Med (Lond). 2014; 64:228–230. doi: 10.1093/occmed/kqu057.CrossrefMedlineGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetailsCited By Lan F, Scheibler C, Hershey M, Romero-Cabrera J, Gaviola G, Yiannakou I, Fernandez-Montero A, Christophi C, Christiani D, Sotos-Prieto M and Kales S (2022) Effects of a healthy lifestyle intervention and COVID-19-adjusted training curriculum on firefighter recruits, Scientific Reports, 10.1038/s41598-022-10979-2, 12:1, Online publication date: 1-Dec-2022. Shin I, Kong S, Park G, Shin D, Chai H, Kim Y, Lee J and Kim S (2022) Effects of Occupational Stress and Health Behaviors on Heart Rate Variability in Live-Fire Instructors, Journal of Occupational & Environmental Medicine, 10.1097/JOM.0000000000002541, 64:6, (e374-e377), Online publication date: 1-Jun-2022. D'Evelyn S, Jung J, Alvarado E, Baumgartner J, Caligiuri P, Hagmann R, Henderson S, Hessburg P, Hopkins S, Kasner E, Krawchuk M, Krenz J, Lydersen J, Marlier M, Masuda Y, Metlen K, Mittelstaedt G, Prichard S, Schollaert C, Smith E, Stevens J, Tessum C, Reeb-Whitaker C, Wilkins J, Wolff N, Wood L, Haugo R and Spector J (2022) Wildfire, Smoke Exposure, Human Health, and Environmental Justice Need to be Integrated into Forest Restoration and Management, Current Environmental Health Reports, 10.1007/s40572-022-00355-7 Ranadive S, Lofrano-Porto A, Soares E, Eagan L, Porto L and Smith D (2021) Low testosterone and cardiometabolic risks in a real-world study of US male firefighters, Scientific Reports, 10.1038/s41598-021-93603-z, 11:1, Online publication date: 1-Dec-2021. Liu C and Yang C (2021) Commentary: Serum Biomarkers Are Potential Diagnosis and Treatment Targets for Depressive Symptoms in Patients With Cardiovascular Diseases, Frontiers in Psychiatry, 10.3389/fpsyt.2021.649705, 12 Hershey M, Sotos-Prieto M, Ruiz-Canela M, Christophi C, Moffatt S, Martínez-González M and Kales S (2021) The Mediterranean lifestyle (MEDLIFE) index and metabolic syndrome in a non-Mediterranean working population, Clinical Nutrition, 10.1016/j.clnu.2021.03.026, 40:5, (2494-2503), Online publication date: 1-May-2021. LAN F, YIANNAKOU I, SCHEIBLER C, HERSHEY M, CABRERA J, GAVIOLA G, FERNANDEZ-MONTERO A, CHRISTOPHI C, CHRISTIANI D, SOTOS-PRIETO M and KALES S (2020) The Effects of Fire Academy Training and Probationary Firefighter Status on Select Basic Health and Fitness Measurements, Medicine & Science in Sports & Exercise, 10.1249/MSS.0000000000002533, 53:4, (740-748), Online publication date: 1-Apr-2021. Gonzalez A, Waldman H, Abel M, McCurdy K and McAllister M (2021) Impact of Time Restricted Feeding on Fitness Variables in Professional Resistance Trained Firefighters, Journal of Occupational & Environmental Medicine, 10.1097/JOM.0000000000002144, 63:4, (343-349), Online publication date: 1-Apr-2021. Manikandan R, Subash K, Joshua sujith T, Jayasuriyan R, Jerendran J, Rajpradeesh T and Rajesh S (2021) Design and development of an industrial firefighting rover, Materials Today: Proceedings, 10.1016/j.matpr.2020.12.961, 45, (7965-7969), . Cornell D, Noel S, Zhang X and Ebersole K (2020) Influence of a Training Academy on the Parasympathetic Nervous System Reactivation of Firefighter Recruits—An Observational Cohort Study, International Journal of Environmental Research and Public Health, 10.3390/ijerph18010109, 18:1, (109) Romanidou M, Tripsianis G, Hershey M, Sotos-Prieto M, Christophi C, Moffatt S, Constantinidis T and Kales S (2020) Association of the Modified Mediterranean Diet Score (mMDS) with Anthropometric and Biochemical Indices in US Career Firefighters, Nutrients, 10.3390/nu12123693, 12:12, (3693) Segedi L, Saint-Martin D, da Cruz C, Von Koenig Soares E, do Nascimento N, da Silva L, Nogueira R, Korre M, Smith D, Kales S, Molina G and Porto L Cardiorespiratory fitness assessment among firefighters: Is the non-exercise estimate accurate?, Work, 10.3233/WOR-203263, 67:1, (173-183) Hershey M, Sotos-Prieto M, Ruiz-Canela M, Martinez-Gonzalez M, Cassidy A, Moffatt S and Kales S (2020) Anthocyanin Intake and Physical Activity: Associations with the Lipid Profile of a US Working Population, Molecules, 10.3390/molecules25194398, 25:19, (4398) Ebersole K, Cornell D, Flees R, Shemelya C and Noel S (2020) Contribution of the Autonomic Nervous System to Recovery in Firefighters, Journal of Athletic Training, 10.4085/1062-6050-0426.19, 55:9, (1001-1008), Online publication date: 1-Sep-2020. Soares E, Smith D and Grossi Porto L (2020) Worldwide prevalence of obesity among firefighters: a systematic review protocol, BMJ Open, 10.1136/bmjopen-2019-031282, 10:1, (e031282), Online publication date: 1-Jan-2020. Muegge C, Zollinger T, Song Y, Wessel J, Monahan P and Moffatt S (2020) Barriers to Weight Management Among Overweight and Obese Firefighters, Journal of Occupational & Environmental Medicine, 10.1097/JOM.0000000000001751, 62:1, (37-45), Online publication date: 1-Jan-2020. Barry A, Lyman K, Dicks N, Landin K, McGeorge C, Hackney K and Walch T (2019) Firefighters' Physical Activity and Waist Circumference as Predictors of VO2max, Journal of Occupational & Environmental Medicine, 10.1097/JOM.0000000000001690, 61:10, (849-853), Online publication date: 1-Oct-2019. Sotos-Prieto M, Jin Q, Rainey D, Coyle M and Kales S (2019) Barriers and solutions to improving nutrition among fire academy recruits: a qualitative assessment, International Journal of Food Sciences and Nutrition, 10.1080/09637486.2019.1570087, 70:6, (771-779), Online publication date: 18-Aug-2019. Haller and Smith (2019) Examination of Strenuous Activity Preceding Cardiac Death during Firefighting Duties, Safety, 10.3390/safety5030050, 5:3, (50) Porto L, Schmidt A, de Souza J, Nogueira R, Fontana K, Molina G, Korre M, Smith D, Junqueira L and Kales S Firefighters' basal cardiac autonomic function and its associations with cardiorespiratory fitness, Work, 10.3233/WOR-192883, 62:3, (485-495) Smith D, Haller J, Korre M, Sampani K, Porto L, Fehling P, Christophi C and Kales S (2019) The Relation of Emergency Duties to Cardiac Death Among US Firefighters, The American Journal of Cardiology, 10.1016/j.amjcard.2018.11.049, 123:5, (736-741), Online publication date: 1-Mar-2019. Siegel A and Noakes T (2019) Aspirin to Prevent Sudden Cardiac Death in Athletes with High Coronary Artery Calcium Scores, The American Journal of Medicine, 10.1016/j.amjmed.2018.09.015, 132:2, (138-141), Online publication date: 1-Feb-2019. Smith D, Haller J, Korre M, Fehling P, Sampani K, Grossi Porto L, Christophi C and Kales S (2018) Pathoanatomic Findings Associated With Duty‐Related Cardiac Death in US Firefighters: A Case–Control Study, Journal of the American Heart Association, 7:18, Online publication date: 18-Sep-2018. Korre M, Sotos-Prieto M and Kales S (2017) Survival Mediterranean Style: Lifestyle Changes to Improve the Health of the US Fire Service, Frontiers in Public Health, 10.3389/fpubh.2017.00331, 5 April 4, 2017Vol 135, Issue 14 Advertisement Article InformationMetrics © 2017 American Heart Association, Inc.https://doi.org/10.1161/CIRCULATIONAHA.117.027018PMID: 28373524 Originally publishedApril 4, 2017 KeywordsEditorialsfirefightingcardiomegalysudden cardiac deathcardiovascular diseasePDF download Advertisement
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