fireEMS ❘ By Megan A. Carty, Rachel L. Dickinson, Cassandra C. Derella, and Deborah Feairheller
Firefighter Luke hears his pager alarm and rushes to the fire station for another day as a volunteer firefighter. Luke is trained and fully aware of his capabilities as a firefighter, but what he does not know is how that pager sound may be adversely affecting his health. The alarm sound triggers an instant sympathetic nervous system response. This response is often associated with a spike in blood pressure (BP), and it may be a main contributor to the cardiovascular-related line-of-duty death (LODD) incidence in firefighters.1
There is a direct relationship between work stress and increased blood pressure.2,3 The occupational demands of firefighters place them at a higher risk of developing cardiovascular disease (CVD).1,4,5 We know that cardiac events remain the leading cause of firefighter LODDs. The firefighter population suffers from increased rates of obesity and high BP (hypertension) compared to civilians, placing them at higher risk for cardiovascular issues.6 CVD remains the leading cause of mortality worldwide, and the American Heart Association recently reclassified the hypertension thresholds in its new guidelines, suggesting that close to half of the population may now be considered hypertensive.7
To diagnose hypertension, the clinical guidelines continue to advocate the use of ambulatory blood pressure (ABP) monitoring.8,9 ABP is a simple technique that collects BP readings throughout the day. For example, one measurement taken in the doctor’s office provides only a single reading, which may be less predictive of CVD risk. ABP could be a better diagnostic tool for detecting unknown hypertension and could identify potential CVD risk related to BP.10 ABP is rapidly becoming a valuable tool to diagnose, manage, and treat hypertension. Hidden types of hypertension cannot be identified in a single reading in the doctor’s office. Sometimes BP goes up at night (nocturnal hypertension); this is a risk, especially for firefighters who may receive a dispatch in the middle of the night and jump to immediate action.
Another type of BP that ABP monitoring can identify is morning surge, which is when pressure levels spike on awaking in the morning. Again, this would be a risk if firefighters are not aware that they have this type of hypertensive response. This information should encourage firefighters to undergo an ABP monitoring.
What Happens to BP When the Pager Sounds?
Recently, we recruited volunteer firefighters from the Philadelphia, Pennsylvania, suburban area. As firefighters age and continue to work as members of local fire departments, they grow in confidence and security. They also may not have the same physiological response to the pager alarm. Since CVD risk increases with age, we were interested to see if CVD risk would relate to BP alarm response.
According to the National Fire Protection Association, roughly 42 percent of volunteer firefighters have more than 10 years of experience.11 It is common for firefighters in the Philadelphia area to be volunteer firefighters for close to 20 years. Therefore, for analysis, we separated the firefighters into two groups: (1) more than 10 years of experience and (2) fewer than 10 years of experience.
All firefighters gave informed consent and completed a general health history form. The Ursinus College Institutional Review Board approved the study.
To capture the BP surge caused by the sounding of the pager alarm, each firefighter wore an ABP monitor during a 12-hour period. The monitor was programmed to record BP every half hour. The firefighters were instructed to force an automatic measurement when they received an audible fire call or page, thus quantifying their alarm response.
So that we could compare the firefighters’ BP responses with civilians’ BP responses, we included a control population of civilians who wore the same ABP cuff for 12 hours. During this time, the civilians were paged using an app called “OnPage,” an incident alert management system that allowed us to simulate actual pages. The OnPage app mimics the pager firefighters wear and has the same tone and volume.
What We Found
We found that firefighters had a larger BP alarm surge than civilians. Systolic BP (the higher number) surged an average of 18.9 mmHg and diastolic BP (the lower number) increased on average by 14 mmHg. The BP surge in civilians was much lower; SBP increased on average by 9 mmHg and DBP increased on average by 6 mmHg.
Interestingly though, some firefighters had very large DBP increases. This is a concern since diastole is representative of the rest phase of the heart cycle, so we hypothesize that firefighters who experience a large surge in DBP could be at risk for cardiac incidents. All firefighters should know what their BP is, how it responds to everyday activity, and how high it spikes when the alarm sounds. This information could save their lives. All emergency responders should know this information.
Firefighters know they are at risk, know they are being called into a potentially dangerous situation, and know that they may need to immediately do a heavy amount of work. All of these things could contribute to this large increase in BP that occurred with the pager alarm sounds. The concerning thing, however, is that many firefighters may already have hypertension. Therefore, any BP surge would put them at even greater risk.
Probationary vs. Experienced Firefighters
We also found that younger and newer firefighters had a larger SBP surge than older and more experienced firefighters. On average, young and newer firefighters had an SBP surge around 21 mmHg, whereas the older, more experienced firefighters had an SBP surge of about 16 mmHg. However, there was another difference between the two groups: It took the BP of the more experienced firefighters 90 minutes on average to return to the prealarm level, whereas it took on average about 40 minutes for the BP of the younger firefighters to return to the prealarm level.
These findings raised some questions: Could the older firefighters have stiffer vessels? Could their nervous system and psyche have adapted to years of listening to the alarm? Could the longer time they are exposed to a higher BP be a risk? Which factor puts a larger stress on the heart—higher BP levels for a shorter time or a lower BP surge for a longer time? Also, could exercise and diet improve the pressure surge responses? These are some of the questions we are examining.
How Can We Improve Firefighter Health and Decrease CVD Risk?
Our results emphasize the importance of taking ownership of your health and looking into what your BP might be. Learn what your day-to-day BP is. Wearing an ABP monitor provides valuable and perhaps life-saving information about fluctuations in pressure and perhaps will allow you to see a BP surge with a dispatch. ABP monitors can be expensive (cost varies between $3,000 and $8,000 for the unit and the software to download the data). If fire department funds are insufficient, firefighters may ask their doctor if they could use one or perhaps the department could arrange for physicals with a provider who has one.
Begin to save your own life. Implement lifestyle changes in your day-to-day routine and that of your crew. Increasing activity levels, improving diet, undergoing a yearly physical, and focusing on reducing stress are some of the ways to modify BP. After all, firefighters need to save themselves before they can save others.
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MEGAN A. CARTY is a research assistant working for Dr. Deborah Feairheller. She plans to study public health as a graduate student. She is the senior investigator on firefighter health, fitness, and ambulatory blood pressure.
RACHEL L. DICKINSON, a former student researcher under Dr. Deborah Feairheller, was one of the lead investigators on the ambulatory blood pressure monitoring data collection.
CASSANDRA C. DERELLA is a doctoral candidate in biomedical sciences in the Georgia Prevention Institute at Augusta University. She was the initial lead investigator for the ambulatory blood pressure monitoring component of the study.
DEBORAH FEAIRHELLER, PHD, FACSM, formerly was a volunteer firefighter with the East Brandywine Fire Company, Limerick Fire Company, and Collegeville Fire Company, all in the Philadelphia, Pennsylvania, area. She is a clinical associate professor in the Department of Kinesiology at the University of New Hampshire. Her research examines the effect of lifestyle modifications on hypertension, ambulatory blood pressure, and vascular structure and function. As a firefighter, she has a vested interest in getting the fire service physically active and improving cardiac health.