BY STEVE MARKEY AND MICHAEL DAVIDSON, M.D.
Although exposure to extreme heat is a common occurrence in the life of a firefighter, not everybody is aware of some of the less obvious, yet equally lethal, ways in which heat can quickly create a life-threatening situation. One danger is the onset of heat stroke, often occurring when core brain temperature exceeds 104°F. However, even a core brain temperature of more than 101.8° F can produce significant central nervous system (CNS) dysfunction, resulting in reduced hand/eye coordination, impaired cognitive functions, loss of appropriate decision-making ability, and impaired short-term memory.
 Photo courtesy of SportsTemp, LLC. |
All of the above can create an extremely hazardous situation for firefighters, whose ability to think quickly under pressure is critical to their survival and the success of their mission. The key is to find a fast, effective method to measure core brain temperature that also provides a clear warning of the onset of heat illness without impeding a firefighter’s performance.
LIVE-BURN EXERCISE
The West Metro Fire District in Lakewood, Colorado, conducted trials using BodyTemp, a two-inch liquid crystal thermostrip developed by SportsTemp LLC, to monitor core brain temperature (photo 1). The self-adhesive strips have a built-in liquid crystal thermometer. When applied to the forehead, the thermostrips quickly provide readout of core brain temperature.
In one test, 10 trainee firefighters spent slightly more than nine minutes participating in a live-burn exercise in a building with an interior temperature of between 1,300°F and 1,500°F.
Firefighters were weighed before and after the exercise to determine weight/fluid loss. Using the BodyTemp thermostrip, four separate core brain temperature measurements were taken: preburn, immediately postburn, five minutes after exiting building, and 10 minutes after exit (Table 1).
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In this test, most of the firefighters exiting the building had a core brain temperature above 102°F, putting them at risk of CNS dysfunction, the possibility of heat stroke, and all the associated life-threatening dangers.
In trying to cool itself down as quickly as possible, the brain may overcompensate, resulting in reactive cerebral hypothermia. In this phenomenon, the brain sends as much blood as possible to the scalp to cool itself; the scalp is extremely rich in blood vessels and thus highly effective in dissipating heat. The brain actually overcompensates in cooling itself down; hence, temperature readings are in the low to mid-90s within five or 10 minutes of exiting the fire building.
MONITORING CORE BRAIN TEMPERATURE
How could monitoring core brain temperature increase firefighter health and safety? The safety officer in charge of rehab might apply the thermostrips to check firefighters’ core brain temperature at the first SCBA bottle exchange. At this stage, “spikers,” individuals most susceptible to heat-illness impairment (temperatures >102°F), can be identified and given extra time to rehydrate and reach an acceptable, safe temperature (<100.5°F) before returning to the fire.
The safety officer can continue to monitor/rehab a firefighter’s core brain temperature to ascertain that member’s readiness to return to the fire. The thermostrips could provide a more accurate means of determining recovery time and help ensuring that a firefighter is physically and mentally ready to return to action.
According to Bob Stratman, M.S., wellness manager for West Metro (CO) Fire District, who managed the live-burn tests using BodyTemp, “The strip allows for real-time accurate data on core temperature that prove to be essential data to implement appropriate hydration strategies for the various crews. Furthermore, after several training exercises at the burn building, the training officers can develop hydration protocols that relate to specific fire attack scenarios that will eventually mirror live structure fires. The strip provides pertinent education for firefighters on their reaction physiologically to working under extreme heat and how their fluid loss affects body weight and body temperature.”
Thermostrips may be appropriate for obtaining temperature measurements on firefighters during simulated or live fireground operations. More research needs to be conducted in this area to determine its validity.
STEVE MARKEY is a vice president of sales and marketing for SportsTemp, LLC.
MICHAEL DAVIDSON, M.D., is president of SportsTemp, LLC.
