NATICK, Mass. -- Recently, in an effort to study ways to predict heat illness, researchers from the U.S. Army Research Institute of Environmental Medicine, or USARIEM, strapped wearable sensors on Soldiers from the 75th Ranger Regiment as they completed the first and second Ranger Assessment and Selection Program, or RASP, at Fort Benning, Georgia.
The data collection was part of a larger research study in collaboration with the Fort Benning Martin Army Community Hospital, or BMACH. USARIEM researchers have been using real-time physiological status monitors, or RT-PSMs, to collect physiological data from 2,000 Soldiers completing Airborne and Basic Combat Training.
The RT-PSMs, which can track Soldiers' core and skin temperatures and heart rates as they train, will help researchers see how the body responds when healthy and when experiencing a heat illness. The researchers aim to complete their study by the end of this summer.
Dr. Mark Buller and Dr. Beth Beidleman, both principal investigators and research physiologists from USARIEM, explained that there is little research that shows whether some individuals might be more susceptible to heat injury than others. This effort would not only help the researchers get closer to finding that answer, but it would also help the researchers evaluate the RT-PSM's capabilities.
"We are collecting data on Soldiers during hot weather training to determine if those who develop heat illness possess a unique physiological profile compared to their peers who perform the same training activities but do not develop heat illness," Buller said. "We would like to use this data in order to evaluate the capabilities of the current RT-PSM, as well as develop an alerting system similar to a radiation badge that can track impending heat casualties without changing training standards."
"The Army has gotten better at treating heat illness when it occurs, but we want to work at preventing it in the first place," Beidleman said. "We are studying to see if using real-time modeling can do that."
Because of the climbing number of heat casualties during the past few years, this data could help the Army develop better preventative practices when dealing with heat illness. The U.S. Army Public Health Center recently reported there have been 480 cases of heat illness since January 2018, with 272 cases occurring in June. Out of those 480 cases, Fort Benning reported 219 of them, according to Maj. Michael Bursey and Maj. Meghan Galer, respectively the medical director and assistant chief of BMACH's Department of Emergency Medicine.
When Buller's team heard about the magnitude of the problem, they traveled down to Fort Benning to meet Bursey and Galer. When Buller demonstrated the RT-PSM's capabilities, USARIEM and BMACH agreed that using RT-PSMs in a study with a large, diverse population of Soldiers could help advance heat illness research and develop practical prevention guidance. Due to the "high heat and humidity and the numerous training programs involving intensive outdoor activity," as Galer described it, Fort Benning was the perfect place to do this.
Bursey and Galer have been two of the biggest driving forces on preventing heat-related deaths across the Department of Defense and are working to establish Fort Benning as the DOD's first "Heat Center." The Heat Center initiative, according to Galer, focuses on developing and optimizing strategies to educate, manage and provide treatment for the force on heat illness prevention. BMACH's partnership with USARIEM is part of this initiative.
"At Fort Benning, we are truly on the cutting edge of clinical management of heat-related illnesses," Galer said. "We see the highest volume of heat-related illnesses in the Army, including over 219 cases to date in 2018. Despite these astronomical numbers, we are very proud that we have had no deaths in over two years. Developing the Heat Center at Fort Benning will be an invaluable means by which to improve readiness through sustainable prevention and mitigation strategies, as well as provide life-saving medical care while advancing the state of medicine."
To collect data, the USARIEM researchers outfitted volunteering Soldiers with RT-PSMs, and the Soldiers completed their training as usual. The RT-PSM, a chest harness, can track a person's heart rate and skin and core temperatures while they train. One of the ways the RT-PSM is able to do this is because of the Estimated Core Temperature, or ECTemp, algorithm that is incorporated into the chest harness.
Buller, the developer of the ECTemp, explained that the algorithm uses mathematics to provide accurate estimates of core body temperature, simply by analyzing heart rate changes over time. USARIEM developed the ECTemp based on years of physiological data collected from multiple studies.
Additional studies have indicated that the ECTemp has been successful in real-world scenarios. In a notable example, researchers from the Air Force Research Laboratory who equipped 350th Training Squadron trainees with wearables using the ECTemp presented data that showed "using the ECTemp has helped them identify and mitigate over 30 cases of heat stress and prevented more serious heat stress casualty situations."
"The ECTemp is incorporated into the RT-PSM in order to provide situational awareness," Buller said. "It is not meant to replace the current procedures for assessing or evacuating people, but it is meant to provide leaders and medics with more objective information so they can identify at-risk people earlier and apply their heat mitigation strategies or casualty standard operating procedures. This kind of technology could improve readiness by helping to increase the number of Soldiers who complete their training successfully."
"Real-time monitoring allows us to compare the core temperature and heart rate data in Soldiers who did not get heat illness to the ones who did," Beidleman said. "We have actually been able to capture data on individuals who have suffered heat stroke. If our analysis shows there are physiological differences between Soldiers who developed heat illness versus the ones who did not, this information could help us find heat illness predictors and establish thresholds for what is considered dangerous during training."
For the past few weeks, the USARIEM researchers have collected physiological data from Soldiers completing a vast array of training courses. Galer and Bursey, using their hospital records, identified events that were considered high-risk, from completing five-mile runs in the summer heat to sitting in a hot cargo plane during Airborne training.
In the July study iteration, 31 Soldiers from the 75th Ranger Regiment, all from diverse climates, wore RT-PSMs while completing RASP training. RASP training includes events where Soldiers have gotten historically hot, such as a five-mile run, 12-mile ruck march and field exercises. USARIEM researchers also outfitted 162 Soldiers from the Officer Candidate School who were completing land navigation training. Buller added that land navigation can be especially high-risk because a Soldier could collapse in the woods from heat stroke while isolated from their battle buddies.
USARIEM continues to respond to the risk of heat illness by advancing their understanding of heat illness and hydration, so that the Heat Center at Fort Benning and the Army's other training centers can continue to use the most accurate scientific information to educate the force on prevention and treatment.
The Army's guidance on heat illness prevention and hydration requirements, Technical Bulletin Medical 507, was written by USARIEM in 2003 based on decades of research and is currently undergoing revision. Meanwhile, USARIEM thermoregulatory scientists are providing up-to-date guidance as members of the Training and Doctrine Command Safety Officer Heat Injury Prevention Subcommittee. In addition to the RT-PSM study at Fort Benning, USARIEM scientists are conducting additional studies at other sites to identify biomedical markers of increased risk for heat-related illness.
Buller and Beidleman hope the findings they gather from the RT-PSMs will support the Army's initiative to improve preventative measures against heat illness so Soldiers will be fit to fight when they train and when they come home.
"You have to be careful about what information you push out there on heat illness prevention," Buller said. "Will the Soldiers understand the quality of the data they're getting, and what will they do with that information? In the last few years, BMACH has rolled out a whole series of procedures and training sessions on heat illness prevention measures.
"They have tried to get the treatment piece down by encouraging fast response and treatment of injuries. Now, they would like to see if USARIEM technology can help prevent heat injury from occurring in the first place."