Personal Physiological Monitors Find Warfighter-Effectiveness Edge

August 2000
By Maryann Lawlor
E-mail About the Author

Matching soldiers’ health status with performance adds critical mission-planning tool.

Through the use of global positioning system technologies, today’s commanders can keep track of man and machine in the battlespace. But in the not-too-distant future, these same decision makers will locate their personnel in physiological space and know how a soldier’s physical condition could affect productivity, performance and ultimately the mission.

The success of many military missions can depend on the ships, the aircraft, the weapons, the computers and the information. However, on all of those bridges, in all of those cockpits and in front of all of those monitors is the real secret to the success of an operation—the people. The global information grid may allow commanders to know their own and their enemy’s locations, but work being conducted by U.S. Army researchers will enable them to assess their troops’ physical condition. This insight could lead to a decision to delay an operation, or, if that is not possible, at least provide the means to assess what additional risks are likely to arise as a direct result of a change in the physical status of personnel.

An integrated research team with members located at the U.S. Army Soldier Systems Center, Natick, Massachusetts, and the Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, is developing a suite of sensors that is scheduled to be incorporated into the Land Warrior soldier system. The group working on the warfighter physiological status monitor (WPSM) is attached to the Army’s Medical Research and Materiel Command, Fort Detrick, Maryland.

The miniature devices would be essentially invisible to the warfighter but would collect a great deal of information about the soldier’s physiological condition. However, the team’s current goal is to do more than just collect a glut of data; it intends to take this information one step further. “This is not just about hardware,” Col. Jack P. Obusek, USA, deputy commander, Army Research Institute of Environmental Medicine, Natick, states. “A large part of this effort is the relationship between physiological conditions and the performance readiness of the warfighter in the field. Is he in danger of becoming a heat casualty? What is the error rate because of a lack of sleep? That’s the piece of science that supports the wearing of sensors,” he explains.

According to Col. Obusek, who is the integrated research team’s chairman, researchers are examining sensors that will collect various types of information, including thermal, hydration and sleep states. In addition, sensors also would support remote triage.

“The first three address operational readiness, so a commander can look at a readiness state like looking at the fuel gauge,” the colonel says. The remote triage piece would allow medics to monitor individuals to determine their physical condition during an operation and, when injuries occur, help the medic prioritize the wounded so that the most gravely injured can be attended to first.

In its current work, the team employs miniaturized radio frequency transmitters that send information to a pager-sized receiver that would be placed on or within the uniform. This data is then downloaded to a computer for the scientists to examine.

According to Dr. Frederick J. Pearce, chief, department of resuscitative medicine, WRAIR, one of the goals of the project is to gain objective assessments of the physical state of military personnel. Although not a medical doctor, Pearce is trained in research physiology. “You can ask someone how tired he is, but that’s subjective. In training, for example, we want to train folks to their limits or near limits … get near the maximum oxygen capacity, and get people to target that knife edge. If they do this consistently, there’s training benefit. These assessments in training or real operations environments can be used as information for the commanders for the status of their troops. A computer algorithm will take this data and give the assessment for a decision about carrying out the mission or delaying it. If the mission cannot be delayed, the commander would at least know the risks that are involved,” Pearce says.

In addition to contributing to an understanding of warfighter readiness, this type of data also fits into the larger battlespace picture and the various items that compose it, Col. Obusek explains. A foot-strike monitor, for example, would collect data about the distance that troops have traveled, which drives the fuel requirements for soldiers. The team is also developing a canteen “drinkometer” that would provide information about water intake. “This type of information would help plan just-in-time logistics and help tailor the requirements right down to the soldier,” the colonel explains.

Col. Gregory Belenky, USA, a medical doctor, is the director of the division of neuropsychiatry, WRAIR, and is focusing on the sleep analysis component of the project. “Part of the problem is that there is a lot of pharmacological work out there, but no one can say when it is appropriate to use it. Nancy Reagan said ‘Just say no’ in referring to drugs. We’re saying ‘Just say sleep.’ Anything else is just postponing things temporarily. It’s not good for the brain to put off sleep.

“We tell the commanders to make sure soldiers get adequate sleep, but we’re telling them to do that without the metrics that support it and show specifically how tired the soldiers are or what the effects would be on productivity. We measure the sleep, then put this data into a production model,” Col. Belenky explains.

“The commander may have 12 helicopter pilots, and they have to go on 36 missions. Each pilot comes to the start line with an immediate sleep/wake history. So, if we can use a software program and propose a schedule of who should go first and who should go to sleep for a while, then we can reoptimize on-the-fly. This information does not lead to a go/no-go decision, but it allows the commanders to factor in how much sleep the pilots have gotten to help them make a decision. It won’t tell the commander what to do, just give them the information. We can’t do this now because there hasn’t been the technology. Commanders can now manage the logistics of missions and put sleep in the list of items of logistics supply, then intelligently manage the people resources,” he adds.

To determine the effect of sleep deprivation on productivity, the group is using an Actigraph. Developed by Precision Control Design Incorporated, Fort Walton Beach, Florida, the wrist-worn device resembles a watch and measures movement. This data is matched with information collected during a psychomotor vigilance test in which a subject holds a box that is dropped within the volunteer’s hands. The equipment then measures the response time in grabbing the item. One of the attributes of this device is that it does not involve a learning process, so the metrics gathered represent performance, not learning abilities, Col. Belenky says.

Current data suggests that apparent and actual changes in performance are dramatically different, and performance and productivity decreases precede accidents and catastrophic failures. The civilian sector, including the transportation industry, has adopted many of these predictors because of the loss of productivity caused by fatigue. “Accidents are just the tip of the iceberg. You can see where the costs are there. But the overall loss in productivity goes up when there is a lack of sleep, and these are the costs that are not easily seen,” Col. Belenky relates.

An invisible factor in the physiological equation is stress. Dr. James L. Meyerhoff, chief of the department of neuroendocrinology, WRAIR, is a member of the warfighter physiological status monitor team focusing on the effects of stress on the military. Rather than relying on personal assessment of the amount of stress a subject is experiencing, Meyerhoff’s work involves collecting validated measures of stress and developing a model that includes physiological, psychological and biochemical information.

To collect this data, soldiers preparing to go before the promotion board or interviewing for the soldier of the month award are asked if they would be willing to be monitored. As with all of the studies being conducted in the project, only volunteers are allowed to participate in the exercises. Risks are evaluated and minimized prior to human subject involvement, and volunteers are apprised of any and all risks, Meyerhoff emphasizes.

In the stress project, personnel are studied for a week prior to meeting with the board, during the interview and for a week after the board examination. The technology to collect physiological measures is designed to be as unobtrusive as possible. These devices include items that measure heart rate and blood pressure and, with the volunteer’s consent, an intravenous line that collects blood samples that are later analyzed to determine the body’s biochemical reaction to stress. Stress hormones can also appear in saliva, so a sample may be taken before and after the subject appears before the board. All of this data is then matched with performance.

“Up to a point, stress helps us, but the problem is when stress gets out of control. We have found that those who are very stressed tend to have lower scores on the boards,” Meyerhoff explains.

One possible future project for research would involve determining if stress levels can be quantified from the qualities of a person’s voice. This would be particularly useful in a military situation because audio transmission during missions is the predominant means of communication, the doctor relates. One approach would be to do a spectral analysis of the voice to determine if cues could be identified that would give more accurate insight into a situation than the words express.

“There are a great many features in the voice to measure. One feature would be pitch or fundamental frequency. The question is do we need a baseline for each individual. Does this require extensive study of a person at rest? Is individuality needed? If so, then it is a more expensive proposition than if you could just generalize the data,” Meyerhoff offers.

While these projects focus on monitoring the individual soldier’s physiological condition to help assess effects on performance, the remote triage sector is evaluating technologies that would assist medics in the field.

The future technology-enhanced soldiers will operate in more widely dispersed groups and on future battlefields that will include urban environments. For these soldiers, equipment that supports remote assessments of injuries could be key to reducing the number of fatalities during missions.

Currently, 90 percent of soldiers killed in action are located forward of the battalion aid station. This number has not decreased despite improvements in medical technology. In addition, two-thirds of the deaths occur during the first 10 to 15 minutes after the injury is incurred, and one-third occur during the first hour.

One goal of remote triage is to minimize the killed-in-action rate, which remains at approximately 20 percent, a statistic that has not changed in 100 years, Pearce says.

“Technologies that allow the medic to treat a casualty better in the field by using telecommunications are good and more near term for the medic arriving on the scene. But that doesn’t help the medic with the ‘Who do I go to first?’ question,” he explains.

Integration of the sensor technologies to collect physiological assessment data and injury information will be important, Pearce relates, because by definition all of the equipment will have to serve both combat and noncombat situations. During maneuvers, for example, readings could be taken at half-hour intervals. However, in a trauma situation, medics would need second-by-second information.

The team is looking at different approaches to initializing the transmission of the information and is considering placing a button device of some kind within easy reach that would act as a 911 call button. Pushing the control would send a signal that includes location and distance/vector data to the medic’s computer system. For security purposes, these signals could not be transmitted over long distances, Pearce offers.

Col. Obusek believes this type of technology can be a combat force multiplier. “Triage, in its most basic form, is determining if a soldier is alive or dead on the battlefield. As a medic you just want to know if you’re going to divide your time between four people or if there are five to take care of,” he offers.

The warfighter physiological status monitors are scheduled to be inserted into the Land Warrior system in fiscal year 2003. The group is also working on the smart sensor web, an initiative proposed by Dr. Jacques S. Gansler, undersecretary of defense, acquisition, technology and logistics. The smart sensor web is envisioned as an intelligent, secure, web-centric distribution and fusion of sensor information that provides enhanced situational awareness on demand to warfighters at the lower echelons.