Army studies high-altitude health effects
January 5, 2010
Climate and altitude commonly inhibits the optimal effectiveness of servicemembers in many theater operations. In the mountainous country of Afghanistan in particular, servicemembers are asked to perform at thousands of feet above sea level, oftentimes hindering their cognitive and physical performance.
At the U.S. Army Research Institute of Environmental Medicine (USARIEM) Thermal and Mountain Medicine Division in Natick, Mass., researchers are studying the causes and medical effects of high-altitude exposure. Researchers are offering information and products to increase resiliency and performance of servicemembers deployed at high altitudes.
Dr. Stephen R. Muza, research physiologist at USARIEM, a laboratory of the U.S. Army Medical Research and Materiel Command (USAMRMC), explains that there are measurable decrements by which physical and cognitive performance can be gauged as an environment increases in elevation. Humans begin to lose their optimal performance as the altitude of the environment increases. This is due to the reduced air and oxygen pressures that decrease the availability of oxygen. The result is hypoxia, an inadequate oxygenation of the blood.
"At 4,000 ft. above sea level you first start seeing a lack of physical performance. 8,000 ft. is usually the altitude at which cognitive performance is affected. And we've found that 10,000 ft. is the threshold where judgment starts to become impaired," said Muza.
When a human reaches 8,000 ft. above sea level certain altitude sicknesses are born. Acute mountain sickness (AMS), in particular, is characterized by headache, nausea, dizziness, and shortness of breath. AMS is common, but recovery is quick with descent and rest. Two more serious but rare altitude sicknesses require medical treatment and can be very dangerous for troops in combat.
There are several ways servicemembers can prepare for high-altitude conditions prior to deployment. A Soldier can start by training at a higher altitude to physically prepare for deployment. High-altitude training facilities can be found at military installations in the continental U.S. including Fort Carson, Colo., the Marine Mountain Warfare Training Center, Calif., and at Hawthorne Army Proving Ground, Nev.
"However, physical training for deployment will not reduce the risk of developing altitude sickness in theater," said Muza. The training will prepare servicemembers to recognize the symptoms of AMS and react appropriately.
In addition to high altitude training before deployment, servicemembers can practice a healthy lifestyle by eating a well-balanced diet and not smoking.
"Since the carbon dioxide in cigarettes decreases the amount of oxygen the hemoglobin in your blood can carry, you're getting even less oxygen and putting yourself at a greater risk at a higher altitude," said Muza. This can be critical when engaged in high-altitude warfare.
High-altitude research is simulated by researchers in a controlled environment with hypobaric chambers. At USARIEM these decompression chambers are used by researchers to control the barometric pressure and oxygen concentration in an enclosed environment to simulate high altitude conditions. The simulation gives researchers the data they need to draw conclusions about acclimatization, acute mountain sickness, hypoxia, and human performance metrics. USARIEM is also studying the effectiveness of hypoxic chambers used by athletes across the world to help their bodies perform better at higher altitudes.
As a result of the research conducted by Muza and his team at USARIEM, several products have been developed. Because there is relatively little data accumulated in regards to altitude sickness, several models are being created to be used as tools for the military. The research team at USARIEM is working on several predictive models which will pivot around the results and findings of three main topics of research: altitude sickness, work performance and altitude acclimatization.
"Information is our major product," said Muza. "In 2010 we will release the Altitude Acclimatization and Illness Management Guidelines (TB Med 505)." This is a collection of much of our work surrounding altitude illnesses and will act as a tool for servicemembers deploying to higher altitudes.
Another product is an "eat-on-the-move" nutrition supplement that allows servicemembers to receive necessary hydration and carbohydrate-based nutrition essential to optimal performance at a high altitude.
There is only one drug which has been approved by the Federal Drug Administration for prevention of altitude illnesses. Diamox helps speed up the process of adjusting to higher altitudes, and reduces minor symptoms. The drug is given to servicemembers to prevent AMS; there is currently no FDA-sanctioned drug to improve cognitive performance.
"Researchers have worked over the past decade to study a variety of drugs as an effective medicine to combat altitude sicknesses. There have been several drugs studied, but all of them have proven to be ineffective," said Muza.
While several significant advances have been made in the field of high altitude research, there are still several capability gaps that present themselves. "Our main gap is a lack of substantial predictive models. There are several controlled variables that affect one's susceptibility to AMS, making it tough to develop an accurate model around the specific altitude thresholds at which different physical and cognitive effects start to set in," said Muza.
There are also other factors that play a role in identifying research needs. Researchers have found that hydration and nutrition is integral to higher-altitude performance. All too often military personnel will restrict their fluid intake because of the long trips to different deployment locations in vehicles and aircraft that have no toilets. "Troops are arriving with dehydration and other related symptoms because of this and are therefore more susceptible to altitude sickness," said Muza.
Researchers are working to remedy many of these capability gaps in their research areas. "We're working to identify and optimize acclimatization strategies that are applicable to military units in an effort to improve their capabilities," said Muza.
USARIEM works with the Human Performance laboratory at the Air Force Academy to study altitude sicknesses and related subject areas. USARIEM also works in collaboration with several other health facilities in related research studies. They work with Massachusetts General Hospital with the early diagnosis of acute mountain sickness; Brigham Women's Hospital Center on MRI neuro-imaging studies; Stanford University with diet and nutrition studies; Oklahoma State University with acute mountain sickness studies; as well as the University of Colorado's Health Science Center.
USARIEM is the only U.S. military organization with a mission focused solely on environmental research issues. With continued research revolving around high altitude sickness and its related effects, researchers are making fast headway on preparing servicemembers for deployment in high altitude locations.
For more information visit www.usariem.army.mil