Predicting acute mountain sickness— published: 07-23-2013
With current and future military operations in mountainous regions, the issue of acute mountain sickness (AMS) is a significant medical concern. AMS can affect anyone, military or civilian, who is unacclimatized and/or ascends too rapidly to high altitudes. Symptoms of AMS can include headache, nausea, fatigue, dizziness, and sleep disturbances. Recently, researchers at USARIEM were able to predict the severity and prevalence of AMS after rapid ascent to various altitudes. What they found was that for every thousand-meter increase in elevation over 2,000 m, a person was over four times more likely to develop AMS. In addition, the severity of sickness doubled, and the odds that the AMS would worsen increased almost five-fold. AMS appeared to peak at 18 to 22 hours of exposure to altitude and then went away after 42 to 48 hours. The severity of sickness is greatest above 4,000 meters and may require evacuation to lower altitude or immediate medical attention. It also appears that men are more likely than women to get AMS and more likely for it to be severe. For both men and women, the more active they were at altitude, the longer it took to recover. These findings support current recommendation to limit activity as much as possible in the first 24 hours at altitude to decrease the risk for AMS.
This information should help military leaders manage and perhaps prevent AMS among troops by knowing the elevation, types of activities, and lengths of stay at altitudes.
In order to reduce the risk for AMS, acclimate to moderate elevations (2,000 – 3,000 m) if/when possible. In addition, stay hydrated and try to limit your physical activity at altitude for the first 24 hours. Read more about the effects of altitude on performance and how to minimize your risk for AMS.