and malnutrition, create obvious difficulties for military operations. Some of these difficulties can be minimized by appropriate military planning, policies, and training. Troops conducting military operations at high altitudes, as they currently do in several mountainous regions of the world, have unique needs for special training and support. To prevent severe dehydration, water discipline is as essential at high altitudes as it is in the desert, and potable water must be supplied, whatever the logistical problems. Despite the tendencies for high-altitude and AMS-induced anorexia, discipline in food intake must also be enforced and military field feeding doctrines (IOM, 1995a) should include specific mention of environmental extremes. Energy and carbohydrate-rich foods must be provided, as outlined earlier in this chapter. Time to prepare and consume adequate energy must also be allowed. Increased energy needs at high altitudes result from an increase in basal energy needs as well as from strenuous activity. In order to prevent loss of body weight and muscle mass, the foods required to supply these needs must be provided, and they must also be compatible with logistical constraints. Palatability also must be considered; for example, provision of an easily consumed, preferred high energy "finger" food or beverage could be important in maintaining body weight and muscle mass.
Because gradual ascent to altitude and gradual acclimatization are not often compatible with military missions, a high incidence of AMS and breakdown in military unit cohesiveness must be anticipated. Military missions must be planned with the expectation that more than half of the troops will suffer from some degree of AMS, and that up to 25 percent may be transiently incapacitated (Hackett et al., 1989). Additional medical problems must be anticipated in troops who remain at altitudes above 18,000 ft (5,486 m) for many weeks (see Butterfield, Chapter 19 in this volume). Acclimatization to moderately high altitudes (8,000-12,000 ft [2,438-3,658 m]) may be accomplished within a week (many physiological systems adapt in this time, but some take far longer). However, full acclimatization to extremely high altitudes may not occur, and accumulations of body salt and water may become a consistent problem (see Cymerman, Chapter 16 in this volume).
All personnel must be trained to recognize the early symptoms of acute pulmonary edema or cerebral edema. These life-threatening problems are most likely to be observed in those individuals who have experienced difficulty in keeping up the pace and lag behind. Troops assigned to high altitudes should also be trained to master the difficulties in treating and evacuating patients with these altitude-induced conditions, as well as the task of dealing with soldiers who fall victim to the inevitable mountain climbing injuries.