Heat stress injuries to the human body as a result of exposure to environments where elevated temperatures, high humidity with minimal air movement can cause raised body temperatures resulting in life threatening illness if not treated quickly and effectively. Of particular medical concern is heat stroke, which if left untreated, or treated ineffectively, can result in the death of the victim. According to the Center for Disease Control “…an average of 618 deaths occur in the United States each year as a result of exposure to excessive natural heat.” When an active, un-acclimatized individual, who lacks adequate protective clothing, is exposed to high temperatures, high humidity situations without adequate supplies of water, and without shade, heat stress injuries are immanent. Heat stress injuries can be viewed as a progression of medical issues that range from mild (heat cramps) to moderate (heat exhaustion) and finally to severe threats to life (heat stroke). A progression that, if not acted upon effectively and quickly can result in the death of the victim. With the limited equipment available in the field the emphasis needs to be on early recognition of what is happening and effective treatment to reverse the cascading events.
Heat Cramps are spasms of the skeletal muscles resulting in excruciating pain. Heat cramps do not typically evolve into heat exhaustion. Nonetheless they should serve as a warning that the body is reacting to heat stress resulting from exposure to high activity levels under elevated environmental heat conditions, inadequate water intake and with salt depletion. Treatment of heat cramps necessitates removing the patient from the environment causing the problem, resting in the coolest area available and replacing the electrolytes with fluids or salty food – not salt tablets. I have also had good results using Emergen-C.
Heat Exhaustion is a mild to moderate form of heat illness that will progress to heat stroke if not treated quickly and effectively. While it is usually not possible under field condition to determine body core temperatures, the victim of heat exhaustion will commonly have core temperature of 101° F. to 105° F. Other signs and symptoms include rapid heart rate, pale color, nausea, dizziness, headache and lightheadedness. Profuse sweating is common but not always present. Treatment of heat exhaustion includes the removal of the victim from the environment if possible, treating for shock, and, assuming the patient can swallow, providing large quantities of water – 1 to 2 quarts minimum.
Heat Stroke is a life threatening medical crisis, which, in the absence of large quantities of cool water, is very difficult to treat in field. A heat-stroked patient will manifest major central nervous system abnormalities – seizures, delirium, stupor, coma and usually, but not always, dry skin. Since heat-stroked victims have lost the ability to sweat and cannot cool themselves their body core temperatures may rise above 107° F. with death following quickly unless external cooling can be accomplished. Treatment. The victim must be cooled as quickly as possible. Transport to shade or erect shade over the victim. Spray with cool water and fan vigorously to promote evaporative cooling and the lowering of the individual’s core temperature. Arms and legs can be massaged to stimulate the flow of cool blood back to the core. Treat for shock.
Heat injuries can be prevented by:
– Acclimatization. The human body has an amazing capacity to adapt to a hot environment. Exercising in a hot environment can bring about acclimatization. The exercise must be of sufficient intensity, frequency and duration to elevate the skin and core temperature and to cause profuse sweating. This adjustment process takes approximately ten days to reach the point where the body is able to maximize its ability to cool itself by sweating efficiently while at the same time minimizing the loss of electrolytes – especially sodium and potassium.
– Water. Every activity that takes place in the human body takes place in a water environment and when adequate supplies of water are not consumed body systems begin to malfunction. Water is also the fundamental component needed to ensure adequate sweating required for evaporative cooling. Sweating, a normal activity of the skin is designed to keep the body cool in hot or humid surroundings. Sweat glands produce a salty fluid that, when evaporated on the skin surface, produces cooling. In a hot, humid environment, with insufficient water intake, the ability to sweat begins to malfunction and the onset of serious medical issues – heat exhaustion and heat stroke, becomes likely. The problem is exacerbated in high humidity environments where sweat drips from the skin rather than being evaporated with little cooling taking place. The amount of water needed to prevent dehydration, a factor in all heat stress medical issues, varies from individual to individual and from one emergency scenario to another. Suffice to say that a person who is drinking enough water to ensure that their urine is clear, or nearly so, and is urinating five to six times a day is unlikely to become dehydrated and therefore unlikely to become a heat stress victim.
– Skin Protection. The body’s skin surfaces must be covered or sunburn – will occur. While some exposure to ultraviolet radiation is necessary for good health – the production of Vitamin D for example, the sunburn that results from prolonged exposure causes early aging of the skin, cataracts, and skin cancer. All fabrics provide some degree of protection but dry, tight weave, dark colored fabrics provide the best protection. Clothing manufactured from fabrics with a high Sun Protection Factor (SPF) is also available. These fabrics are either extremely tightly woven materials or they are chemically treated to provide the needed SPF. In short fabrics used in high heat, high humidity environments should be absorbent and lightweight. The more immediate benefit of covering the skin surfaces is the reduction of body water loss and therefore the prevention of dehydration.
The uses of sunscreens, “…..products designed to moderate the development of sunburn,” are another form of skin protection. The ability of a sunscreen to protect a person’s skin is determined by its SPF. Laboratory studies have shown that a sunscreen with an SPF of 15 blocks 93% of UVB exposure and should provide sufficient protection however, in the field the application of a sun screen is often applied too late, too little is applied and when applied, is too uneven to achieve good protection. Consequently an SPF of 30 should be used in hopes that a higher degree of sunburn protection can be achieved.
Venturing out into hot environments without appropriate clothing and with only limited quantities of water, hoping that nothing bad is going to happen, is like going to the local casino – you might get lucky and win but all too often you loose!