Dizzy 98 degree

Heat is On, The

How to keep your cool when you're hunting where the climate is hot.

Heat, especially the intense kind common in tropical, subtropical, and desert environments, can do strange things to your body and even to your mind. Yet we seldom hear very much about the dangers of heat-related illness, which is known as hyperthermia. Hypothermia-loss of internal warmth caused by cold conditions-yes. Oceans of ink (including a pond or so of my own) have discussed that particular danger, the so-called "silent killer." Yet severe heat can be just as deadly-and just as silent. If anything, heat illness may be more insidious than cold-related illness, because it often builds up slowly and undramatically-no racking shivers or chattering teeth-until there's trouble.

In one sense, both hypothermia and hyperthermia arise from the same basic physiological fact: The human body's range of acceptable inner temperature is narrow and rather fragile. Knock it even a couple of degrees off center (about 98.6 for most of us) and we're in distress. High heat is a tough problem because the body, by itself and even at rest, continues to generate more heat. Vigorous exercise (such as hunting) can increase the body's heat production tenfold. This can quickly overload the main means of cooling, which is through the evaporation of sweat. Note the stress on evaporation. Heavy sweating itself-the outpouring of liquid-is not cooling. Rather, it's evidence that the body is burning water through the sweat glands faster than perspiration can evaporate in the surrounding air. The result is a buildup of interior heat and the potentially dangerous effects of dehydration.

This pattern of sweating-but-not-cooling is most noticeable, of course, in humid conditions, when sweat evaporates slowly in the damp air. Humidity combined with air temperature can create a total heat effect of surprising intensity. Meteorologists call this "apparent temperature" and chart it in a heat index. For example, a 90-degree (Farenheit) air temperature combined with 90 percent relative humidity produces an apparent temperature-or total heat effect-of 122 degrees. This is a danger zone in which heat exhaustion is a real possibility. An air temperature of 95 degrees combined with the same humidity produces an overall heat effect of 150 degrees-a setting primed for a person to fall victim to potentially fatal heatstroke.

In dry climates, air temperature alone can be severe, and baking heat of 95 degrees or more evaporates sweat so efficiently that a different kind of danger is posed: that of steady and serious-but largely unnoticed-dehydration, combined with a loss of important vitamins and minerals (electrolytes).

These severe conditions can lead to heat exhaustion or heatstroke, depending on severity. "Heat exhaustion" is the rather imprecise name for what is mainly heat-induced dehydration. Excessive loss of fluid and electrolytes through sweating disrupts blood circulation to the vital organs, causing the sufferer to feel weak, dizzy, and nauseated. Other symptoms include increased heart rate (fast pulse), rapid breathing, headache, and thirst. Because of heavy sweating, the victim's skin might actually feel cool to the touch.

Treatment for heat exhaustion should begin with getting the victim out of the sun and heat and into a shady, cool place. Cool the person further by dousing the skin with water and fanning to aid evaporation. Fluid replacement is vital. Water, best if mixed with a pinch of salt and two or more pinches of sugar, or a watered-down, electrolyte-balanced drink like Gatorade, should be sipped steadily (do not allow the victim to guzzle the drink-that can cause vomiting). A heat-exhaustion victim should drink lots of water, more than is naturally desired.

Heatstroke, although on the same continuum as heat exhaustion, is the negative extreme, and should be considered a life-and-death emergency. It occurs when the body's efforts to cool itself are overwhelmed. Core temperature shoots up to 105 degrees or more. The first outward sign of heatstroke is altered consciousness. The person will act confused, judgment-impaired, uncoordinated, possibly irritable or combative, and might experience hallucinations. The skin, though it can be either sweaty or dry, will be red and hot to the touch. The victim's pulse and breathing will be rapid. Full collapse into unconsciousness and coma is imminent.

A person suffering heatstroke is essentially burning up inside-"boiling the brain," as medics say. The only hope for survival is immediate, radical cooling. The preferred field method is to remove the person's clothing and re-cover them with soaked cotton cloth, while fanning them vigorously with whatever is on hand to aid the cooling effect of evaporation. Don't rub the person with alcohol or give antifever drugs like aspirin or acetaminophen. If possible, place ice packs or cold cloths in the person's armpits, behind the neck, and in the groin. Full-body immersion in cold water is another (though, contrary to intuition, less effective) option. If the person returns to consciousness, give sipped fluids to reverse dehydration. Heatstroke victims should be evacuated as soon as possible to professional care, even if they seem to have recovered; life-threatening relapses are common.

Although heatstroke is most commonly associated with the elderly, weakened, and ill, hunters should be aware that so-called "exertional heatstroke" can happen to anyone, even the young and fit, in any situation involving unaccustomed heat and relatively vigorous exercise.

Preventing Heat Trouble

When hunting in a hot climate, follow these guidelines for maximum comfort and health:

Drink more water (or "sports drink" mixtures such as Gatorade) than you feel you need. Drink one pint or more of liquid before you begin any kind of vigorous exercise in the heat, then drink between a pint and a quart of water each hour while you're engaged in strenuous physical effort, and/of heavy sweating. (See Survival, Sports Afield April/May 2004, for a detailed look at dehydration and its dangers, as well as strategies for detection and prevention.)

Acclimate to the environment. The human body does learn to adjust its thermal regulation systems to very hot or humid conditions. But it takes some time, and the process can't be rushed. Ease yourself into the heat if at all possible, starting with lighter efforts, then gradually increase both the amount of time you are exposed to the heat and the intensity of your outdoor activity. If possible, schedule less strenuous phases of a hunt for early in the trip, and harder, all-out efforts for the later days.

Eat a healthy diet that includes plenty of fruits and vegetables, especially potassium-rich items like bananas and broccoli, if they are available. Don't take salt pills; the intense concentration of sodium irritates the stomach and is unnecessary as long as you are eating properly. If heavy sweating makes potassium loss a concern, (usually only a factor when you are sweating to the point of losing weight), then add a pinch of table salt per pint of water several times a day.

Wear loose, breathable clothing that aids sweat evaporation. It's okay to expose bare skin in humid climes, but in dry climates, you can reduce excessive water loss and skin heating by wearing long-sleeve shirts, long pants, and a wide-brimmed hat for sun protection. In both humid and dry conditions, remove your headgear often to aid evaporative cooling. Periodically towel off excess sweat from your face and scalp for the same reason. Get out of the direct sun as often as possible and take periodic rests from exercise so your body can cool and regulate.

Limit your intake of alcohol and caffeine; both are dehydrating and increase the risk of heat illness.

Get in shape before heading off to a hot climate. Extra pounds, poor cardiovascular health, and lack of muscular conditioning are invitations to trouble.