Heat Illness/Heat Injuries

Heat illness or heat injury refers to several heat-related problems:

• Heat edema (swelling of hands, feet and ankles)
• Prickly heat or heat rash
• Heat cramps
• Heat exhaustion
• Heat Stroke

We tend to think of heat illness in terms of hot days, but it can happen in cooler air temperatures, too. Several other factors can contribute:

• Strong radiant heat or high air temperature
• Heavy exertion
• Humidity
• Dehydration
• Antihistamines
• Antihypertension drugs
• Stimulants

Dehydration is a huge contributor to serious heat illness. It is such a danger that I ask that if you haven’t already read the dehydration page, please do so now.

Heavy exertion heats your body up from the inside. If you excessively work out or work hard, even in cool temperatures, you can overheat yourself and bring on heat illness. In cold temperatures, a possible double-whammy is that the sweat you generate could lead to hypothermic conditions when you stop.

Humidity defeats your body’s ability to cool itself. Sweat cools you by drying up (hence, wind chill); if it’s so humid that this drying is excessivly slowed, your body’s defense is useless and leads only or mostly to dehydration.

Radiant heat (i.e., the sun shining on you on a cool day, heat reflected from a trail) is just another source of heat besides air temperature.

Prevention

• Stay hydrated. Dehydration reduces your body’s ability to cool itself, by limiting sweating capability by two physiological mechanisms: reduction of ability to produce sweat; and reduction of blood plasma volume, thus disabling the body’s ability to expand blood vessels toward the skin surface
• Do your hardest work in the cool of the day
• Avoid alcohol and caffeine. Alcohol and diuretics are factors for dehydration, while caffeine and other stimulants can raise your internal temperature
• Dress for the heat and reduce activity; reserve strenuous work for the cool parts of the day, and take advantage of shade, breezes, fans, air conditioners, etc.
• Give your body time to condition itself to the heat before extended heavy exertion. This may take a while (up to ten days), and will require that you push a little each day; just don’t get too far from relief and a “bottomless” water source, and stop before you overheat
• Get enough sleep

Symptoms and Treatment,
minor maladies

• Heat edema
• Swelling of hands, feet and ankles during first days in hot environment
• Cures itself after a few days
• Heat rash
• Itchy, red, bumpy rash caused by plugged sweat glands kept wet from sweating
• Cool and dry the area, and try to avoid sweating for a while
• An antihistamine can help relieve itch
• Good cleanliness is helpful as a preventative
• Heat cramps
• Cramps and spasms that occur usually after working a muscle heavily
• Water and hydration salts both prevent and help treat heat cramps
• Apply steady pressure to cramped muscle

Symptoms of serious heat illness

• Sweating, dehydration
• Headache, general weakness
• Dizziness from standing up
• Body temperature of normal to 104 degrees fahrenheit
• Loss of appetite, nausea and vomiting are common
• Normal mental state
• Normal coordination

• Add to symptoms of heat exhaustion:
• The big key is: altered mental state: acting drunk or disoriented, loss of coordination, bizarre behavior, seizure, coma
• Rapid respiration and heart rate
• Low blood pressure
• Sweating may be present or not; if not, recognize that the situation is extremely serious

Treatment of serious heat illness

• Heat exhaustion
• Stop exertion
• Get to cooler place
• Remove or loosen restrictive clothing
• Drink lots of water, use hydration salts
• Spot cool the neck, chest, armpits, and groin
• Sudden cooling (jumping into ice water) isn’t advised
• Heat stroke
• Stop any exertion and cool down as quickly as possible, but not so fast as to cause any (additional) shock
• Spot cool the neck, chest, armpits, and groin
• Drinking can be dangerous, since you could vomit or inhale the water. If you take water, small sips, increasing as the body cools and tolerates it. Rescuer, be advised! Never administer food or drink to an unconscious victm, and do regulate the speed of intake
• Treat for schock
• Get medical attention

My favorite reference book for first aid matters is A Comprehensive Guide to Wilderness & Travel Medicine, by Eric A. Weiss. Handy, small, easy to pack around, but solid in its coverage.

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