Treatment, diagnosis, and prevention of dehydration, heat exhaustion, and heat stroke in the field. Early recognition can save a life.
Heat related medical conditions are often presented in some mystical way. It is pretty simple, and a swallow of Gatorade will not prevent them.
As the outside temperature nears normal body temperatures of 97.8°F – 99.1°F, sweating, perspiration, increased blood flow to the skin, and evaporation account for most of the body’s cooling. High humidity slows the evaporation rate, decreasing the cooling. As sweating continues the body loses electrolytes (primarily sodium and potassium).
In the worst case, heat stroke, the body cannot keep up or adjust fast enough to ambient temperatures; the organs fail and muscles break down leading to death.
The very young and the elderly are most at risk. Knowing the history of those you evaluate is important. Thyroid disorders, diabetes, heart disease, amphetamines, cocaine, PCP, and alcohol can all lower heat tolerance.
As with everything in the field, common sense and knowledge prevails.
The body always screams out warning signs of an impending heat related disorder in the form of:
- Persistent sweating, especially with exertion
- Excessive thirst. This is not a reliable indicator
- Increased heart rate
- Excessive, constant sweating
- A decrease in mental sharpness
- Light-headedness especially with persistent standing or on getting up suddenly
- Cramping muscles. Most often in the hands, back, and feet.
The onset of symptoms varies with, temperature, humidity, age, physical condition, and acclimation.
If the above symptoms of dehydration aren’t addressed, heat exhaustion is the next bodily response. This remains in the non life- threatening early stages and can be treated in the field.
- Increasing weakness and fatigue
- Nausea especially with the rapid drinking of fluids
- Worsening of light-headedness upon standing or after standing for prolonged periods
- Except for a decrease in mental focus and sharpness, memory and logic remains intact
NOTE: At this point, other reasonable causes for the symptoms should be considered. In heat exhaustion, the temperature can be very mildly elevated but rarely over 101°F. If higher, consider infection as a cause. A low blood sugar, stroke, or heart attack can all present with similar symptoms, but the history of dehydration and decreased fluid intake should be obvious.
Heat stroke is a misnomer. It is not a stroke, in that strokes effecting the brain (cerebrovascular accidents), like heart attacks, are caused by blocked or constricted blood vessels. It is uncommon, but not unheard of, for a high body temperature to cause a stroke or cerebrovascular accident. A better term may be, chronic or extreme heat exertion.
- Prolonged; worsening heat exertion
- The body’s temperature regulation system totally fails
- Extreme confusion and /or hallucinations
- Possible seizures (usually generalized causing a jerking or extreme rigidity of all extremities)
- Unresponsive state
- Rapid heart beat
- Temperatures, often greater than 104°F
- 2 categories are distinguished in the Merck Manual:
- Classic: Begins after 2-3 days of heat exposure, affects the elderly and non-active during heat waves. Skin usually feels hot and dry
- Exertional: Begins in hours. Usually the young, athletic, who are non-acclimated to conditions. Associated with intense exertion. The skin is often moist and sweaty.
NOTE: At this point, other conditions must be considered;
- Infections such as malaria
- Meningitis/ encephalitis (the difference being that the former is usually due to bacteria and the latter due to a virus, both inflame the covering of the brain i.e. the meninges)
- Drug intoxication with PCP, cocaine, or other stimulants
- A true stroke (cerebrovascular accident)
Many factors determine the recovery including overall health and age but the main thing is the duration of the symptoms. The death rate is high and studies show about 20% have brain and organ damage.
Treatment in the field:
Get the person to a cool area where they can rest.
Remove unnecessary clothing.
If water is available, sponge it on repeatedly until you see an improvement in the symptoms.
Fan the moistened skin with banana leaves or whatever is available.
If water or ice supply is limited, place on the neck (carotid arteries) and groin (femoral arteries). High volumes of cooling blood flows through these areas.
Immerse in a river or spring.
Mix a teaspoon of salt or baking soda in a pint or quart of a sweetened drink and have the person drink it. Make sure they are alert and there is no risk of choking. This will help address the low sodium and a low sugar. Repeat in 1 hour. After this give plain water frequently without additives.
A heat stroke is an emergency. You must seek a medical facility if at all possible.
The two most important things are acclimation and hydration.
Acclimation: Begins in 12-24 hours; taking 3-4 days to fully adjust to extreme temperatures and humidity levels. This can take longer depending on age, fitness level (obesity slows cooling), and medical conditions.
Hydration: Do not rely on thirst to be your indicator. Drink frequently. Begin with plain water or sports drinks. If the urine is concentrated (dark yellow), increase fluids. A good formula in extreme conditions is a rounded teaspoon of salt (plain or iodinated if no thyroid problems) in 5 gallons of water. I add a mildly sweetened drink mix to increase sugar content.
Ask your doctor if you are on a salt or sugar restricted diet.
Wear light clothing and ventilated head-gear.
Be aware that altitudes greater than 8000 ft. make you more prone to dehydration.
Excessive fluids can be lost with illness, nausea, vomiting, and diarrhea. Start fluid replacement immediately if possible.
Drinking an excessive amount of water without salt can have a detrimental effect by diluting the blood and decreasing salt (hyponatremia). The symptoms are similar. You will know you are at risk if the urine is water clear and you have been drinking excessively.
A final note: There are many electrolyte replacement products available including powders for drink mixes, Pedilyte, and Nuun. The cheapest is salt and chicken bouillon cubes.