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Heat Injuries

Types, treatment, risk factors, control measures

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HEAT INJURIES

Types of Heat Injury

Heat Cramps

Heat Exhaustion

Heat Stroke

Heat Cramps

Painful cramping of the larger muscle groups

legs, arms, abdomen

Due to excessive loss of salt through heavy sweating plus several hours of sustained exertion

acclimatization decreases risk

Treatment

shaded area

massage arms/legs to increase circulation

0.1% salt solution orally (1/2 tsp salt in 1-qt. Water), sports drink, or salted food (MRE) plus fluid

Heat Exhaustion

Symptoms:

heavy sweating, headache, light-headed, nausea/vomiting, tingling sensations

Temperature 99-104 F

Cause:

dehydration plus excessive salt depletion

Treatment:

shaded environment; loosen clothing

If suspect early heat stroke, treat as such

oral fluids if can drink

cold water, 0.1% salt solution, or 6% carbohydrate beverage

1-2 liters over 2-4 hours

EVAC

Heat Stroke

Symptoms:

elevated temperature plus central nervous system disturbance

absence of sweating is a late finding

Can begin as heat exhaustion and progress

End-organ damage:

brain damage, kidney failure, liver failure, blood clotting abnormalities

related to duration of elevated temperature

Treatment of Heat Stroke

ABC

Unconscious patient may vomit and aspirate

IV: no more than 2L unless circulatory collapse

Lower the body temperature as fast as possible!

All clothes off

Cool water with fanning...increase evaporation

Ice packs under groin or axilla

EVAC...open doors/windows in helicopter/vehicle

keep cooling to temp 101-102 F.

Ice-water immersion: controversial

USASOC and TB MED do not recommend

Wilderness Medicine, 3rd ed. supports

Risk Factors for Heat Stroke

Dehydration

Respiratory and GI illnesses most common

Alcohol use

Laxatives and diuretics

Medications

Increase heat production and/or decrease heat loss

pseudoephedrine, thyroid hormone, cocaine

Decrease sweating

antihistamines (Benadryl), anti-nausea (meclazine, phenergan)

Supplements

Ephedrine (MaHuang), caffeine

Control Measures

Water and sports drinks

Salt

Acclimatization

OTSG Guidance for the Field Use of Sports Drinks

Cool water is usually the best rehydration fluid

Prolonged training and operational scenarios

carbohydrates and electrolytes are also required for optimal physical and mental performance

meals and snacks plus water are best

When sports drinks are appropriate:

duration > 6 hours, hot weather, if snacks/meals not consumed

duration > 3 hours, strenuous exercise, if snacks, meals not consumed

duration > 6 hours strenuous exercise, if total food intake is significantly limited

Sports Drink Recommendations

INGREDIENT Amount per 8 ounces (as served)

Sodium 55-160 mg

Potassium 20-55 mg

Carbohydrate 11-19 gm

Acclimatization

Physiologic adaptation that occurs in response to heat exposure in a natural environment

5 days for most

14 days required for 95% of population to have complete acclimatization.

Can deacclimatize as quickly

Results:

sweat at lower temperature

increased volume of sweat

decrease in amount to salt secreted in sweat

increased heat dissipation = lower core body temperature

End result: Decreased risk for heat injury!

Fluid Replacement Guidelines for Warm Weather Training

Questions?