HEAT INJURIES

Types of Heat Injury l Heat Cramps l Heat Exhaustion l Heat Stroke

Heat Cramps l Painful cramping of the larger muscle groups ä legs, arms, abdomen l Due to excessive loss of salt through heavy sweating plus several hours of sustained exertion ä acclimatization decreases risk l Treatment ä shaded area ä massage arms/legs to increase circulation ä 0.1% salt solution orally (1/2 tsp salt in 1-qt. Water), sports drink, or salted food (MRE) plus fluid

Heat Exhaustion l Symptoms: ä heavy sweating, headache, light-headed, nausea/vomiting, tingling sensations ä Temperature F l Cause: ä dehydration plus excessive salt depletion l Treatment: ä shaded environment; loosen clothing ä If suspect early heat stroke, treat as such ä oral fluids if can drink ä cold water, 0.1% salt solution, or 6% carbohydrate beverage ä 1-2 liters over 2-4 hours ä EVAC

Heat Stroke l Symptoms: ä elevated temperature plus central nervous system disturbance ä absence of sweating is a late finding l Can begin as heat exhaustion and progress l End-organ damage: ä brain damage, kidney failure, liver failure, blood clotting abnormalities ä related to duration of elevated temperature

Treatment of Heat Stroke l ABC ä Unconscious patient may vomit and aspirate ä IV: no more than 2L unless circulatory collapse l Lower the body temperature as fast as possible! ä All clothes off ä Cool water with fanning...increase evaporation ä Ice packs under groin or axilla ä EVAC...open doors/windows in helicopter/vehicle ä keep cooling to temp F. l Ice-water immersion: controversial ä USASOC and TB MED do not recommend ä Wilderness Medicine, 3rd ed. supports

Risk Factors for Heat Stroke l Dehydration ä Respiratory and GI illnesses most common ä Alcohol use ä Laxatives and diuretics l Medications ä Increase heat production and/or decrease heat loss ä pseudoephedrine, thyroid hormone, cocaine ä Decrease sweating ä antihistamines (Benadryl), anti-nausea (meclazine, phenergan) l Supplements ä Ephedrine (MaHuang), caffeine

Control Measures l Water and sports drinks l Salt l Acclimatization

OTSG Guidance for the Field Use of Sports Drinks l Cool water is usually the best rehydration fluid l Prolonged training and operational scenarios ä carbohydrates and electrolytes are also required for optimal physical and mental performance ä meals and snacks plus water are best l When sports drinks are appropriate: ä duration > 6 hours, hot weather, if snacks/meals not consumed ä duration > 3 hours, strenuous exercise, if snacks, meals not consumed ä duration > 6 hours strenuous exercise, if total food intake is significantly limited

Sports Drink Recommendations INGREDIENTAmount per 8 ounces (as served) Sodium mg Potassium20-55 mg Carbohydrate11-19 gm

Acclimatization l Physiologic adaptation that occurs in response to heat exposure in a natural environment ä 5 days for most ä 14 days required for 95% of population to have complete acclimatization. ä Can deacclimatize as quickly l Results: ä sweat at lower temperature ä increased volume of sweat ä decrease in amount to salt secreted in sweat ä increased heat dissipation = lower core body temperature l End result: Decreased risk for heat injury!

Fluid Replacement Guidelines for Warm Weather Training

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