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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
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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 INGREDIENTAmount 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!