Published on March 5, 2014
By Sarah-Beth Roach
3 Categories of Heat Injuries Heat Cramps Heat Exhaustion Heat Stroke
Situations Where Heat Injury Is Likely • Prolonged exposure to extreme heat from the sun or high temperatures. • Wearing too much clothing in hot climates. • Wearing MOPP gear or Body Armor in hot climates • Inside closed spaces such as an armored vehicle. • Is wearing body armor in hot weather
Individual Risk Factors History of prior heat injury. Poor fitness. Large body mass. Minor illness. Recent alcohol use. Skin conditions. Improper conditioning. Poor diet. Medications (perscription and OTC). Illecit drug use. Age over 40.
Risk Mitigation and Controls Work within an acceptable work to rest cycle. Accessible water points. Loosen or downgrade clothing. Formations held in shade. Avoid cumulative training. Identify high risk soldiers. Track wet bulb globe temperatures.
Cooling Mechanisms of the Body The body maintains its temperature by balancing heat gain with heat loss regulated by the hypothalmus. As the major heat-dissipating organ, the skin can transfer heat to the environment through conduction, convection, radiation, and evaporation. Factors that interfere with heat dissipation Inadequate intravascular volume Cardiovascular dysfunction Abnormal skin. High temperatures and humidity Drugs hypothalamic dysfunction
Medications Can Affect Heat Regulation Drugs may affect: Ability to sweat. Renal function. Vasodilatation. Cardiac output. Ability to perceive heat. The hypothalamus (portion of the brain that regulates body temperature). The most dangerous of possible affects is the reduction in sweat rate. 90% of the body’s ability to cool itself is the evaporation of sweat.
Medication Classes Affecting Heat Regulation CLASS MEDICATION EXAMPLE EFFECT Antihistamines Benadryl, Zyrtec, Loratadine Sweating Antidepressants Lithium, Elavil, Prosac Perception Antipsychotics Abilify, Seroquel Sweating Diuretics Hydrochlorothiazide Dehydration Natural Health Products Ephedra, Energy Drinks Perception Sympathomimetics Pseudoephedrine Recreational Drugs Fentanyl, Cocaine Sweating. Sweating. Vasodilation Hypothalamus Function
Heat Cramps Heat cramps are painful muscle spasms most often caused by loss of electrolytes from physical exertion in extreme heat, or prolonged exposure to heat without adequate hydration. Muscles most often affected are those in the lower legs, arms, abdominal wall, and back.
Heat Cramps Continued Prevention Acclimate prior to strenuous activity, Wear appropriate clothing Hydrate and maintaining diet rich in sodium. Signs and Symptoms Muscle spasms Thirst Sweating Fatigue & dizziness
Heat Cramps Continued Treatment Move soldier to a cool or shaded area to rest Loosen the soldiers clothing Hydrate soldier orally Ice massages affected muscle
Heat Exhaustion Heat exhaustion is caused by loss electrolytes without proper fluid replacement. Heat exhaustion can affect even those who are not identified as having risk factors for heat injury. Otherwise fit individuals can be affected when involved in strenuous physical activity in a hot climate, especially if they haven't been acclimated.
Heat Exhaustion Continued Prevention Acclimate prior to strenuous activity. Wear of appropriate clothing. Hydrate maintainin diet rich in sodium. Following work/rest cycle. Use shaded areas when available. Signs and Symptoms Excessive sweating & fatigue. Headache & dizziness. Loss of appetite & cramping. Nausea & vomiting. Chills. Tachypnea & tingling in hands or feet. Altered mental status.
Heat Exhaustion Continued Treatment Move soldier to a cool or shaded area to rest. Loosen the soldiers clothing. Hydrate soldier orally with cool water Elevate the legs
Heat Stroke Heatstroke (also known as hyperthermia) is the most severe form of the heat-related illnesses. There are two forms of heatstroke. Exertional heatstroke (EHS) Nonexertional heatstroke (NEHS). In the United States, heat waves claim more lives each year than all other weather-related exposures combined (hurricanes, tornadoes, floods, and earthquakes).
Heat Stroke Continued Prevention Acclimating prior to strenuous activity Wear appropriate clothing Hydrate Use work/rest cycle Signs and Symptoms Weakness Headache & dizziness, Loss of appetite Cramping & nausea Seizures, Tachypnea & weak pulse Tachycardia & altered mental status.
Heat Stroke Continued Treatment Heatstroke is a medical emergency and can be fatal. Soldiers should be medevaced to the nearest MTF ASAP! Position the soldier in the shade and begin cooling immediately. Elevate the legs Massage the limbs to promote blood flow
Cooling Techniques for Heat Injury Evaporative Cooling Remove excess clothing Mist the skin constantly and fan. Complications: None. Ice Sheets Remove excess clothing Wrap soldier in cold wet sheet. Include the head. Monitor the soldier closely. Complications: discomfort or shivering, hypothermia. Strategic Ice Packing Remove excess clothing Place ice packs in the patient’s groin, in the axillae, and around the anterior neck. Complications: discomfort or shivering.
Strategic Ice Packing
Sources National Collaborative Center For Environmental Health http://www.ncceh.ca/en/major_projects/heat_advice/drugs FM 4-25.11 Heatstroke Treatment & Management by Robert S Helman, MD http://emedicine.medscape.com/article/166320-treatment Cooling Techniques for Hyperthermia by Erik D Schrage http://emedicine.medscape.com/article/149546-overview#a01
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TASK. Identify the three types of heat injuries and the treatment for each. CONDITIONS. Given multiple-choice examination items pertaining to heat injuries.