Ch. 25-Heat and Cold Emergencies

1. Ch. 25-Heat and ColdEmergencies 1

2. How the Body Loses Heat 1. Radiation, whereby heat is transferred from the surface of one object to the surface of another without actual contact; radiation is the primary way the body loses heat. 2. Conduction, whereby heat is transferred from the surface of one object to the surface of another through direct contact; heat loss through conduction can be 25 times greater in cold air than in cold water. 3. Convection, whereby cold air in immediate contact with the skin is warmed by the skin; heated molecules move away, cooler ones take their place, and the cycle repeats itself. 4. Evaporation, whereby body heat causes perspiration, which is lost from the body surface when it is changed to vapor; two-thirds of evaporative loss is through perspiration. 5. Respiration, whereby body heat loses through breathing; one-third of evaporative loss is through respiration. 2

3. How the Body Conserves Heat 1. Blood vessels constrict, keeping the warm blood in the core of the body 2. Hairs stand erect, trapping warm air immediately next to the skin 3. Little or no perspiration is released to the skin surface for evaporation 3

4. PROGRESS CHECK 1. Heat loss through radiation involves the transfer of heat from the body to another surface without _________. (interference/direct contact/evaporation) 2. Convection, central to the concept of windchill, occurs when air molecules surrounding the skin get ___________, rise, and are replaced by cooler air. (moved by the wind/caught in a draft/warmed by the skin) 3. Heat loss through conduction involves the transfer of heat from one surface to another through _________. (direct contact/indirect contact/clothing fibers) 4. Through evaporation, perspiration is changed from liquid to ____________ and carries heat away with it. (gas/solid/vapor) 4

5. 25.2 Heat-Related Injuries (Hyperthermia) Most susceptible are • Athletes • Workers near furnaces or ovens • Those in poor physical condition • Alcoholics • The obese • The chronically ill • Those who have not adjusted to the environment • Those with heart disease • People using certain drugs (such as diuretics) • Burn victims • The elderly • Children 5

6. Vocabulary • Evaporation- The loss of body heat when perspiration is changed from liquid to vapor respiration The loss of body heat through normal breathing • Hyperthermia- Greatly increased body temperature • Heatstroke- A life-threatening emergency caused by a disturbance in the body’s temperature regulation mechanism, characterized by extreme fever, hot and dry or moist skin, delirium, or coma • Heat exhaustion A heat-related emergency caused by excessive loss of water and salt through sweating, characterized by cool, clammy skin and a weak, rapid pulse • Heat cramps Muscle spasms caused by a disturbance in the electrolyte balance of the muscles; generally seen when the body loses too much salt and other electrolytes during profuse sweating • Hypothermia- Greatly decreased body temperature 6

7. Signs and Symptoms of Heatstroke • Body temperature of 105°F or more • Hot, red skin that is moist or dry • Initially rapid, strong pulse • Later rapid, weak pulse • Initially constricted pupils • Later dilated pupils • Tremors • Mental confusion or anxiety • Irritability or aggression • Initially deep, rapid breathing • Later shallow, weak breathing • Headache • Dry mouth • Shortness of breath • Loss of appetite • Nausea and vomiting • Dizziness and weakness • Seizures or sudden collapse 7

8. First Aid Care 1. Establish an airway and, when possible, remove the victim from the source of heat. 2. Remove as much of the victim’s clothing as possible, down to his or her underwear; then use a combination of methods to cool the victim until his or her mental status returns to normal. 3. Never give the victim stimulants or hot drinks. 4. As the body cools, seizures or vomiting may occur. Position the victim to allow for easy drainage. 5. Monitor the victim’s temperature while you wait for emergency personnel to arrive. If the temperature starts to climb, start cooling procedures again. (The temperature must drop below 102°F and must stay that low before the danger has passed.) 8

9. Heat Exhaustion 1. Move the victim to a cool place, remove as much of the victim’s clothing as possible, and fan the victim lightly. Make sure the victim does not get chilled or begin to shiver. 2. Have the victim lie down, raise the feet 8 to 12 inches. 3. If the victim is fully conscious, give him or her cool water or commercial sports drink to drink at the rate of half a glass every 10 minutes for 1 hour. Never give the victim salt tablets. If the victim is nauseated or vomits, stop giving fluids and activate the EMS system immediately. 4. If the victim is unconscious, immediately activate EMS, and manage the airway and ventilation. 5. Take the victim’s temperature every 10 to 15 minutes. If the temperature is above 101°F or is rising, or if the victim is unable to drink fluids or vomits after drinking fluids, or the victim does not improve, immediately activate the EMS system. 9

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11. Heat Cramps 1. If the victim is in a hot environment, remove him or her from the heat immediately; have the victim rest in a cool place. 2. Administer sips of water or a sports drink at the rate of half a glass every 15 minutes. Do not use salt tablets. 3. Apply moist towels to the victim’s forehead and over the cramping muscles. To relieve pain, try gently stretching the involved muscle groups. 4. Explain to the victim what happened and why so the victim can avoid a recurrence; the victim should avoid exertion of any kind for at least 12 hours, or heat cramps will recur. Activate the EMS system if the victim has other illnesses or injuries, if other symptoms develop, or if the victim’s condition worsens or does not respond to care. 11

12. PROGRESS CHECK 1. _______________ is a life-threatening condition; untreated, all victims die. (Heatstroke/Heat exhaustion/Heat cramps) 2. The two most reliable and distinct differences between heatstroke and heat exhaustion are body temperature and ____________. (level of consciousness/condition of the skin/pattern of breathing) 3. In heatstroke, the skin is hot, red, and __________. (wet/dry/either wet or dry) 4. The top priority in treatment of heatstroke is ____________. (monitoring pulse/immediate cooling of the body/monitoring body temperature) 5. If the victim’s temperature starts rising again after you have started treatment for heatstroke, you should ____________. (activate the EMS system immediately/submerge the victim in cool water/begin cooling procedures again) 6. Heat exhaustion results from ____________. (elevated body temperature/loss of fluid and electrolytes/vessel dilation) 7. The most critical problem in heat exhaustion is ____________. (dehydration/overheating/circulatory disturbance) 8. Heat cramps occur because of disruption in the muscle’s balance of calcium, water, and ____________. (sodium/potassium/phosphorus) 9. To treat heat cramps, give the victim sips of ____________. (hot water/cold water/salt water) 12

13. 25.3 Cold-Related Injuries (Hypothermia) Factors contributing to hypothermia, even in the absence of cold environment, include • Certain drugs (i.e., central nervous system depressants) • Surgery • Water activities • Existing disease • Trauma • Massive blood loss • Extremes of age (very young or very old) • Immobility 13

14. Signs and Symptoms • Skin that is cold to the touch (To test, place the back of your hand against the skin of the victim’s abdomen.) • Uncontrollable shivering • Vague, slurred, thick speech • Amnesia and incoherence • Disorientation, confusion • Poor judgment • Staggering gait • Dizziness • Pale, cold, waxen skin • Stiff and hard muscles • Sluggish pupils • Increased heart and respiratory rates (early) • Decreased heart and respiratory rates (late) • Dehydration • Drowsiness and/or stupor • Apparent exhaustion • Unconsciousness 14

15. First Aid Care 1. Check the victim’s vital signs. Measure for 1 full minute, because vital signs are slowed and weak in hypothermia. If there is no pulse, open the airway and begin CPR. If an AED is available, deliver only one shock. If that does not correct the rhythm, continue CPR and do not deliver any additional shocks. 2. Handle the victim very gently. Don’t let the victim walk around or move much on his or her own. 3. Keep the victim in a supine position to prevent shock and increase blood flow to the brain. Do not elevate the legs; doing so causes cold blood to flow to the heart. 4. Prevent further heat loss 5. Never rub or manipulate the arms or legs; you could force cold blood from the veins into the core circulation and heart, causing abnormal heart rhythm or cardiac arrest. 6. Never give the victim tobacco, coffee, or alcohol. Give warm fluids only after uncontrollable shivering stops and the victim is completely conscious. 15

16. First Aid Care for Severe Hypothermia 1. Never try to rewarm a severely hypothermic victim. Insulate the victim against further heat loss, but do not apply any source of heat. Handle the victim extremely gently. 2. Assess vital signs over a 1-minute period; if there is no heartbeat during the 1 minute, start CPR. 3. If the victim is not breathing, administer gentle mouth-to-mouth or mouth-to-mask/barrier device at a rate of 10 to 12 breaths per minute in an adult or 12 to 20 breaths per minute in an infant or child. 4. Maintain airway, breathing, and circulation until EMTs arrive. 16

17. Immersion Hypothermia 1. Activate the EMS system immediately. 2. Maintain the victim’s airway, breathing, and circulation. 3. Keep the victim still and quiet; the coldest blood is in the extremities, and it will circulate rapidly to the heart with movement. 4. Follow insulating and rewarming guidelines as for general hypothermia, remembering to handle the victim very gently. 17

18. Frostbite 1. Immediately remove the victim from the cold environment. 2. Keep the tissue frozen until you can initiate care; never thaw tissue if there is any chance of its refreezing 3. Protect the injured tissue from friction or pressure; never poke or squeeze the tissue. Remove constricting clothing or jewelry that is not sticking to the skin. 4. Thaw frostbitten tissuein a water bath. 5. Keep rewarming until the skin color no longer improves (rewarming to this point may take as long as 40 minutes). 6. Cover the thawed parts with loose, dry, sterile dressings and elevate the extremities. Place sterile gauze between the fingers and toes to reduce the risk of increased injury. 7. While waiting for emergency personnel to arrive, monitor vital signs and keep the victim warm. Do not let the victim walk if the feet are involved, and do not let the victim smoke. Do not re-expose the thawed part to the cold. 18

19. PROGRESS CHECK 1. Because taking core temperature is difficult in the field, you should rely on ____________ to identify hypothermia. (skin temperature/signs and symptoms/what the victim tells you) 2. The priority in treating hypothermia is to ____________. (start rewarming right away/remove the victim from the cold environment/rewarm rapidly) 3. Rewarm a hypothermia victim only if the victim ____________. (does not respond to other treatment/has a further temperature drop/cannot be transported immediately) 4. The priority in treating immersion hypothermia is _________. (getting the victim out of the water/preventing drowning/drying the victim) 5. You should never thaw frostbitten tissue if there is any danger of ____________. (refreezing/delayed transport/increased injury) 6. Frostbitten tissue should be thawed using __________. (steam/dry heat/warm water) 19