Heat and Cold Emergencies

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Heat and Cold Emergencies : 

Heat and Cold Emergencies

Thermoregulation : 

Thermoregulation Homeostasis requires stable temperature ~98.6ºF

Thermoregulation : 

Thermoregulation Control mechanism Hypothalamus Peripheral thermoreceptors Balance between heat production, heat loss

Heat Production : 

Heat Production Metabolism Voluntary large muscle movement Shivering

Heat Loss : 

Heat Loss Conduction Convection Radiation Evaporation Skin Respiratory tract

Heat Production>Heat Loss : 

Heat Production>Heat Loss Increased Body Temperature

Heat Loss > Heat Production : 

Heat Loss > Heat Production Decreased Body Temperature

Heat and Cold Induced Illness : 

Heat and Cold Induced Illness Results from: Increase or decrease in body temperature outside normal range Prolonged efforts to compensate

Hyperthermia : 

Hyperthermia Caused by Overwhelmed thermoregulatory system Environmental conditions (exogenous) Excessive exercise (endogenous) Drugs Excessive clothing Failure of thermoregulatory system Geriatric patients CVA

Heat-Related Illness : 

Heat-Related Illness Increased temperature: Cutaneous blood vessel dilation increased radiant, conductive heat loss Sweating increased evaporative heat loss

Heat Cramps : 

Heat Cramps Pathophysiology Hot environment causes profuse sweating Na+ lost in sweat Lack of Na+ causes muscle cramping

Heat Cramps : 

Heat Cramps Signs/Symptoms Patient usually in good condition; working in hot, humid environment Cramps of fingers, arms, legs, abdominal muscles Nausea Normotensive, mild hypotension; tachycardia Cool, pale skin Awake, alert, normal body temperature

Heat Cramps : 

Heat Cramps Management Move to cool place, rest, lie down Give balanced salt/water solution Salt alone leads to increased nausea, increased water loss Water alone leads to worsened cramping (dilutional hyponatremia)

Heat Cramps : 

Heat Cramps Management IV NS, LR if patient too nauseated to drink Avoid massaging muscles Avoid activity Increase fluid, salt intake

Heat Exhaustion : 

Heat Exhaustion Pathophysiology Increased vascular space due to vasodilation Decreased blood volume due to sweating Decreased CNS perfusion

Heat Exhaustion : 

Heat Exhaustion Epidemiology People working in hot, humid environments Elderly, due to decreased thirst mechanism Hypertensives, due to medication effects

Heat Exhaustion : 

Heat Exhaustion Signs/Symptoms Headache, dizziness, fatigue, nausea, confusion Weakness, syncope Profuse perspiration, pallor Tachycardia, hypotension, tachypnea Orthostatic changes Normal core temperature

Heat Exhaustion : 

Heat Exhaustion Management Move to cool place, stop activity, lie down Supine, legs elevated Sponge with cool water, fan Balanced salt/water solution, or IV with NS, LR if too nauseated to drink Assess glucose if altered mental status

Heat Exhaustion : 

Heat Exhaustion Management Transport indicated if: Loss of consciousness occurs Underlying cardiovascular disease Oxygen, EKG monitor if transport indicated

Heat Stroke : 

Heat Stroke Pathophysiology Body heat accumulation leads to increased temperature above 1060F Increased temperature damages hypothalamus: Heat regulating mechanism failure occurs 25 - 50% mortality

Types of Heat Stroke : 

Types of Heat Stroke Exertional Heat Stroke Occurs in healthy, young people in hot environments Heat builds up faster than it is removed Damage to hypothalamus occurs Patient sweats heavily

Types of Heat Stroke : 

Types of Heat Stroke Classic Heat Stroke Elderly, alcoholics, obese, heart disease patients, phenothiazine users Body heat builds up slowly over several days Dry skin, absence of sweating

Heat Stroke : 

Heat Stroke Signs/Symptoms Headache, dizziness, irritability Decreased LOC, seizures Bounding pulse progressing to rapid, weak pulse Hypotension secondary to vasodilation Presence, absence of sweating NOT reliable

Heat Stroke : 

Heat Stroke Altered LOC + Hot Environment = ? Heat Stroke

Heat Stroke : 

Heat Stroke Management Secure airway High concentration oxygen Rapid cooling to 1020F IV with NS, LR Avoid volume in classic heat stroke Exertional heat stroke may need volume replacement Monitor EKG

Heat Stroke : 

Heat Stroke Management Drugs as necessary Glucose for hypoglycemia Diazepam for seizures/sedation Reassess for secondary complications Cardiac dysrhythmias Pulmonary edema Transport

Cold-Related Illness : 

Cold-Related Illness Local cold injury Generalized cooling

Local Cold Injury : 

Local Cold Injury Nonfreezing Chilblains Trench foot Freezing Frostnip Frostbite

Chilblains : 

Chilblains Caused by chronic exposure to damp, nonfreezing ambient temperatures Painful, inflammatory lesions on skin Hands, ears, lower legs, feet common sites Pruritus, burning, paresthesias Tends to recur Rewarm, bandage, elevate

Trench Foot : 

Trench Foot Caused by prolonged skin exposure to cool, wet conditions Skin becomes pale, mottled, anesthetic Sloughing, gangrene may occur Clean, warm, dry bandages; elevation

Frostnip/Frostbite : 

Frostnip/Frostbite Local freezing of tissue Commonly affected areas: Toes, feet Hands, fingers Nose Ears

Frostnip/Frostbite : 

Frostnip/Frostbite Risk Factors Poor clothing Poor nutrition Diabetes Decreased tissue perfusion Tobacco, tight clothing Vasodilation EtOH, medications

Frostnip/Frostbite : 

Frostnip/Frostbite Pathophysiology: Phase I Exposure to cold Vasoconstriction Decreased blood flow to periphery Ice crystal formation in extracellular space, ischemia Cellular dehydration, hyperosmolarity

Frostnip/Frostbite : 

Frostnip/Frostbite Pathophysiology: Phase I Edema Increased pressure, blood vessel damage Worsened ischemia Destruction of cellular components

Frostnip/Frostbite : 

Frostnip/Frostbite Pathophysiology: Phase II Tissue is rewarmed Blood flow returns Damaged capillaries leak fluid Swelling occurs Sludging of blood, thrombus formation occurs

Frostnip : 

Frostnip Extremity appears pale, discomfort present No extracellular ice crystal formation Symptoms resolve on rewarming Tissue loss does not occur

Frostbite : 

Frostbite Extent of injury frequently cannot be determined until rewarming occurs

Frostbite : 

Frostbite Signs/Symptoms 1st degree Partial skin freezing; redness, mild edema; lack of blisters 2nd degree Full thickness freezing; substantial edema, formation of clear blisters

Frostbite : 

Frostbite Signs/Symptoms 3rd degree Full-thickness skin and subcutaneous freezing; hemorrhagic blisters, skin necrosis, bluish-gray discoloration 4th degree Full-thickness damage affecting muscles, tendons, bones; little edema, initially mottled or cyanotic, eventually dry, black, mummified

Frostbite : 

Frostbite

Frostbite : 

Frostbite

Frostbite : 

Frostbite Management: Short transport ABCs Protect affected area Bandage Avoid rewarming, thawing Prevent, treat hypothermia Remove wet or constrictive clothing Dry patient Warm IV fluids Minimal analgesics (NSAIDS) for pain

Frostbite : 

Frostbite Management: Long transport Remove patient from cold Remove clothing from affected area Rewarm in water 100 - 1050F until flushing/tingling present Dry gently, bandage Treat concurrent hypothermia Analgesia for pain

Frostbite : 

Frostbite Do NOT: Allow refreezing Massage injured part Allow patient to smoke Puncture or drain blebs

Hypothermia : 

Hypothermia Core Temp < 95 ºF May be caused by: Decreased heat production Excess heat loss Various associated factors Environment (temperature, wet vs. dry) Energy (food, water) Ambulatory ability

Hypothermia : 

Hypothermia Risk factors Extremes of age Those outdoors Hypothyroidism Diabetes, hypoglycemia Alcohol, depressant drug abuse Poor nutrition

Hypothermia : 

Hypothermia Pathophysiology Immediate vasoconstriction Catecholamine release Increased HR, RR, BP Shivering until glucose depleted temperature below 90oF Shivering stops  rapid cooling Eventual  in RR, HR, BP Cardiac Arrest < 86 ºF

Hypothermia : 

Hypothermia Pathophysiology Left shift of oxyhemoglobin dissociation curve Decreased oxygen release to tissues Depression of insulin release, effectiveness Hyperglycemia Depression of ADH release Increased urine output, “cold diuresis”

Hypothermia : 

Hypothermia Signs/Symptoms Pallor, shivering Ataxic gait Apathy, drowsiness, coma Slowing pulse rate, respirations Cardiac arrest Altered LOC + Cool Environment = ? Hypothermia

Hypothermia : 

Hypothermia Altered LOC + Cool Environment = ? Hypothermia

Hypothermia : 

Hypothermia ECG changes (mostly late) Bradycardia (possibly unresponsive to atropine) Small, absent P wave Abnormal ST segments, T waves J (Osborn) wave

Hypothermia : 

Hypothermia J waves

Hypothermia : 

Hypothermia Management Mild = core temperature 90-95oF Moderate = core temperature 86-89oF Severe = core temperature <86oF

Hypothermia : 

Hypothermia Management: Mild Hypothermia Handle gently Prevent further heat loss Insulate from cold Add heat to head, neck, chest, groin Warm oral fluids after uncontrolled shivering stops

Hypothermia : 

Hypothermia Management: Moderate Hypothermia Prevent further heat loss Remove wet clothing Cover with blankets Avoid active rewarming IV with NS EKG

Hypothermia : 

Hypothermia Management: Severe Hypothermia Secure airway/assist ventilations Do NOT hyperventilate Avoid rough handling Prevent further heat loss Remove wet clothing Cover with blankets EKG, IV with NS Internal rewarming only

Hypothermia : 

Hypothermia Hypothermic Cardiac Arrest < 86 ºF Limit 3 shocks No medications > 86 ºF  drug dosing intervals Repeat shocks as core temp rises

Hypothermia : 

Hypothermia Hypothermic Cardiac Arrest Resuscitate aggressively Little consideration given to terminating resuscitation efforts You’re not dead until you’re warm and dead