Cold Emergencies Prepared by: Steven Jones, EMT-P

Thermoregulation Homeostasis requires stable temperature ~98.6ºF

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

Hypothalamus The main function of the hypothalamus is homeostasis, or maintaining the body's status quo. Factors such as blood pressure, body temperature, fluid and electrolyte balance, and body weight are held to a precise value called the set-point. Although this set-point can migrate over time, from day to day it is remarkably fixed.

Heat Production n Metabolism n Voluntary large muscle movement n Shivering

Heat Loss n Conduction n Convection n Radiation n Evaporation  Skin  Respiratory tract

Heat Loss > Heat Production Decreased Body Temperature

Cold Induced Illness n Results from:  Decrease in body temperature outside normal range  Prolonged efforts to compensate

Cold-Related Illness n Local cold injury n Generalized cooling

Localized Cold Injury n Nonfreezing  Chilblains  Trench foot n Freezing  Frostnip  Frostbite

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

Chilblains

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

Trench Foot

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

Frostnip/Frostbite n Risk Factors  Poor clothing  Poor nutrition  Diabetes  Decreased tissue perfusion »Tobacco, tight clothing  Vasodilation »ETOH, medications

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

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

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

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

Frostnip

Frostbite Extent of injury frequently cannot be determined until rewarming occurs

Frostbite n 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 n 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

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

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

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

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

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

Hypothermia n Pathophysiology  Decreased oxygen release to tissues  Depression of insulin release, effectiveness  Hyperglycemia  Depression of ADH release  Increased urine output, “cold diuresis”

Hypothermia n Signs/Symptoms  Pallor, shivering  Ataxic gait  Apathy, drowsiness, coma  Slowing pulse rate, respirations  Cardiac arrest

Hypothermia Altered LOC + Cool Environment = THINK Hypothermia

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

Hypothermia n J waves

Hypothermia n Management  Mild = core temperature o F  Moderate = core temperature o F  Severe = core temperature <86 o F

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

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

Hypothermia n Hypothermic Cardiac Arrest  Resuscitate aggressively  Little consideration given to terminating resuscitation efforts

Hypothermia They’re not dead until they’re warm and dead !!