Heat and Cold Emergencies

1
Heat and Cold Emergencies
2
Thermoregulation

• Homeostasis requires stable temperature
• 98.6ºF

3
Thermoregulation

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

4
Heat Production

• Metabolism
• Voluntary large muscle movement
• Shivering

5
Heat Loss

• Conduction
• Convection
• Radiation
• Evaporation
• Skin
• Respiratory tract

6
Heat ProductionHeat Loss

• Increased Body Temperature

7
Heat Loss Heat Production

• Decreased Body Temperature

8
Heat and Cold Induced Illness

• Results from
• Increase or decrease in body temperature outside
  normal range
• Prolonged efforts to compensate

9
Hyperthermia

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

10
Heat-Related Illness

• Increased temperature
• Cutaneous blood vessel dilation increased
  radiant, conductive heat loss
• Sweating
  increased evaporative heat loss

11
Heat Cramps

• Pathophysiology
• Hot environment causes profuse sweating
• Na lost in sweat
• Lack of Na causes muscle cramping

12
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

13
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)

14
Heat Cramps

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

15
Heat Exhaustion

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

16
Heat Exhaustion

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

17
Heat Exhaustion

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

18
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

19
Heat Exhaustion

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

20
Heat Stroke

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

21
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

22
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

23
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
24
Heat Stroke
Altered LOC Hot Environment ? Heat
Stroke
25
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

26
Heat Stroke

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

27
Cold-Related Illness

• Local cold injury
• Generalized cooling

28
Local Cold Injury

• Nonfreezing
• Chilblains
• Trench foot
• Freezing
• Frostnip
• Frostbite

29
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

30
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

31
Frostnip/Frostbite

• Local freezing of tissue
• Commonly affected areas
• Toes, feet
• Hands, fingers
• Nose
• Ears

32
Frostnip/Frostbite

• Risk Factors
• Poor clothing
• Poor nutrition
• Diabetes
• Decreased tissue perfusion
• Tobacco, tight clothing
• Vasodilation
• EtOH, medications

33
Frostnip/Frostbite

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

34
Frostnip/Frostbite

• Pathophysiology Phase I
• Edema
• Increased pressure, blood vessel damage
• Worsened ischemia
• Destruction of cellular components

35
Frostnip/Frostbite

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

36
Frostnip

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

37
Frostbite

• Extent of injury frequently cannot be determined
  until rewarming occurs

38
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

39
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

40
Frostbite
41
Frostbite
42
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

43
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

44
Frostbite

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

45
Hypothermia

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

46
Hypothermia

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

47
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

48
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

49
Hypothermia

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

50
Hypothermia
Altered LOC Cool Environment ? Hypothermia
51
Hypothermia

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

52
Hypothermia

• J waves

53
Hypothermia

• Management
• Mild core temperature 90-95oF
• Moderate core temperature 86-89oF
• Severe core temperature

54
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

55
Hypothermia

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

56
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

57
Hypothermia

• Hypothermic Cardiac Arrest
• Limit 3 shocks
• No medications
• 86 ºF
• ? drug dosing intervals
• Repeat shocks as core temp rises

58
Hypothermia

• Hypothermic Cardiac Arrest
• Resuscitate aggressively
• Little consideration given to terminating
  resuscitation efforts

Youre not dead until youre warm and dead