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Heat and Cold Emergencies. Jonathan Rochlin, MD February 22, 2010. Outline. Physiology primer Local injuries due to the cold Hypothermia Hyperthermia Take home points. Objectives. Learn about the wide range of local cold injuries Learn the dos and don’ts of frostbite treatment

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heat and cold emergencies

Heat and Cold Emergencies

Jonathan Rochlin, MD

February 22, 2010

outline
Outline
  • Physiology primer
  • Local injuries due to the cold
  • Hypothermia
  • Hyperthermia
  • Take home points
objectives
Objectives
  • Learn about the wide range of local cold injuries
  • Learn the dos and don’ts of frostbite treatment
  • Understand the management of hypothermia
  • Understand the spectrum of hyperthermic disorders and their treatments
  • Understand how to prevent hyperthermia in the young athlete
slide4
Physiology primer
  • Local injuries due to the cold
  • Hypothermia
  • Hyperthermia
  • Take home points
physiology primer
Physiology Primer
  • Core temperature maintained within 0.6°C (1°F)
  • Balance between heat production and heat loss
  • Heat production:
    • Basal cellular metabolism
    • Muscle activity
  • Heat loss:
    • Conduction
    • Convection
    • Evaporation
    • Radiation
  • Behavioral control
slide6
Physiology primer
  • Local injuries due to the cold
  • Hypothermia
  • Hyperthermia
  • Take home points
local injuries due to the cold8
Local Injuries Due To The Cold
  • Frostnip:
    • Milder form of freezing local cold injury
    • Symptoms: Pain, pallor
    • Prognosis: Resolves with rewarming
local injuries due to the cold frostbite
Local Injuries Due To The Cold – Frostbite
  • Frostbite:
    • The most severe local cold injury
    • Who is at risk?
      • Those exposed to cold environments or materials
      • Comorbidities
      • Alcohol intoxication
      • Inappropriate clothing
local injuries due to the cold frostbite10
Local Injuries Due To The Cold – Frostbite
  • Sites most often affected:
    • Head:
      • Ears
      • Nose
      • Cheeks
      • Chin
    • Fingers
    • Toes
local injuries due to the cold frostbite11
Local Injuries Due To The Cold – Frostbite
  • Pathophysiology:
    • Immediate damage: ice crystals  cell death
    • Gradual damage: inflammatory process  tissue ischemia
local injuries due to the cold frostbite15
Local Injuries Due To The Cold – Frostbite
  • Symptoms and appearance:
    • Cold
    • Numb
    • White, pale or gray
    • Hard or waxy
    • Edema and erythema
    • Blisters
    • Eschars
local injuries due to the cold frostbite16
Local Injuries Due To The Cold – Frostbite
  • Treatment – rewarming:
    • Dos:
      • As soon as possible
      • Immerse in warm water (about 40°C)
      • Until pink (about 20-30 minutes)
      • Increase body temperature
    • Don’ts:
      • Use hot water
      • Dry heat, stoves or fire
      • Rub or massage
      • Don’t rewarm if the part will be refrozen
local injuries due to the cold frostbite17
Local Injuries Due To The Cold – Frostbite
  • Treatment – wound care:
    • Goal: prevent infection
    • Don’t pop blisters
    • Let the area dry
    • Apply bulky dressing:
      • Sterile technique
      • Non-stick first layer
      • Separate digits
      • Non-occlusive
      • Watch for pressure spots
local injuries due to the cold frostbite18
Local Injuries Due To The Cold – Frostbite
  • Treatment – other interventions:
    • Dos:
      • Cardiac monitor
      • Warmed fluids
      • Elevate
      • IV narcotics
      • Ibuprofen
      • Tetanus prophylaxis
      • IV antibiotics (only for signs of infection)
      • X-ray
      • Consult surgery
local injuries due to the cold frostbite19
Local Injuries Due To The Cold – Frostbite
  • Treatment – other interventions:
    • Don’ts:
      • Debride or amputate immediately
      • Walk on frostbitten feet
      • Use vasoconstrictive agents
local injuries due to the cold frostbite20
Local Injuries Due To The Cold – Frostbite
  • Complications:
    • Short-term
    • Long-term
  • Prognosis:
    • Must wait until demarcation
    • Disease of morbidity, not mortality
slide21
Physiology primer
  • Local injuries due to the cold
  • Hypothermia
  • Hyperthermia
  • Take home points
hypothermia
Hypothermia
  • Epidemiology:
    • About 700 deaths per year in the U.S.
    • Mortality rate ~ 40%
    • It can happen anywhere
hypothermia23
Hypothermia
  • Definition:
    • Core temperature ≤ 35°C (≤ 95°F)
      • Mild hypothermia: 32-35°C (89.6-95°F)
      • Moderate hypothermia: 28-32°C (82.4-89.6°F)
      • Severe hypothermia: < 28°C (< 82.4°F)
hypothermia24
Hypothermia
  • Physiologic response to cold:
    • Heat production increased:
      • Metabolism increased
      • Muscle tone increased  shivering
    • Heat loss decreased:
      • Sweating stopped
      • Vasoconstriction occurs
hypothermia25
Hypothermia
  • Populations most at risk:
    • Neonates
    • Elderly
    • Homeless
    • But it can happen to anyone
  • Risk factors:
    • Physical disability
    • Psychiatric disorders
    • Medications and drugs
    • Vehicular breakdown
hypothermia26
Hypothermia
  • Causes:
    • Exposure to cold water or air
    • Sepsis
    • Burns
    • CNS dysfunction
    • Endocrinopathies
    • Metabolic disorders
    • Neuromuscular diseases
    • Hypoglycemia
    • Iatrogenic
hypothermia27
Hypothermia
  • Clinical manifestations:
    • General appearance: pale, gray or cyanotic and cold
hypothermia28
Hypothermia
  • Clinical manifestations – CNS:
    • Decreased consciousness is most consistent finding
    • Progressive decline from confusion to coma
    • Decrease in DTRs
    • Dilated pupils
    • EEG changes
hypothermia29
Hypothermia
  • Clinical manifestations – respiratory:
    • Early findings:
      • Tachypnea
      • Bronchorrhea  airway obstruction/aspiration
    • Late findings:
      • Hypoventilation
      • Pulmonary edema
      • Apnea
hypothermia30
Hypothermia
  • Clinical manifestations – cardiovascular:
    • Early findings:
      • Increased BP
      • Tachycardia
    • Late findings:
      • Bradycardia
      • Hypotension
      • Conduction abnormalities:
        • Prolonged intervals
        • V fib
        • Asystole
hypothermia31
Hypothermia
  • Clinical manifestations – cardiovascular:
    • J wave
hypothermia32
Hypothermia
  • Clinical manifestations – metabolic:
    • Decreased metabolic rate
    • Respiratory and metabolic acidosis
    • Hyper- or hypoglycemia
hypothermia33
Hypothermia
  • Clinical manifestations – renal:
    • Early findings:
      • “Cold diuresis”
    • Late findings:
      • Decreased renal perfusion
      • Oliguria
      • Hyperkalemia
      • Edema
hypothermia34
Hypothermia
  • Clinical manifestations – hematologic:
    • Hematocrit increases
    • WBC and platelet counts fall
    • DIC
hypothermia35
Hypothermia
  • Clinical manifestations – GI:
    • Ileus
    • Hepatic dysfunction
    • Pancreatitis
hypothermia36
Hypothermia
  • Clinical manifestations – musculoskeletal:
    • Early findings:
      • Shivering
    • Late findings:
      • No shivering
      • Pseudo rigor mortis
hypothermia37
Hypothermia
  • Severe hypothermia mimics death
  • But the patient may be alive
  • You’re not dead until you’re warm and dead
  • Resuscitate until temperature is 32-35°C (90-95°F)
hypothermia38
Hypothermia
  • Initial resuscitation:
    • Airway, breathing (A/B):
      • Supplemental oxygen
      • Intubate early, and gently
      • Ventilate at ½ normal minute ventilation
hypothermia39
Hypothermia
  • Initial resuscitation:
    • Circulation (C) – rate and rhythm:
      • Is there an organized rhythm?
      • PALS/ACLS algorithm:
        • V fib:
          • Defibrillation
          • Bretylium
        • Asystole:
          • Pharmacotherapy
        • Rarely effective
      • CPR
      • Try again after temperature rises
      • Handle gently
      • Correcting temperature can correct rhythm
hypothermia40
Hypothermia
  • Initial resuscitation:
    • Circulation (C) – blood pressure support:
      • Obtain IV access
      • Warmed fluids
      • Dopamine
      • Watch for rebound hypotension
hypothermia41
Hypothermia
  • Initial resuscitation:
    • Disability (D)
    • Exposure (E)
hypothermia42
Hypothermia
  • Monitoring:
    • Core temperature – low reading thermometer
    • Cardiac monitor
    • Place pulse ox probe on ear or forehead
    • Foley
hypothermia43
Hypothermia
  • Laboratory evaluation:
    • CBC
    • BMP
    • Amylase
    • pt, ptt, INR
    • ABG
    • BCx
    • UDS and alcohol level
    • EKG
    • CXR
  • Treat abnormalities accordingly
  • Frequent reassessments
hypothermia44
Hypothermia
  • Rewarming:
    • Immediately
    • Passive external rewarming:
      • For mild hypothermia (> 32°C or 89.6°F)
      • Remove wet clothing
      • Place under blankets
      • The patient rewarms himself
hypothermia45
Hypothermia
  • Rewarming – active external rewarming:
    • For moderate to severe hypothermia (< 32°C or 89.6°F)
    • Place patient is warm room with overhead warmers
    • Warm blankets and clothes
    • Heating pads
    • Forced warm air
hypothermia46
Hypothermia
  • Rewarming – active external rewarming:
    • Complications:
      • Core temperature afterdrop
        • Rewarm trunk and head first
        • Keep patient still
      • Body surface burns
hypothermia47
Hypothermia
  • Rewarming – active internal rewarming:
    • Pleural irrigation
    • Peritoneal irrigation
    • Bladder irrigation
    • Hemodialysis or CVVH
    • Cardiopulmonary bypass
    • Forced air rewarming
  • Complications:
    • Hyperthermia
hypothermia48
Hypothermia
  • Why isn’t the patient getting warmer?
    • Hypoglycemic?
    • Septic?
    • Adrenocortical insufficiency?
    • Hypothyroidism?
hypothermia49
Hypothermia
  • Continued monitoring
  • Transfer
slide50
Physiology primer
  • Local injuries due to the cold
  • Hypothermia
  • Hyperthermia
  • Take home points
hyperthermia
Hyperthermia
  • Epidemiology:
    • About 400 deaths per year in the U.S.
    • Mortality rate ~ 10%
    • Not just a tropical disease
hyperthermia52
Hyperthermia
  • Definition:
    • Core temperature > 38°C (> 100.4°F)
    • Different from fever
hyperthermia53
Hyperthermia
  • Physiologic response to heat:
    • Heat loss increased:
      • Vasodilation occurs (radiation)
      • Sweating begins (evaporation)
        • Up to 4L/hour
        • Low rates: NaCl preserved
        • High rates: NaCl depleted
hyperthermia54
Hyperthermia
  • But when it’s really humid and hot, the body gains heat from the environment  excessive heat storage
hyperthermia55
Hyperthermia
  • Populations most at risk:
    • Elderly
    • Those that work or play in heat, humidity
    • It can happen to anyone
  • Risk factors:
    • Underlying medical conditions
    • Alcohol and drug use
    • Cystic fibrosis and congenital anhidrosis
    • Children left in cars
hyperthermia56
Hyperthermia
  • Causes of hyperthermia:
    • Exposure to heat
    • Malignant hyperthermia
    • Neuroleptic malignant syndrome
    • Infections
    • CNS dysfunction
    • Endocrinopathies
    • Drug or alcohol withdrawal
    • Drug toxicities
    • Serotonin syndrome
hyperthermia57
Hyperthermia
  • Broad spectrum of illnesses:
    • Heat cramps
    • Heat exhaustion
    • Heat stroke
hyperthermia58
Hyperthermia
  • Heat cramps:
    • Characteristics:
      • Very painful cramps in affected muscle
      • Occurring in clusters
    • When:
      • After severe work stress
      • When relaxing
      • Triggered by cold or extension
    • Who:
      • Acclimated people
    • Pathophysiology:
      • Salt depletion
hyperthermia59
Hyperthermia
  • Heat cramps:
    • Laboratory analysis:
      • Serum Na+ and Cl-: ↓
      • Urine Na+: ↓↓
    • Treatment:
      • Rest
      • Intake of salty foods and liquids
      • NS boluses
hyperthermia60
Hyperthermia
  • Heat exhaustion:
hyperthermia heat stroke
Hyperthermia – Heat Stroke
  • Definition:
    • Core body temperature ≥41°C (≥105.8°F)
  • Clinical manifestations:
    • General appearance:
      • Hot
      • Pink or ashen skin
      • Usually no sweat
hyperthermia heat stroke62
Hyperthermia – Heat Stroke
  • Clinical manifestations – CNS:
    • Severe CNS dysfunction is a hallmark
    • Many symptoms
    • Seizures
    • Coma
    • Damage related to duration and height of hyperthermia
    • Dysfunction improves when temperature falls
hyperthermia heat stroke63
Hyperthermia – Heat Stroke
  • Clinical manifestations – cardiovascular:
    • Tachycardia
    • Hypotension
    • Thready pulses
    • Circulatory collapse
    • Dysrhythmias and conduction abnormalities
  • Clinical manifestations – respiratory:
    • Tachypnea
    • Pulmonary edema
    • ARDS
hyperthermia heat stroke64
Hyperthermia – Heat Stroke
  • Clinical manifestations – musculoskeletal:
    • Rhabdomyolysis:
      • With or without cramps and pain
      • Elevated CPK
      • UA: heme positive
      • UMicro: no RBCs
hyperthermia heat stroke65
Hyperthermia – Heat Stroke
  • Clinical manifestations – renal and electrolytes:
    • Possibly severe dehydration
    • Na+ and Cl- may be low or normal
    • Polyuria
    • Hypokalemia
    • Initial hypocalcemia
    • Acute renal failure
  • Clinical manifestations – metabolic:
    • Hypoglycemia
hyperthermia heat stroke66
Hyperthermia – Heat Stroke
  • Clinical manifestations – hematologic:
    • Bleeding diathesis and DIC
  • Clinical manifestations – GI:
    • N/V/D
  • Clinical manifestations – hepatic:
    • Liver failure
hyperthermia heat stroke67
Hyperthermia – Heat Stroke
  • Management:
    • A/B/Cs
    • Cooling:
      • Remove clothing
      • Place in cool room
      • Evaporative cooling
      • Ice packs
      • Iced peritoneal irrigation
      • Adjuncts:
        • Cooling blankets
        • Cool IV fluids
        • Cold oxygen
hyperthermia heat stroke68
Hyperthermia – Heat Stroke
  • Management – cooling:
    • Don’ts:
      • Antipyretic agents
      • Alcohol sponge baths
      • Immerse the patient in ice water
      • Allow patient to shiver
    • Continue until core temp < 38.5°C (≤ 101.3°F)
hyperthermia heat stroke69
Hyperthermia – Heat Stroke
  • Management – cardiovascular support:
    • Guided by patient’s condition
    • Severe dehydration is uncommon
    • Titrate fluids and electrolytes to the patient
    • Dobutamine
    • Avoid α-agonists
    • Avoid anticholinergic drugs
  • Treat any complications that arise
hyperthermia heat stroke70
Hyperthermia – Heat Stroke
  • Laboratory evaluation:
    • CBC
    • CMP
    • CPK
    • pt, ptt, INR
    • ABG
    • UDS and alcohol level
    • UA/UMicro
    • EKG
    • CXR
  • Treat abnormalities accordingly
  • Frequent reassessments
hyperthermia heat stroke71
Hyperthermia – Heat Stroke
  • Monitoring:
    • Core temperature
    • Cardiac monitor
    • Foley
    • CVP
    • CNS status
hyperthermia prevention73
Hyperthermia -- Prevention
  • Reduce outdoor activities when it is hot outside
hyperthermia prevention74
Hyperthermia -- Prevention
  • Allow time for acclimation to the heat over 10-14 days
  • Hydration before and during the activity
  • Wear appropriate clothing
take home points
Take Home Points
  • Hypothermia:
    • It can happen in the summer
    • You’re not dead until you’re warm and dead
    • Low reading thermometer
    • Defibrillation and cardiac drugs usually don’t work
    • Watch for “afterdrop”
take home points76
Take Home Points
  • Hyperthermia:
    • It is not just a disease of the tropics
    • It can happen to anyone
    • CNS changes are the hallmark
    • Multi-organ system involvement with many complications
    • Dobutamine