Transcript Document

Heat and Cold
Emergencies
Jonathan Rochlin, MD
February 22, 2010
Outline
 Physiology primer
 Local injuries due to the cold
 Hypothermia
 Hyperthermia
 Take home points
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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
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 Physiology primer
 Local injuries due to the cold
 Hypothermia
 Hyperthermia
 Take home points
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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
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 Physiology primer
 Local injuries due to the cold
 Hypothermia
 Hyperthermia
 Take home points
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Local Injuries Due To The Cold
 Frostnip
 Frostbite
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Local Injuries Due To The Cold
 Frostnip:
• Milder form of freezing local cold injury
• Symptoms: Pain, pallor
• Prognosis: Resolves with rewarming
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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
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Local Injuries Due To The Cold –
Frostbite
 Sites most often affected:
• Head:
 Ears
 Nose
 Cheeks
 Chin
• Fingers
• Toes
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Local Injuries Due To The Cold –
Frostbite
• Pathophysiology:
 Immediate damage: ice crystals  cell death
 Gradual damage: inflammatory process 
tissue ischemia
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Local Injuries Due To The Cold –
Frostbite
 Classification:
Thickness of
Tissue Necrosis
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Appearance
1st Degree
-No necrosis
-Central area of pallor and
numbness surrounded by edema
and erythema
2nd Degree
-Partial thickness skin
necrosis
-Large clear (or milky) blisters
surrounded by edema and
erythema
3rd Degree
-Full thickness skin and
subcutaneous tissue
necrosis
-Hemorrhagic blisters that
progress to black eschar over
several weeks
4th Degree
-Full thickness skin and
subcutaneous tissue
necrosis, with muscle
and bone involvement
Local Injuries Due To The Cold –
Frostbite
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Local Injuries Due To The Cold –
Frostbite
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Local Injuries Due To The Cold –
Frostbite
 Symptoms and appearance:
• Cold
• Numb
• White, pale or gray
• Hard or waxy
• Edema and erythema
• Blisters
• Eschars
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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
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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
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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
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Local Injuries Due To The Cold –
Frostbite
 Treatment – other interventions:
• Don’ts:
 Debride or amputate immediately
 Walk on frostbitten feet
 Use vasoconstrictive agents
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Local Injuries Due To The Cold –
Frostbite
 Complications:
• Short-term
• Long-term
 Prognosis:
• Must wait until demarcation
• Disease of morbidity, not mortality
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 Physiology primer
 Local injuries due to the cold
 Hypothermia
 Hyperthermia
 Take home points
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Hypothermia
 Epidemiology:
• About 700 deaths per year in the U.S.
• Mortality rate ~ 40%
• It can happen anywhere
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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)
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Hypothermia
 Physiologic response to cold:
• Heat production increased:
 Metabolism increased
 Muscle tone increased  shivering
• Heat loss decreased:
 Sweating stopped
 Vasoconstriction occurs
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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
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Hypothermia
 Causes:
• Exposure to cold water or air
• Sepsis
• Burns
• CNS dysfunction
• Endocrinopathies
• Metabolic disorders
• Neuromuscular diseases
• Hypoglycemia
• Iatrogenic
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Hypothermia
 Clinical manifestations:
• General appearance: pale, gray or cyanotic and
cold
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Hypothermia
 Clinical manifestations – CNS:
• Decreased consciousness is most consistent
finding
• Progressive decline from confusion to coma
• Decrease in DTRs
• Dilated pupils
• EEG changes
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Hypothermia
 Clinical manifestations – respiratory:
• Early findings:
 Tachypnea
 Bronchorrhea  airway obstruction/aspiration
• Late findings:
 Hypoventilation
 Pulmonary edema
 Apnea
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Hypothermia
 Clinical manifestations – cardiovascular:
• Early findings:
 Increased BP
 Tachycardia
• Late findings:
 Bradycardia
 Hypotension
 Conduction abnormalities:
– Prolonged intervals
– V fib
– Asystole
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Hypothermia
 Clinical manifestations
– cardiovascular:
• J wave
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Hypothermia
 Clinical manifestations – metabolic:
• Decreased metabolic rate
• Respiratory and metabolic acidosis
• Hyper- or hypoglycemia
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Hypothermia
 Clinical manifestations – renal:
• Early findings:
 “Cold diuresis”
• Late findings:
 Decreased renal perfusion
 Oliguria
 Hyperkalemia
 Edema
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Hypothermia
 Clinical manifestations – hematologic:
• Hematocrit increases
• WBC and platelet counts fall
• DIC
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Hypothermia
 Clinical manifestations – GI:
• Ileus
• Hepatic dysfunction
• Pancreatitis
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Hypothermia
 Clinical manifestations – musculoskeletal:
• Early findings:
 Shivering
• Late findings:
 No shivering
 Pseudo rigor mortis
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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)
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Hypothermia
 Initial resuscitation:
• Airway, breathing (A/B):
 Supplemental oxygen
 Intubate early, and gently
 Ventilate at ½ normal minute ventilation
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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
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Hypothermia
 Initial resuscitation:
• Circulation (C) – blood pressure support:
 Obtain IV access
 Warmed fluids
 Dopamine
 Watch for rebound hypotension
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Hypothermia
 Initial resuscitation:
• Disability (D)
• Exposure (E)
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Hypothermia
 Monitoring:
• Core temperature – low reading thermometer
• Cardiac monitor
• Place pulse ox probe on ear or forehead
• Foley
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Hypothermia
 Laboratory evaluation:
• CBC
• BMP
• Amylase
• pt, ptt, INR
• ABG
• BCx
• UDS and alcohol level
• EKG
• CXR
 Treat abnormalities accordingly
 Frequent reassessments
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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
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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
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Hypothermia
 Rewarming – active external rewarming:
• Complications:
 Core temperature afterdrop
– Rewarm trunk and head first
– Keep patient still
 Body surface burns
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Hypothermia
 Rewarming – active internal rewarming:
• Pleural irrigation
• Peritoneal irrigation
• Bladder irrigation
• Hemodialysis or CVVH
• Cardiopulmonary bypass
• Forced air rewarming
 Complications:
• Hyperthermia
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Hypothermia
 Why isn’t the patient getting warmer?
• Hypoglycemic?
• Septic?
• Adrenocortical insufficiency?
• Hypothyroidism?
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Hypothermia
 Continued monitoring
 Transfer
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 Physiology primer
 Local injuries due to the cold
 Hypothermia
 Hyperthermia
 Take home points
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Hyperthermia
 Epidemiology:
• About 400 deaths per year in the U.S.
• Mortality rate ~ 10%
• Not just a tropical disease
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Hyperthermia
 Definition:
• Core temperature > 38°C (> 100.4°F)
• Different from fever
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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
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Hyperthermia
 But when it’s really humid and hot, the body gains
heat from the environment  excessive heat
storage
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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
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Hyperthermia
 Causes of hyperthermia:
• Exposure to heat
• Malignant hyperthermia
• Neuroleptic malignant syndrome
• Infections
• CNS dysfunction
• Endocrinopathies
• Drug or alcohol withdrawal
• Drug toxicities
• Serotonin syndrome
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Hyperthermia
 Broad spectrum of illnesses:
• Heat cramps
• Heat exhaustion
• Heat stroke
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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
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Hyperthermia
 Heat cramps:
• Laboratory analysis:
 Serum Na+ and Cl-: ↓
 Urine Na+: ↓↓
• Treatment:
 Rest
 Intake of salty foods and liquids
 NS boluses
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Hyperthermia
 Heat exhaustion:
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When
Cause
Lab Analysis
Treatment
Water
depletion
-After physical
exertion in hot
environment
-Poor water
replacement
-Hct: ↑
-Urine Sgrav: ↑
-Serum Na+: ↑
-Serum Cl-: ↑
-Cool room
-PO liquids
-PO salt
-hypotonic IV
fluids: ¼ - ½ NS
(hypernatremic
dehydration)
Salt
depletion
-After physical
exertion in hot
environment
-Cystic fibrosis
-Poor salt
replacement
-Serum Na+: ↓
-Serum Cl-: ↓
-Urine Na+: ↓↓
-Cool room
-Salty food and
drink
-NS boluses
-3% hypertonic
saline
Hyperthermia – Heat Stroke
 Definition:
• Core body temperature ≥41°C (≥105.8°F)
 Clinical manifestations:
• General appearance:
 Hot
 Pink or ashen skin
 Usually no sweat
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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
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Hyperthermia – Heat Stroke
 Clinical manifestations – cardiovascular:
• Tachycardia
• Hypotension
• Thready pulses
• Circulatory collapse
• Dysrhythmias and conduction abnormalities
 Clinical manifestations – respiratory:
• Tachypnea
• Pulmonary edema
• ARDS
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Hyperthermia – Heat Stroke
 Clinical manifestations – musculoskeletal:
• Rhabdomyolysis:
 With or without cramps and pain
 Elevated CPK
 UA: heme positive
 UMicro: no RBCs
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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
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Hyperthermia – Heat Stroke
 Clinical manifestations – hematologic:
• Bleeding diathesis and DIC
 Clinical manifestations – GI:
• N/V/D
 Clinical manifestations – hepatic:
• Liver failure
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Hyperthermia – Heat Stroke
 Management:
• A/B/Cs
• Cooling:
 Remove clothing
 Place in cool room
 Evaporative cooling
 Ice packs
 Iced peritoneal irrigation
 Adjuncts:
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– Cooling blankets
– Cool IV fluids
– Cold oxygen
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)
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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
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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
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Hyperthermia – Heat Stroke
 Monitoring:
• Core temperature
• Cardiac monitor
• Foley
• CVP
• CNS status
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Hyperthermia -- Prevention
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Hyperthermia -- Prevention
 Reduce outdoor activities when it is hot outside
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Hyperthermia -- Prevention
 Allow time for acclimation to the heat over 10-14
days
 Hydration before and during the activity
 Wear appropriate clothing
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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”
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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
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