Transcript Hyperthermia/Heat Stoke

Heat
Illness/Hyperthermia
Victor Politi, M.D., FACP
Medical Director - SVCMC
Physician Assistant Program
Risk factors for heat illness
Obesity
Fatigue
Drugs
Alcohol
Sunburn
Unacclimatized
Fluid deficit
Previous history of heat injury
Many medical conditions
Febrile illness
Cystic fibrosis
Diabetes
Malnutrition
Heat Illness Classification
Heat
 Heat
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 Heat
 Heat
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Rash
syncope
tetany
edema
cramps
exhaustion
stroke
Minor Heat Illness Heat Cramps
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Brief, intermittent, often severe muscular cramps
typically occurring in muscles that are fatigued by
heavy work
Usually occur after exertion
Copious hypotonic fluid replacement during
exertion
Hyperventilatoin not present in cool environment
Minor Heat Illness Heat Cramps
Related to salt deficiency
 Victims exhibit -hyponatremia,
hypochloremia, low urinary sodium and
chloride levels
 Usually rapidly relieved by salt solutions
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Minor Heat Illness Heat Edema
Minimal edema - feet/ankles
 Not accompanied by any other significant
impairment in function
 Often resolves after several days of
acclimatization
 Brief diagnostic evaluation to rule out
thrombophlebitis, lymphedema or CHF is
appropriate
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Minor Heat Illness
Heat Syncope
Individuals at risk should be warned to
move frequently, flex leg muscles
repeatedly whenever standing
 Scintillating scotomata, tunnel vision,
vertigo, nausea, diaphoresis, and
weakness are prodromal symptoms of
syncope
 Adequate oral volume replacement may
prevent some conditions
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Minor Heat Illness - Prickly Heat
AKA miliaria rubra, lichen tropicus, heat rash
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Acute phase 
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Produces intensely pruritic vesicles onan
erythematous base
Rash confined to clothed areas
Effected area completely anhydrotic
produnda stage
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may persist for weeks
chronic dermatitis -frequent complication
Heat Exhaustion - two types classically described
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Water depletion heat exhaustion
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inadequate fluid replacement by persons in heat “
voluntary dehydration”
weakness, fatigue, frontal headache, impaired
judgement, vertigo, nausea/vomiting, occasional
muscle cramps,sweating, body temperature near
normal
orthostatic dizziness/syncope may occur
results in progressive hypovolemia
Untreated can progress to heat stroke
Heat Exhaustion - two types classically described
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Salt depletion heat exhaustion
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takes longer to develop than water depletion
form
systemic symptoms occur
hyponatremia, hypochloremia, low urinary
sodium and chloride concentrations
Symptoms similar to water depletion type,
body temperature remains near normal
Heat Exhaustion: Diagnosis
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Vague malaise, fatigue, headache
Core temperature often normal; if elevated less
than 1040F
Mental function essentially intact; no coma or
seizures
Tachycardia, orthostatic hypotension, clinical
dehydration (may occur)
Other major illness ruled out
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If in doubt, --- treat as heat stroke !!
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Heat Exhaustion - Treatment
Rest
 cool environment
 Assess volume status (orthostatic
changes, BUN, hematocrit, serum sodium)
 Fluid replacement
 Consider admission if patient is elderly,
has significant electolyte abnormalities or
would be at risk of recurrence if d/c
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A catastrophic life-threatening medical
emergency ---
HEAT STROKE
Heat Stroke Diagnosis
Exposure to heat stress, endogenous or
exogenous
 Signs of severe CNS dysfunction (coma,
seizures, delirium
 Core temperature usually 410C (105.80F)
or more, but may be lower
 Dry, hot skin frequent, but sweating may
persist
 Marked elevation of hepatic transaminases
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In 80% of cases - sudden onset
 Patient becomes delirious or comatose
 Nonspecific Prodromal symptoms lasting
minutes to hours occur in approximately
20% of cases - (reminiscent of heat stoke
symptoms)
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There are two types of heat stroke classic and exertional
Both types characterized by
extreme hyperthermia
and multiple metabolic, hemodynamic
abnormalities
but arise in very different clinical settings
Hyperthermia
A patient presents to the ED with elevated
body temperature 1st thought ??
? Infectious etiologies/severe infection
but some patients with elevated
temperature, including some with extreme
pyrexia, do not have fever at all, they
have hyperthermia !
Fever versus Hyperthermia
Body temperature can become elevated
through either of two very different
processes
 In fever, thermoregulation remains intact
while hyperthermia represents
thermoregulation failure
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Causes of HyperthermiaDisorders of excessive heat production
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Exertional hyperthermia
Heatstroke (exertional)
Malignant hyperthermia of anesthesia
Neuroleptic malignant syndrome
Lethal catatonia
Thyrotoxicosis / Pheochromocytoma
Salicylate intoxication / Delirium tremens
Cocaine, amphetamines, other drugs of
abuse
Status epilepticus /Generalized tetanus
Causes of HyperthermiaDisorders of diminished heat production
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Heatstroke (classic)
Occlusive dressings
Dehydration
Autonomic dysfunction
Anticholinergics
Neuroleptic malignant syndrome
Causes of HyperthermiaDisorders of Hypothalamic Function
Neuroleptic malignant syndrome
 Cerebrovascular accidents
 Encephalitis
 Sarcoidosis and granulomatous infections
 Trauma
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Hyperthermia
Splanchnic
vasoconstriction
Thermal injury
Rhabdomyolysis
Disseminated intravascular
coagulation
Diminished
renal blood flow
Glomerular
damage
Myoglobinuria
Hyperuricemia &
urinary acidification
Renal Failure
Classic Heatstroke
Occurs primarily in epidemics during
summer heat waves
 Most likely to effect the elderly and
patients with serious underlying illnesses
 Infants also at risk
 Typical victim confined at home w/no fan
or A/C
 Dehydration - predisposing factor
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Classic Heatstroke
Other risk factors - obesity, neurologic or
cardiovascular disease, use of diuretics,
neuroleptics, or medications with
anticholinergic properties that interfere
with sweating
 Alcohol use may be a risk factor
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Exertional Heat Stroke
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Like classic heat stroke- occurs during
hot,humid weather
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Occurs sporadically - effecting young,
healthy persons engaged in strenuous
physical activity
Exertional Heat Stroke
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Predisposing factors include
acclimatization to the heat, lack of
cardiovascular conditioning, heavy
clothing and dehydration
Initial Treatment of Heat Stroke
Immediate cooling
 Protect airway (intubate if comatose or
seizing)
 IV line with 0.9% NaCl or Ringer’s lactate
 CVP or Swan Ganz catheter in hypotensive
patients
 Foley catheter; monitor output
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Initial Treatment of Heat Stroke
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Rectal probe - monitor temperature
Oxygen, 5-10L/min
ABGs
Labs - CBC, electrolytes, BUN, glucose, SGOT,
LDH, CPK, calcium phosphate, lactate, PT/PTT,
fibrin degradation products
Check glucose by dextrostix method & treateadminister D50 if hypoglycemia present
Cooling Modalities to lower body temperature in
heat stroke
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Ice-water immersion
Evaporative cooling using large circulating fans
and skin wetting
Ice packs
Peritoneal lavage
Rectal lavage
Gastric lavage
Cardiopulmonary bypass
Alcohol sponge baths (caution)
Phenothiazines (caution)
Treatment of early complications of Heat
Stroke
Shivering
 Convulsions
 Myoglobinuria
 Acidosis
 Hypokalemia
 Hypocalcemia
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Heat Illness Prevention
A Crucial issue
 Counsel persons with any risk factors
regarding symptoms of heat stroke
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Elderly persons
persons with chronic diseases
those on medications predisposing them to
heat illness
Heat Illness Prevention
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Exertional heat stroke is most likely to
strike young, healthy persons involved in
strenuous physical activity
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many of these people have risk factors for heat
illness -commonly obesity,diarrhea,febrile
illness
other variables to consider- hydration,salt
intake, clothing, and climatic conditions
Heat Illness Prevention
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Fluid intake is the most critical variable
Questions ?