Heat Illness/Hyperthermia Victor Politi, M.D., FACP Medical Director - SVCMC Physician Assistant...
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Transcript of Heat Illness/Hyperthermia Victor Politi, M.D., FACP Medical Director - SVCMC Physician Assistant...
Heat Illness/Hyperthermi
a
Victor Politi, M.D., FACPMedical Director - SVCMC
Physician Assistant Program
Risk factors for heat illness
ObesityFatigueDrugsAlcoholSunburnUnacclimatizedFluid deficitPrevious history of heat injuryMany medical conditionsFebrile illnessCystic fibrosisDiabetesMalnutrition
Heat Illness Classification Heat Rash Heat syncope Heat tetany Heat edema Heat cramps Heat exhaustion Heat stroke
Minor Heat Illness - Heat Cramps 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
Related to salt deficiency Victims exhibit -hyponatremia,
hypochloremia, low urinary sodium and chloride levels
Usually rapidly relieved by salt solutions
Minor Heat Illness - Heat Cramps
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
Minor Heat Illness - Heat Edema
Minor Heat IllnessHeat 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
Minor Heat Illness - Prickly Heat AKA miliaria rubra, lichen tropicus, heat rash
Acute phase - Produces intensely pruritic vesicles onan
erythematous base Rash confined to clothed areas Effected area completely anhydrotic
produnda stage- may persist for weeks chronic dermatitis -frequent complication
Heat Exhaustion - two types classically described
Water depletion heat exhaustion 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
Salt depletion heat exhaustion 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 - two types classically described
Heat Exhaustion: Diagnosis 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 If in doubt, --- treat as heat stroke !!
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
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
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)
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
HyperthermiaA patient presents to the ED with elevated
body temperature - 1st thought ??
? Infectious etiologies/severe infectionbut 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
Thermoregulation: Effects of EnvironmentalConditions
Causes of Hyperthermia- Disorders of excessive heat production
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
Heatstroke (classic) Occlusive dressings Dehydration Autonomic dysfunction Anticholinergics Neuroleptic malignant syndrome
Causes of Hyperthermia- Disorders of diminished heat production
Neuroleptic malignant syndrome Cerebrovascular accidents Encephalitis Sarcoidosis and granulomatous infections Trauma
Causes of Hyperthermia- Disorders of Hypothalamic Function
Hyperthermia
Splanchnic vasoconstriction Rhabdomyolysis
Disseminated intravascularcoagulation
Thermal injury
Diminishedrenal blood flow
Renal Failure
Glomerulardamage
Myoglobinuria Hyperuricemia &urinary acidification
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
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
Classic Heatstroke
Exertional Heat Stroke Like classic heat stroke- occurs during
hot,humid weather
Occurs sporadically - effecting young, healthy persons engaged in strenuous physical activity
Predisposing factors include acclimatization to the heat, lack of cardiovascular conditioning, heavy clothing and dehydration
Exertional Heat Stroke
Effects of Exercise in Heat
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
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 & treate- administer D50 if hypoglycemia present
Initial Treatment of Heat Stroke
Cooling Modalities to lower body temperature in heat stroke
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
Heat Illness Prevention A Crucial issue Counsel persons with any risk factors
regarding symptoms of heat stroke Elderly persons persons with chronic diseases those on medications predisposing them to
heat illness
Exertional heat stroke is most likely to strike young, healthy persons involved in strenuous physical activity 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
Fluid intake is the most critical variable
Heat Illness Prevention
Questions ?