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 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
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
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
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
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
Heat Exhaustion - two types classically described
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: Diagnosis
Vague malaise, fatigue, headache Core temperature often normal; if elevated less than 104 0 F 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 41 0 C (105.8
0 F) 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
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
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
Causes of Hyperthermia Disorders of diminished heat production Heatstroke (classic) Occlusive dressings Dehydration Autonomic dysfunction Anticholinergics Neuroleptic malignant syndrome
Causes of Hyperthermia Disorders of Hypothalamic Function Neuroleptic malignant syndrome Cerebrovascular accidents Encephalitis Sarcoidosis and granulomatous infections Trauma
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
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
Exertional Heat Stroke
Like classic heat stroke- occurs during hot,humid weather Occurs sporadically - effecting young, healthy persons engaged in strenuous physical activity
Exertional Heat Stroke
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
Initial Treatment of Heat Stroke
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
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
Heat Illness Prevention
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