Definition

A potentially fatal medical emergency that develops secondary to malfunctioning thermo regulatory mechanisms, also called heat stroke.

History

Symptoms: Headache, dizziness, and confusion. If untreated, rapid progression to delirium, euphoria, stupor, and coma. Generalized convulsions and/or focal neurologic signs may be present.

General: Typically occurs on hot, humid days to a susceptible population (e.g., overexerting athletes, laborers, military recruits, elderly, those with cardiovascular disease, Parkinson’s disease, obesity, and patients consuming anticholinergics, alcohol, diuretics, laxatives, tranquilizers, or beta blockers).

Age: Any.

Onset: Rapid progressive, within hours.

Duration: Hours.

Intensity: Initially mild, however, rapidly develop severe central nervous system symptoms.

Aggravating Factors: Hot, humid weather, physical exertion, chronic disease, medications (see above), alcohol consumption.

Alleviating Factors: Hydration and cooling.

Associated Factors: Anhidrosis (may see diaphoresis in rapidly progressive heatstroke secondary to exertion).

Physical Examination

General: Temperature greater than 104 F (400 C), hypotension, tachycardia, and respiratory depression.

Cardiovascular: May have sinus or supraventricular tachycardia, or peripheral vasodilation.

Neurologic: May have confusion, disorientation, generalized seizures, focal deficits, or coma.

Pulmonary: Tachypnea progressing to bradypnea.

Skin: Hot and dry.

Pathophysiology

Any drug or disease that causes hypothalmic dysfunction or interferes with sweating creates the physiologic opportunity for developing hyperthermia.

Diagnostic Studies

Laboratory

Complete blood count with differential: Elevated white blood-cell count with infectious process.

Electrolytes: To look for evidence of volume depletion; hypokalemia. PT: To look for prolongation (patient with hyperthermia may develop disseminated intravascular coagulopathy).

Urinalysis: To rule out infection and rhabdomyolysis.

Blood culture: To differentiate from infectious process.

Radiology: Not applicable.

Other

Lumbar puncture: To differentiate from infectious process.

ECG: May show tachycardia, ST-T wave changes, premature ventricular contractions, or arrhythmias.

Differential Diagnosis

Traumatic

Head injury: Differentiated on history.

Infectious

Meningitis: May see nuchal rigidity, positive Brudzinski and/or Kemig signs, leukocytosis with a shift, positive cerebral spinal fluid.

Sepsis: Positive blood cultures.

Metabolic

Epilepsy: History of generalized or focal seizure.

Neoplastic

Hypothalamic tumors: Positive computed. tomography/magnetic resonance imaging (CT/MRI) scan of brain.

Vascular

Stroke: History of transient or permanent neurologic deficit, positive CT/MRI of brain.

Congenital: Not applicable.

Acquired

Overdose: Of phencyclidine, cocaine, amphetamines, or withdrawal states.

Treatment

Patient should be immersed in ice water. During cooling, the extremities should be massaged to prevent vasoconstriction. Body temperature should be monitored, and cooling discontinued when patient’s temperature is lowered to 101 degree F (38.50 C).Intravenous fluids (normal saline or Ringer lactate solution) should be administered to correct for dehydration, hypovolemia, and electrolyte imbalances.

Pediatric Considerations

Malignant hyperthermia is an autosomal dominant pattern inherited disease which usually presents initially in childhood. Clinical suspicion of malignant hyperthermia should be raised for children with fevers of unknown etiology, muscle cramps and increased CK values.

Obstetrical Considerations

No specific indications. Fever may be treated with acetaminophen.

Tagged under:anticholinergics complete blood count disease medications Diseases elevated white blood cell count heatstroke peripheral vasodilation supraventricular tachycardia tranquilizers

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