Internal Medicine

0521779407-09 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:13

768 Hyperthermia

■Severe hyperthermia (>40◦C): confusion, delirium, stupor, or coma;

hyperpnea and hyperventilation; petechiae from DIC; red urine from

rhabdomyolysis

■Heat stroke: temperature >40.6◦C with altered mental status and

anhidrosis

■Malignant hyperthermia of anesthesia, neuroleptic malignant

syndrome: temp often >41◦C, muscle rigidity, hypotension, arrhyth-

mias, hypoxia, extrapyramidal abnormalities, altered consciousness

■Heart rate increases by 8 bpm/1◦C increase in temperature in young

healthy individuals

■Intravascular volume contraction very common

tests

Diagnostic Tests

■Check CBC with differential, electrolytes, renal panel, glucose, cal-

cium, coagulation profile, DIC panel, creatinine kinase, LFTs, arterial

blood gas, urinalysis, and ECG

■Azotemia, elevated liver, muscle enzymes, hemoconcentration,

leukocytosis, thrombocytosis common with temperature 38.6–40◦C

■Hypoxia, respiratory alkalosis, metabolic acidosis, hypokalemia,

hypernatremia, hypophosphatemia, hypomagnesemia and hypo-

glycemia occur with temperature >40◦C; renal failure, hepatic fail-

ure, rhabdomyolysis, and DIC less frequent; rhabdomyolysis more

common in exertional hyperthermia

■Lactate elevated in exertional heat stroke; often normal in classical

heat stroke

Other Tests as Appropriate

■Screen for drugs of abuse

■Cultures, esp in older patients with preexisting medical conditions

■Malignant hyperthermia of anesthesia: caffeine-halothane contrac-

ture test useful for susceptibility screening; formal diagnosis requires

muscle biopsy

differential diagnosis

n/a

management

What to Do First

■Confirm hyperthermia.