Hyperthermia

Key Features

• A rapidly life-threatening complication

• May be due to poisoning by

  • Amphetamines and other synthetic stimulants (cathinones, piperazines)

  • Atropine and other anticholinergic drugs

  • Cocaine

  • Salicylates

  • Strychnine

  • Tricyclic antidepressants

• Overdose of serotonin reuptake inhibitors (eg, fluoxetine, paroxetine) alone or combined with monoamine oxidase inhibitor may cause agitation, hyperactivity, hyperthermia (serotonin syndrome)

• Antipsychotic agents can cause rigidity and hyperthermia (neuroleptic malignant syndrome)

• Malignant hyperthermia is associated with general anesthetic agents (rare)

Clinical Findings

• Severe hyperthermia (temperature > 40–41°C) can rapidly cause brain damage and multiorgan failure, including

  • Rhabdomyolysis

  • Acute kidney injury

  • Coagulopathy

Treatment

• Remove clothing

• Spray skin with tepid water

• High-volume fanning of the patient

• Alternatively, the patient can be placed in an ice water bath (not simply applying ice to selected surfaces)

• Induce neuromuscular paralysis with a nondepolarizing neuromuscular blocker (eg, rocuronium, vecuronium)

  • If rectal temperature not normal in 30–40 min

  • If there is significant muscle rigidity or hyperactivity

• Once paralyzed, patient must be intubated, mechanically ventilated, and sedated

• Once the patient is paralyzed, the absence of visible muscular convulsive movements may give the false impression that brain seizure activity has ceased; bedside electroencephalography may be useful in recognizing continued nonconvulsive seizures

• Dantrolene, 2–5 mg/kg intravenously, may be effective for muscle rigidity unresponsive to neuromuscular blockade (ie, malignant hyperthermia)

• Bromocriptine, 2.5–7.5 mg daily orally, for neuroleptic malignant syndrome

• Cyproheptadine, 4 mg every hour for 3–4 doses orally, or chlorpromazine, 25 mg intravenously or 50 mg intramuscularly, for serotonin syndrome