Cyanide

General Principles

  • The most common source of cyanide poisoning in the US and other western countries is combustion of plastics and other synthetic materials in house fires.
  • Patients may also be exposed to cyanide in laboratory or industrial settings, during therapy with sodium nitroprusside, or by ingestion of compounds that liberate cyanide during metabolism (such as acetonitrile, the pits of stone fruits, and inappropriately processed cassava).

Pathophysiology

  • Cyanide is a chemical asphyxiant. It induces cellular hypoxia by inhibiting complex IV (also known as cytochrome c oxidase or cytochrome oxidase aa3) in the electron transport chain and thus preventing the formation of adenosine triphosphate which results in anaerobic metabolism and metabolic acidosis.
  • Cyanide is also an excitotoxin in the central nervous system.

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