Cyanide directly inhibits cytochrome oxidase aa3, and blocks the routine transfer of electrons and free hydrogen ions to oxygen, thus paralyzing both oxidative phosphorylation and cellular metabolism. In the electron transport chain, cytochrome oxidase aa3 (also known as cytochrome c oxidase) is responsible for delivering electrons and free hydrogen ions to oxygen molecules in the final steps of aerobic respiration. Cytochrome oxidase is a critical enzyme of aerobic respiration, generating ATP from the cellular metabolism of glucose. PathophysiologyĬyanide is an inhibitor of multiple enzymes, including succinic acid dehydrogenase, superoxide dismutase, carbonic anhydrase, and cytochrome oxidase. Although these cyanide metabolites are neutralized endogenously, some malnourished or postoperative patients may have depleted concentrations of precursors necessary for neutralization, leading to accumulation of cyanide and clinical toxicity. Each nitroprusside molecule contains five molecules of cyanide, which slowly dissociate from the parent compound. Nitroprusside infusions may also be a source of iatrogenic cyanide poisoning. Amygdalin has been used medicinally in the form of the controversial antineoplastic agent Laetrile. The pits and seeds of “stone” fruit (such as apricots), almonds, and cassava contain amygdalin, a cyanogenic glycoside.
Many plants contain cyanogenic glycosides that are metabolized into cyanide. Certain chemicals such as acetonitrile (found in artificial fingernail remover), and acrylonitrile are metabolized by the liver into cyanide. Cyanide can be found as a gas (hydrogen cyanide), or salt (potassium cyanide, sodium cyanide). The majority of cyanide exposures are unintentional, involving chemists or laboratory workers (where cyanide is used as a common reagent), or through the production of cyanide due to combustion of common household materials during fires. In 2006 The American Associations of Poison Control Centers reported 215 exposures and 7 deaths from cyanide. Cyanide salts are commercially available for use as jewelry cleaner (though the industry is moving away from its use for obvious reasons). What antidotes are available for cyanide?Ĭyanide is widely used as a reagent in laboratory and industrial settings.How did the patient obtain cyanide, and what are common sources of exposure?.Is this a typical time course for cyanide poisoning?.After a brief period of observation he was transferred to a psychiatric facility. Overnight the patient’s laboratory studies remained within normal limits and he was extubated the following morning. After 1 hour and 2 ampules of sodium bicarbonate the patient’s pH was 7.34 with a bicarbonate of 28 mEq/L. His initial ABG reflected a metabolic acidosis with a pH of 6.79 and bicarbonate of 8 mEq/L. Within minutes the patient was awake and following simple commands. The patient was administered sodium nitrite and sodium thiosulfate from a cyanide antidote kit in the ED. CPR was initiated, the patient was intubated and administered epinephrine and atropine. Once connected to the monitor he was found to be in a sinus bradycardia. He then quickly stopped breathing in the ambulance, and upon arrival to the ED had no pulse. During the several minute transport to the emergency department (ED) the patient became confused, then obtunded. His fiancé immediately notified EMS, who arrived within 5 minutes to find the patient awake and alert, but anxious and tachypneic. He called his fiancé telling her of his intentions to drink sodium cyanide, which he had mixed in a light beer. Case presentationĪ 53-year-old male presents to the emergency department after a suicide attempt. Cyanide is often described as having an odor of “bitter” almonds however, this odor is detectable by only 60% of the general population. Currently, however, cyanide exposures are most likely to occur due to products of combustion of many household materials (including nylon, wool, silk and many plastics), or due to laboratory or industrial use.
Concern for cyanide’s potential as a weapon of terror continues to loom, and it is recognized as a possible chemical weapon by the Centers for Disease Control. Cyanide was publicized again in 1978 with the mass suicide in Jonestown when more than 900 people died, and in 1982 with seven reported deaths due to cyanide-tainted acetaminophen. Cyanide was used on the battlefield by Napoleon III, during the First World War, and by the Germans in World War II. Fear of cyanide is augmented by its quick and lethal action, and numerous sources.
Since that time cyanide has earned its reputation as a powerful and deadly poison. He reportedly died due to cyanide poisoning in 1786. Swedish chemist Carl Wilhelm Scheele first isolated cyanide in 1782.
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