#EMConf: Cyanide Toxicity

What is it?

  • Colorless gas, crystal & solid form
  • Rapidly lethal
  • Bitter almond smell

Where does it come from? 

  • Combustion of products that contain carbon & nitrogen
    • Fires! Burning of insulation, fabrics, plastics
    • Industrial: Mining, Jewelers (putting metal coat on), photography, rubber/ plastic, manufacturing, pesticides
    • Food: Pits & seeds of rosacea family (laurell cherry, bitter almonds, apricot, plum, peach pear)
    • Medicine: Sodium Nitroprusside, Amygdalin (alternative medicine chemotherapy)
    • Illicit PCP Synthesis, nail polish, cigarrettes

What's it do?

  • Inhibits Fe3+ portion of cytochromoe oxidase which is final enzyme in Electron Transport Chain
  • Inhibits Oxidative Phosphorylation --> No ATP production --> Anaerobic Metabolism --> Lactic Acidosis
  • Induces neuronal apoptosis 
  • Some affinity for Fe2+ --> Binds Hemoglobin 


  • Greatest effects on CNS, CV
    • Decreased conciousness, loss of conciousness, seizure
    • Bradycardic, Hypotensive
    • Initially Tachypneic followed by Apnea 
    • Normal Pulse Oximetry reading as problem is not with circulating O2, problem is with utilization 


  • Hydroxycobalamin 
    • Binds CN and removes from cytochrome oxidase, excreted by kidney 
    • Effective, cheap, safe
    • Can cause reddish discoloration of skin, urine, mucus membranes
  • Amyl Nitrate (inhaled), Sodium Nitrate (IV)
    • Induces Methemoglobinemia
    • Can cause hypotension but not a contraindication 
    • Contraindicated if suspected concurrent carbon monoxide poisoning patient (fire)
  • Thiosulfates
    • Enhances bodies naturial elimination process
    • Minimal effect on own; combine with one of the above options