Cyanide Toxicity

• Causes
• Infusion with Nitroprusside
• Smoke Inhalation (MCC)
• Combustion of polyurathane (found in mattresses – just look at the tag)
• Effects
• Inhibits cytochrome oxidase (cytochrome a/a3) of the electron transport chain
• NOT cytochrome C (commonly mistaken)
• Blocks the use of oxygen → tissue hypoxia and rapid death
• Si/Sx
• Bitter almond-scented breath
• Agonal respiration
• Nausea and headache
• Treatment
• Amyl and Sodium Nitrite
• Produces methemoglobin (met-HB)
• note: nitrates used for anginal therapy do not cause formation of cy
• Met-HB sucks up CN from the mitochondria
• Iron in met-HB (Fe3+) has stronger affinity for CN than does cytochrome oxidase’s iron
• Results in formation of cyanomethemoglobin
• Sodium Thiosulfate
• Converts cyanomethemoglobin into:
• Thiocyanate
• less toxic & easier to excrete than cyanomethemoglobin
• Methemoglobin
• Methemoglobinemia is treated with methylene blue