14. Cyanide poisoning Flashcards
Where does one find cyanide?
- chemical synthesis
- rodenticides/insecticides
- photographic solutions
- jewelry cleaner
- burning of plastics
- wool
- released from natural food substances e.g. almonds or lima beans.
- medical exposures such as sodium-nitroprusside.
What is the MOA of cyanide?
- It binds to the trivalent irons of cytochrome oxidase (last enzyme in the respiratory electron transport chain).
- Inhibition of cellular respiration causes lactic acidosis and cytotoxic hypoxia.
What are the symptoms of cyanide poisoning?
Signs and symptoms begin at blood cyanide concentration of approximately 40 mol/L. (one minute after inhalation, few minutes after ingestion).
- Shortness of breath (Dyspnea)
- Agitation
- Tachycardia
- Seizures
- Coma
- Hypotension
- Death
- Venous oxygen content may be elevated?
What are the treatment options for cyanide poisoning or its management?
- General supportive care formation of methemoglobin with amyl-nitrite binds CN−, creating the less toxic cyanomethemoglobin.
- Thiosulfate iv. 50 ml 25% –> formation of thiocyanate (SCN-) –> excretion in the urine.
- Hydroxocobalamin (Antidote?) (one form of vitamin B12) combines rapidly with CN− to form nontoxic cyanocobalamin.
(Antidote: Hydroxycobalamin, sodium-nitrite, sodium- thiosulphate.)
What forms does cyanide come in?
Can exist as a Gas form- Hydrogen Cyanide or a Salt form- Potassium Cyanide.
What forms of exposure do we have to cyanide?
Exposure happens via IV administration, inhalation, skin contact and GI mucosa. Good absorption through the respiratory tract and mucous membranes, as well as GI and skin.
How do you diagnose cyanide poisoning?
Evaluation of:
- Complete Blood Count (CBC)
- Electrolytes
- Urinalysis
- Urine toxins screen
- Arterial blood gas
- Carboxyhemoglobin level (if in a fire).
- Chest x-ray
- ECG
- Plasma lactate (8mmol/L is 94% sensitive and 70% specific for significant cyanide toxicity).
- Increased anion gap metabolic acidosis.
How is the metabolism and elimination of cyanide in the body?
Metabolism and neutralization is via detoxification in liver and muscles, by Thiosulfate that serves as a sulfur donor in the reaction catalyzed by rhodanese that converts cyanide to thiocyanate, a water- soluble molecule excreted in the urine.
