Cyanide Poisoning

Key points

• Cyanide: inhibits cytochrome oxidase (aerobic respiration) — consider in smoke inhalation (burning plastics) and industrial exposure.
• Features: 'bitter almonds' smell (only ~50% can detect), dyspnoea, anxiety, seizures, coma; high anion gap acidosis with raised lactate.
• Classically normal oxygen saturation with lactic acidosis (cells cannot use oxygen).
• Treatment: hydroxocobalamin (binds cyanide → non-toxic cyanocobalamin) is first-line; dicobalt edetate or sodium thiosulphate alternatives.