Clinical presentation

Cyanide binds to cytochrome oxidase and inhibits oxidative metabolism. Cyanide poisoning can be rapidly fatal. If patients with cyanide poisoning survive long enough to be seen in hospital, they usually only have mild to moderate toxicity.

Effects of acute cyanide poisoning include:

• central nervous system (CNS) effects:
  • mild poisoning—headache, weakness, dizziness
  • moderate to severe poisoning—agitation, confusion, CNS depression (altered conscious state ranging from drowsiness to coma), tetany, collapse, seizures
• cardiovascular effects—tachycardia, hypotension, myocardial ischaemia, bradycardia, arrhythmias, cardiorespiratory arrest
• respiratory effects—dyspnoea, tachypnoea, cyanosis, respiratory depression
• gastrointestinal effects—nausea, vomiting
• metabolic effects—lactic acidosis.