Cyanide Poisoning — Management Pathway

Step-by-step decision

Choose step by step as prompted; reaching an endpoint gives the management recommendation. You can go back a step or restart anytime.

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Full pathway

1. [Decision] Antidote needed?
   Fire/industrial exposure + lactate/acidosis — is an antidote needed? (Inhibits cytochrome c oxidase → stops oxidative phosphorylation → cellular asphyxia → high lactate + high-anion-gap metabolic acidosis, narrowed arteriovenous oxygen difference (tissue cannot extract oxygen). Sources: enclosed-space fire smoke (most common), industrial/HCN, suicide, nitroprusside. Rapid onset (deterioration hours later is not cyanide); early hypertension/tachycardia → severe coma/seizures/bradycardia-hypotension/arrest. Lactate ≥8–10 suggests it, <8 excludes significant poisoning; in fire victims with altered mentation/instability assume cyanide (often with co-existing CO).)
   • Severe/high lactate/altered mentation/unstable → Severe → hydroxocobalamin
   • Mild, asymptomatic exposure → Mild exposure · oxygen, observe
2. [End] Mild exposure · oxygen, observe
   Mild, asymptomatic exposure: remove from source, 100% high-flow oxygen, monitor; check lactate/blood gas (lactate <8 excludes significant poisoning); most improve with removal and oxygen. Treat as severe with antidote if symptoms/rising lactate/instability appear.
3. [End] Severe → hydroxocobalamin
   Severe (high lactate/altered mentation/hemodynamic instability/fire arrest): remove from source, 100% high-flow oxygen (also treats co-existing CO), airway/cardiopulmonary support; first-line antidote hydroxocobalamin (Cyanokit) 5 g IV (may repeat to 10 g) given empirically (does not cause methemoglobinemia, safe with co-existing CO) ± sodium thiosulfate. Avoid nitrite antidotes in smoke-inhalation victims (cause methemoglobinemia, dangerous with co-existing CO; only for pure cyanide without CO). Correct acidosis, control seizures.

Source guidelines & references

• Cyanide poisoning (StatPearls; hydroxocobalamin in smoke inhalation review)

This pathway is our own synthesis of the decision logic in the guidelines above (not the guideline verbatim); thresholds and workflows change as guidelines update — in practice follow the latest guideline, your institution's protocol and the individual patient.

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