cyanide toxicity
EnvC7 Environmental emergencies MRCEM syllabus, PhC2 Pharm and poisoning MRCEM syllabus where it is specifically namedropped
| Housefires rather than Miss Marple stories | |
|---|---|
| Typical exposures | Housefire/smoke inhalation → from combustion of plastics, industrial exposure Sodium nitroprusside Poison for pest control Glycosides - almond kernels (you need a lot of seeds) |
| Epidemiology | |
| Clinical presentation | Acute ingestion: rapid LOC Chronic/mild exposure: non-specific systemic s/s; hypertension, seizures Progressing to resp depression, lactic acidosis, bradycardia, hypotension Ddx: |
| Pathogenesis | - Binds Fe3+ in cytochrome oxidase → lactic acidosis - stimulates NMDA release + amine release → pulm/coronary vasoconstriction |
| Diagnostic investigations | ABG: COHb (Carbon monoxide toxicity), expect ↑ lactate, high SvO2 |
| Management | A/B: high flow oxygen C: Antidote: Hydroxycobalamin or sodium thiosulfate - 5g hydroxycobalamin chelates 100mg cyanide Some kits deliberately induce Methaemoglobinaemia as cyanide binds avidly to MetHb...! |