Background: Nerve gas agents were originally used as pesticides and thus are similar to organophosphates. They were later developed by the military for use as chemical weapons. Each agent has a chemical name and a military name(two letters). For example: Soman (GD), methylphosphonothioate (VX), Sarin (BG). Sarin is the most commonly used agent. There are two “varieties” of nerve agents using the military nomenclature: “V-series” and “G-series”.
Like organophosphates, nerve gases inhibit acetylcholinesterase so ACh accumulates at nicotinic and muscarinic nerve terminals. The SLUDGE (Salivation, Lacrimation, Urination, Diarrhea, GI distress, Emesis) or DUMBBELSS (Diarrhea, Urination, Miosis, Bradycardia, Bronchoconstriction, Emesis, Lacrimation, Salivation, Sweating) mnemonics summarize the muscarinic symptoms. Nicotinic symptoms include weakness, fasciculations, hyperthermia and RESPIRATORY FAILURE.
Treatment:
• Removal of offending agent (“V-series” gases can be absorbed through clothing and leather).
• Atropine (muscarinic antagonist): give 2-6mg IV or IM every 5-10 minutes until secretions decrease and or ventilation improves. Do not stop redosing atropine if the patient develops tachycardia or mydriasis.
• Pralidoxime- induces or reactivates acetylcholinesterase and can unbind the nerve agent. Can help with paralysis and muscle weakness but does not have much effect on ventilation. Should not be given without atropine as it may worsen muscarinic effects of gas if given alone.
The national poisoning and toxicology center sells a “Duo-Dote” injector that contains 600mg of pralidoxime and 2mg of atropine. Treatment varies based on symptom severity and age but, in general, current guidelines recommend 2mg Atropine IM q 5-10 minutes until secretions and/or ventilation improves and up to 45 mg/kg of pralidoxime per hour.
“Prophylaxis” is possible with pyridostigmine (reversible inhibitor of acetylcholinesterase) if it is given 30 minutes before exposure.
Other aspects of treatment include protection of rescuers, standard monitoring, benzodiazepines for seizures and, often, intubation.
Other References
- User: Nerve Agents - Emergency Department/Hospital Management Link
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