Prehospital Care
Keep in mind that rescue personnel may themselves become affected by nerve agents. The cornerstones of prehospital management are based on rapid termination of exposure (ie, evacuation and decontamination), treatment of life-threatening emergencies, and administration of antidotes, if available. Whenever possible, decontamination should take place prior to transportation of the patient to a clean area. This prevents cross-contamination and additional exposures.
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Decontamination techniques vary according to the extent and route of exposure. [2]
After exposure to any toxic vapor, evacuation and provision of fresh air is the most important first step. Clothes should be removed, since they can trap enough vapor to cause secondary victims. In the Tokyo subway attack, 10% of the caregivers at the hospital developed miosis after exposure to nondecontaminated victims.
In dermal exposures, the patient should be undressed. Any visible droplets should be blotted away. Abrasion of the skin by vigorous scrubbing increases absorption of the agent and should be avoided. Nerve agents can be neutralized with alkaline solutions such as soap and water or 0.5% hypochlorite solution (which releases chlorine), followed by a water rinse. [3] However, decontamination should not be delayed to seek hypochlorite or other special solutions; copious water is generally good enough for decontamination.
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The military has autoinjector kits (MARK 1) that contain 2 antidotes, an oxime (AChE reactivator) and atropine. [4] Some ambulance systems and hazardous materials (HAZMAT) teams also have these kits available for use in the prehospital setting.
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During a mass casualty incident, most patients arrive to the emergency department without the benefit of prior emergency medical services (EMS) or HAZMAT intervention. According to the 1998 report by Okumura et al, in the Tokyo subway sarin attack, 85% of patients arrived to the ED by private car. [5] This means that the emergency department must be prepared to treat potentially large numbers of contaminated individuals.
Emergency Department Care
If decontamination has not occurred, the emergency department should be able to provide this service prior to the patient's entrance to the hospital. If weather permits, decontamination stations can be set up outside. All hospital personnel in contact with contaminated individuals must wear full protective gowns (eg, rubber apron, rubber gloves, protective mask). Medical management is discussed in Medication.
Consultations
Contact the regional poison center (1-800-222-1222) whenever nerve agent poisoning is suspected. In case of a multiple casualty incident, activate the hospital emergency plan and notify local authorities for advice and support.
Tables
Agent |
Chemical Name |
LCt50, mgXmin/m3 |
LD50, mg |
GA |
Ethyl N -dimethylphosphoramidocyanidate |
400 |
1000 |
GB |
Isopropyl methylphosphonofluoridate |
100 |
1700 |
GD |
Pinacolyl methylphosphonofluoridate |
50 |
100 |
VX |
O-Ethyl S-2-diisopropylaminoethyl methylphosphonothioate |
10 |
10 |
Severity of Exposure |
Signs and Symptoms - Liquid* |
Signs and Symptoms - Vapor† |
Minimal |
Localized sweating at site Localized fasciculations at site |
Miosis Rhinorrhea Slight dyspnea |
Moderate |
Above-mentioned symptoms and the following: Nausea, vomiting, and diarrhea Generalized weakness |
Above-mentioned symptoms and the following: Moderate-to-marked dyspnea (bronchorrhea and/or bronchoconstriction) |
Severe |
Above-mentioned symptoms and the following: Loss of consciousness Seizures Generalized fasciculations Flaccid paralysis and apnea |
Above-mentioned symptoms and the following: Loss of consciousness Seizures Generalized fasciculations Flaccid paralysis and apnea |
* Onset possibly delayed † Rapid onset of symptoms |
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Drug |
Dose (Adult) |
Route |
Indications |
Contraindications |
Atropine |
2 mg q5-10min prn Note: The MARK 1 kit contains 2 mg of atropine. |
IV/IM/ETT |
Excessive muscarinic symptoms |
Relative: IV route in hypoxia has been associated with ventricular fibrillation. |
Pralidoxime chloride (Protopam, 2-PAM) |
15-25 mg/kg over 20 min; can be repeated after 1 h Note: The MARK 1 kit contains 600 mg of pralidoxime. |
IV/IM |
Symptomatic nerve agent poisoning |
Rapid infusion may result in hypertension; may worsen symptoms in carbamate poisoning |
Diazepam (Valium) |
2-5 mg IV 10 mg IM |
IV/IM |
Moderate or severe signs of poisoning, seizures |
None |
*Adapted from Sidell, 1992. [6] |
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Severity/Route of Exposure |
Atropine (Adult Dose) |
Pralidoxime |
Diazepam |
Other |
Suspected |
No |
No |
No |
Decontamination and 18-h observation for liquid exposures |
Mild |
2 mg for severe rhinorrhea or dyspnea; may be repeated |
Administer if dyspnea is not improving or if GI symptoms occur |
No |
Decontamination and 18-h observation for liquid exposures; oxygen |
Moderate |
6 mg; may need to repeat |
Administer with atropine |
Administer even in absence of seizures |
Decontamination; oxygen |
Severe |
Start with 6 mg; may need to repeat |
Administer with atropine; should repeat once or twice |
Administer even in absence of seizures |
Airway, breathing, and circulation; decontamination |
*Adapted from Sidell, 1992. [6] |
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