Medical Aspects of Chemical Warfare (2008) - The Black Vault

Nerve AgentsTABLE 5-7RECOMMENDED THERAPY FOR CASUALTIES OF NERVE AGENTSExposure Route Exposure Category Signs and Symptoms TherapyInhalational(vapor)Dermal(liquid on skin)MinimalMildModerateModerately severeSevereMiosis with or without rhinorrhea;reflex nausea and vomitingMiosis; rhinorrhea; mild dyspnea;reflex nausea and vomitingMiosis; rhinorrhea; moderate to severedyspnea; reflex nausea and vomitingSevere dyspnea; gastrointestinal orneuromuscular signsLoss of consciousness; convulsions;flaccid paralysis; apnea< 5 min of exposure: 1 Mark I kit> 5 min of exposure*: observation< 5 min of exposure: 2 Mark I kits> 5 min of exposure: 0 or 1 Mark I kit,depending on severity of dyspnea< 5 min of exposure: 3 Mark I kits anddiazepam> 5 min of exposure: 1–2 Mark I kits3 Mark I kits; standby ventilatory support;diazepam3 Mark I kits; ventilatory support, suction;diazepamMild Localized sweating, fasciculations 1 Mark I kitModerate Gastrointestinal signs and symptoms 1 Mark I kitModerately severe Gastrointestinal signs plus respiratoryor neuromuscular signs3 Mark I kits; standby ventilatory supportSevere Same as for severe vapor exposure 3 Mark I kits; ventilatory support, suction;diazepam*Casualty has been out of contaminated environment during this time.Suspected ExposureSuspected but unconfirmed exposure to a nerveagent sometimes occurs in an area where liquid agentwas present. Workers without signs or symptomsmay not be sure they are contaminated. In such cases,the suspected casualty should be thoroughly andcompletely decontaminated and kept under closemedical observation for 18 hours. If a laboratory facilityis available, blood should be drawn to measureRBC-ChE activity.An individual working with nerve agent in an industrialor laboratory environment will have a baselineRBC-ChE activity value on record. If this value is still atbaseline after a possible exposure, then no significantabsorption has occurred and the new value providesconfirmation of the baseline. (See Blood Cholinesterasessection, above, on RBC-ChE activity monitoring.)If the activity is decreased, however, then absorptionof the agent has occurred, but the decision to begintherapy should be based on signs or symptoms, noton the RBC-ChE activity (with one possible exception:an asymptomatic worker with decreased ChE activity;see Oxime Therapy section, above). The medical careprovider must remember that the nadir of RBC-ChEactivity may not occur for 18 to 24 hours, and if therehas been no oxime therapy, then the final sample foranalysis must be drawn during that time period.Because the onset of effects caused by nerve agentexposure may occur as late as 18 hours after skin contact,prolonged observation is prudent. The longer theinterval until the onset of signs and symptoms, the lesssevere they will be, but medical assistance will still benecessary. Since vapor (or inhaled aerosol) causes effectswithin seconds or minutes, it is extremely unlikelythat a “suspected” asymptomatic casualty would beproduced by this route.Minimal ExposureMiosis, with accompanying eye symptoms, andrhinorrhea are signs of a minimal exposure to a nerveagent, either vapor or vapor and liquid. This distinctionis quite important in the management of this casualty.There are many situations in which one can bereasonably certain that exposure was by vapor alone(if the casualty was standing downwind from munitionsor a container, for example, or standing across alaboratory or storeroom from a spilled agent or leakingcontainer). On the other hand, if an unprotected191