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

Medical Aspects of Chemical WarfareWOUND DECONTAMINATIONAll casualties entering a medical unit after experiencinga chemical attack must be consideredcontaminated unless they have been certified as noncontaminated.The initial management of a casualtycontaminated by chemical agents requires removalof IPE and decontamination before treatment withinthe field MTF.Initial Wound DecontaminationDuring thorough patient decontamination at apatient decontamination station, all bandages suspectedof contamination are removed and the woundsare flushed with isotonic saline solution or water.Bandages are replaced only if bleeding begins afterdecontamination. Tourniquets suspected of beingcontaminated are replaced with clean tourniquets, andthe sites of the original tourniquets decontaminated.Both bandage replacement and tourniquet replacementare performed by medical personnel. Splintsare thoroughly decontaminated but removed onlyby a physician or under physician supervision. Oncethe patient has been thoroughly decontaminated andenters the medical facility, the new dressings are removedand submerged in 5% hypochlorite or sealedin a plastic bag. 55General ConsiderationsThree classes of chemical agent (vesicants, nerveagents, and cyanide) might present a hazard fromwound contamination. Hydrogen cyanide is a bluewhiteliquid with a boiling point of 26°C (79°F). It canbe absorbed slowly through unbroken skin but muchmore rapidly through an open wound. Cyanide maybe delivered as pure hydrogen cyanide (liquid or gasdepending on temperature), pure solid salt (sodiumcyanide), or an aqueous solution of the metal salt.Cyanide is very toxic but less so than vesicants andnerve agents, and therefore less of a concern in openwounds.Mustard converts to a reactive cyclic intermediatecompound within a few minutes of absorption intoa biological milieu, and the cyclic intermediate reactsrapidly (within a few minutes) with blood and tissuecomponents. 13 In a wound, the compound reacts withblood, the necrotic tissue, and the remaining viabletissue. If the amount of bleeding and tissue damage issmall, mustard will rapidly enter the surrounding viabletissue, where it will quickly biotransform and attach totissue components, and its biological behavior will besimilar to an intramuscular absorption of the agent.Although nerve agents cause their toxic effects byvery rapid attachment to the enzyme acetylcholinesterase,they also quickly react with other enzymesand tissue components. As with mustard, the bloodand necrotic tissue of the wound “buffers” the nerveagents. Nerve agent that reaches viable tissue will berapidly absorbed, and because of the high toxicityof nerve agents (a small fraction of a drop is lethal),casualties with wounds contaminated by liquid nerveagent are unlikely to reach medical care alive. 56 Thepotential risk from contaminated wounds arises fromchemical agent on foreign bodies in the wound andfrom thickened agents. 57Thickened AgentsThickened agents are chemical agents mixed withanother substance (commonly an acrylate) to increasetheir persistency. They do not dissolve as quickly inbiological fluids, nor are they absorbed by tissue asrapidly as other agents. (VX, although not a thickenedagent, is absorbed less quickly and may persist in awound longer than other nerve agents.) Thickenedagents are not known to be stockpiled by any country.In a chemical attack, the intelligence and chemical staffshould be able to identify thickened agents and alertmedical personnel of their use.Casualties with thickened agents in wounds (eg,from pieces of a contaminated battle-dress uniform orprotective garment being carried into the wound tract)require more precautions and are unlikely to surviveto reach surgery. Thickened mustard has delayed systemictoxicity and can persist in wounds even whenlarge fragments of cloth have been removed. Althoughthe vapor hazard to surgical personnel is low, contacthazard from thickened agents remains and shouldalways be assumed. 56Foreign Material and Off-GassingThe contamination of wounds with mustard, nerveagents, or cyanide is mostly confined to the pieces ofcontaminated fabric in the wound tract. The removalof this cloth from the wound effectively eliminatesthe hazard. Little chemical risk is associated withindividual fibers left in the wound. No further decontaminationof the wound for un-thickened chemicalagent is necessary. 56 Cooper et al 56 reported that therisk from vapor off-gassing of chemically contaminatedfragments and cloth in wounds is low or nonexistent,and that off-gassing from a wound during surgicalexploration is negligible. Eye injury is not expected538