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

Triage of Chemical CasualtiesWith nondepolarizing relaxants (eg, vecuronium), theactions are opposed, leading to a higher effective dose.Opiates and similar drugs reduce respiratory drive andshould be used with caution in cases of nerve agentpoisoning.Persistent Nerve AgentsWhen a conventional injury is contaminated by apersistent nerve agent, the danger of absorbing a lethaldose is great and the prognosis is poor. The skinsurface surrounding the wound must be decontaminated,followed by application of a surface dressingwith a protective cover to prevent further contamination.In a superficial wound the entire skin surfacewould be decontaminated. Surgery on contaminatedwounds poses minimal danger to medical staff whenbutyl rubber gloves are worn. If these gloves are notavailable, two pair of latex rubber gloves, washed atshort intervals in hypochlorite solution and changedfrequently, should suffice. These casualties requirecareful observation during evacuation to the surgicalunit. If signs of poisoning persist or worsen, Mark Ior ATNAA treatment should be continued (for furtherinformation see Chapter 5, Nerve Agents).If the wound is not directly contaminated by liquidagent on the skin but the surrounding skin is affected,the casualty should be decontaminated and given theappropriate agent therapy. If the injury is not directlycontaminated but skin absorption is thought to haveoccurred, the skin must be decontaminated. Becauseliquid nerve agent can penetrate the skin within 2minutes but the effects from agent absorption intothe bloodstream may be delayed up to 18 hours afterexposure, the casualty should be kept under close observationduring this period and given an autoinjectorwhen indicated.VesicantsVesicant agents weaken those exposed, and theagent’s systemic effects could lead to serious delayin the healing of any wound because of depression ofthe immune system (see Chapter 8, Vesicants, for moreinformation) even if the wound is not directly contaminated.Casualties with a Lewisite-contaminatedwound will feel immediate pain disproportionate tothe severity of the wound. Early treatment with dimercaprol(BAL) is required. The first responder (medicor buddy) should decontaminate the area around thewound and dress it with a protective material to preventfurther contamination.Thickened vesicant agent may be carried into conventionalwounds on fragments and debris. Thesewounds need to be carefully explored using the notouchtechnique. Wounds should be irrigated using asolution containing 3,000 to 5,000 ppm free chlorine forapproximately 2 minutes, followed by irrigation withsaline (this can be done by squeezing the fluid from intravenousbags into the wound). This technique shouldnot be used in the abdominal or thoracic cavities, or incasualties with intracranial head injuries.Lung-Damaging AgentsA conventional wound in a casualty exposed to alung-damaging agent is compounded by developmentof pulmonary edema. The latent period betweenexposure and the onset of pulmonary edema may beshort. The resultant pulmonary edema may be servere.Casualties exposed to lung-damaging agents shouldbe kept at rest. When indicated, steroid treatmentshould be started early. The use of opiates and othersystemic analgesics to treat pain or shock from theconventional injury is not contraindicated. Oxygentherapy is required; however, fluid replacement shouldbe used with caution to avoid precipitating or increasingpulmonary edema.CyanideContamination of conventional injuries with cyanidecan result in respiratory depression and reduction ofoxygen-carrying capacity of the blood. Urgent use ofcyanide poisoning antidote is required (see Chapter11, Cyanide Poisoning). Oxygen therapy combinedwith positive pressure resuscitation may be requiredsooner in the presence of marked hemorrhage from theconventional injury. Opiates and other drugs that reducerespiratory drive must be used with extreme caution.Incapacitating AgentsA casualty presenting with a major wound andintoxication by an incapacitating compound mightbe delirious and unmanageable. If the compound isa cholinergic-blocking agent such as BZ, the administrationof physostigmine may temporarily calm thepatient (the effects diminish in 45–60 min) so that carecan be given. However, physostigmine may have a limitedeffect on muscle relaxants used during anesthesia.At various stages the incapacitating compounds causetachycardia, suggesting that heart rate may not be areliable indication of cardiovascular status. Otherwise,review of these compounds indicates that they do notinterfere with wound healing or further care. 7523