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

Medical Aspects of Chemical Warfarelarger areas or evidence suggesting more than minimalpulmonary involvement would place this casualty inanother triage group.Peripherally Acting Lung-Damaging AgentsA casualty exposed to phosgene or other peripherallyacting lung-damaging agents rarely belongs in theminimal group. If development of pulmonary edemais suspected, the casualty is placed in a different triagegroup. On the other hand, if a casualty gives a reliablehistory of exposure several days before, reports milddyspnea in the intervening time, and is now improving,the triage officer should consider holding the casualtyfor 24 hours for reevaluation and determinationof return-to-duty status.CyanideA casualty who has been exposed to cyanide but hasnot required therapy will recover quickly.Incapacitating AgentsCasualties exposed to an incapacitating agentshould be evaluated in a similar manner as those exposedto peripherally acting lung-damaging agents.If the casualty’s condition is worsening, evacuationis necessary. On the other hand, if there is a reliablehistory of exposure with an intervening period ofmild symptoms and evidence of recovery, the casualtymay be observed for 24 hours on-site and returned toduty.ExpectantNerve AgentsAny nerve agent casualty who is pulseless or apneic(duration unknown) should be categorized asexpectant. (However, as noted above, some of thesecasualties may survive if prolonged, aggressive careis possible.)VesicantsA vesicant casualty who has burns covering morethan 50% of body surface area from liquid exposure,or who has signs of more than minimal pulmonaryinvolvement, can survive only with extensive medicalcare. This care may be available at rear levelsof medical care, but advanced treatment shouldbe initiated for those with the greatest chance ofsurvival. 7Peripherally Acting Lung-Damaging AgentsA casualty with moderate or severe dyspnea andsigns of advanced pulmonary edema from exposureto phosgene or other peripherally acting lung-damagingagents requires a major expenditure of rear-areamedical assets. 7CyanideA cyanide casualty who is pulseless belongs in theexpectant group.CasuAlties with Combined InjuriesCombined injury casualties have wounds causedby conventional weapons and have been exposedto a chemical agent. The conventional wounds mayor may not be contaminated with chemical agent.Limited experimental data on this topic exists, andlittle has been written about the treatment for combinedinjury chemical casualties in World War I orthe Iran–Iraq War. Uncontaminated wounds shouldbe dressed and treated in the usual way. The woundshould be covered with agent-proof (nonporous)material (for additional information, see Chapter16, Decontamination of Chemical Casualties), and ifa pressure bandage is needed, it should be appliedafter the protective covering. These safety measuresmay prevent the patient from becoming a combinedchemical and conventional casualty. This section willconsider the effects of chemical agent poisoning onconventional wounds, the results of treatment forsuch poisoning, and possible drug interactions ofthe treatments.Nonpersistent Nerve AgentsNerve agents interact with anesthetic drugs, causingincreased respiratory depression and reduced cholinesteraseactivity, which affects metabolism. Bloodloss complicates respiratory failure, so casualties mayrequire supplemental oxygen or resuscitation withpositive pressure ventilation. Need for replacement ofblood lost through conventional injury is increased inthe presence of respiratory depression. The action ofanticholinesterase (including pyridostigmine pretreatment,to a lesser extent) may potentiate or prolong theaction of depolarizing relaxants (eg, succinylcholine).522