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

Medical Management of Chemical Toxicity in Pediatricsbronchodilate and reduce the need for nondepolarizingdrugs, which are often reversed by the use of neostigmine.Halothane should be avoided in infants becausethe cardiac side effects can be accentuated in the presenceof nerve agents. Depression of the cardiovascularsystem by halothane may cause further bradycardia,hypotension, and reduction in cardiac output. In general,the use of muscle relaxants is not recommended inpatients exposed to nerve agents. Nerve agents providea depolarizing block, and in the presence of inhibitedAChE activity, drugs such as succinylcholine can havelonger effects than expected. 75Analgesia must be used carefully when caring forvictims of nerve agent exposure. 74 In general, opioidsare considered safe to use because they do not act onthe cholinergic system directly. However, some sideeffects of the drugs, such as histamine release and raremuscle rigidity, can cause difficulty in patient management,making careful dose titration and side-effectmonitoring critical. The potent opiod remifentanyl containsan ester linkage susceptible to hydrolysis becauseit is partially metabolized by plasma cholinesterase.This is the same enzyme that is inactivated by nerveagents, resulting in a prolonged duration of actionfor remifentanyl. Therefore, using remifentanyl in thepostoperative care of nerve-agent–exposed victims isnot recommended. 75VesicantsVesicants, or blister agents, are chemicals thatcause blister or vesicle formation upon dermal contact(Exhibits 21-3 and 21-4). Agents such as mustards orlewisite have been used in chemical warfare in thepast, 76 and although vesicants are less toxic than nerveagents, they cause prolonged morbidity. There aretwo types of mustard: sulfur mustard (also known as“HD”) and nitrogen mustard (also known as “HN”).Sulfur mustard caused more casualties in World WarI than any other chemical weapon. It also caused asignificant number of casualties, both civilian andmilitary, during the Iran-Iraq War in the 1980s. Sulfurmustard vapor is the vesicant most likely to be usedby terror groups. 76 It affects multiple organ systemsincluding skin, eyes, respiratory and gastrointestinaltracts, and bone marrow. 76 Nitrogen mustards, on theother hand, have never been used on the battlefield,probably because they are harder to make than sulfurmustards; thus, their potential use in a terrorist attackis unlikely.Lewisite, a vesicant with sulfur-mustard–like properties,causes similar signs and symptoms involvingthe skin, eyes, and airways, as well as systemic effects(eg, increased capillary permeability) after absorption.However, lewisite does not suppress the immunesystem like mustard. Lewisite exposure can betreated with an antidote, British Anti-Lewisite. Themechanism of action, clinical effects, and treatment oflewisite injury are not discussed further in this chapterbecause they are reviewed elsewhere in this textbook(see Chapter 8: Vesicants).Mechanism of ToxicitySulfur mustard rapidly penetrates cells and generatesa highly toxic reaction that disrupts cell functionand eventually causes cell death. 77 It is classified asan alkylating agent and targets poorly differentiatedand rapidly reproducing cells. 76 Death results frommassive pulmonary damage complicated by infection(see Chapter 8: Vesicants).Clinical PresentationMustard can cause local effects on skin, airways,and eyes; however, large doses can cause fatal systemiceffects. 76 In a study of clinical findings among childrenexposed to vesicants, the most prevalent signs of toxicitywere ocular, cutaneous, and respiratory (Table21-5). 78 Erythema occurs 4 to 8 hours after exposure,and pruritus can occur with or prior to erythema. 76,78Over the 24 hours following exposure, large yellowishblisters form in areas of thin skin, such as the groinand underarms. 76 Eye damage can occur, ranging inspectrum from pain and irritation to blindness. 76,77Mustard also causes clinical effects that can be delayedExhibit 21-3Case History: Mustard Gas Exposurein 14 children and teenagersfrom Halabja, IraqMustard gas was used on the civilian populationduring the Iraq-Iran War (1980–1988). A case seriesof 14 children and teenagers affected by mustard gaswas reported by Momeni et al. They found that facialinvolvement was the most frequent disorder (78%),followed by genital (42%), trunkal and axillar lesions(both 14%). The most prominent laboratory abnormalitywas eosinophilia (12% of patients). Skin lesionsappeared 4–18 hours after exposure and erythemadeveloped within 20–30 hours. Blisters appeared afterthe erythema. The authors concluded that the time oftoxicity onset was shorter and more severe in childrenand teenagers than in adults.Data source: Momeni A, Aminjavaheri M. Skin manifestationsof mustard gas in a group of 14 children and teenagers: aclinical study. Inter J Dermatol. 1994:33(3):184–187.667