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

Medical Management of Chemical Toxicity in Pediatricsmortality among children. 6In the 1990s the Japanese Aum Shinrikyo cult manufacturedand used nerve agents to target civilians ofMatsumoto and Tokyo (see Chapter 4). 24,26–28,32,34 In 1995the Aum deployed the nerve agent sarin in a Tokyosubway attack, and approximately 5,000 people, rangingfrom 3 to 86 years old, sought medical attention. 32Around the same time, the Federal Bureau of Investigationuncovered a terrorist plot to release a chlorinegas bomb at Disneyland. 32 These events confirm thatchemical weapons pose a threat to the US pediatricpopulation.GENERAL PRINCIPLES OF CHEMICAL EXPOSUREChemical weapons include nerve agents, vesicatingor blistering agents, choking or pulmonaryirritants, cyanides, vomiting agents, incapacitatingagents, and riot control agents. 35 The most importantagents used for terrorism are nerve agents (tabun,sarin, soman, VX), vesicants (mustards, lewisite),pulmonary agents (phosgene, chlorine), and cyanide.Injury from each agent is related to its chemical properties(eg, volatility, persistence), route of entry, anddose. 36 Volatility, or an agent’s tendency to vaporize, isaffected by temperature, wind, and delivery method.Persistence, or the tendency of a liquid agent to remainin the environment, is affected by temperatureand surface texture. The major routes of agent entryare inhalation, cutaneous absorption, ingestion, andinjection. Exposure through inhalation, which oftenoccurs with toxic agents like sarin and chlorine, mayresult in asphyxia, lung damage, and upper airwayobstruction. Their higher metabolic and respiratoryrates put children at increased risk for toxicity afterchemical agent exposure, and their diminutive statureexposes children to toxic agents that concentratecloser to the ground.The extent of an agent’s toxicity is determined by theconcentration of the agent in the air and the amount oftime a person is exposed. Low doses of agent can causesymptoms such as airway irritation, bronchospasm,and increased secretions, exacerbating underlyinglung diseases. High doses can result in airway edema,obstruction, and copious secretions. Direct alveolardamage from pulmonary toxicants, such as chlorineor phosgene, can result in pulmonary edema. Whenmanaging affected patients, it is necessary to anticipatethe need for emergency intubation; children’s smallerairway calibers put them at greater risk for airwayobstruction and lead to more rapid progression of narrowingand impending airway obstruction.Cutaneous exposure affects the eyes and skin, andcorrosive chemicals can cause ischemic necrosis thatresults in small vessel thrombosis, especially in theeyes. Acidic or alkali chemical burns can result incoagulation necrosis or liquefaction. Skin absorptioncan lead to systemic toxicity, and when skin is damaged,transepidermal water loss is inevitable. This isespecially concerning because hypovolemic shockcan occur when water loss is excessive. Extensive skinloss, prolonged exposure, and the temperature of thewater used for decontamination can rapidly lead tohypothermia in children, whose surface-to-volumeratio is greater than that of adults.Negative pressure, full-face gas mask use by untrainedcivilians is not a recommended method of preventingchemical toxicity. 37 Gas masks and respiratorsincrease the work of breathing and physiologic deadspace, factors that tend to reduce alveolar ventilation.Also, respirators require a proper fit and filter canistermaintenance to adequately protect users, and canisterintegrity can be altered by handling, water damage,and excessive breathing pressure. In Israel, improperuse of gas masks led to 13 suffocation deaths in adultswhen the filter caps were not removed, and 114 adultdeaths from cardiorespiratory arrest when the maskswere used in sealed rooms. 37In general, managing children exposed to chemicalagents may be challenging. For example, it may be difficultto obtain vascular access in children because theyhave smaller caliber blood vessels than adults. Urinarycatherization may also be challenging. Healthcarepractitioners should be aware of and appropriatelyprepare for these issues by maintaining trained staffand a supply inventory that includes a range of equipmentsizes; because there is no single pediatric size, arange of appropriate pediatric-sized equipment mustbe available.CHALLENGES TO MANAGING PEDIATRIC CHEMICAL CASUALTIESManaging pediatric victims of chemical terrorismis especially difficult. In addition to the obvious physiologicaland anatomical differences between childrenand adults (Table 21-1), there are important psychologicaland behavioral differences that put children at risk. 33Anecdotal reports have claimed that children are likelyto be the first to manifest symptoms, to develop moresevere manifestations, and to be hospitalized for otherrelated illnesses after chemical agent exposure. Children’ssmaller mass reduces the dose of toxic agent needed657