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

Medical Aspects of Chemical WarfareTable 21-1Pediatric Vulnerabilities and Implications for Clinical ManagementUnique Vulnerability in ChildrenImplications and Impact From Chemical ToxicityBody composition • Larger BSA compared to body mass • Greater dermal absorption• Lower total lipid/fat content• Less partitioning of lipid-soluble componentsVolume status • More prone to dehydration • Can be more symptomatic and show signs of• Chemical agents lead to diarrhea and severe dehydrationvomitingRespiratory • Increased basal metabolic rate compared • Enhanced toxicity via inhalational routeto greater minute volumeBlood• Limited serum protein binding capacity • Potential for greater amount of free toxicant and• Greater cutaneous blood flowgreater distribution• Greater percutaneous absorptionSkin • Thinner epidermis in preterm infants • Increased toxicity from percutaneous absorption• Greater cutaneous blood flowof chemical agentsOrgan size and enzymatic • Larger brain mass• Greater CNS exposurefunction • Immature renal function • Slower elimination of renally cleared toxins,• Immature hepatic enzymeschemicals, and metabolites• Decreased metabolic clearance by hepatic phasei and II reactionsAnatomical • Short stature means breathing occurs • Exposure to chemicals can have significantconsiderations closer to ground where aerosolized impact on bone marrow and developing CNSchemical agents settle• Increased airway narrowing from chemical-• Smaller airwayagent–induced secretions• Greater deposition of fine particles in the • Mustard significantly affects rapidly growingupper airwaytissues• Higher proportion of rapidly growingtissuesCentral nervous system • Higher BBB permeability • Increased risk of CNS damage• Rapidly growing CNSMiscellaneous • Immature cognitive function • Inability to discern threat, follow directions, and• Unable to flee emergencyprotect self• Immature coping mechanisms• High risk for developing PTSDBBB: blood-brain barrierBSA: body surface areaCNS: central nervous systemPTSD: posttraumatic stress disorderto cause observable or lethal effects. Studies involvingorganophosphates (OPs), compounds related to nerveagents, have shown greater vulnerability in immatureanimals than in adults. Some OPs produce the same degreeof lethality in juveniles at a fraction of the dose thatproduces lethality in adults. 33 The increased toxicity seenin children compared to adults from various routes ofexposure can be attributed to a wide variety of factors:• differences in anatomy,• allometric scaling factors (eg, increased surfacearea-to-volume ratio),• cardiovascular status,• permeability of the pediatric blood-brain barrier,• dermatologic factors (eg, increased cutaneousblood flow),• increased skin pH,• plasma protein binding,• volume of distribution,• organ size and maturity, and• pharmacokinetic maturity (eg, metabolicdifferences). 38–42These unique anatomical and physiological featurescause pediatric rates of absorption, distribution, metabolism,and excretion to differ from those of adults.658