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

Vesicantsmainly by the time needed for healing of the deeperskin lesions. Despite medical advances since WorldWar I, there was a 14% mortality rate among this group;this higher rate is because some of the most severelyinjured Iranian patients were sent to Europe.SkinThe threshold amount of mustard vapor requiredto produce a skin lesion (erythema) is a Ct of about200 mg•min/m 3 . This amount varies greatly dependingon a number of factors, including temperature,humidity, skin hydration, and body site. Warm, moistareas with thin skin, such as the perineum, externalgenitalia, axillae, antecubital fossae, and neck aremuch more sensitive than other areas of the body. Aliquid droplet of about 10 µg will produce vesication.About 80% evaporates, and 10% enters the circulation,leaving about 10% on the skin surface to cause localtopical injury. As little as 1 µg can cause simple vesicleformation. Evaporation of small droplets is rapid andnearly complete in 2 to 3 minutes; amounts largerthan several hundred milligrams may take hours toevaporate. 65Mustard vapor rapidly penetrates the skin at therates of 1.4 µg/cm 2 /min at 70°F, and 2.7 µg/cm 2 /minat 88°F. 27 Liquid mustard penetrates the skin at 2.2 µg/cm 2 /min at 60°F and at 5.5 µg/cm 2 /min at 102°F. 65The mildest and earliest form of visible skin injuryis erythema, which resembles sunburn (Figure 8-2).Erythema begins to appear 1 to 24 hours after theFig. 8-2. Erythema of the chest of an Iranian casualty as itappeared 5 days after his exposure to mustard. He also hada pulmonary injury with an associated bronchopneumoniafrom infection with Haemophilus influenzae.Reproduced with permission from: Willems JL. Clinicalmanagement of mustard gas casualties. Ann Med Milit Belg.1989;3S:13.Fig. 8-3. The back of an Iranian casualty seen 16 hours afterexposure to mustard. Note the large bullae that have resultedfrom coalescence of small vesicles.Reproduced with permission from: Willems JL. Clinicalmanagement of mustard gas casualties. Ann Med Milit Belg.1989;3S:8.skin is exposed to mustard, although onset can belater. Erythema is usually accompanied by pruritus(itching), burning, or stinging. After a small exposure,this might be the extent of the lesion. More commonly,small vesicles will develop within or on the peripheryof the erythematous areas (like a string of pearls);these vesicles will later coalesce to form larger blisters(Figure 8-3). The effects from liquid mustard appearmore rapidly than the effects from mustard vapor.Characteristically, the onset of erythema is about 4to 8 hours after mustard exposure. Vesication beginsabout 2 to 18 hours later and may not be complete forseveral days.The typical bulla (large blister) is dome-shaped,thin-walled, superficial, translucent, yellowish, andsurrounded by erythema; it can be 5 cm in diameteror larger (Figure 8-4). The blister fluid is initially thinand clear or slightly straw-colored; later it turns yellowishand tends to coagulate. 17,65,66 The blister fluiddoes not contain mustard and is not itself a vesicant.Thiodiglycol, a breakdown product of mustard, hasbeen found in blister fluid and can be used to aid indiagnosis. Vapor injury is generally a first- or seconddegreeburn; liquid mustard may produce deeperdamage comparable to a third-degree burn.After exposure to extremely high doses, such asthose resulting from contact with liquid mustard, lesionsmay be characterized by a central zone of coagulationnecrosis, with blister formation at the periphery.These lesions are more severe, take longer to heal, andare more prone to secondary infection than lesionsresulting from smaller doses. 29267