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

Vesicants• the inflammatory reaction from lewisite generallyoccurs much faster;• the lesions from lewisite heal much faster;• secondary infection is less common after lewisiteexposure; and• subsequent hyperpigmentation or hypopigmentationis likewise less common. 59Goldman and Dacre provide a further review of lewisiteand its toxicology. 256EyeA person is less likely to receive severe eye injuryfrom lewisite vapor than from mustard vapor becausethe immediate irritation and pain caused by lewisitewill produce blepharospasm, effectively preventingfurther exposure. A small droplet of lewisite (0.001 mL)can cause perforation and loss of an eye. 257In tests performed on rabbits, lewisite caused almostimmediate edema of the lids, conjunctiva, and cornea,as well as early and severe involvement of the iris andciliary body, followed by gradual depigmentation andshrinkage of the iris stroma. 257 Miosis appeared early. Inthis same study, miosis was not noted after mustard exposure.No long-term effects of lewisite were noted, suchas the delayed keratitis seen after mustard exposure.AirwaysLewisite vapor is extremely irritating to the nose andlower airways, causing exposed individuals to seek immediateprotection, thus limiting further exposure. Theairway lesion of lewisite is very similar to the lesioncaused by mustard exposure except that lewisite vaporis extremely irritating to the mucous membranes. Thisresults in sneezing, coughing, choking, and eventualnecrosis of the epithelial surface. In large amounts,lewisite causes pulmonary edema.After exposure to lewisite, dogs exhibited massivenasal secretions, lacrimation, retching, vomiting, andlabored respiration. These symptoms worsened untildeath occurred. On autopsy, the lungs were edematous,and a pseudomembrane often extended from thenostrils to the bronchi. Tracheal and bronchial mucosawas destroyed, and the submucosa was congested andedematous. Bronchopneumonia was commonly mixedwith edema. 61Other Effects“Lewisite shock” is seen after exposure to largeamounts of lewisite. This condition is the result ofprotein and plasma leakage from the capillaries andsubsequent hemoconcentration and hypotension.A small amount of lewisite on the skin causes localedema because of its effects on local capillaries. Witha large amount of lewisite, the pulmonary capillariesare also affected; there is edema at the site ofexposure and pulmonary edema. With even largeramounts of lewisite, all capillaries are affected, andproteins and plasma leak from the circulation intothe periphery. Even after small amounts of lewisite,the fluid loss can be sufficient to cause diminutionof renal function and hypotension. 256 Arsines areknown to cause hemolytic anemia, but there is littlemention of this in reports on lewisite exposure. A“true or hemolytic anemia” has been noted withlewisite shock. 256DiagnosisLewisite exposure can be distinguished from mustardexposure by the history of pain on contact withthe agent. Phosgene oxime also causes pain on contact,but phosgene oxime does not produce a liquid-filledblister. If a single individual has an isolated blister,other plant or animal causes of vesication should besought. See also Chapter 22, Medical Diagnostics.Laboratory TestsNo specific laboratory test exists for lewisite. Urinaryarsenic excretion might be helpful. Hemolyticanemia may be seen in lewisite-exposed patients.Patient ManagementMedical personnel should follow the same principlesfor managing lewisite skin, eye, and airwaylesions that they follow for managing mustard lesions.BAL prevents or greatly decreases the severity of skinand eye lesions if applied topically within minutesafter the exposure and decontamination (however,preparations of BAL for use in the eyes and on theskin are no longer available). Given intramuscularly,BAL reduces the severity of systemic effects. BALbinds to the arsenic of lewisite more strongly than dotissue enzymes, thereby displacing lewisite from thecellular receptor sites. 250,256 BAL reduced mortality indogs when it was given within 100 minutes after theyhad inhaled a lethal amount of lewisite. 258 Burns ofthe eyes from lewisite can be prevented if BAL is appliedwithin 2 to 5 minutes of exposure; when it wasapplied within an hour after exposure, BAL preventedvesication in humans. 256,259 BAL has some unpleasantside effects, including hypertension and tachycardia;the user should read the package insert.293