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

Nerve AgentsExhibit 5-1 continuedistered on randomly assigned days. The patient did better mentally (by examination) and on a written arithmetic test after receivingscopolamine than after methscopolamine.]There was no detectable RBC-ChE until about the tenth day after exposure. . . . Apparently neither the RBC nor plasma ChE wassignificantly reactivated by the initial oxime therapy, which reflects the rapid irreversible phosphorylation and hence refractorinessof the soman-inhibited enzyme to reactivation by oxime.Hematocrit, hemoglobin, white blood cell count, prothrombin time, blood urea nitrogen, bilirubin, creatinine, calcium, phosphorus,serum glutamic oxaloacetic transaminase, alkaline phosphatase, sodium, potassium, chloride, and carbon dioxide were all withinnormal limits the day of admission and on repeated measurements during his hospitalization.About five weeks after his admission, the subject again received scopolamine (5 mg/kg, i.m.) and had a decrement in mental functioning,including a 25-30% reduction in NF [Number Facility] scores, which are the findings in normal subjects. This contrasts with theparadoxical improvement in mental status seen earlier.About a week later, the psychiatrist noted that “he is probably close to his premorbid level intellectually and there is no evidence ofany serious mood or thinking disorder.”A battery of standard psychological tests was given the subject 16 days, 4 months, and 6 months after the accident. He scored wellon the Wechsler-Bellevue IQ test with a slight increase in score on the arithmetic section at the later testings. He had high Hs (hypochondriasis)and Hy (hysteria) scales on the Minnesota Multiphasic Personality Inventory (MMPI) on the early test and their laterimprovement indicated to the examiner that he had a decreased concern about bodily function. He did poorly on a visual retentiontask (the object of which was to remember and then reproduce a simple drawing) on first testing as he attempted to improve alreadycorrect drawings, made several major errors, and showed poor motor control; his later tests were normal. On word association, proverbs,and the ink blot he was slow and sometimes used delaying tactics, had difficulty generating verbal associations, and failed theharder proverbs, responses that in the examiner’s opinion were not consistent with his IQ. The results of his later tests were faster,imaginative, and indicated full use of his intellectual facilities.When last seen, six months after his exposure, the patient was doing well.Reproduced with permission from Sidell FR. Soman and sarin: clinical manifestations and treatment of accidental poisoning byorganophosphates. Clin Toxicol. 1974;7:1–17.cupational health physician for review to determineif the depression in RBC-ChE activity is related toexposure to ChE-inhibiting substances. If RBC-ChEis depressed to 75% or below baseline, the worker isconsidered to have had an exposure and is withdrawnfrom work. Investigations are undertaken to discoverhow the worker was exposed. Although workers maybe asymptomatic, they are not permitted to return toa work area around nerve agents until their RBC-ChEactivity is higher than 90% of their baseline activity. 21 Ifworkers have symptoms from a possible nerve agentexposure or if an accident is known to have occurredin their work area, RBC-ChE activity is immediatelymeasured and the criteria noted above, as well assigns and symptoms, are used for exclusion fromand return to work. The values of 75% and 90% wereselected for several reasons, including the following:(a) the normal variation of RBC-ChE in an individualwith time; (b) laboratory reproducibility in analysisof RBC-ChE activity; and (c)the lower tolerance tonerve agents with a low RBC-ChE as demonstratedin animals (see below).In training responders to deal with acute nerveagent poisoning, little emphasis should be given tothe use of laboratory diagnosis of ChE activity. Timedoes not permit using this determination to guideimmediate treatment. On the other hand, laboratoryvalues in patients are particularly helpful in twospecific instances: (1) as a screen for exposure to aChE inhibitor, as in agricultural workers or militarypersonnel who may have been exposed to a nerveagent, and (2) as a way to follow exposed patients asthey recover over time.ButyrylcholinesteraseThe enzyme BuChE is present in blood andthroughout tissue. Its physiological role in humansis unclear 22 ; however, it may be important in caninetracheal smooth muscle, 23 the canine ventricular conductingsystem, 24 and rat atria. 25BuChE is synthesized in the liver and has a replace-163