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

Nerve Agentsimpairment such as wheezes and rales), marked secretionsfrom the mouth and nose, nausea and vomiting(or retching), and muscular fasciculations and twitches.Miosis may be present if exposure was by vapor, butit is a relatively insignificant sign as a guideline fortherapy in this context.The contents of three Mark I kits or ATNAAs shouldbe administered immediately. Preferably, if the meansare available, 2 or 4 mg of atropine should be givenintravenously, and the remainder of the total amount of6 mg of atropine, along with the three oxime injections,should be given intramuscularly. Diazepam shouldalways be given when the contents of three Mark I kitsor ATNAAs are administered together. The casualtyshould be thoroughly decontaminated and have blooddrawn for AChE assay before oxime is given.Again, knowledge of the route of exposure is usefulin planning further treatment. If the exposure wasby vapor only and the casualty is seen in a vaporfreeenvironment some minutes later, drug therapyshould result in improvement. If the casualty has notlost consciousness, has not convulsed, and has notbecome apneic, improvement should be expected. Ifthe exposure was the result of liquid agent or a combinationof liquid and vapor, there may be a reservoirof unabsorbed agent in the skin; despite the initialtherapy, the casualty ’ s condition may worsen. In eithercase, medical care providers should be preparedto provide ventilatory assistance, including adequatesuction, and additional drug therapy (atropine alone)if there is no improvement within 5 minutes after IVadministration of atropine, or 5 to 10 minutes after IMadministration of atropine.The triad of consciousness, lack of convulsive activity,and spontaneous respiration is an indicator ofa good outcome, provided adequate therapy is givenearly.Severe ExposureCasualties who are severely exposed to a nerveagent will be unconscious. They may be apneic orgasping for air with marked cyanosis, and may beconvulsing or postictal. These casualties will havecopious secretions from the mouth and nose and willhave generalized fasciculations in addition to convulsiveor large-muscle twitching movements. If they arepostictal, or in nonconvulsive status epilepticus, theymay be flaccid and apneic.If the casualty shows no movement, including nosigns of respiration, the initial response should be todetermine if the heart is beating. This is not an easytask when the rescuer and the casualty are both infull mission-oriented, protective posture, level 4 gear,but it must be accomplished because a nonmoving,nonbreathing casualty without a heartbeat is not acandidate for further attention on the battlefield. Acarotid pulse may be the easiest for the examiner to feelin mission-oriented, protective posture, level 4 gear.In a medical treatment facility, the medical personnelmay be slightly more optimistic and proceed with aggressivetherapy. After the Aum Shinrikyo sarin releasein the Tokyo, Japan, subways, several casualties whowere not breathing and who had no cardiac activitywere taken to a hospital emergency department. Becauseof very vigorous and aggressive medical management,one or two of these casualties were able towalk out of the hospital several days later.Despite the circumstances, self-protection from contaminationvia the patient is important. Since decontaminationof the patient may not be the first priority,caregivers must wear appropriate protective equipmentuntil they have an opportunity to decontaminatecasualties and to remove them and themselves fromthe contaminated area.The success of therapy under these circumstances isdirectly proportional to the viability of the casualty ’ scardiovascular system. If the heart rate is very slowor nonexistent, or if there is severe hypotension, thechances for success are poor, even in the best possiblecircumstances.Medical personnel must first provide oxygenationand administer atropine by a technique that ensuresit will be carried to the heart and lungs. If ventilatoryassistance is not immediately available, the best treatmentis to administer the contents of three Mark I kitsor ATNAAs and diazepam. If ventilatory assistancewill be forthcoming within minutes, the contents of thethree Mark I kits or ATNAAs should be administeredwhether the circulation is intact or not. When thereis no chance of rapid ventilatory assistance, little isgained by Mark I/ATNAA therapy, but an attempt attreatment should be made anyway.In the case of a failed or failing cardiovascularsystem, routes of atropine administration other thanIM should be considered. The IV route generallyprovides the fastest delivery of the drug throughoutthe body, but it is not without danger in an apneicand cyanotic patient. Whether or not concomitantventilatory support can be provided, military medicalpersonnel may consider administering atropineintratracheally by needle and syringe, if available,or with the atropine autoinjector (the AtroPen). Evenif the casualty ’ s systemic blood pressure is low, theperibronchial circulation may still have adequateblood flow to carry the drug to vital areas. If an endotrachealtube can be inserted, atropine could beinjected into the tube either by needle and syringe or193