Nerve agents moderately severe exposure

Pralidoxime (2-PAM) Pralidoxime is a commonly used oxime and is rccom-mended for all cases of moderate-to-severe nerve agent poisoning. The optimal dosage is dependent on the nerve agent, time since exposure and the cholinesterase activity of the victim, i here has been considerable experience with pralidoxime and other oximes over many years in the treatment of OP pesticide poisoning. 

Meat from animals that have suffered only mild to moderate effects from exposure to nerve agents should be safe to consume. Milk should be discarded for the first 7 days postexposure and then should be safe to consume. Meat, milk, and animal products, including hides, from animals severely affected or killed by nerve agents should be destroyed. 

Exposure to nerve agents occurs from either vapor or liquid forms. A patient s vapor or liquid exposure can be classified as mild, moderate, and severe based on clinical criteria. 

Determining whether exposure to nerve agents or other OPs has occurred is particularly difficult if acute signs and symptoms are absent. In situations such as the terrorist use of sarin in Japan, the priorities following the event will, wholly appropriately, be primarily concerned with saving life. Subsequent medical monitoring will undoubtedly be focused on monitoring the condition of survivors who have exhibited moderate to severe acute effects. 

Miosis may also occur as a systemic feature, although more usually it follows direct exposure. This explains why, for example, modest dermal exposure may produce systemic features but not miosis. Abdominal pain, nausea and vomiting, involuntary micturition and defecation, muscle weakness and fasciculation, tremor, restlessness, ataxia and convulsions may follow dermal exposure, inhalation or ingestion of a nerve agent. Bradycardia, tachycardia and hypertension may occur, dependent on whether muscarinic or nicotinic effects predominate. If exposure is substantial, death may occur from respiratory failure within minutes, whereas mild or moderately exposed individuals usually recover completely, although EEG abnormalities have been reported in those severely exposed to sarin in Japan (Murata etal., 1997 Sekijima et al., 1997). 

Additionally, after both vapor and liquid agent exposure, there are CNS effects that vary in intensity and duration. After mild to moderate exposure to nerve agent, there may be forgetfulness, an inability to concentrate, insomnia, impaired judgment, nightmares, irritability, and depression. These effects may be present for 4 to 6 weeks. They may also occur upon recovery from acute, severe effects of exposure. Longterm and low-dose effects of the nerve agents are the topic of Chapter 1 of this text. 

This section discusses the general principles of treating nerve agent poisoning. The specific treatment of casualties in the six exposure categories (suspected, minimal, mild, moderate, moderately severe, and severe) is addressed in the next section. Terminating the Exposure... 

A casualty who has had moderate exposure to either a nerve agent vapor alone or to vapor and liquid will have severe dyspnea, with accompanying physical signs, and probably also miosis and rhinorrhea. The casualty should be thoroughly decontaminated (Remember exposure to vapor alone does not require decontamination) and blood should be drawn for assay of RBC-ChE activity if assay facilities are available. The contents of three MARK I kits and diazepam should be given if the casualty is seen within minutes of exposure. If seen later than 10 minutes after exposure, the casualty should receive the contents of two kits. Additional atropine should be given at 5- to 10-minute intervals until the dyspnea subsides. No more than three MARK I kits should be used however, additional atropine alone should be administered if the contents of three kits do not relieve the dyspnea after 10 to 15 minutes. If there is reason to suspect liquid contamination, the patient should be kept under observation for 18 hours. 

Much information on both the short-term and the long-term effects of mustard in man comes from its battlefield use in World War I and the Iran-Iraq War, and from experimental studies during the World War I and World War II periods.24 In contrast, no data from the battlefield use of nerve agents are available. Information on the effects of nerve agents in man comes from the accidental exposure of hundreds of people who were mildly or moderately exposed while working with nerve agents and from a handful of workers who had severe exposures. Investigational studies carried out in hundreds of people also provide information. 

Mild or moderately exposed people usually recover completely. Severely exposed people are not likely to survive. Unlike some organophosphate pesticides, nerve agents have not been associated with neurological problems lasting more than 1 to 2 weeks after the exposure. 

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