Agent 15 Poisoning Clinical Presentation
- Author: Geoffrey M Fitzgerald, MD; Chief Editor: Duane C Caneva, MD, MSc more...
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- The patient may complain of dry mouth, a hot feeling, or blurred vision.
- Changes in mental status produced by incapacitating agents may leave some patients delirious to the point that they fail to or are unable to report symptoms.
Remarkably little variation exists among individuals when anticholinergics are administered.
- Following exposure, typically a latent period of 30 minutes to 24 hours occurs before signs and symptoms appear.
- Anticholinergic toxicity caused by BZ or Agent 15 can last up to 3-4 days, depending on the amount of drug absorbed.
- Peripheral effects usually precede CNS effects and can be summarized by the mnemonic "dry as a bone, hot as Hades, red as a beet, and blind as a bat."
- "Dry as a bone" results from decreased glandular secretions in the oral pharynx, GI tract, and eccrine and apocrine glands. Urinary retention also is common.
- "Hot as Hades" refers to hyperthermia caused by decreased sweating.
- The body attempts to maintain thermoregulation via compensatory cutaneous vasodilatation, hence "red as a beet."
- Decreased cholinergic stimulation of the pupillary sphincter muscle causes mydriasis. Anticholinergic effects on the ciliary muscles inhibit accommodation, hence "blind as a bat."
- Anticholinergic effects on the heart produce tachycardia. This occasionally is preceded by a bradycardia that results from anticholinergic effects in the brain stem.
- The CNS effects of BZ and Agent 15 make them effective incapacitants.
- Patients receiving these agents react with mental status changes ("mad as a hatter") in a dose-dependent fashion.
- After a latent period and following the appearance of the peripheral effects, the casualty's mental status begins to fluctuate between a relatively conscious state and frank delirium.
- Level of consciousness can range from drowsiness to coma.
- Disorientation to time and place, decreased social restraint with inappropriate behavior, and decreased short-term memory are common.
- Speech becomes slurred and indistinct.
- Poor coordination leads to ataxia and agraphia.
- Anticholinergic toxicity can produce vivid and realistic hallucinations that tend to decrease in size over time. For example, a polar bear may be replaced by a smaller animal such as a rabbit as the toxidrome clears.
- When multiple victims of anticholinergic toxicity interact, they may play off each other's delirium. An example is 2 victims playing tennis with imaginary racquets. Another term for this shared hallucination is "folie a deux."
- Phantom behaviors such as plucking or picking at one's clothes (ie, wool gathering) often were observed in Army test subjects who received BZ.
- As the BZ victim's delirium clears, paranoid tendencies are not uncommon.
- Of final note on the examination is an increase in deep tendon reflexes. Anticholinergic effects on the Renshaw interneurons in the spinal cord cause hyperreflexia.
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- Consider any cause of delirium. Psychiatric disorders such as anxiety reaction also are in the differential diagnosis.
- The presence of peripheral anticholinergic signs suggests another source of anticholinergic such as scopolamine, atropine, jimsonweed, or other anticholinergic source exposure.
- Usually, 6-7 MARK-1 Autoinjectors (ie, 12-14 mg of IM atropine) are needed to cause a significant degree of confusion.
- Nerve agent poisoning can be differentiated by its hyperstimulation of glands.
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