CBRNE - Nerve Agents, Binary - GB2, VX2 Workup

Updated: Dec 18, 2018
  • Author: Larissa I Velez-Daubon, MD; Chief Editor: Duane C Caneva, MD, MSc  more...
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Workup

Laboratory Studies

Many studies have related symptoms to laboratory parameters in cases of nerve agent exposures. A review of those studies is beyond the scope of this article but can be found in Chemical Warfare Agents: Toxicology and Treatment by Marrs, Maynard, and Sidell.

However, laboratory tests do not aid in the immediate treatment of patients exposed to nerve agents. Laboratory studies are most useful in observing long-term exposures over time when the individual's baseline measurement is known. Never withhold treatment while waiting for laboratory results. Nevertheless, laboratory analysis may be used to help document an exposure to a nerve agent, may help quantify the exposure, and may aid in the evaluation of the patient's recovery.

Red blood cell cholinesterase (RBC-ChE) levels: RBC-ChE is believed to be the most reliable indicator of the tissue cholinesterase status. However, baseline cholinesterase values vary significantly depending on age, ethnicity, nutritional status, and other individual factors. RBC-ChE levels are altered later in the course of the acute illness or with chronic exposures.

Plasma cholinesterase (butyrylcholinesterase [BuChE]) levels: This enzyme is also termed pseudocholinesterase. With organophosphate pesticide toxicity, this is the earliest enzyme to be inhibited and the earliest to be regenerated. However, sarin and VX preferentially bind RBC-ChE; thus, for these agents, the RBC cholinesterase is a more sensitive indicator of acute nerve agent exposure.

Blood concentrations of nerve agents are not available in clinical laboratories. The US Army Medical Research Institute of Chemical Defense can process blood samples and can be used as a reference laboratory.

Order basic laboratory studies in all but minimally symptomatic patients. Electrolytes and arterial blood gases aid in the evaluation of fluid status, oxygenation, and the acid/base balance. Observe the temperature in a serial fashion because patients can become hypothermic.

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Imaging Studies

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  • Request chest radiography for any severely dyspneic or intubated patient.

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Other Tests

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  • Additional tests do not provide information that aids in the treatment of patients with nerve agent poisoning. Presently, no information supports the use of tests to predict outcome.

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Procedures

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  • Endotracheal intubation and mechanical ventilation may be needed for patients with ventilatory and/or respiratory failure.

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