CBRNE - Nerve Agents, V-series - Ve, Vg, Vm, Vx Workup

Updated: Feb 06, 2015
  • Author: Daniel C Keyes, MD, MPH; Chief Editor: Duane C Caneva, MD, MSc  more...
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Workup

Laboratory Studies

Exposure to VX in both the vapor and liquid forms has been studied since the 1950s. Laboratory tests do not aid in the acute treatment of patients exposed to nerve agents; however, measurement of acetylcholinesterase (AChE) levels for documentation and ongoing treatment is nevertheless prudent. Since there is a wide variability in baseline levels, AChE testing is most useful in treating chronic exposures when the clinician is able to compare values to an individual's baseline. Never withhold treatment while waiting for laboratory results.

AChE can be measured in red blood cells or plasma. The red blood cell cholinesterase (RBC-AChE) level is believed to be the most reliable indicator of the tissue cholinesterase status. Plasma cholinesterase (butyrylcholinesterase) levels also are referred to as pseudocholinesterase levels, because they are less predictive of central nervous system (CNS) cholinesterase activity. This often is the earliest enzyme to be inhibited by organophosphates, but that is not true for some nerve agents, particularly VX and GB.

Order basic laboratory tests for all but minimally symptomatic patients. Measurement of electrolytes and arterial blood gases may aid in the evaluation of the patient's fluid status and the acid/base balance.

A number of new tests for the detection and quantification of chemical warfare agents are being developed. These include an active capillary dielectric barrier discharge plasma ionization (DBDI) technique for mass spectrometry, which may be useful in combination with hand-held instruments for on-site monitoring [6] and a highly accurate method for detecting G- and V-series organophosphorus nerve agent adducts to butyrylcholinesterase in filtered blood, serum, or plasma. [7]

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Other Tests

Electrocardiography - For palpitations or for any dysrhythmias noted on monitor

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Procedures

Because a significant cause of morbidity and mortality of these patients relates to the airway and breathing, ensure that ventilation (which can be impaired from the respiratory muscle fatigue) and oxygenation (which can be impaired from the bronchorrhea and bronchoconstriction) are adequate. Endotracheal intubation may be needed for those with ventilatory and/or respiratory compromise.

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Radiography

Typically, request a chest radiograph for dyspneic and intubated patients. A chest radiograph may also help in the diagnosis of noncardiogenic pulmonary edema.

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