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CBRNE - Nerve Agents, Binary: GB2, VX2: Differential Diagnoses & Workup

Author: Larissa I Velez-Daubon, MD, Associate Professor, Associate Program Director, Department of Surgery, Division of Emergency Medicine, University of Texas Southwestern Medical School, Parkland Memorial Hospital; Associate Program Director and Staff Toxicologist, Department of Surgery, Division of Emergency Medicine, North Texas Poison Center, Parkland Memorial Hospital
Coauthor(s): Fernando L Benitez, MD, Assistant Medical Director, Dallas Metropolitan BioTel (EMS) System; Associate Professor in Emergency Medicine, Department of Surgery, Division of Emergency Medicine, University of Texas Southwestern Medical Center and Parkland Health and Hospital; Daniel C Keyes, MD, MPH, Director of Terrorism Response Education, John Peter Smith Hospital; Clinical Associate Professor, Department of Surgery, Division of Emergency Medicine and Toxicology, University of Texas Southwestern School of Medicine
Contributor Information and Disclosures

Updated: Dec 19, 2007

Differential Diagnoses

CBRNE - Chemical Warfare Agents
CBRNE - Nerve Agents, G-series: Tabun, Sarin, Soman
CBRNE - Nerve Agents, V-series: Ve, Vg, Vm, Vx
Toxicity, Organophosphate and Carbamate

Other Problems to Be Considered

Diagnosis of toxicity due to a nerve agent is suggested when several persons present with the symptoms discussed above.

Differential diagnoses mainly include poisoning by organophosphate or carbamate insecticides. However, an exposure to hydrogen cyanide or hydrogen sulfide could also be confused with a severe nerve agent exposure, since exposure to all the agents can result in sudden cardiovascular collapse.

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.

Imaging Studies

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

Other Tests

  • 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.

Procedures

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

More on CBRNE - Nerve Agents, Binary: GB2, VX2

Overview: CBRNE - Nerve Agents, Binary: GB2, VX2
Differential Diagnoses & Workup: CBRNE - Nerve Agents, Binary: GB2, VX2
Treatment & Medication: CBRNE - Nerve Agents, Binary: GB2, VX2
Follow-up: CBRNE - Nerve Agents, Binary: GB2, VX2
Multimedia: CBRNE - Nerve Agents, Binary: GB2, VX2
References
Further Reading
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References

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Further Reading

For a discussion about Novichok agents, see Chemical Weapons Disarmament in Russia: Problems and Prospects.

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Keywords

nerve agents, binary agents, GB2, VX2, sarin, chemical warfare, acetylcholinesterase inhibitors, AChE inhibitors, GA, tabun, GD, soman, chemical weapons, GB, VX, GD2, acetylcholine, cholinergic overstimulation, organophosphate, carbamate, pralidoxime chloride, Protopam, 2-PAM, anticholinergics, oximes, AChE reactivator, muscarinic receptor

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Contributor Information and Disclosures

Author

Larissa I Velez-Daubon, MD, Associate Professor, Associate Program Director, Department of Surgery, Division of Emergency Medicine, University of Texas Southwestern Medical School, Parkland Memorial Hospital; Associate Program Director and Staff Toxicologist, Department of Surgery, Division of Emergency Medicine, North Texas Poison Center, Parkland Memorial Hospital
Larissa I Velez-Daubon, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Emergency Physicians, American College of Medical Toxicology, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Fernando L Benitez, MD, Assistant Medical Director, Dallas Metropolitan BioTel (EMS) System; Associate Professor in Emergency Medicine, Department of Surgery, Division of Emergency Medicine, University of Texas Southwestern Medical Center and Parkland Health and Hospital
Fernando L Benitez, MD is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, and National Association of EMS Physicians
Disclosure: Nothing to disclose.

Daniel C Keyes, MD, MPH, Director of Terrorism Response Education, John Peter Smith Hospital; Clinical Associate Professor, Department of Surgery, Division of Emergency Medicine and Toxicology, University of Texas Southwestern School of Medicine
Daniel C Keyes, MD, MPH is a member of the following medical societies: American College of Emergency Physicians, American College of Medical Toxicology, American College of Occupational and Environmental Medicine, and American College of Physicians-American Society of Internal Medicine
Disclosure: Nothing to disclose.

Medical Editor

Fred Henretig, MD, Medical Director, Delaware Valley Regional Poison Control Center, Departments of Emergency Medicine and Pediatrics, Director, Section of Clinical Toxicology, Professor, University of Pennsylvania School of Medicine, Children's Hospital
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Rick Kulkarni, MD, Medical Director, Assistant Professor of Surgery, Section of Emergency Medicine, Yale-New Haven Hospital
Rick Kulkarni, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: WebMD Salary Employment

CME Editor

John Halamka, MD, Chief Information Officer, CareGroup Healthcare System, Assistant Professor of Medicine, Department of Emergency Medicine, Beth Israel Deaconess Medical Center; Assistant Professor of Medicine, Harvard Medical School
John Halamka, MD is a member of the following medical societies: American Academy of Emergency Medicine and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Robert G Darling, MD, FACEP, Clinical Assistant Professor of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, F Edward Hebert School of Medicine; Director, Center for Disaster and Humanitarian Assistance Medicine
Robert G Darling, MD, FACEP is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, and Association of Military Surgeons of the US
Disclosure: Nothing to disclose.

 
 
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