Difference between revisions of "Chemical weapons"

(Nerve Agents)
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==Management==
 
==Management==
*Appropriate personal protective equipment (PPE)  
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*Depends on specific agent used
*Decontamination  
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*Regardless of agent, Decontamination and ABCs are of primary importance
**Prevents further damage from the exposure as well as protects others from contamination
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**Use appropriate personal protective equipment (PPE)
*ABCs
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**Decontamination (should take place pre-hospital or otherwise prior to entering the ED)
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***Remove all patient clothing
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***Brush off dry agent (e.g. powders), copiously irrigate skin of any liquid contaminant
  
 
==See Also==
 
==See Also==
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*[[Weapon of mass destruction]]
 
*[[Weapon of mass destruction]]
  
== References ==
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==References==
#’’Basic Disaster Life Support V.3.0 Course Manual.’’ N.p.: American Medical Association, 2012. Print.
+
<references/>
#’’Campbell, John E. Tactical Medicine Essentials.’’ Sudbury, MA: Jones & Bartlett Learning, 2012. Print
 
#Schultz, Carl, and Kristi Koenig. “Weapons of Mass Destruction.” ‘’Rosen's Emergency Medicine Concepts and Clinical Practice.’’ By John A. Marx, Robert S. Hockberger, Ron M. Walls, James Adams, and Peter Rosen. 8th ed. Philadelphia: Mosby/Elsevier, 2013. N. pag. Print.
 
#http://www.ncbi.nlm.nih.gov/pubmed/15094583
 
  
[[Category:Tox]][[Category:EMS]][[Category:Featured]]
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[[Category:Tox]]
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[[Category:EMS]]
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[[Category:Featured]]

Revision as of 06:45, 27 February 2016

Background

  • Can be released via unintended means such as a spill from a damaged railroad tank car or industrial explosion as well as by intentional means as chemical weapons.

Pediatric considerations

  • Higher metabolic rate and faster basal respiratory rate, causing more rapid and larger exposures
  • Skin is thinner and more permeable
  • Agents heavier than air have increased concentrations closer to the ground exposing children > adults

Types

Chemical weapons

Cyanide Agents (CN)

  • AKA Hydrocyanic acid, Formonitrile, Prussic acid
  • Mimics carbon monoxide poisoning
  • Smell of bitter almonds but not all people can smell cyanide
  • Absorbed through skin, inhaled or ingested
  • Can affect individuals near fire with synthetic materials or plastics
  • Can penetrate rubber and barrier fabrics

Pathophysiology

  • Cyanide inhibits cytochrome oxidase on mitochondria
  • Cells unable to use oxygen in bloodstream
  • Cellular asphyxiation

Symptoms

  • Symptoms can be delayed up to 60 minutes
  • Symptoms dependent on concentration, form of cyanide, and route of exposure
  • CNS and cardiovascular system most susceptible
  • Initially hypertension and tachycardia progressing to bradycardia, hypotension, and arrhythmias late
  • Anxiety, dizziness, headache, apnea, seizures, and coma

Treatment

  • 100% oxygen and antidote therapy
  • Sodium nitrite (IV) or amyl nitrite (inhaled) to displace cyanide from cytochrome oxidase
  • Sodium thiosulfate: For conversion of cyanide to excretable thiosulfate
  • Repeat sodium nitrite and sodium thiosulfate in 30min at half initial dose if needed
  • Hydroxocobalamin (Vit B12a): makes CN water soluble and non-toxic
  • Cyanide Antidote Kit: Amyl nitrite pearls, sodium nitrite (IV), sodium thiosulfate (IV)
  • Cyanokit: Less toxic than cyanide antidote kit and shown effective in cardiac arrest

Nerve Agents

  • Acetylcholinesterase inhibitors
  • Includes household and commercial pesticides (diazinon and parathion)
  • G-series (sarin, tabun, soman) and V-series (VX)
    • G-series are volatile non-persistent agents that evaporate quickly
    • V-series high viscosity with oily consistency
  • Rapidly absorbed through skin, symptoms generally develop within 1 hour
  • Vapors are heavier than air and tend to sink into low places
  • Sarin used in Tokyo subway attack in 1995; 5,000 sought medical attention with 12 deaths.

Pathophysiology

  • Inhibits acetylcholinesterase → excess acetylcholine at both nicotinic and muscarinic receptors

Symptoms

  • DUMBELLS
    • D-Diarrhea, U-Urination, M-Miosis, B-Bronchorrhea/Bradycardia, E-Emesis, L-Lacrimation, S-Salivation/Seizures
  • Cholinergic toxidrome Toxidromes

Management

  • Nerve agents prolong succinylcholine's paralytic effect
  • Atropine for bronchorrhea and bronchoconstriction
    • Start at 2-6mg, double the dose q5-30min until control of secretions (no max dose)
  • Pralidoxime to restore function of acetylcholinesterase (given over approx 30 minutes; rapid infusion can cause HTN)
    • Give as soon as possible - must be given before "aging" occurs to be effective
  • Benzodiazepines for seizures (standard AEDs may be ineffective)
  • Mark 1 Nerve Agent antidote Kit (NAAK): 2 autoinjectors:
    • 2mg atropine
    • 600mg pralidoxime
  • DuoDote Autoinjector: 2.1mg atropine, 600mg pralidoxime in one autoinjector

Differential Diagnosis

Mass casualty incident

Management

  • Depends on specific agent used
  • Regardless of agent, Decontamination and ABCs are of primary importance
    • Use appropriate personal protective equipment (PPE)
    • Decontamination (should take place pre-hospital or otherwise prior to entering the ED)
      • Remove all patient clothing
      • Brush off dry agent (e.g. powders), copiously irrigate skin of any liquid contaminant

See Also

References