Difference between revisions of "Chemical weapons"

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Revision as of 13:21, 14 October 2014

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

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)
  • Rapidly absorbed through skin
  • Vapors are heavier than air and tend to sink into low places
  • G-series are volatile non-persistent agents that evaporate quickly
  • V-series high viscosity with oily consistency
  • Exposure to volatile agent, symptoms can develop within 1 hour
  • Sarin used in Tokyo subway attack in 1995; 5,000 sought medical attention with 12 deaths.

Pathophysiology

  • Acetylcholinesterase inhibitors causing excess acetylcholine at 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

Treatment

  • Nerve agents prolong succinylcholine's paralytic effect
  • Atropine for bronchorrhea and bronchoconstriction, no max dose
  • Pralidoxime to restore function of acetylcholinesterase (given over approx 30 minutes; rapid infusion can cause HTN)
  • 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

Management

  • Appropriate personal protective equipment (PPE)
  • Decontamination
    • Prevents further damage from the exposure as well as protects others from contamination
  • ABCs

See Also

References

  1. ’’Basic Disaster Life Support V.3.0 Course Manual.’’ N.p.: American Medical Association, 2012. Print.
  2. ’’Campbell, John E. Tactical Medicine Essentials.’’ Sudbury, MA: Jones & Bartlett Learning, 2012. Print
  3. 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.
  4. http://www.ncbi.nlm.nih.gov/pubmed/15094583