• Information
  1. Nerve Agents
  2. Vesicants
  3. Pulmonary Toxins

A. Nerve Agents

1. Mechanism
   1. Inactivate acetylcholinesterase by phosphorylation
   2. Leads to accumulation of acetylcholine at nicotinic and muscarinic receptors
   3. Similar to organophosphates
2. Agents (Liquid or Vapor)
   1. Tabun (GA)
   2. Sarin (GB)
   3. Soman (GD)
   4. Cyclosarin (GF)
   5. VX Nerve Gas
3. Properties
   1. Denser than air
   2. Tend to accumulate in low-lying areas
   3. Lipophilic and hydrophilic
   4. Rapidly penetrate clothing, skin and mucous membranes
4. Dose dependent peripheral (PNS) and central nervouse system (CNS) effects
5. Respiratory Effects
   1. Mild: rhinorrhea, bronchorrhea
   2. Moderate: bronchospasm (muscarinic)
   3. Severe: respiratory muscle paralysis (nicotinic), reduced respiratory drive
6. Cardiovascular
   1. Muscarinic: bradycardia and heart block
   2. Nicotinic: tachycardia
7. CNS Effects
   1. Mild: headache, agitation
   2. Moderate: vertigo
   3. Severe: reduced level of consciousness, seizures
8. Gastrointestinal (muscarinic): nausea, vomiting, diarrhea
9. Ocular: miosis, eye pain, blurred vision, dim vision, conjunctival injection, tearing
10. Exposure
    1. Liquid: may be asymptomatic for 10-30 minutes, then respiratory and CNS effects
    2. Vapor: large amount causes fulminant respiratory failure within seconds to minutes
    3. Small amount of vaport causes ocular and respiratory symptoms
11. Prevention
    1. Use of military gas masks should be restricted to trained military personnel
    2. Preatment with pyridostigmine (Mestinon®) 30mg po q8 hours
    3. Pyridostigmine binds peripheral AChE and prevents inactivation by nerve agents
    4. Somewhat effective against tabun or soman, not against sarin, VX, cyclosarin (variable)
12. Antidotes
    1. Atropine - 2mg IM for mild dyspnea, 6mg IM for severe dyspnea
    2. Pralidoxime (Protopam®) - AChE reactivator, 1-2 gm IV (20-30 minutes) or IM initially
    3. Pralidoxime may be repeated hourly, or given IV at 500mg/hour
    4. Diazepam (Valium®) may prevent CNS damage, 10mg IM
    5. Tropicamide (Mydriacyl®), blocks cholinergic stimulation of iris sphincter, 1-2 drops
    6. Morphine 10mg IM may be useful

B. Vesicants

1. Mechanism
   1. Oily liquid vaporizes at high temperatures
   2. Lipophilic and penetrates skin, most textiles, rubber
   3. Irreversibility alkylates DNA, RNA, and protein, causes cell death
2. Agents: Mustard and its derivatives (usually sulfur mustard)
3. Mucosa, perineum, axillae are most vulnerable
4. Treatment
   1. Rapid removal of clothing
   2. Flushing with soap and water
   3. Endotracheal intubation may be required for airway sluffing
   4. Severe burns: irrigation, debridgement, topical antibiotics (silver sulfadiazine)
   5. Eye care: irrigation, topical antibiotics, mydriatics; petroleum jelly on burned lids
   6. Granulocyte-CSF (filgrastim, Neupogen®) for mustard induced neutropenia

C. Pulmonary Toxins

1. Mechanism
   1. React with water to form hydrochloric acid (damages tissues)
   2. Phosphgene and diphosgene also acylate amino, hydroxyl and sulfhydryl groups
   3. Long and/or high dose exposure may lead to adult respiratory distress syndrome (ARDS)
2. Agents
   1. Chlorine
   2. Phospgene
   3. Diphosgene (degrades to phosgene and low levels of chloroform)
3. Chlorine
   1. Dissolves in mucosa of upper respiratory tract
   2. Rhinorrhea, hyperslaivation, laryngeal edema
   3. Lower respiratory tract (LRI): coughing, wheezing, rales
4. Phosgene
   1. Denser than chlorine with increased penetration to LRI
   2. Bronchoalveolar injury, dyspnea, bronchospasm, non-cardiogenic pulmonary edema, ARDS
5. Treatment
   1. Oxygen
   2. Bronchodilators - albuterol (Proventil®) 2mg in 3mL water nebulized
   3. Theophylline may be effective
   4. Glucocorticoids (prednisolone or methylprednisolone) 250-1000mg IV
   5. Possible effects with high dose ibuprofen and/or acetylcysteine aerosol

References

1. Chemical Warfare Agents. 2002. Med Let. 44(1121):1