Notes – Acetylcholinesterase Inhibitors (Carbamates, Nerve Agents, Organophosphates) Exposure

Acetylcholinesterase Inhibitors (Carbamates, Nerve Agents, Organophosphates) Exposure

Patient Safety Considerations

  1. Continuous and ongoing patient reassessment is critical
  2. Clinical response to treatment is demonstrated by the drying of secretion and the easing of respiratory effort
  3. Initiation of and ongoing treatment should not be based upon heart rate or pupillary response
  4. Precautions for pralidoxime chloride administration:
    1. Although Duodote® and ATNAA® contains atropine, the primary antidote for an acetylcholinesterase inhibitor agent poisoning, the inclusion of pralidoxime chloride in the auto-injector can present challenges if additional doses of atropine are warranted by the patient condition and other formulations of atropine are unavailable:
  5. Pediatrics: an overdose of pralidoxime chloride may cause profound neuromuscular weakness and subsequent respiratory depression
  6. Adults: Especially for the geriatric victim, excessive doses of pralidoxime chloride may cause severe systolic and diastolic hypertension, neuromuscular weakness, headache, tachycardia, and visual impairment
  • Geriatrics: victim who may have underlying medical conditions, particularly impaired kidney function or hypertension, the EMS provider should consider administering the lower recommended adult dose of intravenous pralidoxime chloride
  1. Considerations during the use of auto-injectors
    1. If an auto-injector is administered, a dose calculation prior to administration is not necessary
    2. For atropine, additional auto-injectors should be administered until secretions diminish.
    3. Mark I® kits, Duodote® and ATNAA® have not been approved for pediatric use by the Food and Drug Administration (FDA), but they can be considered for the initial treatment for children of any age with severe symptoms of an Acetylcholinesterase inhibitor agent poisoning especially if other formulations of atropine are unavailable
    4. Pediatric Atro-Pen® auto-injectors are commercially available in a 0.25 mg auto-injector (yellow) and a 0.5 mg auto-injector (red). Atro-Pen® auto-injectors are commercially available in a 1 mg auto-injector (blue) and a 2 mg auto-injector (green)
    5. A pralidoxime chloride 600 mg auto-injector may be administered to an infant that weighs greater than 12 kg

 

Notes/Educational Pearls

Key Considerations

  1. Clinical effects of acetylcholinesterase inhibitor agents
    1. The clinical effects are caused by the inhibition of the enzyme acetylcholinesterase which allows excess acetylcholine to accumulate in the nervous system
    2. The excess accumulated acetylcholine causes hyperactivity in muscles, glands, and nerves
  2. Organophosphates (certain Insecticides)
    1. Can be legally purchased by the general public
    2. Organophosphates (e.g. pesticides) penetrate tissues and bind to the patient’s body fat producing a prolonged period of illness and ongoing toxicity even during aggressive treatment
  3. Nerve agents
    1. Traditionally classified as weapons of mass destruction (WMD)
    2. Not readily accessible to the general public
    3. Extremely toxic and rapidly fatal with any route of exposure
    4. GA (tabun), GB (sarin), GD (soman), GF, and VX are types of nerve agents and are WMDs
    5. Nerve agents can persist in the environment and remain chemically toxic for a prolonged period of time

Pertinent Assessment Findings

The signs and symptoms exhibited with the toxidrome of DUMBELS [see Patient Presentation – Inclusion Criteria above]

Quality Improvement

Associated NEMSIS Protocol(s) (eProtocol.01)

  • 9914047 – Exposure-Nerve Agents

Key Documentation Elements

  • Time to recognize initial signs and symptoms
  • Number of repeated doses of atropine required for the secretions diminish and respirations to improve
  • Patient reassessments
  • Patient responses to therapeutic interventions
  • Measures taken to decontaminate the patient
  • Measures taken to protect clean environments from contamination

Performance Measures

  • Ability of the EMS system to rapidly locate additional and adequate antidote assets
  • Ability of the EMS system to rapidly deploy additional and adequate antidote assets
  • Survival rates of victims
  • Complication rates from the toxin
  • Complication rates from the antidotes
  • Long-term clinical sequelae of the victims

References

  1. Barkin RM, Rosen P, Seidel JS, Caputo GL, Jaffe DM. Pediatric Emergency Medicine: Concepts and Clinical Practice. St Louis, MO: Mosby; 1992:490-1.
  2. Burillo-Putze G, Nogue Xarau SN. In Tintinalli JE, ed. Tintinalli’s Emergency Medicine, 8th Edition. McGraw-Hill Education; 2016:1318-21.
  3. Eddelston M, Buckley NA, Eyer P, Dawson AH. Management of acute organophosphorus poisoning. Lancet. 2008;371(9612):597-607.
  4. Hoffman RS, Howland MA, Lewin NA, Nelson LS, Goldfrank LR. Goldfrank’s Toxicologic Emergencies, 10th Edition. China: McGraw-Hill Education; 2015.
  5. Horowitz BZ, Hendrickson RG. Chemical disasters. In Tintinalli JE, ed. Tintinalli’s Emergency Medicine, 8th Edition. McGraw-Hill Education; 2016:44-5.
  6. Marx JA et al. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 2014:825-6,2057-60,2476-7.
  7. Nelson LS. Goldfrank’s Toxicologic Emergencies, 10th Edition. China: McGraw-Hill Education; 2015:1450-76.
  8. Nerve Agents – Prehospital Management. Chemm.nlm.nih.gov. https://chemm.nlm.nih.gov/na_prehospital_mmg.htm. Updated April 28, 2017. Accessed August 27, 2017.