Difference between revisions of "Organophosphate toxicity"

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==Clinical Features==
==Clinical Features==
*Symptoms caused by acetylcholine buildup in CNS and PNS.
*Symptoms caused by acetylcholine buildup in CNS and PNS.
*CNS symptoms = headache, confusion, seizures coma, vertigo
*CNS symptoms = [[headache]], [[confusion]], [[vertigo]], [[seizures]], [[coma]]
*Muscarinic Receptors
*Muscarinic Receptors
**SLUDGE(M) = '''S'''alivation, '''L'''acrimation, '''U'''rination, '''D'''iarrhea, '''G'''I pain, '''E'''mesis, '''M'''iosis
**SLUDGE(M) = '''S'''alivation, '''L'''acrimation, '''U'''rination, '''D'''iarrhea, '''G'''I pain, '''E'''mesis, '''M'''iosis
**DUMBELLS = '''D'''iarrhea, diaphoresis, '''U'''rination, '''M'''iosis, '''B'''radycardia, '''B'''ronchorrea, '''E'''mesis, '''L'''acrimation, '''L'''ethargic, '''S'''alivation
*Nicotinic Receptors (NMJ)
*Nicotinic Receptors (NMJ)
**MTWThF = '''M'''ydriasis/Muscle cramps, '''T'''achycardia, '''W'''eakness, '''T'''witching, '''H'''ypertension/Hyperglycemia, '''F'''asiculations
**MTWThF (days of week) = '''M'''ydriasis/Muscle cramps, '''T'''achycardia, '''W'''eakness, '''T'''witching, '''H'''ypertension/Hyperglycemia, '''F'''asciculations, '''S'''eizures, '''S'''omnolent
*Common causes of death in [[organophosphate]] toxicity
*Common causes of death in [[organophosphate]] toxicity
**Killers B's = '''B'''radycardia, '''B'''ronchorrhea, '''B'''ronchospasm
**Killers B's = '''B'''radycardia, '''B'''ronchorrhea, '''B'''ronchospasm
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*Comprehensive Metabolic Panel
*Comprehensive Metabolic Panel
**Pulmonary edema in severe cases
**[[Pulmonary edema]] in severe cases
**Ventricular dysrhythmias, torsades, QT prolongation, AV block
**[[Ventricular dysrhythmias]], [[torsades]], [[QT prolongation]], [[AV block]]

Latest revision as of 15:23, 31 August 2019


  • Organophosphates found in:
  • Highly lipid soluble: absorbed via dermal, gastrointestinal or respiratory routes
  • Colorless, odorless, low volatility, and high lipophilicity
  • These compounds act as Acetylcholinesterase inhibitors
    • Block acetylcholinesterase, resulting in excess accumulation of acetylcholine at the neuromuscular junction and cholinergic toxicity
  • LD50 of 0.04mg/kg (10 mg). Death can occur within 15 minutes after absorption

Autonomic Nervous System Receptors and Their Effects

  • Parasympathetic - ACh is transm
    • Muscarinic
      • receptors in heart, eye, lung, GI, skin and sweat glands
      • Bradycardia
      • Miosis
      • Bronchorrhea / Bronchospasm
      • Hyperperistalsis (SLUDGE)
      • Sweating
      • Vasodilation
    • Nicotinic
  • Sympathetic
    • Alpha effects (vessels, eye, skin)
    • Beta effects (heart, lungs)

Clinical Features

  • Symptoms caused by acetylcholine buildup in CNS and PNS.
  • CNS symptoms = headache, confusion, vertigo, seizures, coma
  • Muscarinic Receptors
    • SLUDGE(M) = Salivation, Lacrimation, Urination, Diarrhea, GI pain, Emesis, Miosis
    • DUMBELLS = Diarrhea, diaphoresis, Urination, Miosis, Bradycardia, Bronchorrea, Emesis, Lacrimation, Lethargic, Salivation
  • Nicotinic Receptors (NMJ)
    • MTWThF (days of week) = Mydriasis/Muscle cramps, Tachycardia, Weakness, Twitching, Hypertension/Hyperglycemia, Fasciculations, Seizures, Somnolent
  • Common causes of death in organophosphate toxicity
    • Killers B's = Bradycardia, Bronchorrhea, Bronchospasm

Intermediate Syndrome

Differential Diagnosis

SLUDGE Syndrome


Chemical weapons

Symptomatic bradycardia




  • Clinical diagnosis
  • Blood tests such as RBC and plasma pseudocholinesterase levels are available, but little clinical utility



  • Providers should wear appropriate PPE during decontamination.
    • Neoprene or nitrile gloves and gown (latex and vinyl are ineffective)
  • Dispose of all clothes in biohazard container
  • Wash patient with soap and water

Supportive Care

  • IVF, O2, Monitor
  • Aggressive airway management is of utmost importance.
    • Intubation often needed due to significant respiratory secretions / bronchospasm.
    • Use nondepolarizing agent (Rocuronium or Vecuronium)
    • Succinylcholine is absolutely contraindicated


  • Dosing with atropine and pralidoxime are time dependent and provides ability to reverse symptoms while awaiting agent metabolism
  • For exposure to nerve agents, manufactured IM autoinjectors are available for rapid administration:
    • Mark 1
      • Contains 2 separate cartridges: atropine 2 mg + 2-PAM 600 mg
      • Being phased out with newer kits
    • DuoDote
      • Single autoinjector containing both medications
      • Same doses as Mark 1: atropine 2 mg + 2-PAM 600 mg



  • Competitively blocks muscarinic sites (does nothing for nicotinic-related muscle paralysis)
  • May require massive dosage (hundreds of milligrams)
  • Dosing[1]
  • Adult: Initial bolus of 2-6mg IV; titrate by doubling dose q5-30m until tracheobronchial secretions controlled
    • Once secretions controlled → start IV gtt 0.02-0.08 mg/kg/hr
    • Child: 0.05-0.1mg/kg (at least 0.1mg) IV; repeat bolus q2-30m until tracheobronchial secretions controlled
    • Once secretions controlled → start IV gtt 0.025 mg/kg/hr


  • AKA 2-PAM
  • For Organophosphate poisoning only - reactivates AChE by removing phosphate group → oxime-OP complex then excreted by kidneys.
    • This must be done before "aging" occurs - conformational change that makes OP bond to AChE irreversible[2]
    • Pralidoxime can actually bind and inhibit AChE once all AChE enzymes have aged, and can make the toxicity worse
    • Window to aging depends on the agent, and is a matter of debate, but pralidoxime within 1-2 hours of exposure is the goal
  • Dosing[1]
    • Adult: 1-2gm IV over 15-30min; repeat in 1 hour if needed or 50 mg/hr infusion.
    • Child: 20-40mg/kg IV over 20min; repeat in 1 hour if needed or 10-20 mg/kg/hr infusion.


  • Minimal exposure + asymptomatic at least 12 hours after exposure can likely be discharged.
  • Admit all symptomatic patients!
  • If evidence of deliberate self harm, place on hold and consult psychiatry

See Also


  1. 1.0 1.1 Agency for Toxic Substances and Disease Registry, Case Studies in Environmental Medicine, Cholinesterase Inhibitors: Including Pesticides and Chemical Warfare Nerve Agents. Centers for Disease Control (CDC). PDF Accessed 06/21/15
  2. Eddleston M, Szinicz L, Eyer P, Buckley, N (2002) Oximes in Acute Organophosphate Pesticide Poisoning: a Systematic Review of Clinical Trials. QJM. 95(5): 275–283.