Organophosphate toxicity

Background

• Irreversibly binds acetylcholinesterase -> cholinergic crisis
• Used as insecticides (malathion) and chemical warfare (sarin, VX)
• Consider in ddx of pt w/ AMS + miotic pupils

Clinical Features

1. SLUDGE(MM)
   1. Salivation, lacrimation, urination, diarrhea, GI pain, emesis, miosis, muscle weakness
2. Killers B's
   1. Bradycardia, bronchorrhea, bronchospasm

Diagnosis

• CBC
  • May show leukocytosis
• Lipase
• LFT
• CXR
  • Pulmonary edema in severe cases
• ECG
  • Ventricular dysrhytmias, torsades, QT prolongation, AV block

Treatment

1. Protection
   1. Wear protective clothing to prevent secondary poisoning
   2. Use neoprene or nitrile gloves (not latex)
2. Decontamination
   1. Dispose of all clothes
   2. Wash pt with soap/water
3. Airway
   1. Suction as needed
   2. Intubation if needed d/t respiratory secretions / bronchospasm
      1. Use nondepolarizing agent
4. Breathing
   1. Use O2 100% NRB
5. Antidotes
   1. Atropine
      1. May require massive dosage (hundreds of milligrams)
      2. Does not reverse muscle weakness
      3. Dosing
         1. Adult: 1mg or more IV; repeat q5min until tracheobronchial secretions attenuate
         2. Child: 0.01-0.04mg/kg (but never <0.1mg) IV
   2. Pralidoxime
      1. Displaces organophosphate from acetylcholinesterase (if given early)
      2. Dosing
         1. Adult: 1-2gm IV over 5-10min; continuous infusion of 500mg/hr if no initial response
         2. Child: 20-40mg/kg (up to 1gm) IV over 5-10min; 5-10mg/kg/hr if no initial response

Disposition

• Minimal exposure only requires decon and 6-8hr obs

See Also

Toxidromes

Source

• Tintinalli