Organophosphate insecticides and related nerve agents block the enzyme acetylcholinesterase, so acetylcholine builds up at nerve endings. The result is a cholinergic crisis with heavy secretions, slow heart rate and muscle weakness, and death usually comes from respiratory failure.
Key symptoms
- Heavy salivation, tearing, sweating and runny nose
- Vomiting, diarrhea, abdominal cramps and urination
- Shortness of breath, wheeze and heavy airway secretions
- Muscle twitching, weakness and later paralysis
- Confusion, seizures or coma
What you find on exam
- Scene safety and PPE; decontaminate before treating
- Pinpoint pupils
- Wet lungs: wheeze, crackles, bronchorrhea
- Heart rate: often slow, but it can be fast
- Muscle twitching and strength; chemical smell on clothing
Tests
- Diagnosis is clinical, from exposure and toxidrome
- Red blood cell cholinesterase level in hospital
- ECG: slow rhythm, QT prolongation
- Blood gas, electrolytes and glucose
Treatment basics
- Remove clothing and wash the skin with soap and water
- Atropine 1 to 2 mg IV, doubling the dose every 5 minutes until lung secretions dry
- Pralidoxime to reactivate the enzyme
- Airway support, suction and oxygen; avoid succinylcholine for intubation
- Benzodiazepines such as midazolam for seizures
Red flags
- Respiratory failure or heavy secretions
- Seizures
- New muscle weakness 24 to 96 hours later (intermediate syndrome)
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Related guides
Sources: NASEMSO National Model EMS Clinical Guidelines; NREMT psychomotor skill sheets (EMT and Paramedic); National EMS Education Standards (2021). Written by Making Synapses. Making Synapses is not affiliated with these organizations.