Treatment of organophosphorus poisoning

Check airway, breathing, and circulation

Check airway, breathing, and circulation.

  • Place patient in the left lateral position, preferably with head lower than the feet, to reduce risk of aspiration of stomach contents.
  • Provide high flow oxygen, if available.
  • Intubate the patient if their airway or breathing is compromised

Atropine – 1–3 mg of atropine as a bolus

0·9% normal saline – aim to keep the systolic blood pressure above 80 mm Hg and urine output above 0·5 mL/kg/h

Record pulse rate, blood pressure, pupil size, presence of sweat, and auscultatory findings at time of first atropine dose

Pralidoxime chloride 2 g (or obidoxime 250 mg) intravenously over 20–30 min into a second cannula; follow with an infusion of pralidoxime 0·5–1 g/h (or obidoxime 30 mg/hr) in 0·9% normal saline

Infusion of pralidoxime

Infusion of pralidoxime 0·5–1 g/h (or obidoxime 30 mg/hr) in 0·9% normal saline

Double the original dose of atropine if no improvement after 5 minutes

5 min after giving atropine, check pulse, blood pressure, pupil size, sweat, and chest sounds. If no improvement has taken place, give double the original dose of atropine

Once parameters have begun to improve- stop dose doubling

Continue to review every 5 min; give doubling doses of atropine if response is still absent. Once parameters have begun to improve, cease dose doubling. Similar or smaller doses can be used

Give atropine boluses until

Keep heart rate is more than 80 beats per minute and systolic blood pressure is more than 80 mm Hg

Give atropine boluses until the heart rate is more than 80 beats per minute, the systolic blood pressure is more than 80 mm Hg, and the chest is clear (appreciating that atropine will not clear focal areas of aspiration).

Sweating – Sweating stops in most cases.

Tachycardia – not a contraindication

Dilated pupil

Once the patient is stable

Start an infusion of atropine giving every hour about 10–20% of the total dose needed to stabilise the patient.

Atropine toxicity

Tachycardia – not a contraindication to atropine since it can be caused by many factors .

Very dilated pupils – indicator of atropine toxicity

Atropine toxicity – patients will become agitated and pyrexial, and develop absent bowel sounds and urinary retention.

Atropine toxicity – Stop the infusion and wait 30–60 min for these features to settle before starting again at a lower infusion rate

Oxime infusion

Continue the oxime infusion until atropine has not been needed for 12–24 h and the patient has been extubated

Intermediate syndrome

Assess flexor neck strength

Ask to lift their head off the bed and hold it in that position while pressure is applied to their forehead.

Any sign of weakness is a sign that the patient is at risk of developing peripheral respiratory failure (intermediate syndrome).


Treat agitation by reviewing the dose of atropine being given and provide adequate sedation with benzodiazepines.

Cholinergic crises

Monitor cholinergic crises – due to release of fat soluble organophosphorus from fat stores.

Cholinergic crises can occur for several days to weeks after ingestion of some organophosphorus.

Recurring cholinergic features

Patients with recurring cholinergic features will need retreatment with atropine and oxime

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