Cholinergic crisis: secure the airway, then atropinise fast by doubling boluses every 5 min until the chest is clear, HR > 80, SBP > 80 mmHg, axillae dry and pupils no longer pinpoint; then infuse 10-20% of the loading dose per hour. Watch for the intermediate syndrome on days 1-4.
At the bedside
Timed steps- 1
Recognise
0 minMiosis, salivation, bronchorrhoea, bronchospasm, bradycardia, vomiting, diarrhoea, fasciculations, weakness, coma; kerosene-like smell. Plasma (butyryl) cholinesterase supports diagnosis.
- 2
Airway
0 minLeft-lateral position, suction, oxygen; intubate if GCS low, respiratory failure or copious secretions. Avoid succinylcholine (prolonged block); use rocuronium.
- 3
Atropine
0-30 min1.8-3 mg IV bolus; if not atropinised in 5 min, double the dose; repeat doubling until the five targets are met.
- 4
Infusion
Then10-20% of the total loading dose per hour; review every 15 min initially; if toxic (confusion, hyperthermia, ileus), stop for 30-60 min then restart at 70-80%.
- 5
Consider
OximePralidoxime 2 g IV over 30 min then 1 g/h for 48 h (Pawar regimen) in moderate-severe OP; benefit is uncertain (Eddleston 2009, Cochrane). Not for carbamates.
- 6
Safely
DecontaminateRemove clothes and wash skin (staff wear gloves). Gastric lavage only if early (< 1 h), airway protected; no forced emesis.
- 7
Intermediate syndrome
Days 1-4Proximal limb, neck flexor and cranial nerve weakness with respiratory failure despite atropinisation; check neck flexion power and single breath count every 4-6 h; ventilate.
Atropinisation
Atropine
- Dose
- 1.8-3 mg, double every 5 min until atropinised
- Worked example
- 2 mg → 4 mg → 8 mg → 16 mg (cumulative 30 mg) achieves targets; infusion 3-6 mg/h
Targets: clear chest on auscultation, HR > 80/min, SBP > 80 mmHg, dry axillae, pupils no longer pinpoint. Tachycardia is not a reason to withhold atropine if the chest is wet.
Moderate-severe OP poisoning
Pralidoxime (PAM)
- Dose
- 2 g over 30 min, then 1 g/h for 48 h, then 1 g every 4 h until weaned
Calculators for this topic
References
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OP poisoning: atropine titration
Step 1 of ~6
Decision: Airway or ventilation compromised?
Based on Eddleston M, Buckley NA, Eyer P, Dawson AH. Educational use; follow local protocol.
Pathophysiology
- OPs phosphorylate acetylcholinesterase; "ageing" makes inhibition irreversible (hours for dimethyl, days for diethyl compounds), which is why oximes work early, if at all. Carbamates inhibit reversibly.
Evidence
- Eddleston 2008: practical atropine titration protocol.
- Abedin 2012: incremental doubling boluses plus infusion reduced mortality vs conventional bolus dosing (8% vs 22.5%).
- Pawar 2006 vs Eddleston 2009: conflicting oxime results.
Controversies
- Oximes: Cochrane 2011 found insufficient evidence; many Indian units continue them. Fresh frozen plasma, magnesium and lipid emulsion remain experimental.
🇮🇳 India notes
- OP poisoning is one of the commonest causes of ICU admission and death from self-harm in rural India; monocrotophos, chlorpyrifos, quinalphos and profenofos are common agents.
References
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Test yourself
Module quiz · score 70% to complete the module
Educational reference for trained clinicians. Check doses against your hospital protocol and the patient in front of you.