IM22.6 | Insecticide Poisoning — Summary & Reflection

KEY TAKEAWAYS

Organophosphate and carbamate insecticide poisoning:

- Mechanism: OP → irreversible phosphorylation of AChE (ageing within hours); carbamate → reversible carbamylation (spontaneous recovery)
- Clinical features: cholinergic toxidrome — muscarinic (SLUDGE: salivation, lacrimation, urination, defecation, GI cramps, emesis; PLUS miosis, bradycardia, bronchospasm, bronchorrhoea, hypotension) + nicotinic (fasciculations → NMJ paralysis) + CNS (seizures, coma)
- Diagnosis: clinical + serum cholinesterase (< 25% = severe); ECG (QTc prolongation)
- Management:
1. Decontamination (remove clothing, wash skin; staff protective equipment)
2. Atropine: loading 2–4 mg IV, doubling every 5 minutes until SECRETIONS DRY — no dose ceiling; maintain infusion
3. Pralidoxime 1–2 g IV over 30 min (OP only, NOT carbamate; within 24–48 hours ideally)
4. Benzodiazepines for seizures
5. Ventilatory support as needed
- Complications: Intermediate syndrome (day 2–4, proximal weakness + respiratory paralysis — treat with ventilation); OPIDN (2–4 weeks, distal neuropathy — no treatment); QTc prolongation and arrhythmia
- Carbamate vs OP: carbamate — pralidoxime NOT needed; shorter clinical course; NO intermediate syndrome or OPIDN

REFLECT

The farmer in the opening hook died not because the diagnosis was missed, but because the treatment was administered incorrectly. How many such preventable deaths occur in district hospitals across India each week because the clinician was never taught — or did not believe — that 100 mg of atropine can be appropriate in a single 24-hour period for a severely poisoned patient? Reflect on what systemic changes are needed to reduce OP poisoning mortality: better personal protective equipment and safety training for agricultural workers; restricted access to highly toxic formulations (WHO Class I OPs); availability of atropine in adequate quantities at primary health centres and district hospitals; and training of all interns and postgraduate medical officers in the correct atropine titration protocol. As a future physician, your understanding of this single drug (atropine) and this single endpoint (dry secretions) will directly determine how many OP poisoning patients in your district hospital survive. What will you teach the junior nurses and medical officers who work with you?