Define Organophosphate Poisoning. Describe its clinical features and diagnosis.

Definition

Organophosphate (OP) poisoning results from insecticides that inhibit acetylcholinesterase, causing accumulation of acetylcholine and a cholinergic crisis. It is a common and serious poisoning in India.

Clinical Features

• Muscarinic — remembered as dumbels (Diarrhoea, Urination, Miosis, Bronchorrhoea/Bradycardia, Emesis, Lacrimation, Salivation); pinpoint pupils.
• Nicotinic — muscle fasciculations, weakness, and paralysis (including respiratory).
• CNS — anxiety, seizures, coma; a characteristic garlic odour.

Diagnosis & Management

• Clinical (cholinergic toxidrome) supported by low plasma/RBC cholinesterase levels.
• Decontamination (remove clothes, wash skin) and airway/ventilatory support.
• Atropine — titrated to reverse bronchorrhoea/bronchospasm ('atropinisation').
• Pralidoxime (2-PAM) — reactivates cholinesterase (best given early, for nicotinic effects).

Intermediate & Delayed Effects

• Intermediate syndrome — proximal muscle/respiratory weakness 1–4 days after apparent recovery.
• Delayed peripheral neuropathy can follow some agents.

Decontamination Detail

• Remove contaminated clothing and wash the skin/hair thoroughly (staff should protect themselves).
• Airway protection is critical — bronchorrhoea and weakness can cause respiratory failure.

Key Points Recap

• OP inhibits acetylcholinesterase → cholinergic crisis (muscarinic + nicotinic + CNS).
• Atropine to atropinisation + early pralidoxime + airway/ventilatory support; beware the intermediate syndrome.