A 42-year-old farmer from Punjab presents to the emergency department 45 minutes after accidental exposure to an organophosphate pesticide spray. He is conscious but anxious, with profuse salivation, lacrimation, and bronchorrhea. Vital signs: HR 52/min, BP 110/70 mmHg, RR 28/min. Pupils are pinpoint. He has muscle fasciculations visible over the chest and limbs. Serum cholinesterase activity is 25% of normal. Which of the following is the most appropriate immediate management?

Explanation

## Organophosphate Poisoning: Acute Management Protocol **Key Point:** Organophosphate compounds irreversibly inhibit acetylcholinesterase, causing accumulation of acetylcholine at cholinergic synapses (muscarinic and nicotinic effects). ### Clinical Presentation (SLUDGE Syndrome) - **S**alivation, **L**acrimation, **U**rination, **D**efecation, **G**astrointestinal upset, **E**mesis - Miosis (pinpoint pupils) - Muscle fasciculations and weakness (nicotinic) - Bradycardia and bronchospasm (muscarinic) - Altered consciousness in severe cases ### Treatment Algorithm ```mermaid flowchart TD A[Organophosphate Exposure]:::outcome --> B[Decontamination + Remove clothing]:::action B --> C[Establish airway, O₂, IV access]:::action C --> D[Atropine 2–5 mg IV bolus]:::action D --> E{Signs of atropinization?}:::decision E -->|No| F[Repeat Atropine q5–10 min]:::action E -->|Yes| G[Start Pralidoxime 1 g IV]:::action G --> H[Pralidoxime 500 mg–1 g IV q4–6h]:::action H --> I[Monitor cholinesterase recovery]:::outcome ``` ### Drug Roles | Drug | Mechanism | Timing | Notes | | --- | --- | --- | --- | | **Atropine** | Muscarinic antagonist | First-line, immediate | Relieves salivation, bronchospasm, bradycardia; does NOT affect nicotinic effects (fasciculations, weakness) | | **Pralidoxime (2-PAM)** | Nucleophilic oxime; reactivates acetylcholinesterase by removing phosphoryl group | Within 24–48 hrs (ideally <6 hrs) | Effective only if enzyme-phosphate bond not yet "aged"; addresses both muscarinic AND nicotinic effects | **High-Yield:** Atropine is ESSENTIAL and MUST be given first. Pralidoxime is adjunctive and works best when given early, before "aging" of the enzyme-inhibitor complex (which varies by agent: minutes to hours). **Clinical Pearl:** The presence of muscle fasciculations and weakness (nicotinic signs) indicates severe poisoning and reinforces the need for early pralidoxime, as atropine alone cannot reverse nicotinic blockade. **Warning:** Pralidoxime alone is insufficient — atropine is required to manage life-threatening muscarinic effects (bronchospasm, bradycardia, hypersalivation). Neostigmine is contraindicated as it would worsen cholinergic excess. [cite:Harrison 21e Ch 481]