Organophosphate poisoning is a high-volume presentation across much of India, and the commonest reason patients do badly is under-atropinisation. The instinct is to give a dose, watch, give another, and to use pupil size as the guide. Pupils are the wrong endpoint: they respond late, they respond poorly to systemic atropine, and waiting for dilatation delivers far too little drug far too slowly.
The endpoints that matter are respiratory and haemodynamic. Aim for a chest clear of crackles on auscultation, dry axillae, a systolic blood pressure above 80 mmHg and a heart rate above 80 beats per minute. Those four together mean the muscarinic effects that kill — bronchorrhoea and bronchospasm flooding the airway — have been reversed. Get there by doubling the dose every few minutes rather than repeating the same dose, then hold the patient there with an infusion, because atropine wears off while the organophosphate does not.
Two things that get forgotten in the rush. Bronchorrhoea, not bronchospasm, is what fills the lungs, and it responds to atropine rather than to salbutamol. And atropine does nothing for the nicotinic effects — fasciculation, weakness, respiratory muscle failure — so a patient can be adequately atropinised and still need intubation for neuromuscular failure. Watch the respiratory effort separately from the secretions.
- Titrate atropine to a clear chest, dry axillae, systolic BP above 80 and heart rate above 80 — not to pupils.
- Double the dose every few minutes until those endpoints are met, rather than repeating a fixed dose.
- Follow with an infusion; atropine wears off long before the organophosphate does.
- Treat bronchorrhoea with atropine, not bronchodilators — it is secretion, not bronchospasm.
- Assess respiratory muscle strength separately; atropine does not touch the nicotinic effects that cause it to fail.
The statistics, in plain English
The evidence base here is mostly observational and drawn from case series in the countries where this poisoning is common, rather than from randomised trials — deliberate self-poisoning is difficult to study prospectively. What is well established is the direction of the problem: audits repeatedly show under-dosing rather than over-dosing as the modifiable failure, and the endpoint-based approach exists because dose-based rules cannot account for how enormously the required dose varies between patients and compounds.
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