Organophosphate Poisoning

Key points

• • Organophosphates are widely used insecticides and a very common cause of poisoning, especially by self-harm, in farming areas.
• • They block the enzyme acetylcholinesterase, which normally breaks down the nerve messenger acetylcholine, so acetylcholine builds up and over-stimulates its receptors.
• • The muscarinic effects give a picture remembered as SLUDGE: Salivation, Lacrimation, Urination, Defecation, Gastrointestinal upset and Emesis, with small pupils and a slow heart.
• • The nicotinic effects cause muscle twitching, weakness and paralysis, and the central effects cause confusion, fits and coma.
• • Death is usually from paralysis of the breathing muscles together with flooding of the airways with secretions.
• • The diagnosis is supported by finding a low level of cholinesterase in the blood; a garlic-like smell may be noticed but is unreliable.