Organophosphate Poisoning
Basics
This is a very dangerous agent. It can be absorbed through the skin, orally, or by inhaling the agent. The patient presents with both muscarinic and nicotinic effects.
Presentation
- Muscarinic: DUMBELS and SLUDGE:
- DUMBELS: Diarrhoea, Urination, Miosis, Bronchospasm, Emesis, Lacrimation, and Salivation.
- SLUDGE: Salivation, Lacrimation, Urination, Defecation, Gastrointestinal cramps, and Emesis.
- Nicotinic: MTWTF (Days of the week):
- Muscle cramps, Tachycardia, Weakness, Twitching, and Fasciculations.
Acetylcholine is released from the presynaptic neuron. It enters the synaptic cleft and binds to the post-synaptic receptors. These receptors are usually either nicotinic or muscarinic receptors. However, normally after exerting its effect on these receptors, acetylcholine is broken down into acetate and choline by acetylcholinesterase. This prevents the overstimulation of these receptors. However, organophosphate is known to inactivate acetylcholinesterase. This results in an accumulation of acetylcholine in the synaptic cleft. Meaning that more muscarinic and nicotinic receptors will become activated and overstimulated.
2. Pralidoxine: (Not commonly available in all public hospitals). Also known as 2-PAM, is responsible for reactivating the acetylcholinesterase that was phosphorylated by the organophosphates.
Investigations
- The diagnosis may be supported by the presence of low serum pseudocholinesterase levels.
- Formal Bloods: FBC, UE +Creatinine, CRP
- Arterial Blood Gas
- Chest X-Ray
Management
General
- Personal protective equipment: Gloves, gowns, and eye protection.
- Decontamination, is usually done after the patient is resuscitated. Remove the patient’s clothes and place them in a closed bag.
- ABC approach – maintain the airway and ensure that the patient is hemodynamically stable. Suction the secretions as necessary. Ventilatory support should be considered.
Medical
- Activated charcoal once the patient is stabilized.
- Treatment of bronchorrhoea, bronchospasm, or bradycardia:
- This is treated with boluses of Atropine, followed by an atropine infusion.
- Atropine 2-5mg IV bolus. Re-assess every 3-5 minutes. Look out for signs of atropinization. Give the patient repeated boluses by doubling the dose until there is adequate clinical response (2mg, 4mg, 8mg, 16mg, and so on). If the patient responds then either give the same dose or reduce the dose.
- Atropine infusion: Calculate the total dose of atropine given as boluses and give 10-20% of this dose per hour.
- NB: Atropine should not be stopped immediately but weaned off over a period of 24 hours.
- This is treated with boluses of Atropine, followed by an atropine infusion.
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