Organophosphate Poisoning
OVERVIEW
- common cause of poisoning in the developing world
- covalent bonding with inactivation of acetylcholinesterase
- results in cholinergic crisis
CLINICAL FEATURES
Risk factors
- insecticides/fertilisers
- surface and room sprays
- baits for cockroaches
- shampoos against head lice
- pet preparations
- crop protection and livestock dipping
- fumigation
- nerve agents (sarin)
Clinical features (cholinergic syndrome)
- DUMBBELS: diarrhoea, urination, miosis, bronchorhea, bradycardia, emesis, lacrimation, salivation
- SLUDGE: salivation, lacrimation, urination, defaecation, emesis
INVESTIGATIONS
- butyrylcholinesterase or acetylcholinesterase activity
MANAGEMENT
Resuscitation
- aspiration/bronchospasm/seizures may necessitate airway protection and mechanical ventilation
- haemodynamic monitoring and management with the below agents
- remove contaiminated clothes -> wash
Acid-base and Electrolytes
Specific Therapy
- atropine: 0.02mg/kg boluses -> recurrent boluses q5min doubling the dose each time, treats bradycardia, hypotension and excess secretion production
- pralidoxime chloride 30mg/kg IV -> 8mg/kg/hr: muscle weakness
- benzodiazepines: midazolam 0.2mg/kg, seizures or agitation
- activated charcoal if presents with 1-2 hours
Underlying Cause
- psychiatric assessment
- work place health and safety review
References and Links
CCC Toxicology Series
General
Approach to acute poisoning, ECGs in Tox, Evidenced-based Tox, Toxicology literature summaries, Does anti-venom work?
Toxins / Overdose
Amphetamines, Barbituates, Benzylpiperazine, Beta Blockers, Calcium Channel Blocker, Carbamazepine, Carbon Monoxide, Ciguatera, Citrate, Clenbuterol, Cocaine, Corrosive ingestion, Cyanide, Digoxin, Ethanol, Ethylene Glycol, Iron, Isoniazid, Lithium, Local anaesthetic, Methanol, Monoamine oxidase inhibitor (MAOI), Mushrooms (non-hallucinogenic), Opioids, Organophosphate, Paracetamol, Paraquat, Plants, Polonium, Salicylate, Scombroid, Sodium channel blockers, Sodium valproate, Theophylline, Toxic alcohols, Tricyclic antidepressants (TCA)
Envenomation
Marine, Snakebite, Spider, Tick paralysis
Syndromes
Alcohol withdrawal, Anticholinergic syndrome, Cholinergic syndrome, Drug withdrawals in ICU, Hyperthermia associated toxidromes, Malignant hyperthermia (MH), Neuroleptic malignant syndrome (NMS), Opioid withdrawal, Propofol Infusion Syndrome (PrIS) Sedative toxidrome, Serotonin syndrome, Sympatholytic toxidrome, Sympathomimetic toxidrome
Decontamination
Activated Charcoal, Gastric lavage, GI Decontamination
Enhanced Elimination
Enhanced elimination, Hyperbaric therapy for CO
Antidotes
Antidote summary, Digibind, Glucagon, Flumazenil, HIET – High dose euglycaemic therapy, Intralipid, Methylene Blue, N-Acetylcysteine (NAC), Naloxone
Miscellaneous
Cocaine chest pain, Digoxin and stone heart theory, Hyperbaric oxygen, Hypoxaemia in tox, Liver failure in tox, Liver transplant for paracetamol, Methaemoglobinaemia, Urine drug screen
- Abedin MJ, Sayeed AA, Basher A, Maude RJ, Hoque G, Faiz MA. Open-label randomized clinical trial of atropine bolus injection versus incremental boluses plus infusion for organophosphate poisoning in Bangladesh. J Med Toxicol. 2012 Jun;8(2):108-17. PMC3550249.
- Buckley NA, Eddleston M, Li Y, Bevan M, Robertson J. Oximes for acute organophosphate pesticide poisoning. Cochrane Database Syst Rev. 2011 Feb 16;(2):CD005085. PMID: 21328273.
- Eddleston M, Dawson A, Karalliedde L, Dissanayake W, Hittarage A, Azher S, Buckley NA. Early management after self-poisoning with an organophosphorus or carbamate pesticide – a treatment protocol for junior doctors. Crit Care. 2004 Dec;8(6):R391-7. PMC1065055.
- Eddleston M, Buckley NA, Eyer P, Dawson AH. Management of acute organophosphorus pesticide poisoning. Lancet. 2008 Feb 16;371(9612):597-607. PMC2493390.
- Gussow L. Toxicology Rounds: Atropine Dosing Regimen Suboptimal for Organophosphate Poisoning. Emergency Medicine News. 2013; 35(5)p8 [Free Full Text]
Critical Care
Compendium
