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

  • 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]

CCC 700 6

Critical Care

Compendium

Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM with a passion for rugby; medical history; medical education; and informatics. Asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | vocortex |

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