1 / 67

Organophosphate Pesticide Poisoning

Organophosphate Pesticide Poisoning. Bishan Rajapakse MBChB Otago Emergency Medicine Advanced Trainee Registrar, MPhil Student (ANU), South Asian Clinical Toxicology Research Collaboration (SACTRC). OP Poisoning - Overview. Epidemiology Mechanism Clinical features Management

esheldon
Télécharger la présentation

Organophosphate Pesticide Poisoning

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. OrganophosphatePesticidePoisoning Bishan Rajapakse MBChB Otago Emergency Medicine Advanced Trainee Registrar, MPhil Student (ANU), South Asian Clinical Toxicology Research Collaboration (SACTRC)

  2. OP Poisoning - Overview • Epidemiology • Mechanism • Clinical features • Management • Current developments in Oxime therapy

  3. 0900 hrs (village) 0930 hrs 1000 hrs 1115 hrs CASE • Drunk 100mls after dispute • Found by family vomiting • Taken to nearest peripheral hospital (1 doctor, 2 nurses) • Sent by Ambulance (no paramedics) to nearest General hospital 36 yo female Ingestion of Dimethoate (Severely Toxic OP) Village

  4. Management • Initial Management? • ABC’s • Atropine • Ongoing Assessment & Management • Oximes (Pralidoxime, Obidoxime) -yes/no? • Dose? Duration? • Acetylcholinesterase assays?

  5. Organophosphorus (OP) Pesticide Poisoning

  6. Organophosphate Poisoning in Sri Lanka • Organophosphorus poisoning • High acuity and fatality • 12,000 admissions • 800 deaths • Mostly self-ingestion in Young adults • South Asian Clinical Toxicology Research Colaboration (SACTRC) • 5 Hospitals

  7. Organophosphate Poisoning in Sri Lanka • Case Fatality rates (CFR) • 10-30% for most OP’s • In west CFR • 0.3% from all poisons • Multifactorial • Toxicity of OP’s • Patient transport • Lack of resources • Training • Although less common OP Poisoning is still a problem in West • Occupational exposure • Threat of Chemical warfare

  8. Mechanism of OP toxicity

  9. Inhibition of Acetycholinesterase

  10. Nicotinic, Muscurinic & Central Syndrome

  11. Simplified Acute OP ToxicityOP’s are Cholinomimetics Organophosphate

  12. } Respiratory failure + Death Clinical Features • Acute Cholinergic Syndrome: • Central • Peripheral Muscarinic • Peripheral Nicotinic • Intermediate Syndrome • OPIDN: Delayed peripheral neuropathy • Neurocognitive dysfunction

  13. Cholinergic Effects – “DUMBELS” • D iarrhoea • U rination • M iosis • B radycardia, Bronchorrhoea, Bronchospasm • E mesis • L acrimation • S alivation

  14. Nicotinic Effects • Muscle Weakness • Respiratory difficulty • diaphragmatic weakness • respiratory arrest • Stimulation of sympathetic nervous system

  15. CNS effects • Serious Effects • Coma • Respiratory centre depression • Seizures • Other effects • Confusion • Memory loss • Disorientation • Delirium

  16. Case 2 • 24 yo female ingested 50 mls of Chlorpyrifos after an argument with her husband • Forced emesis at the local hospital • Arrived at the district hospital 4 hours later

  17. A- Airway threatened,  secretions present • B - RR 20, O2 sats 79-90% on oxygen • Widespread creps and poor air entry • C- P80 BP 100/70  • D- Pupils 2mm • GCS 10/15 (M5 V2 E3) • about V on the A V P U scale

  18. Fasiculations

  19. Intermediate Syndrome • Delayed Respiratory Failure • Proximal muscle weakness and CN lesions • Typically 1-4 days after cholinergic crisis has resolved • Prolonged Effects on Nicotinic receptors • Primary motor end plate degeneration • Clinical importance • Delayed respiratory failure leads to death if not aware of it or prepared for it • Wadia et. al 1974 : “Type II Paralysis, Senanayake and Karalliedde 1987”

  20. Chronic Effects • Organophosphate induced delayed neuropathy (OPIDN) • 1-3weeks • Peripheral neuropathy • Axonopathy due to Neuropathy Target Esterases (NTE) • Chronic organophosphate induced neuropsychiatric disorder (COPIND)

  21. Difference in OPs - Toxicity • 3most common OP’s ingested in NCP • Chlorpyrifos (Diethly OP) • Dimethoate & Fenthion (Dimethly OP) • Higher case fatality and intubation rates • in Dimethoate (CFR 23%, Intu 35%) and Fenthion (CFR 16%, Intu 31%) • compared with Chlorpyrifos (CFR 8%, Intu 15%)

  22. Clinical Variation Risk: Relative human toxicity of pesticides in self-poisoning X dimethoate Dimethyl fenthion X X Diethyl chlorpyrifos 0 1 0 2 0 3 0 4 0 C a s e f a t a l i t y r a t i o ( 9 5 % C I ) Xsymptomatic Eddleston M et al Differences between organophosphorus insecticides in human self-poisoning: a prospective cohort study. Lancet. 2005

  23. Difference in OPs - Toxicity • AChE inhibition responded poorly to oxime therapy in the 2 Dimethyl OP’s • Short half life of Ageing • (Dimethly vs Diethyl)

  24. t1/2 Spontaneous reactivation • 0.7 hr for diMethyl • 31 hrs for diEthyl • t1/2 of Ageing • 3.7 hrs for diMethyl • 33 hrs for diEthyl Different rates of OP - AChE inhibition, reactivation and ageing • t 1/2 inhibition • Milliseconds for both diMethyl and diEthyl OPs Eddleston M, Eyer P, Worek F, Mohamed F, et al Differences between organophosphorus insecticides in human self-poisoning: a prospective cohort study. Lancet. 2005 Oct 22-28;366(9495):1452-9

  25. Time to Death Eddleston M, Eyer P, Worek F, Mohamed F, et al Differences between organophosphorus insecticides in human self-poisoning: a prospective cohort study. Lancet. 2005 Oct 22-28;366(9495):1452-9

  26. Eddleston M, Eyer P, Worek F, Mohamed F, et al Differences between organophosphorus insecticides in human self-poisoning: a prospective cohort study. Lancet. 2005 Oct 22-28;366(9495):1452-9

  27. Effectiveness of 1 gram pralidoxime treatment ChlorpyrifosDimethoate

  28. Dimethyl OPs - specific features • Oximes less effective • Dimethoate patients died sooner • Hypotensive shock • Fenthion patients had higher incidence of delayed respiratory failure • Initially few symptoms • Later required intubation

  29. Management ?

  30. Management The priorities in management are : Resuscitation! A,B,C,D,E Atropinisation of symptomatic patients Decontamination Other Treatments - Oximes

  31. Resuscitation of OP poisoned patients • ABCDE – Careful attention to management of “airway + breathing” • ATROPINE is part of A, B, and C and • administer simultaneously to resuscitation • GI Decontamination is NOT a life saving procedure! • Should not be performed before resuscitation

  32. Respiratory Failure in OP patients • Review of 376 OP poisoned patients in NCP1 • 90pts (24%) required intubation • 52 (58%) intubated within 2 hours • 46 (51%) died • 29 (32%) Well on admission but required intubation >24hrs • 1Eddleston M, Mohamed F, Davies JO, Eyer P, Worek F, Sheriff MH et al. Respiratory failure in acute organophosphorus pesticide self-poisoning. QJM. 2006;99(8):513-22.

  33. All OP’s >24hours <2hours 2-24hours Fenthion When OP Patients were intubated in NCP Eddleston et al. Respiratory failure in acute organophosphorus pesticide self-poisoning. QJM. 2006;99(8):513-22.

  34. Atropine administration in OP poisoning • Indications • How fast to give • For how long • Toxicity of Atropine

  35. Indications for AtropineSpeed of intial Atropinisation Indications Atropinisation – Endpoint Poor air entry in lungs caused bronchospasm and bronchorrhoea Hypotension Bradycardia Excessive sweating (Miosis) Chest Clear Systolic BP >80mmHg Heart rate >80/min Dry Axillae Pupils no longer pinpoint Atropine

  36. Speed of intial Atropinisation • Study looked at severely poisoned OP patients in Sri Lanka • 22 patients, all required intubation, but survived to discharge • Mean dose of atropine required 23.4mg (range 1-75mg) Eddleston et al. Speed of initial atropinisation in significant organophosphorus pesticide poisoning--a systematic comparison of recommended regimens. J.Toxicol.Clin.Toxicol. 2004;42(6):865-75. • Text book recommendations for atropinisation varied markedly • Average patient 23.4mg – (8 to 1380 mins) • Severely ill patient 75mg – (25 to 4440 mins)

  37. Suggested Atropine Regimen • Loading • Doubling dose regime e.g. 2 4 8 16 mgs every 5 minutes • Maintenance • Continuous infusion < 3mg/hr • 10-20% of loading dose/hour • Endpoints • Clear chest on auscultation with no wheeze • Heart rate >80 beats/min

  38. What if you give too much Atropine ? • Anticholinergic Syndrome: • Hot as hell • Blind as a bat • Red as a beet • Dry as a bone • Mad as a hatter • CVS - Severe Tachycardia (eg HR >120) • Risk of ischaemia in elderly patients • CNS - Confusion, Agitation • Hyperthemia

  39. Gastrointestinal Decontamination ?

  40. Benefits Gastrointestinal Decontamination Risks • Aspiration • Trauma • Electrolyte Imbalances • Cardiac Arrest • Cost • Removal of poison load • Prevention of ongoing poison absorption • More beneficial in Toxic OP’s

  41. Gastrointestinal Decontamination Options: • Nothing • Emesis • Gastric Lavage • Activated Charcoal

  42. Risk of Intervention • Aspiration • Trauma • Oesphageal Injury • Nasopharyngeal injury 1. Eddleston M, Haggalla S, Reginald K, Sudarshan K, Senthilkumaran M, Karalliedde L, et al. The hazards of gastric lavage for intentional self-poisoning in a resource poor location. Clin Toxicol (Phila) 2007;45(2):136-43.

  43. Risk of Intervention • Electrolyte Abnormalities • Cardiac Arrest • Increased Vagal Tone especially with toxin induced bradycardia • Induced emesis, Lavage • Cost

  44. Summary of Experimental Evidence • GI decontamination should be done in ideal settings • Means to protect airway • Expertise to carry out procedure safely • Little benefit in outcomes after 1 hour • Position statement: single-dose activated charcoal. J Toxicol Clin Toxicol 1997;35:721-41. • Position statement and practice guidelines on the use of multi-dose activated charcoal in the treatment of acute poisoning. J Toxicol Clin Toxicol 1999;37:731-51.

  45. Decontamination for OPs • Within 1 hour • Gastric lavage if no contraindications • Able to protect airway • GCS >12 • Followed by single dose AC • 1-2 hours – debatable • In some centres the above treatment is acceptable • > 2 hours ingestion • No place for Gastric Lavage or AC

  46. Oximes ?

  47. Oximes • Ineffective in some situations • Ageing • Variation between organophosphates • Effective protocols not established • Variation in use • Zero – 24 grams a day • Expensive • USA $30-600 / gram • India $6- 9 / gram • Sri Lanka 55 cents / gram • Unlikely to address Non-ACh effects

More Related