This presentation explains about epidemiology of organophosphate poisoning, the toxic mechanism and pathophysiological basis of clinical features. It briefly outlines diagnosis in an emergency situation and management.

1. ORGANOPHOSPHATE
POISONING
DR KTD PRIYADARSHANI
REGISTRAR IN EMERGENCY MEDICINE
TEACHING HOSPITAL- PERADENIYA
2023/03/24

2. SCOPE
• Overview
• Toxic mechanism
• Clinical features
• Diagnosis
• Management

3. OVERVIEW
• Important clinical problem in rural Asia
• Mostly self ingestion in young adults
• Case fatality rate 10-30% for most Ops
• self poisoning kills 150, 000 every year world wide – 20%
of suicide*
• Fall in deaths 260,000 to 150,000 with tighter regulation
*Case fatality of agricultural pesticides after self-poisoning in Sri Lanka: a prospective cohort study
Buckley, Nicholas A et al. 2021 The Lancet Global Health, Volume 9, Issue 6, e854 - e862

5. TOXIC MECHANISM

8. CLINICAL FEATURES
4 clinical syndromes
• Acute poisoning
• Intermediate syndrome
• Chronic toxicity
• Organophosphate induced delayed neuropathy

9. ACUTE EFFECTS
• Most within 8 hrs all with in 24
hrs
• Local irritation of skin and
respiratory tract without
evidence of sysytemic
absorption
• Mild to moderate-
combinations
• Severe- nicotinic features first-
time depend on route and
dose Tintinali emergency medicine 9E

10. INTERMEDIATE SYNDROME
• Delayed 1-5 days
• In 40% of patients following ingestion
• Clinical features- paralysis of neck muscles, muscles innervated by
cranial nerves, proximal limb muscles, respiratory muscles
paralysis
• Absent symptoms and signs of cholinergic excess
• Electromyography
• Prevention
• Aggressive early antidote therapy and supportive therapy

11. OP INDUCED DELAYED NEUROPATHY
(OPIDN)
• Chronic toxicity- agricultural
• Symmetrical sensorimotor axonopathy
• Begin with leg crams and ascend- mimic GBS

12. CHRONIC OP-INDUCED
NEUROPSYCHIATRIC DISORDER (COPIND)
• Cognitive dysfunction, impaired memory, mood changes,
autonomic dysfunction, peripheral neuropathy and
extrapyramidal signs
• Chronic fatigue syndrome and multiple chemical sensitivity
• Children are at greater risk
• Small body size
• Lower baseline level of cholinesterase activity
• BDZ may help if given during acute poisoning

13. MANAGEMENT
Peter, John Victor & Moran, J &
Pichamuthu, Kishore & Chacko,
Binila. (2008). Adjuncts and
Alternatives to Oxime Therapy in
Organophosphate Poisoning—is
There Evidence of Benefit in
Human Poisoning? A Review.
Anaesthesia and intensive care. 36.
339-50.
10.1177/0310057X0803600305.

14. RESUSCITATION
1. Airway
• Gentle suction
• Intubate
2. Breathing
• Oxygen
• PPV
3. Circulation
• IV access
• Fluid- fluid bolus
4. Disability
• Seizures

15. INTUBATION
• Indications
• Coma, Seizure, respi failure, excessive respi secretions, severe
bronchospasm
• TV <5 mL/kg, VC <15 mL/kg, apneic spells, Pa O2<60 mmHg on FiO2 >60%
• Drugs
• Non depolarizing agent (sux- prolonged paralysis)

16. RISK ASSESSMENT
• Agent
• Quantity absorbed
• Route – oral > dermal/ inhalation
• Additives

17. SUPPORTIVE CARE AND MONITORING
• Monitor
• Cardiac monitor
• Pulse oximeter
• 100% oxygen NRBM
• Seizure- IV benzodiazepine
• AVOID
• Sux
• Ester anesthetics
• Beta blockers

18. INVESTIGATIONS
• Plasma butyryl cholinesterase level/ red cell
cholinesterase level
• Markers of AchE activity at the synaptic junction
• Not reliable due to
• Baseline varies
• degree of inhibition needed to produce
symptomatic illness also variable

19. • Look for
• Hypo/hyperglycemias
• Leukocytosis
• Abnormal liver function
• Evidence of pancreatitis
• Chest x-ray- Pulmonary edema, aspiration
• ECG- torsade pointes, VT, VF, ST segment changes,
peaked T waves, AV block, Prolonged QT

20. DECONTAMINATION
• Protective clothing must be worn to prevent secondary poisoning
of healthcare workers.
• Handle and dispose of all clothes as hazardous waste.
• Wash patient with soap and water.
• Handle and dispose of water runoff as hazardous waste
• Gastric lavage- no proven benefit
• Given with in 2 hrs

21. ENHANCED ELIMINATION
• Activated charcoal- no proven benefit
• Hemodialysis, hemofiltration and hemoperfusion- no
proven value

22. ANTIDOTE- ATROPINE
• Competitive antagonist of Ach at central and peripheral muscarinic receptors
1. Initial bolus depending on symptoms
• 1.2-3 mg IV in adult
• 0.05 mg/kg IV in pediatric
• No IV access- 2-6 mg IM
• Absence of anticholinergic symptoms after initial dose- confirms OP poisoning
2. Double dose every 5 min
• Check for end points
3. Continuous infusion of 10-20% per hour of initial dose to
achieve adequate atropinization (0.4-4 mg/hr IV in adult)

23. • KUO for atropine toxicity
• Absent bowel sounds
• Hyperthermia
• delirium
• Tachycardia is not a contraindication for atropine if other features suggest
under atropinisation
• Pupil dilatation is sometimes delayed and other parameters usually improve
much more rapidly
• Atropine reduces bronchorrhea, but does not reverse muscle weakness.
• Recurrence of toxicity with fat soluble Ops for weeks- need continuous
atropine infusion
• Febrile patient-
• Sedate if agitated- IV diazepam 10mg
• Active cooling

24. PRALIDOXIME
• Give as soon as possible- 24-48 hr after exposure
• 30 mg/kg IV in adults
• 30mg/kg up to 1g in children
• Mix with NS and infused over 5-10 min
• Continuous infusion 8 mg/kg per hour for 24-48 hrs
• End points
• Atropine has not been needed for 12-24 h
• Patient is extubated
• No evidence about reduce mortality or complication
rate-
• Not recommended for asymptomatic pts
• Carbamate exposure with minimal symptoms

25. DISPOSITION
• Minimal exposure
• Decontamination
• Observe 6-8 hrs
• Avoid re-exposure- cumulative toxicity
• Significant poisoning
• Admit
• Symptomatic recovery 10 days
• if toxins are fat soluble Pralidoxime infusion – assess 24 hr after stopping
• Follow up for intermediate or delayed syndromes

26. REFERENCES
1. Management of poisoning 4th edition- prof Ravindra Fernando
2. Tinitnali Emergency Medicine 9th Edition
3. Case fatality of agricultural pesticides after self-poisoning in Sri Lanka: a prospective cohort study
Buckley, Nicholas A et al. 2021 The Lancet Global Health, Volume 9, Issue 6, e854 - e862
4. Peter, John Victor & Moran, J & Pichamuthu, Kishore & Chacko, Binila. (2008). Adjuncts and
Alternatives to Oxime Therapy in Organophosphate Poisoning—is There Evidence of Benefit in Human
Poisoning? A Review. Anaesthesia and intensive care. 36. 339-50. 10.1177/0310057X0803600305.
5. Giyanwani P, Zubair U, Salam O, et al. (September 03, 2017) Respiratory Failure Following
Organophosphate Poisoning: A Literature Review . Cureus 9(9): e1651. doi:10.7759/cureus.1651
6. Umakanth M. Intermediate Syndrome Following Organophosphate Poisoning; Review Article. Asia Pac J
Med Toxicol 2019;8:19-24.
7. Kharel H, Pokhrel N B, Ghimire R, et al. (March 04, 2020) The Efficacy of Pralidoxime in the Treatment of
Organophosphate Poisoning in Humans: A Systematic Review and Meta-analysis of Randomized Trials.
Cureus 12(3): e7174. doi:10.7759/cureus.7174