A brief account on Organophosphate poisoning and management practised in Sri Lanka. It includes a description of toxic mechanism, clinical features and management with atropinisation and pralidoxime.

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