What is the management of organophosphorous poisoning?

Management of Organophosphate Poisoning

The management of organophosphate poisoning requires immediate administration of atropine and pralidoxime, along with supportive care including airway management, decontamination, and monitoring of cholinesterase activity. 1

Initial Assessment and Stabilization

• Diagnosis: Based primarily on clinical suspicion and history of exposure

  • Confirmation through measurement of cholinesterase activity in blood (reduction below 50% of normal indicates poisoning)
  • Do not delay treatment while awaiting laboratory confirmation 1

• Immediate Interventions:

  1. Ensure proper personal protective equipment (PPE) for healthcare providers to prevent secondary contamination
  2. Remove patient from exposure source and perform decontamination
  3. Establish airway, breathing, and circulation
  4. Initiate continuous monitoring of vital signs

Decontamination

• Remove all contaminated clothing
• Wash skin and hair thoroughly with soap and water
• Perform decontamination before patient enters healthcare facility 1
• For ingestion: Consider gastric lavage and activated charcoal (only after patient is stable) 2

Pharmacological Management

Atropine Administration

• Initial Dosing: 2-4 mg IV in adults 1
• Repeat: Every 5-10 minutes until atropinization achieved (secretions inhibited) 3
• Maintenance: 10-20% of total loading dose per hour (up to 2 mg/hour) 1
• Duration: Maintain atropinization for at least 48 hours and until cholinesterase activity improves 1, 3

Pralidoxime (Oxime) Administration

• Initial Dosing: 1-2 grams IV over 15-30 minutes in adults 1, 3
• Maintenance: 400-600 mg/hour for adults (10-20 mg/kg/hour for pediatrics) 1
• Duration: Continue for at least 24-48 hours 1
• Administration Method: Preferably as continuous infusion rather than intermittent bolus dosing 1
• Timing: Most effective when administered early before "aging" of acetylcholinesterase occurs 1

Respiratory Management

• Indications for Intubation and Mechanical Ventilation:

  • Respiratory failure
  • Depressed level of consciousness with inability to protect airway
  • Hemodynamic instability 1, 2

• Ventilation Strategy:

  • Synchronized intermittent mandatory ventilation + pressure support mode
  • Titrate PEEP to maintain SaO₂ above 94% with 40% FiO₂ 2

Monitoring and Follow-up

• Laboratory Monitoring:

  • Cholinesterase activity (RBC acetylcholinesterase and plasma cholinesterase)
  • Creatine kinase
  • Serum potassium levels 1

• Observation Period:

  • Minimum 48-72 hours of observation
  • Longer observation may be needed with fat-soluble organophosphates due to delayed absorption 3

Complications to Monitor

• Intermediate syndrome (19.1% of cases) 2
• Respiratory failure (most common cause of mortality, 74.4% of cases) 1, 2
• Aspiration pneumonia
• Seizures
• Acute respiratory distress syndrome (ARDS)
• Myoglobinuric renal failure 1

Important Precautions

• Contraindicated Medications:

  • Succinylcholine (may cause prolonged paralysis)
  • Morphine
  • Theophylline and aminophylline
  • Reserpine
  • Phenothiazine-type tranquilizers 1, 3

• Special Considerations for Children:

  • Infants may present with drowsiness rather than muscle twitching
  • Symptoms like drooling may be normal in young children 1

Pitfalls to Avoid

1. Delayed Treatment: Early administration of atropine and pralidoxime is crucial for improved outcomes
2. Inadequate Atropinization: Insufficient atropine dosing is a common error
3. Secondary Contamination: Failure to use proper PPE can lead to healthcare provider exposure
4. Premature Discontinuation: Treatment should continue until cholinesterase activity improves
5. Failure to Recognize Respiratory Failure: Early recognition and intervention is essential as respiratory failure is the leading cause of mortality 2

The mortality rate for patients requiring mechanical ventilation is significantly higher (50%) compared to non-ventilated patients (21.6%), highlighting the importance of respiratory management 2.

Emerging Therapies

While atropine and pralidoxime remain the mainstay of treatment, several promising adjunctive therapies are being investigated, including:

• Magnesium sulfate
• Calcium channel blockers (nimodipine)
• Plasma alkalinizing agents
• β-2 agonists
• Nicotinic receptor antagonists 4

However, these require further large-scale clinical trials before being incorporated into standard treatment protocols.