Management of Organophosphate Poisoning
The management of organophosphate poisoning requires immediate administration of atropine and pralidoxime, along with supportive care, decontamination, and continuous monitoring for at least 48-72 hours. 1
Initial Assessment and Decontamination
Personal Protection First
- Healthcare providers must wear appropriate PPE (respiratory protection, gloves, gowns, eye protection) before approaching patients 1
- Decontamination must occur before patient enters healthcare facility to prevent secondary contamination
Immediate Decontamination
- Remove contaminated clothing
- Thoroughly wash skin and hair with soap and water
- For ingestion, consider gastric lavage and activated charcoal if presenting early 2
Treatment Algorithm
Step 1: Supportive Care
- Secure airway, breathing, and circulation
- Provide respiratory and cardiovascular support as needed
- Correct metabolic abnormalities
- Control seizures if present 3
Step 2: Atropine Administration
- Start atropine immediately after improving hypoxemia (avoid giving with significant hypoxia due to risk of ventricular fibrillation)
- Adult dosing: 2-4 mg IV, repeated at 5-10 minute intervals until secretions are inhibited or signs of atropine toxicity appear 3
- Maintain atropinization for at least 48 hours 1
- Continuous infusion maintenance dose: 10-20% of total loading dose per hour (up to 2 mg/h) 1
Step 3: Pralidoxime (Protopam) Administration
- Adult dosing: Initial dose of 1000-2000 mg IV, preferably as infusion in 100 mL normal saline over 15-30 minutes 3
- If infusion not practical or pulmonary edema present, give slowly over at least 5 minutes as 50 mg/mL solution 3
- Second dose of 1000-2000 mg may be given after one hour if muscle weakness persists 3
- Additional doses every 10-12 hours if needed 3
- Maintenance dose: 400-600 mg/hour for at least 24-48 hours 1
- Continuous infusion has shown better outcomes than intermittent bolus dosing in severe cases 1
Monitoring and Follow-up
Laboratory Monitoring
- Cholinesterase activity (RBC acetylcholinesterase and plasma cholinesterase)
- Creatine kinase and serum potassium levels to prevent myoglobinuric renal failure 1
- Treatment should continue until depressed cholinesterase activity is reversed
Duration of Monitoring
- Observe for at least 48-72 hours after exposure 3
- Be vigilant for "rebound" symptoms, especially with fat-soluble organophosphates
Special Considerations
Medications to Avoid
- Succinylcholine (risk of prolonged paralysis)
- Mivacurium
- Morphine
- Theophylline/aminophylline
- Reserpine
- Phenothiazine-type tranquilizers 1, 3
Severity Assessment
Symptoms indicating severity include:
- Mild: Blurred vision, teary eyes, runny nose, increased salivation, chest tightness, tremors, nausea/vomiting
- Severe: Confusion, severe breathing difficulty, severe muscle twitching/weakness, involuntary urination/defecation, convulsions, unconsciousness 3
Prognostic Factors
Poor prognostic indicators include:
- Delayed treatment initiation 4
- Low Glasgow Coma Scale on admission
- High APACHE II and SOFA scores
- Elevated LDH levels 4
Adjunctive Therapies
Several adjunctive therapies show promise but require further research:
- Sodium bicarbonate infusion for mild to moderate alkalinization 5
- Magnesium sulfate may decrease hospitalization duration 5
- Fresh frozen plasma as a bio-scavenger 5
- Hemoperfusion in severe cases 2
Pitfalls and Caveats
Treatment Timing is Critical
Beware of Continued Absorption
- With ingestion, continued absorption from lower bowel can cause fatal relapses after initial improvement
- Additional doses of pralidoxime may be needed every 3-8 hours; effectively "titrate" the patient 3
Pediatric Considerations
- Infants and young children may present with drowsiness rather than muscle twitching
- Some symptoms like drooling may be normal in young children 1
Respiratory Complications
- Respiratory failure is the most common cause of mortality (74.4% of cases)
- Need for mechanical ventilation is associated with higher mortality (50% vs 21.6%) 1