Management of Adequate Atropinisation in Organophosphate Compound (OPC) Poisoning
Rapid incremental dose atropinization followed by atropine infusion is the optimal approach for managing OPC poisoning, as it reduces mortality and morbidity while shortening hospital stay and recovery time. 1
Initial Management
- Ensure proper personal protective equipment (PPE) when caring for patients with organophosphate exposure to prevent contamination of healthcare providers 2
- Perform immediate dermal decontamination for external exposure by removing contaminated clothing and washing thoroughly with soap and water 2
- Administer atropine immediately for severe poisoning manifestations such as bronchospasm, bronchorrhea, seizures, or significant bradycardia 2
Atropine Dosing Protocol
Initial Atropinization
- Start with atropine 1-2 mg IV for adults (0.02-0.1 mg/kg for children) 2
- Double the dose every 5 minutes until full atropinization is achieved (secretions are inhibited) 2, 3
- Signs of adequate atropinization include:
Maintenance of Atropinization
- After initial atropinization, maintain with continuous atropine infusion 2, 1
- Some degree of atropinization should be maintained for at least 48 hours, and until any depressed blood cholinesterase activity is reversed 3
- Monitor patients for at least 96 hours, as relapses can occur 1
Pralidoxime (2-PAM) Administration
- Administer pralidoxime concurrently with atropine for optimal management 2, 3
- Initial adult dose: 1000-2000 mg IV, preferably as an infusion in 100 mL of normal saline over 15-30 minutes 3
- If infusion is not practical or pulmonary edema is present, give slowly over at least 5 minutes as a 50 mg/mL solution 3
- A second dose of 1000-2000 mg may be given after about one hour if muscle weakness persists 3
- Additional doses may be given every 10-12 hours if muscle weakness continues 3
Airway Management
- Early endotracheal intubation is recommended for life-threatening organophosphate poisoning 2, 4
- Avoid neuromuscular blockers metabolized by cholinesterase (succinylcholine and mivacurium) as they can cause prolonged paralysis in patients with OPC poisoning 2, 5
Seizure Management
- Administer benzodiazepines such as diazepam or midazolam to treat seizures and agitation 2
Monitoring and Complications
- Monitor patients for at least 48-72 hours after exposure, as fatal relapses have been reported after initial improvement 3
- Watch for development of intermediate syndrome, which can occur 24-96 hours after exposure and is characterized by respiratory muscle weakness 1, 4
- Be vigilant for signs of atropine toxicity: delirium, hyperthermia, muscle twitching 3
- Common complications include respiratory failure, aspiration pneumonia, urinary system infection, and convulsions 4
Advantages of Incremental Atropine Dosing with Infusion
- Significantly shorter time to achieve atropinization (23.9 minutes vs. 151.7 minutes with conventional bolus dosing) 1
- Lower mortality rate (8% vs. 22.5% with conventional bolus dosing) 1
- Reduced incidence of atropine toxicity (12% vs. 28.4% with conventional bolus dosing) 1
- Decreased need for respiratory support (8% vs. 24.7% with conventional bolus dosing) 1
- Lower incidence of intermediate syndrome (4% vs. 13.6% with conventional bolus dosing) 1
Special Considerations
- Continued absorption from the lower bowel can constitute new exposure, requiring additional doses of atropine and pralidoxime 3
- Patients should be "titrated" with atropine as long as signs of poisoning recur 3
- In severe cases, patients may require very high cumulative doses of atropine (up to 1000 mg in some cases) 6