What is the protocol for atropine (antimuscarinic agent) drip in cases of organophosphate poisoning?

From the Guidelines

Atropine infusion is recommended for severe organophosphate poisoning, with an initial bolus dose of 1-2 mg IV, doubled every 5 minutes until full atropinization is achieved, followed by a maintenance infusion of 10-20% of the total loading dose per hour, up to 2 mg/hour. This protocol is based on the most recent guidelines from the American Heart Association, as outlined in the 2023 focused update on the management of patients with cardiac arrest or life-threatening toxicity due to poisoning 1. The goal of atropine therapy is to achieve full atropinization, characterized by a clear chest on auscultation, heart rate >80/min, and systolic blood pressure >80 mm Hg.

Key Considerations

• The initial bolus dose of atropine should be titrated every 5 minutes until the desired clinical effect is achieved, with a maximum dose of 3 mg 1.
• The maintenance infusion should be adjusted based on clinical response, with a typical dose range of 0.5-2 mg/hour 1.
• Atropine works by competitively blocking muscarinic acetylcholine receptors, counteracting the excess acetylcholine that accumulates when organophosphates inhibit acetylcholinesterase.
• This treatment should be accompanied by decontamination measures, airway management, and administration of oximes like pralidoxime (2-PAM) at 1-2 g IV initially, followed by 500 mg/hour continuous infusion for 24-48 hours to reactivate inhibited acetylcholinesterase 1.

Monitoring and Titration

• Vital signs, pupil size, secretions, and mental status should be monitored continuously during atropine infusion.
• The infusion rate should be titrated based on clinical response, increasing if cholinergic symptoms return or decreasing if signs of atropine toxicity develop (confusion, hyperthermia, urinary retention).
• The infusion should continue for at least 24 hours after stabilization, with gradual tapering by 10-20% every 4-6 hours while monitoring for recurrence of cholinergic symptoms.

From the FDA Drug Label

Atropine should be given as soon as possible after hypoxemia is improved Atropine should not be given in the presence of significant hypoxia due to the risk of atropine-induced ventricular fibrillation. In adults, atropine may be given intravenously in doses of 2 to 4 mg. This should be repeated at 5- to 10-minute intervals until full atropinization (secretions are inhibited) or signs of atropine toxicity appear (delirium, hyperthermia, muscle twitching) Some degree of atropinization should be maintained for at least 48 hours, and until any depressed blood cholinesterase activity is reversed.

The protocol for atropine drip in cases of organophosphate poisoning is to administer 2 to 4 mg of atropine intravenously, repeated at 5- to 10-minute intervals until full atropinization is achieved or signs of atropine toxicity appear. Atropinization should be maintained for at least 48 hours. Atropine should not be given in the presence of significant hypoxia due to the risk of atropine-induced ventricular fibrillation 2.

From the Research

Atropine Drip Protocol in Organophosphate Poisoning

The protocol for atropine drip in cases of organophosphate poisoning involves administering high doses of atropine until secretions disappear, with intensive care exerted in follow-up 3. The initial dose and infusion rate may vary depending on the severity of the poisoning and the patient's response to treatment.

Key Considerations

• Atropine can be administered in high doses, with one study reporting a maximum dose of 100 mg intravenously on admission and 100 mg/h/day during follow-up 3.
• The total dose of atropine given may be high, with one study reporting a total dose of 11.6 g over 12 days 3.
• Atropine therapy may need to be prolonged, with one study reporting a case of severe organophosphate poisoning that required 2 months of atropine therapy 4.
• Monitoring for complications associated with prolonged atropine therapy and intensive care is crucial, including cardiac complications such as cardiogenic shock and arrhythmias 5.

Administration Guidelines

• Atropine can be administered intravenously, with an initial dose of 1-2 mg followed by an infusion of 0.5-1 mg/h, titrated to effect 6, 7.
• The infusion rate may need to be adjusted based on the patient's response to treatment, with some patients requiring higher doses to control secretions and other muscarinic symptoms 3.
• The duration of atropine therapy will depend on the severity of the poisoning and the patient's response to treatment, with some patients requiring prolonged therapy to prevent recurrence of symptoms 4.