Atropine Dosing for Cholinesterase Inhibitor Toxicity

Patient Weight

Severity of Cholinesterase Inhibitor Toxicity

Adult Dosing: –

Awaiting input

Select severity to view adult dose. Enter weight for pediatric dosing.

Doses atropine for cholinesterase inhibitor toxicity (prescribed drugs, nerve gas, insecticides).

Why Use

Atropine is a competitive antagonist at muscarinic receptors and can reverse the deleterious or life-threatening symptoms of cholinergic toxicity, particularly bronchospasm and bronchorrhea.

When to Use

Use for patients with cholinergic toxicity (causative agents are typically organophosphate compounds or carbamate, found in pesticides, or agents used in chemical warfare and terrorist attacks). Many symptoms of cholinergic toxicity are recalled with the “SLUDGE and killer B’s” mnemonic: S alivation. L acrimation. U rination. D efecation. G astric E mesis. B radycardia. B ronchospasm. B ronchorrhea.

Formula

Initial dose: Pediatric: 0.02 mg/kg, up to adult dose. Adult, mild toxicity: 1-2 mg. Adult, severe toxicity (hemodynamic compromise, unconsciousness): 3-5 mg. Assess for atropinization every 5 minutes: Clear lung exam on auscultation is the most important factor. Additional factors: heart rate >80, systolic blood pressure >80. If atropinization has not been achieved, double previous dose and reassess in another 5 minutes. Repeat doubling every 5 minutes until atropinization achieved. Once atropinization achieved, begin continuous infusion at an hourly rate of 10% of the sum of all doses necessary to achieve initial atropinization. Titrate as necessary.

Pearls / Pitfalls

This dosing guide was created to facilitate early and safe atropinization of the patient exhibiting signs of acute cholinergic toxicity. May be used in patients exposed to either pesticide agents (more common) or agents of chemical warfare/terrorism. Markers of atropinization vary, but the most clinically significant is resolution of bronchorrhea, as assessed by auscultation. Large cumulative doses of atropine may be necessary to treat toxicity. Cases requiring hundreds to thousands of milligrams over the course of treatment have been reported ( Hopmann 1974 ).

Management

Management of organophosphate / carbamate toxicity includes: Prompt, safe, and thorough decontamination. Early intubation for airway protection in severe cases. Avoid succinylcholine for rapid sequence intubation, given prolonged duration of action in cholinergic poisonings. Early atropinization. Administration of pralidoxime. Administration of benzodiazepines for seizure activity. Admission to a higher level of care for close monitoring.

Critical Actions

Patients exposed to organophosphate or carbamate agents should be immediately decontaminated by removing all clothing and abundantly irrigating all exposed areas before initiating treatment.

Advice

Patients suspected of cholinergic toxicity exhibiting signs of neuromuscular dysfunction should also be treated with pralidoxime (2-PAM). Doses of atropine delivered intravenously should be given rapidly and in their entirety—slow administration or subtherapeutic doses have been associated with paradoxical bradycardia.