From the Guidelines
For bradycardic arrest, administer atropine 0.5 to 1 mg IV push, which can be repeated every 3 to 5 minutes as needed up to a maximum total dose of 3 mg. Start with 0.5 to 1 mg IV push as soon as bradycardic arrest is identified, as doses of atropine sulfate of <0.5 mg may paradoxically result in further slowing of the heart rate 1. If there's no response after 3-5 minutes, repeat the dose. A third dose can be given if needed, but do not exceed 3 mg total. Ensure IV access is established and that you have the medication drawn up and ready to administer quickly. Always confirm the correct dose before administration. Atropine works by blocking parasympathetic (vagal) influences on the heart, thereby increasing heart rate. It's most effective for bradycardia caused by vagal stimulation or AV block at the nodal level. However, it may be less effective in infranodal blocks or in cardiac transplant patients due to the lack of vagal innervation 1. Some key points to consider when administering atropine for bradycardic arrest include:
- Use atropine cautiously in the presence of acute coronary ischemia or MI; increased heart rate may worsen ischemia or increase infarction size 1.
- Atropine administration should not delay implementation of external pacing for patients with poor perfusion 1.
- Be prepared to initiate transcutaneous pacing if atropine is ineffective, and address any underlying causes of the bradycardia. Atropine remains the first-line drug for acute symptomatic bradycardia (Class IIa, LOE B) 1.
From the FDA Drug Label
Bradyasystolic cardiac arrest: 1 mg dose, repeated every 3 to 5 minutes if asystole persists. ( 2) The dose of Atropine for bradycardic arrest is not explicitly stated, but for bradyasystolic cardiac arrest, which is a related condition, the dose is 1 mg, repeated every 3 to 5 minutes if asystole persists 2.
- Key points:
- The label does not directly address bradycardic arrest.
- The dose for bradyasystolic cardiac arrest may not be directly applicable to bradycardic arrest. However, based on the information provided for bradyasystolic cardiac arrest, a conservative approach would be to consider a dose of 1 mg.
From the Research
Atropine Dosage for Bradycardic Arrest
- The dosage of atropine for bradycardic arrest is not explicitly stated in the provided studies 3, 4, 5, 6, 7.
- However, study 6 mentions that the maximum total dose of atropine in the treatment of asystole and electromechanical dissociation has been increased from 2 mg to 0.04 mg/kg.
- Study 4 mentions that atropine-treated patients received 1 mg atropine intravenously with a repeat dose at one minute if no rhythm change occurred.
- Study 5 describes a case where a patient received a single dose of 600 micrograms IV atropine for bradycardia and 2:1 heart block.
- Study 7 used atropine 50 µg/kg in an experimental setting to explore the therapeutic effects of atropine for hypoxic bradycardia during the occurrence of cardiac arrest.
Administration Route and Considerations
- Study 3 suggests that the ideal route for drug administration during CPR is one that combines rapid access with quick delivery of the drug to the central circulation.
- It is recommended to administer drugs into the central circulation when possible, and if administered through a peripheral IV site, the extremity should be elevated, and a 20-mL bolus of IV fluid should be given to facilitate access of the agent to the central circulation 3.
- If there is a delay in obtaining venous access, atropine may be administered through the endotracheal tube at 2.5 times the IV dose 3.