Florida State Paramedic Practice Exam

A dose of Atropine of less than 0.5 mg in an adult patient will primarily lead to which outcome?

1. Hypertension

2. Bradycardia

3. Tachycardia

4. Arrhythmia

The correct answer is: Bradycardia

Atropine is an anticholinergic medication that primarily works by blocking the effects of the vagus nerve on the heart. When administered in doses less than 0.5 mg, Atropine can actually lead to bradycardia, especially in patients with vagally-mediated bradycardia. This paradoxical effect occurs because low doses of Atropine may not sufficiently block the vagal influence on the heart, allowing for the persistent vagal tone to predominate, which in turn can slow down the heart rate. In higher doses, Atropine effectively increases the heart rate by inhibiting the parasympathetic nervous system's effects. However, in the context of lower doses, the drug does not achieve the intended result of increasing the heart rate and may instead have the opposite effect, resulting in bradycardia as the primary outcome. It's important for paramedics and healthcare providers to recognize this potential effect, as patient responses to medications can vary based on dosage and individual physiology.