North Carolina EMT State Practice Exam

What is a possible effect of administering epinephrine?

1. Decreased blood viscosity

2. Constricted airways

3. Increased heart rate

4. Lowered blood pressure

The correct answer is: Increased heart rate

Administering epinephrine has a well-documented physiological effect of increasing heart rate, primarily due to its action as a potent sympathomimetic agent. When epinephrine is released into the body, it stimulates beta-adrenergic receptors in the heart, which leads to an increased rate of myocardial contraction and an enhancement of cardiac output. This is particularly important in emergency situations, such as anaphylaxis or cardiac arrest, where raising the heart rate can help maintain adequate blood flow and oxygen delivery to vital organs. The other choices reflect potential misunderstandings of epinephrine's pharmacological effects. For example, decreased blood viscosity is not a primary action associated with epinephrine; rather, it may relate to hydration status or other factors. Constricted airways would actually be the opposite of what occurs, as epinephrine causes bronchodilation to facilitate breathing. Lowered blood pressure is also inaccurate; in fact, epinephrine typically increases blood pressure through vasoconstriction effects on alpha-adrenergic receptors alongside its increase in heart rate. Thus, increasing heart rate is the primary and accurate effect associated with the administration of epinephrine.