Paramedic National Registry Practice

What is the primary effect of adrenergic drugs?

1. Decrease heart rate

2. Increase afterload

3. Reduce blood pressure

4. Minimize oxygen consumption

The correct answer is: Increase afterload

The primary effect of adrenergic drugs is primarily associated with their ability to stimulate the sympathetic nervous system. These drugs can lead to an increase in heart rate and cardiac output, which in turn can contribute to an increase in afterload, as the heart works harder against the increased vascular resistance. Adrenergic drugs achieve this by activating adrenergic receptors, which can lead to vasoconstriction in the peripheral vasculature, thereby raising the systemic vascular resistance that the heart must pump against. While adrenergic drugs can have varying effects depending on the specific type (e.g., alpha vs. beta agonists), their overall action often includes increasing blood pressure through these mechanisms. This is particularly important in situations of shock or severe hypotension, where adrenergic agents can effectively restore hemodynamic stability by augmenting systemic vascular resistance and improving perfusion. Other answer choices do not accurately capture the primary action of these drugs in physiological context. For instance, adrenergic drugs do not minimize oxygen consumption as a primary effect, rather they often increase cardiac workload, which could lead to higher oxygen demand.