Vasopressors 101: A Bedside Guide to the Common Agents

When fluids alone cannot restore a safe blood pressure in shock, vasopressors take over. These drugs tighten blood vessels, and some also strengthen the heart’s contraction, to defend perfusion of the brain, heart, and kidneys. This guide introduces the agents you will see most often in the ICU and the principles behind using them.

The Common Agents

• Norepinephrine: the first-line pressor for most shock, especially septic shock. A potent vasoconstrictor with modest cardiac stimulation.
• Vasopressin: a non-adrenergic agent often added to norepinephrine in septic shock to reduce the catecholamine dose.
• Epinephrine: strong vasoconstriction plus cardiac stimulation; used in anaphylaxis, cardiac arrest, and as a second-line pressor.
• Phenylephrine: a pure vasoconstrictor, useful when tachycardia or arrhythmia limits other agents.
• Dopamine: less favored today because of a higher risk of arrhythmias.
• Dobutamine: not a pressor but an inotrope; it boosts cardiac output in low-output states and is sometimes paired with a vasopressor.

Principles of Safe Use

First, treat the underlying cause and make sure intravascular volume is reasonable before leaning hard on pressors. The usual target is a mean arterial pressure of at least 65 mmHg, individualized to the patient. Pressors are ideally given through central access, since extravasation of potent vasoconstrictors can injure tissue. Watch closely for the downsides of excessive vasoconstriction: limb and gut ischemia, arrhythmias, and a rising lactate despite a normal-looking blood pressure.

The Bottom Line

Norepinephrine is the workhorse, vasopressin a common partner, and the others have specific roles. Vasopressors buy time and protect organs, but they are a bridge, not a cure: the priority is always to fix the cause of shock. For deeper, evidence-based hemodynamics guidance, explore more from the Interprofessional Critical Care Network.