Vasoconstrictors

Nursing Knowledge

Vasoconstrictors

Vasoconstrictors are used to constrict blood vessels, leading to increased systemic vascular resistance and therefore elevated blood pressure. They are important in managing conditions like hypotension, shock, and migraines. Important points include minding drug interactions and avoiding adverse effects.

Last updated: October 9, 2024

What are vasoconstrictors?

Definition

Vasoconstrictors are medications used to narrow (constrict) blood vessels, which leads to an increase in blood pressure.

How do vasoconstrictors work?

Vasoconstrictors often work by stimulating receptors on the smooth muscle cells of blood vessels. As the blood vessels constrict, the resistance to blood flow (systemic vascular resistance, SVR) increases. According to the formula for blood pressure (BP = CO [cardiac output] x SVR [systemic vascular resistance]), an increase in SVR directly increases blood pressure if cardiac output remains constant.

Indications

Vasoconstrictors can be used to treat cardiovascular collapse, refractory hypotension, and allergic reactions.

What is peripheral vasoconstriction?

Peripheral vasoconstriction is the narrowing of blood vessels specifically located outside the heart and brain, particularly those in the extremities (arms and legs).

How does peripheral vasoconstriction maintain homeostasis?

Increasing the resistance to blood flow in the peripheral arteries and therefore raising blood pressure helps maintain adequate perfusion of vital organs. Focusing perfusion and conserving heat to the vital organs instead of the extremities is helpful in emergency situations. In cases of severe blood loss, peripheral vasoconstriction helps maintain blood pressure.

Overview of vasoconstrictors

Norepinephrine

Effects:

Peripheral vasoconstriction
Works on alpha 1 and beta 1 cells
Increase in contractility at higher amounts

Adverse effects:

Small vessel injury
Decrease in organ perfusion
Increase in lactic acid
Extravasation injury

Common doses:

Range: 0.01–0.2 mcg/min
First-line medication

https://youtube.com/shorts/Tk9tdiuq-4g?si=6W1qiE-S8fV2T9EO

Phenylephrine

Effects:

Vasoconstriction
Works on alpha 1 cells
Only works on arteries, not venous

Adverse effects:

Small vessel injury
Decrease in organ perfusion
Decrease in CO from increased SVR
Reflex bradycardia

Common doses:

Range: 5–180 mcg/min
No effect on contractility, good choice for tachycardia/arrhythmias
Third-line medication

Angiotensin II

Effects:

Vasoconstriction
Natural hormone in body, typically converted from angiotensin I in the lungs

Adverse effects:

Small vessel injury
Decrease in organ perfusion
DVT
Reflex bradycardia

Common doses:

Range: 1.5–80 ng/kg/min
Delayed onset of action, no or slow titration
Third-line medication

Vasopressin (ADH)

Effects:

Vasoconstriction
Natural hormone in the body
Antidiuretic

Adverse effects:

Small vessel injury
Decrease in organ perfusion
Increase in lactic acid
Decrease in CO from increased SVR
Decrease in urine output

Common doses:

Range: 0.01–0.04 mcg/min
Delayed onset of action, no or slow titration

Natural vasoconstrictors

In some cases, natural vasoconstrictors can be of interest for example for clients with migraines looking for alternative options. Well-known natural vasoconstrictors that could help reduce pain in clients looking for natural remedies include:

Caffeine in moderation
Peppermint
Cold compresses

Nursing considerations for vasoconstriction medications

Screen for drug interactions: beta adrenergic blockers, antidepressants, anti-HTN, cardiac glycosides
Common goal is achieving a mean arterial pressure of (MAP) 60–65 mm Hg.
Should be used at the lowest effective dose to avoid adverse effects
May require invasive methods to closely monitor hemodynamic effects: arterial line, central venous cath, or pulmonary artery cath

Vasodilators

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