Vasoactive agents

What is the primary job of the autonomic nervous system (sympathetic + parasympathetic)?

to prioritize blood flow to the essential/needed organs

Where are alpha 1 receptors located?

blood vessels

Where are beta 1 receptors located?

heart

Where are beta 2 receptors located?

lungs

What do alpha receptors cause?

vasoconstriction → increased BP

What do beta 1 receptors cause?

increased HR + contractility → increased BP

What do beta 2 receptors cause?

bronchodilation

What is the SVR (systemic vascular resistance)?

how constricted or dilated the vessels are (so vasoconstricted = higher SVR; vasodilated = lower SVR)

What is a normal SVR range?

800-1200

What would an SVR of 1400 signify?

vasoconstriction

What is the CO?

the amount of blood ejected from the ventricles each minute (HR x SV)

What is a normal CO range?

4-8L/min

What is the purpose of vasopressors?

to increase BP

How are most vasopressors administered?

IV infusion via a large-enough vein

What are the general side effects of vasopressors?

GI (n/v), SNS, limb necrosis

What are SNS side effects of vasopressors?

arrhythmias, angina, palpitations, dyspnea

When does limb necrosis occur with vasopressors?

if the vein isn’t large enough + breaks open OR vasoconstriction is too strong

What should you monitor in a patient receiving vasopressors?

HR, rhythm, BP, and MAP

What is the desired MAP when using vasopressors?

65

TRUE or FALSE: it is within the scope of nursing to titrate vasopressors according to the patient’s MAP.

true

Which two things should you check on the pump before administering a vasopressor?

• accurate weight/dose for weight

• accurate concentration (based on dose in mg/g, not mL)

Name the five vasopressor drugs to know.

• norepinephrine

• epinephrine

• phenylephrine

• midodrine

• vasopressin

What is the only PO vasopressor?

midodrine

Which two vasopressors are not weight-based?

midodrine + vasopressin

Which drugs are weight-based (mcg/kg/min)?

norepinephrine, epinephrine, phenylephrine (all of the “-ephrine’s”)

What does norepinephrine cause?

mostly vasoconstriction + some increased HR

What is the most common use for norepinephrine?

septic shock

TRUE or FALSE: epinephrine has a stronger effect on the heart than norepinephrine.

true

What is epinephrine used for?

anaphylaxis + cardiac arrest

What does phenylephrine do?

vasoconstriction ONLY

Which condition is phenylephrine used for?

distributive shock (where all of the body’s blood vessels become extremely dilated)

TRUE or FALSE: midodrine still has a risk of limb necrosis despite being a PO med.

false

TRUE or FALSE: midodrine does not need to be titrated.

true

Which part of the body does midodrine act on?

blood vessels only

Which two situations is midodrine used for?

weaning IV vasopressors OR prior to hemodialysis (if the patient’s BP keeps dropping during treatment)

Which condition is vasopressin used for?

septic shock (vasopressin)

TRUE or FALSE: vasopressin can be titrated.

false

How does vasopressin work?

it’s a synthetic version of ADH, so it retains fluid (which raises the BP indirectly)

Which situation is vasopressin used for?

when norepinephrine doesn’t work for septic shock

Give an example of inotropes.

dobutamine

When is dobutamine used?

HF + cardiogenic shock

How does dobutamine work?

it increases CO by increasing contractility

By which route is dobutamine given?

continuous IV infusion

What is the goal of using dobutamine?

to get CO up to 4+L/min

What are side effects of dobutamine?

SNS (arrhythmias, hypertension, angina, palpitations), headache, limb necrosis

How should dobutamine be administered?

in a large vein via a 20g catheter (preferably a CVL)

What should you monitor in a patient on dobutamine?

HR, rhythm, BP, and CO