Vasoactive Drugs

Question 1

What are some of the classes of vasoactive drug?

Answer 1

Inotrope - increase cardiac contractility - seperate from preload and afterload

Vasopressors - increase vascular tone (used to increase BP), often increase preload

Vasodilators - decrease vascular tone/Blood pressure and decrease afterload

You can have

• pure inotropes
• inotropes + vasopressors
• inotropes + vasodilators
• pure vasopressors

Question 2

Name some examples of different drugs in each classification

Answer 2

Pure inotrope

• doesn’t exist
• levosimendan (calcium sensitiser - inodilator
• high dose insulin
• glucagon

Inotrope and vasocontrictor

• increase contractility and vascular tone
• adrenaline in ICU (high dose)
• ephedrine in anaesthetics

Inotrope and vasodilator

• increase contractility and relax vascular tone
• used for poor LV or RV
• e.g. milrinone/dobutamine/low dose adrenaline

Pure vasoconstrictor

• increase vascular tone and BP
• increasing afterload/preload helps with coronary perfusion
• e.g. noradrenaline and vasopressin
• e.g. metaraminol and phenylephrine in short term

Pure vasodilator
- GTN, hydralazine, NA nitroprusside

Question 3

What are some factors to consider when choosing vasoactive drugs?

Answer 3

• indication (vasodilatory shock vs cardiogenic)
• contraindications (adrenaline and high lactate)
• route
• user preference

Question 4

Patient comes in with septic shock due to pneumonia - what would be your choice agent, why?

Answer 4

Noradrenaline - reduces systemic vascular resistance due to sepsis.

• improved vascular tone will improve cardiac output
• alpha 1 agonist active will result in vasoconstriction
• ECHO in sepsis to determine cardiac function (no end organ hypoperfusion depsite adequate BP)

Vasopressin - could be added if high dose norad needed

Question 5

Patient comes in with severe chest pain - anterior STEMI. with cardiogenic shock.

Answer 5

Adrenaline - beta 1 agonist (positive inotropy) and alpha 1 agonist (vasoconstriction)
to increase cardiac contractility
- to increase coronary artery perfusion increase SVR and diastolic BP

adrenaline can increase lactate.

Dobutamine infusion (racemic mixture) - beta1 adrenoceptor (increase HR) and beta 2 adrenoreceptor (decrease SVR)

Question 6

Patient post total hip with a massive PE and subsequent acute R) heart failure

Answer 6

Milrinone - pulmonary vasodilation and reduces RV afterload - increasing cardiac output without increasing cardiac O2 consumption

Dobutamine - compared to milrinone has higher tachy-arrhythmias