Vasoactive drugs

Question 1

Only inotrope that can be bolused

Answer 1

adrenaline in cardiac arrest

Question 2

Adrenaline receptors and effects at low / high dose?

Answer 2

ß and α adrenoreceptors. Positive Inoptope

In a low dose infusion the ß effects predominate, leading to an increase in heart rate, contractility and cardiac output.

In high doses the α effects predominate,
leading to vasoconstriction and an increase in blood pressure.

Question 3

Adrenaline disadvantages

Answer 3

Excessive tachycardia, dysrhythmias, myocardial ischaemia, hyperglycaemia,
lactic acidosis (which is usually transient)

Question 4

How long onset of action ionotropes

Answer 4

All inotropes/vasopressors work within 1-2 minutes and their effect wears off within minutes

Question 5

Noradrenaline receptors and effects?

Answer 5

• α1 vasoconstriction and increasing SVR. -> increases BP (perfusion pressure).
• ß1 contractility and heart rate.

Question 6

noradrenaline disadvantages

Answer 6

Excessive vasoconstriction seen as blue/ black peripheries, dysrhythmias, myocardial ischaemia

Question 7

main uses noradrenaline

Answer 7

improvement of BP in septic shock.

Used in neuro ICU patients to increase BP to maintain cerebral perfusion pressure.

Question 8

main uses adrenaline

Answer 8

cardiac arrest

anaphylaxis (stabilise mast cells and prevent further histamine release as well as treat hypotension.)

Shock of unknown origin

Question 9

Dopamine receptors

Answer 9

α, ß, and dopamine receptors to varying degrees.

non specific inotrope/vasopressor that can be used to increase cardiac output and SVR.

Question 10

Dopamine disadvantages

Answer 10

Excessive tachycardia and dysrhythmias

Question 11

When use dopamine

Answer 11

positive inotrope to increase cardiac output and provide vasoconstriction at higher doses.

Rx of Bradycardia -5-10mcg/kg/min (B1 receptor ↑HR)
Rx of Shock: 10-20mcg/kg/min (B1+A1 - ↑CO and vasoconstriction)

Used in septic shock in some centres.

Question 12

Dobutamine receptors ? effect?

Answer 12

ß receptors leading to an increase in heart rate and contractility together with vasodilatation mediated via the ß2 receptors.

The net effect is an increase in cardiac output

Question 13

Dobutamine disadvantages

Answer 13

Hypotension, tachycardia

Question 14

Dobutamine uses

Answer 14

Low cardiac output states especially cardiogenic shock

Question 15

how does GTN work ?

Answer 15

In a low dose it acts as a venodilator, thus offloading the heart and reducing preload.

In higher doses it acts as an arterial dilator, thus reducing afterload.

The net effect is to improve the function of the myocardium and cardiac output by reducing both preload and afterload.

It also causes relaxation of the coronary arteries and is therefore useful in angina.

Question 16

For shock of unknown cause use?
For septic shock use ?
For cardiogenic shock use ?

Answer 16

For shock of unknown cause use adrenaline.

For septic shock use noradrenaline.

For cardiogenic shock use dobutamine.

Question 17

Meteraminol class? receptor ?

Answer 17

synthetic amine 
Primarily A1 (with some b action)

Question 18

Metaraminol use ?

Answer 18

Rx of anaesthesia / spinal hypotension

Can be given peripherally 20 mg metaraminol in 40 mL 0.9% NaCl), which can be given peripherally at an infusion rate up to 20 mL/h

Question 19

Key side effects meteraminol

Answer 19

decrease HR / CO

Question 20

Noradrenaline dosing in sepsis

Answer 20

4 mg made up to 40 mL

with 5% glucose started at 5 mL/hour and titrated up or down against response.

Question 21

Dobutamine dose in low CO? if not working?

Answer 21

250 mg made up to 50 mL with normal saline, started at 5 mL/hour and titrated up or down according to response.

If the response to dobutamine is not adequate, consider adrenaline, 5 mg made up to 50 mL with normal
saline, started at 5 mL/hour and titrated up or down.

Question 22

In a hypotensive patient after beta-blocker overdose: drug? dose?

Answer 22

Glucagon,

20 mg made up to 40 mL with 5% glucose, infused at 0–20 mL/hour according to response.

Question 23

Basic a / b / v / dopamine receptors and action

Answer 23

a1 - peripheral vessles - constriction -> increase SVR

b1 - myocardium - chronotrophy / ionotrophy

b2 - pulmonary / vessels - bronchodilation / vasodilation

v1- vessels - constriction

v2 - kidney - fluid retention

Dopamine - vessels and kidney - dilation - decrease MAP

Question 24

inotrophy vs chronotrophy

Answer 24

inotropy- force of contraction

chronotrophy - heart rate

Question 25

2 main classes of ionotropes

Answer 25

catecholamines - Eg adrenaline, dobutamine, dopamine

phosphodiesterase inhibitors - milrinone

Question 26

Milrinone uses ? side effects

Answer 26

ionotropic

Vasodilation
Has long half life vs other inotropes

Question 27

in a hypertensive patient, with normal or high heart rate: ? dose ?

Answer 27

Labetalol,

which is available as 100 mg in 20 mL, given neat at a rate of 5–30 mL/hour according to response.

Question 28

In a hypertensive patient in whom beta blockers are contraindicated: drug? dose?

Answer 28

glyceryl trinitrate (GTN), premixed at 1 mg/mL, given at a rate of
1–20 mL/hour.