Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Anaesthetic FRCA Primary - eLFH Pharmacology > eLFH - Inotropes and Vasopressors > Flashcards

eLFH - Inotropes and Vasopressors Flashcards

(61 cards)

Start Studying
1
Q

Inotrope definition

A

Drugs which increase myocardial contractility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Vasopressor definition

A

Drugs which cause peripheral arteriolar vasoconstriction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Mean arterial pressure equation

A

MAP = CO x SVR
= HR x SV x SVR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Systemic vascular resistance definition

A

Resistance to blood flow throughout the systemic peripheral vasculature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Systemic vascular resistance vs Afterload

A

Both often interchanged as SVR is the only part of afterload that can be manipulated

Afterload is a theoretical concept which includes SVR and LV outflow obstruction (e.g. aortic stenosis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Determinants of Stroke volume

A

Preload

Contractility

Afterload

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Preload definition

A

Measure of initial stretch on cardiac myocytes prior to contraction (i.e. end of diastole)

Amount of stretch determines number of myocardial cross bridges available to interact during contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Contractility definition

A

Intrinsic ability of cardiac muscle fibres to change the force of contraction independent of preload and afterload

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Inotropy definition

A

Change in force of myocardial contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Afterload definition

A

Force required by the myocardium to eject the stroke volume during systole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Chronotropy definition

A

A change in the heart rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Determinants of heart rate

A

Autonomic innervation - sympathetic and parasympathetic

Circulating catecholamines

Hormones (e.g. thyroxine)

Electrolytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Starling’s law

A

Force of myocardial contraction is proportional to the initial fibre length, up to a certain point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Closest physiological variable that can represent preload

A

LV end diastolic volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Closest physiological variable that can represent force of contraction

A

Stroke volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Methods of assessing LVEDV

A

Cannot be routinely measured

Surrogate markers to assess it are:
- Echo
- Central venous pressure
- Pulmonary wedge pressures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Starling’s curve

A

Increasing preload causes increase in SV up to a certain point and then myocardial failure occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Effect of inotropes on Starling’s curve

A

Inotropes shift curve up and to left

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Effect of increased afterload on Starling’s curve

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Effect of sympathetic stimulation on cardiac output

A

Acts via beta 1 (and to lesser extent beta 2) adrenergic receptors in the heart

Causes positive inotropy and chronotropy

beta adrenergic receptor stimulation increases available cAMP intracellularly, which results in increased intracellular calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Overall common final pathway of all inotropic drugs

A

Increasing intracellular calcium to increase force of myocardial contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Mechanisms of action of inotropes

A

Beta 1 and Beta 2 adrenoreceptor stimulation (sympathomimetics)

Phosphodiesterase inhibition

Other mechanisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Sympathomimetic inotrope examples

A

Adrenaline
Dopamine
Dobutamine
Isoprenaline
Dopexamine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Adrenaline as an inotrope

A

Non selective agonist of all adrenergic receptors

Low dose infusion has inotropic beta effects

Increasing adrenaline dose increases alpha adrenoreceptor agonism

Laeva isomers are 15x more potent than dextro isomers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Side effect of adrenaline as inotrope
Diastolic BP can drop due to beta 2 agonism linked to peripheral vasodilatation
26
Isoprenaline as inotrope
Potent beta 1 and beta 2 agonist Increases CO but afterload / SVR can drop due to beta 2 agonism Commonly used for bradyarrhythmia
27
Methods of administration of isoprenaline
Usually IV can also be inhaled or PO
28
Dopamine as inotrope
Low dose infusion mainly beta 1 agonism Higher doses increase alpha agonism Does not cross blood brain barrier Stimulates noradrenaline release
29
Side effect of dopamine as inotrope
Nausea and vomiting - acts on chemoreceptor trigger zone via D2 receptors Inhibits prolactin secretion Vasodilatation of renal and mesenteric beds by peripheral D1 receptor activation Increases atrio-ventricular conduction and can cause tachycardia at higher doses
30
Dobutamine as inotrope
Structurally similar to isoprenaline Mainly beta 1 agonism with some beta 2 and alpha 1 action Half life 2 mins
31
Side effect of dobutamine as inotrope
Decreases LV end diastolic pressure via beta 2 agonism Beta 2 linked vasodilatation reduces venous return and SVR
32
Dopexamine as inotrope
Analogue of dopamine Action on beta 2 and D1 receptors Minimal beta 1 action and no alpha 1 action Causes inotropy via cardiac beta 2 agonism
33
Side effect of dopexamine as inotrope
Peripheral vasodilatation reduces SVR / afterload via peripheral beta 2
34
Phosphodiesterase inhibitor mechanism of action
Phosphodiesterases breakdown cyclic adenosine monophosphate (cAMP) Inhibition of phosphodiesterase therefore increases intracellular cAMP and thus calcium levels
35
Predominant phosphodiesterase isoenzymes working in the myocardium
Phosphodiesterase types III and IV
36
Selective Phosphodiesterase III inhibitor examples
Enoximone Milrinone
37
Non-selective phosphodiesterase inhibitor examples
Aminophylline Therefore also has some positive inotropic effects
38
Administration of enoximone and milrinone
IV as infusion +/- loading dose Cause peripheral vasodilatation - often require co-administration of vasopressor to maintain BP
39
Other mechanism inotrope examples (usually not first line)
Levosimendan Digoxin Glucagon Calcium Thyroxine (T3)
40
Levosimendan as inotrope
Increases myocyte sensitivity to calcium by binding to troponin C Relaxes smooth muscle by opening ATP sensitive potassium channels causing peripheral vasodilatation Used in severe acute cardiac failure
41
Digoxin as inotrope
Inhibits Na+/K+ ATPase pump, increasing myocyte intracellular Na+ Therefore decreases inward movement of sodium via Na+/Ca2+ exchanger pump Therefore increases intracellular calcium Used in chronic cardiac failure
42
Glucagon as inotrope
Glucagon receptors are Gs protein linked Activation increases intracellular cAMP Used in beta blocker OD
43
Calcium as inotrope
IV calcium transiently improves cardiac output and BP Effect is short lived Used in cardiac arrest secondary to hyperkalaemia or calcium channel antagonist overdose
44
Thyroxine (T3) as inotrope
Positively inotropic and chronotropic Via intracellular Ca2+ ATPase pump (probably) Not used for its inotropy
45
Use of vasopressors
Treat hypotension secondary to reduced SVR
46
Mechanisms of action of vasopressors
Alpha 1 adrenergic receptor agonism Vasopressin receptor activation
47
Structure of adrenoreceptors
7 transmembrane G protein couples receptors
48
Site of alpha 1 adrenoreceptors
Smooth muscle of peripheral vasculature
49
Alpha 1 agonism vasopressor examples
Noradrenaline Ephedrine Metaraminol Phenylephrine
50
Noradrenaline as vasopressor
Alpha 1 agonism with some beta 1 agonism Minor inotropic action which is offset by baroreceptor reflex vagal response to increased BP causing drop in HR
51
Ephedrine as vasopressor
Mixed alpha and beta stimulation Works directly and indirectly by displacing noradrenaline from storage granules Also inhibits monoamine oxidase (MAO) Crosses blood brain barrier and placenta
52
Function of Monoamine oxidase
Breaks down noradrenaline Therefore MAO inhibitors (e.g. ephedrine and Parkinson's medications) reduce noradrenaline break down and therefore lower doses of vasopressor required
53
Side effect of Ephedrine
Tachyphylaxis occurs as noradrenaline stores depleted
54
Administration of Ephedrine
IV Can be PO
55
Phenylephrine as vasopressor
Potent alpha 1 agonist No effect on beta receptors Causes reflex bradycardia due to baroreceptor response
56
Metaraminol as vasopressor
Mainly alpha 1 with some beta action Direct and indirect actions by causing noradrenaline release
57
Side effects of Metaraminol
Increases pulmonary vascular resistance Tachyphylaxis as noradrenaline stores depleted
58
Vasopressin synonyms
Anti-diuretic hormone (ADH) Arginine vasopressin (AVP)
59
Site of vasopressin receptors
Throughout body Including vascular smooth muscle cells
60
Features of vasopressin receptors
Gq protein coupled Stimulation of V1 receptors causes peripheral vasoconstriction
61
Use of vasopressin
Second line vasopressor for severe septic shock

Anaesthetic FRCA Primary - eLFH Pharmacology (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions