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Inotropes in Cardiac Surgery

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Presentation on theme: "Inotropes in Cardiac Surgery"— Presentation transcript:

1 Inotropes in Cardiac Surgery

2 Basics

3 Cardiac Cycle Phase 1 - Atrial Contraction
Phase 2 - Isovolumetric Contraction Phase 3 - Rapid Ejection Phase 4 - Reduced Ejection Phase 5 - Isovolumetric Relaxation Phase 6 - Rapid Filling Phase 7 - Reduced Filling

4 Sympathetic / Parasympathetic
Sympathetic Parasympathetic Heart Chronotropy (rate) + + + _ _ _ Inotropy (contractility)   _ Dromotropy (conduction velocity) + + Vessels (Vasoconstriction) Resistance (vasoconstriction)   0 Capacitance (venous volume)

5 Starlings Law

6 BEFORE INOTROPES Fluid Rhythm Tamponade Bleeding Pneumothorax
Bolus Legs up Rhythm ECG, SR, slow, fast, paced on ventricle, ST’s, ectopics Tamponade CVP, BE, UO, temp, CXR, echo Bleeding Drains, CXR, Hb Pneumothorax CXR, examine, vent alarms Fight Ventilator Paralyse, sedate or extubate

7 Which Inotrope Ohms Law V=I x R BP=CO x SVR Simple terms
Low or high cardiac output, what is the PA pressure

8 Inotropes Atropine Ca2+ Dopamine Dopexamine Dobutamine Adrenaline
Noradrenaline Isoprenaline Enoximone Aminophylline Vasopressin Methylene blue NO

9 Receptors

10 Atropine Antimuscurinic ie causes tachycardia
Some pateints have muscurinic receptors on ventricle as well ie inotropic Increases HR CO=SV x HR

11 Ca2+ Inotrope and vasoconstrictor Short acting
Beware radial artery patients Warn patient if awake

12 Dopamine Acts on dopamine receptors on heart and kidney
Causes a tachycardia (CO=SV x HR) Increases urine output in some patients Less metabolic side effects compared with adrenaline Beware patients with tachycardia (give k+, Mg2+)

13 Dopexamine Tachycardia Increase splanchnic and renal blood flow
VASODILATOR Beware Vasodilated patients

14 Dobutamine Like dopamine
Has less effect on pulmonary artery pressure good for mitral valve patients

15 Adrenaline Excellent inotrope but dirty
Increased heart rate and inotropy (ß1-adrenoceptor mediated) Vasoconstriction in most systemic arteries and veins (postjunctional a 1 and a 2 adrenoceptors) Vasodilation in muscle and liver vasculatures at low concentrations (b2-adrenoceptor); vasoconstriction at high concentrations (a1-adrenoceptor mediated)

16 Adrenaline

17 Noradrenaline Vasoconstrictor
Increased heart rate and increased inotropy (ß1-adrenoceptor mediated) Vasoconstriction occurs in most systemic arteries and veins (postjunctional a 1 and a 2 adrenoceptors) Ask can I wake patient up to avoid Norad Must have a good cardiac output

18 Noradrenaline

19 Isoprenaline Causes tachycardia and vasodilatation
Good in patients with high PA pressures Beware vasodilated patients

20 Enoximone Phosphodiesterase Inhibitor
Good in patients with high PA pressure “2nd line when adrenaline having no effect “receptor dissociation”

21 Aminophylline Phosphodiesterase inhibitor
Main effect on lung compared to heart Good in patients who have hypoxic vasoconstriction “short fat little smoker with poor urine output”

22 Vassopresin 2nd line vasoconstrictor Most powerful available
Associated with organ ischaemia

23 Methylene blue Whatever the mechanism the final step of vasodilatation is NO Methylene blue inhibits NO synthesis

24 Nitric Oxide


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