Positive Inotropes - Quiz 3 Flashcards by Donny Le

What are the CV Effects of Septic Shock?

↑Cardiac Index

↓SVR

↓PCWP

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What are the CV Effects of Hypovolemic Shock?

↓Cardiac Index

↑SVR

↓PCWP

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What are the CV Effects of Cardiogenic Shock?

↓Cardiac Index

↑SVR

↑PCWP

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What happens to Intracellular cAMP w/ CHF?

Decreased cAMP

Beta Receptor Downregulation & Impaired Coupling

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What does CHF respond to?

Preload & Afterload Reduction

Improved Contraction

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What happens w/ Low Cardiac Output Syndrome after coming off Cardio-Pulmonary Bypass?

Inadequate O2 Delivery

Hemodilution

Hypocalcemia

Hypomagnesemia

Kaliuresis

Tissue Thermal Gradients

Variable SVR

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What risk factors contribute to Low Cardiac Output Syndrome (LCOS)?

> 65 y.o.

Female

Decreased LVEF

Prolonged Cardio-Pulmonary Bypass > 6hrs

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What might Hypotension in the setting of LCOS NOT respond to?

Vasodilators Alone

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What is the Goal when treating LCOS?

↑O₂ Delivery (SvO₂) > 70%

↑O₂ Consumption

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What causes Low Cardiac Output Syndrome?

Stunned Heart in response to Ischemia & Reperfusion

Beta Receptor Downregulation

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What classes of Positive Inotropes are cAMP Dependent?

Beta Agonist

Dopaminergic Agonists

PDE Inhibitors

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What classes of Positive Inotropes are cAMP Independent?

Cardiac Glycosides

Calcium

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What is Levosimendan used for and how does it work?

LCOS Treatment & Prophylaxis - Calcium Sensitizer to existing calcium in the body

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What do Pure Beta-1 Agonists (Inodilators), like Dobutamine & Isoproterenol do?

↑HR

↑AV Condution

↓SVR & PVR (Beta-2)

Variable O₂ Consumption Effects

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What do Mixed Alpha/Beta Agonists like NE, Epi, & Dopamine do?

↑SVR

↑HR

↑Myocardial O₂ Consumption

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What are complications from using Postive Inotropes?

Prolonged High Doses = Reduced Perfusion

Tachyarrhythmias

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What are the problems w/ using Digoxin?

Narrow Therapeutic Index

Renal Failure

Bradycardia

Drug Interations

Caution w/ Hypokalemia

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Which med has the most risk of causing Arrhythmias from most to least?

Isoproterneol > Epi > Dopamine > Dobutamine

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What do cAMP Dependent Inotropes do?

↑Calcium Influx

↑Calcium Sensitivity

↑Contraction

↑Relaxation

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What do low doses (1-2 mcg/min) of Epinephrine do?

Beta 2 Stimulation - > Vasodilate to ↓SVR, but MAP stays the same

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What do Intermediate doses (4 mcg/min) of Epinephrine do?

Beta-1 Stimulation - Inotrope

↑HR

↑Contractility

↑Cardiac Output

↑Automaticity

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What do High Doses (> 10 mcg/min) of Epinephrine do?

Alpha 1 Stimlulation

Potent Vasoconstriction –> Reflex Bradycardia

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Which receptors does Norepi act on?

ALPHA 1 > Beta 1

Minimal Beta 2

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How does Norepi affect Cardiac Output at Low Doses?

↑Cardiac output

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Why do High Doses of Norepi decrease Cardiac Output?

↑Afterload & Reflex Bradycardia

Which receptors does Isoproteronal act on?

Beta 1 & Beta 2

What does Isoproterenol do?

↑CO, HR, Contractility, and Automaticity ↓SVR & DBP Bronchodilation

When should Isoproterenol be avoided?

In Cardiogenic Shock & Ischemic Heart Disease

When is Isoproterenol used?

S/P Heart Transplant Complete Heart Block Bronchospasms Pulm. HTN RV Failure

What are the Off-Label uses for Isoproterenol?

Torsades Ventricular Arrhythmias Short QT Syndrome

What class of drug is Dobutamine?

Synthetic Catecholamine that acts primarily on **BETA 1** Receptors w/ Very Little Beta 2 & Alpha 1 effects

What does Dobutamine do?

Dose Dependent ↑CO & ↑HR ↓Fillling Pressures Dilate Coronary Vessels NO Dopamine Receptor effects

What dose of Dobutamine would cause Tachycardia & Dysrrhythmias?

\> 10 mcg/kg/min

Why should Dobutamine & Dopamine be mixed in D5W instead of NS?

NS Inactivates these meds

What happens with D1 & D5 Receptor stimulation?

Stimulates Adenylate Cyclase & cAMP **Vasodilation** Naturesis Diuresis

What happens w/ D2, D3, & D4 Receptor stimulation?

_Inhibits_ Adenylate Clases & cAMP Inhibit Norepi Release **Vasodilation** ↑Renal Blood Flow

What does Low Dose (1-3 mcg/kg/min) Dopamine do?

Renal Dose - D1 & D2 effects Inhibits Aldosterone **NOT RENAL PROTECTIVE**

What does a 3-10 mcg/kg/min dose of Dopamine do?

Beta Effect ↑Contractility & CO **WITHOUT** HR & BP Changes Indirectly Releases Norepi

What does a 10-20 mcg/kg/min dose of Dopamine do?

Alpha \> Beta Effects | (Alpha starts to take over)

Which receptor is effected with Dopamine doses \> 20 mcg/kg/min?

Alpha

How does Dopamine affect Ventilation during Hypoxia?

↓Ventilatory Response d/t Carotid Body Inhibition

How does Dopamine affect Blood Sugar?

Hyperglycemia

What are some side effects of Dopamine?

N/V Angina Headache Tachyarrhythmias HTN

Which receptor does Fenoldopam act on?

Mostly D1 Some Alpha 2

What are the effects of Fenoldopam?

↓SVR ↑Renal Blood Flow (NOT Renal Protective) Reflex Tachy

How does Fenoldopam compare with Sodium Nitroprusside?

Same Effectiveness for BP Control, but also ↑RBF

How does Fenoldopam compare w/ Dopamine?

10-100x more potent

How should Fenoldopam be adminstered?

Slow Titration No Bolus

What are the side effects of Fenoldopam?

Headache Flushing Restless Legs N/V T-Wave Inversion

What do PDE3 Inhibitors like Milrinone & Inamrinone do?

↓cAMP breakdown = ↑Calcium & ↑Calcium Sensitivity ↑Cardiac Output Vasodilation

How does Inamrinone compare to Dobutamine?

More Effective & Less Complications

How does Inamrinone compare to Epi?

Same Effectiveness, but even more if *added* to Epi

When should Inamrinone be avoided?

**Thrombocytopenia** Elevated LFTs Arrhythmias **Aortic Stenosis**

How does Milrinone compare to Inamrinone?

15-20x more potent Shorter Half-Life No Thrombocytopenia risk

What are the side effects of Milrinone?

Hypotension Syncope Arrhythmias V-Tach w/ AFib/Flutter

Which receptor does Glucagon work on?

Increases cAMP via Glucagon Receptor, NOT Beta

What are the CV effects of Glucagon?

↑CI ↑HR ↑BP ↓SVR ↓LVEDP

What are the side effects of Glucagon?

↑Blood Sugar ↑Coronary & Pulmonary Vascular Resistance

How do Anticholinergic Meds affect Glucagon?

Enhances the GI Side Effects (N/V)

How does Glucagon affect clotting times?

Vitamin K Antagonist --\> Increases INR

What is Digoxin?

A Cardiac Glycoside w/ the effects of Positive Inotrope & Negative Dromotrope & Chronotrope

How does Dixogin work?

Inhibits Na/K-ATPase Pump & causes Calcium to remain in the Myocyte

When is Digoxin used?

Heart Failure & A-Fib

What is the Therapeutic Range of Digoxin?

0.8 - 2 ng/mL

What conditions increases the risks of Digoxin Toxicity?

Hypokalemia Hypomagnesemia Hypoxemia Hypothyroid Hypercalcemia

How does Digoxin Toxicity present?

Anorexia N/V Paroxysmal Atrial Tach w/ Block Mobitz II Block **_V-Fib_**

What is the Antidote for Digoxin Toxicity?

**Digibind** - Antibody Fragments that bind to drug and decrease Digoxin levels via Kidneys

What is the Strategy for treating Low Cardiac Output?

1. **Optimize Preload** - Venous Dilators, Fluids 2. **Optimize Afterload** - Arterial Dilators, then Inodilator 3. **Add Inotrope** 4. **IABP or LVAD**