Positive Inotropes - Quiz 3 Flashcards
What are the CV Effects of Septic Shock?
↑Cardiac Index
↓SVR
↓PCWP
What are the CV Effects of Hypovolemic Shock?
↓Cardiac Index
↑SVR
↓PCWP
What are the CV Effects of Cardiogenic Shock?
↓Cardiac Index
↑SVR
↑PCWP
What happens to Intracellular cAMP w/ CHF?
Decreased cAMP
Beta Receptor Downregulation & Impaired Coupling
What does CHF respond to?
Preload & Afterload Reduction
&
Improved Contraction
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
What risk factors contribute to Low Cardiac Output Syndrome (LCOS)?
DM
> 65 y.o.
Female
Decreased LVEF
Prolonged Cardio-Pulmonary Bypass > 6hrs
What might Hypotension in the setting of LCOS NOT respond to?
Vasodilators Alone
What is the Goal when treating LCOS?
↑O2 Delivery (SvO2) > 70%
&
↑O2 Consumption
What causes Low Cardiac Output Syndrome?
Stunned Heart in response to Ischemia & Reperfusion
&
Beta Receptor Downregulation
What classes of Positive Inotropes are cAMP Dependent?
Beta Agonist
Dopaminergic Agonists
PDE Inhibitors
What classes of Positive Inotropes are cAMP Independent?
Cardiac Glycosides
&
Calcium
What is Levosimendan used for and how does it work?
LCOS Treatment & Prophylaxis - Calcium Sensitizer to existing calcium in the body
What do Pure Beta-1 Agonists (Inodilators), like Dobutamine & Isoproterenol do?
↑HR
↑AV Condution
↓SVR & PVR (Beta-2)
Variable O2 Consumption Effects
What do Mixed Alpha/Beta Agonists like NE, Epi, & Dopamine do?
↑SVR
↑HR
↑Myocardial O2 Consumption
What are complications from using Postive Inotropes?
Prolonged High Doses = Reduced Perfusion
Tachyarrhythmias
What are the problems w/ using Digoxin?
Narrow Therapeutic Index
Renal Failure
Bradycardia
Drug Interations
Caution w/ Hypokalemia
Which med has the most risk of causing Arrhythmias from most to least?
Isoproterneol > Epi > Dopamine > Dobutamine
What do cAMP Dependent Inotropes do?
↑Calcium Influx
↑Calcium Sensitivity
↑Contraction
↑Relaxation
What do low doses (1-2 mcg/min) of Epinephrine do?
Beta 2 Stimulation - > Vasodilate to ↓SVR, but MAP stays the same
What do Intermediate doses (4 mcg/min) of Epinephrine do?
Beta-1 Stimulation - Inotrope
↑HR
↑Contractility
↑Cardiac Output
↑Automaticity
What do High Doses (> 10 mcg/min) of Epinephrine do?
Alpha 1 Stimlulation
Potent Vasoconstriction –> Reflex Bradycardia
Which receptors does Norepi act on?
ALPHA 1 > Beta 1
Minimal Beta 2
How does Norepi affect Cardiac Output at Low Doses?
↑Cardiac output
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?
- Optimize Preload - Venous Dilators, Fluids
- Optimize Afterload - Arterial Dilators, then Inodilator
- Add Inotrope
- IABP or LVAD