Therapeutics I Exam V (Pressors) Flashcards
Vasopressors, Inotropes, Coronary Artery Disease, and Heart Failure
What is end-diastolic volume?
This is the volume of blood in the ventricles at the end of diastole. It is the amount of blood that fills the entire ventricle before it contracts.
What is preload?
Preload refers to the amount of stretch experienced by the heart muscle (myocardium) before it contracts. It is a measure of the volume of blood in both ventricles at the end of diastole.
What is afterload?
Afterload is the pressure/resistance the heart must pump against to get blood out of the ventricles.
What is stroke volume?
This is the volume of blood ejected from the ventricles during systole with each heartbeat.
100% saturation of oxygen on a red blood cells is ________ molecules of oxygen.
4
Define hemodynamics?
It describes the global mechanics and performance of the circulatory system. It is the driving force behind the supply and perfusion of blood to maintain tissue and cellular oxygen delivery.
What is the goal of hemodynamics?
Maintain tissue viability and function, adequate tissue perfusion, and adequate oxygen delivery.
The ______________ valve separates the right atria and right ventricle.
Tricuspid valve
The ____________ valve separates the right ventricle and the pulmonary artery.
Pulmonary semilunar valve
The ______________ valve separates the left atria and left ventricle.
Bicuspid valve
The __________ valve separates the left ventricle and the aorta.
Aortic semilunar
Anaerobic metabolism is a mismatch between what two things?
Mismatch between oxygen delivery and oxygen demand
What is Ohm’s Law?
Flow (perfusion) = Pressure/ Resistance
What defines the presence or absence of global shock?
Blood pressure
What is the global marker of hemodynamics?
Blood pressure
What is the equation for the mean arterial pressure?
MAP= Cardiac output x systemic vascular resistance
MAP= CO x SVR
What two things go into cardiac output?
CO= Heart rate x stroke volume
What 3 things go into stroke volume?
Preload, contractility, and afterload
____________ and _____________ are directly related to stroke volume.
Preload and contractility
_________ is inversely related to stroke volume.
Afterload
Afterload/ vascular resistance represents what?
Vascular tone
Systemic vascular resistance is the afterload of the __________ heart.
Left heart
Pulmonary vascular resistance is the afterload of the ________ heart.
Right heart
What is cardiac output?
The measure of ventricular contractile performance. It is the volume of blood pumped by the ventricle per minute.
What is the cardiac index?
This is cardiac output that accounts for body surface area (BSA). Normal range is 2.5-4 L/min/m^2
What is the normal range for cardiac index?
2.5-4 L/min/m^2
What is the normal range for cardiac output?
4-6 L/min
Two individuals present with the same cardiac output being 4.5 L/min. However, the smaller person has a cardiac index of 2.6 while the bigger person has a cardiac index of 1.8. Which person is worse off?
The cardiac index of 1.8 is worse off compared to the cardiac index of 2.6.
What is the normal stroke volume?
45-60 mL/beat
Using the frank-starling curve, what are the associations between preload (EDV) and stroke volume or cardiac output in healthy patients?
In a person with a healthy heart, as preload/EDV increases so does stroke volume or cardiac output until a certain point.
Using the frank-starling curve, what are the associations between preload (EDV) and stroke volume or cardiac output in heart failure or cardiogenic shock patients?
In a person with HF or cardiogenic shock, increasing fluid will actually decrease cardiac output due to fluid overload.
What are the 4 major determinants of cardiac output?
Heart rate, stroke volume, afterload, and preload
Oxygen delivery (DO2) is related to what 3 things?
Cardiac output, concentration of hemoglobin, and saturation of hemoglobin with oxygen.
What are vasopressors?
Vasopressors are agents that cause arterial and venous vasoconstriction. Vasopressors are used for states with decreased vascular tone.
What are inotropes?
Agents that directly or indirectly cause myocardial force of contraction. Inotropes are used for states with decreased or insufficient cardiac output.
When are vasopressors used?
Vasopressors are used in states of decreased or insufficient vascular tone.
When are inotropes used?
States of decreased or insufficient cardiac output.
What are inodilators?
Inodilators increase the stroke volume and cardiac output by directly stimulating myocardial contractility and reducing afterload through systemic vasodilation.
What are inopressors?
What is iontropy?
Inotropy is the force of contraction of the heart.
What is chrontropy?
Chronotropy is the heart rate
What is an inotrope?
An inotrope is a drug that causes increased myocardial contractility. It increases cardiac output (cardiac index).
What is a chronotrope?
A chronotrope is a drug that increases the heart rate.
Vasopressors increase __________ __________ resistance.
Systemic vascular via narrowing of blood vessels.
Where are V1 receptors located (Vasopressin 1 Receptor)?
Peripheral vasculature
Where are the V2 receptors located (Vasopressin 2 Receptors)?
Renal Collecting Duct
When V1 receptors are activated, what occurs to the peripheral vasculature?
Vasoconstriction (increases SVR)
When V2 receptors are activated, what occurs to the renal collecting duct?
Water retention
What type of receptors are V1 and V2 receptors?
G-protein coupled receptors
Under normal conditions, what is the function of vasopressin (ADH)?
Vasopressin is released when blood volume has decreased and plasma osmolarity has increased. When released, it tells the kidneys to reabsorb water to increase blood volume. It also is a vasoconstrictor that increases blood pressure.
Alpha 2 receptors are located in the ____________ site. What happens when you activate this receptor?
Presynaptic site
Alpha-2 are autoreceptors that when activated, they inhibit the release of catecholamines therefore allowing for vasodilation.
What are the goals of vasopressor/inotropic therapy?
- Maintain organ perfusion (MAP >65 mmHg)
- Maintain adequate oxygen delivery
To increase systemic vascular resistance directly, what 2 classes of medications can be used?
Alpha-1 agonist or vasopressin
(activating alpha 1 on vasculature causes vasoconstriction and vasopressin activates V1 receptors on peripheral vasculature to cause vasoconstriction as well)
To increase cardiac output/cardiac index and stroke volume, what class of medications are used?
Beta-1 agonist
What is the indication for use for inopressors and inodilators?
These are indicated when a person has adequate intravascular volume but inadequate tissue perfusion.
What are 3 drugs/natural catecholamines that are inopressors (inotropes and vasopressors both)?
Epinephrine, norepinephrine, and dopamine
What are the 2 drugs that are inodilators (inotropes and vasodilators)?
Milrinone and dobutamine
Inopressors (inotropes and vasopressors both) increase both _______ and ______.
CO and SVR
Inodilators (inotropes and vasodilators) increase _______ but decrease ________.
Increase CO but decrease SVR
What are the 2 vasopressors we need to know?
Phenylephrine and vasopressin
What type of medication is dopamine?
Inopressor
T or F: Dopamine has dose-dependent pharmacology
True. Dopamine hits different targets at different doses
What is the historic low-dosing for dopamine and what receptors does it target?
3-5 mcg/kg/min
This dose targeted dopamine receptors in kidneys causing renal dilation leading to increased urine output (diuresis). This dose has been disproven.
What is the moderate dosing for dopamine and what receptors does it act on?
5-10 mcg/kg/min
This dose targets beta-1 on the heart in addition to dopamine receptors in the kidneys. The beta-1 activation increases both inotropy and chronotropy (increase in CO and HR)
What is the high dosing for dopamine and what receptors does it act on?
10 mcg/kg/min
This dose targets alpha-1 as well in addition to beta-1 and dopamine receptors in the kidneys. The alpha-1 activation causes vasoconstriction. This increases systemic vascular resistance in addition to cardiac output and heart rate.
When is the only time that dopamine is actually used in a clinical setting?
Hypotensive (shock) and bradycardic patients
What are the 4 main adverse effects of dopamine?
Tachycardia
Arrhythmias
Limb and gut ischemia
Neurohormonal abnormalities
T or F: Low dose dopamine (3-5 mcg/kg/min) is recommended.
False. This low of a dose is not recommended and has been disproven to be a ‘renal dose’.
T or F: Patients on any type of ‘pressor’ are NPO due to the high risk for gut ischemia.
True
What medication is the gold standard for anaphylactic shock?
Epinephrine
(Epi is 2nd line for septic shock after maxed out on norepinephrine)
T or F: Epinephrine does not have dose dependent pharmacology.
False. At different doses, epinephrine acts at different receptors.
What is the low dose for epinephrine and what receptor does it act on?
2-10 mcg/min
This dose acts only on beta-1 receptors to increase inotropy and chronotropy
What is the high dose for epinephrine and what receptors does it act on?
> 10mcg/ min
This dose acts on beta-1 and alpha-1 causing increases inotropy, chronotropy, and systemic vascular resistance through alpha-1 activation.
What medication is indicated in all cardiac arrest algorithms?
Epinephrine
What are the adverse effects of epinephrine?
Catabolism; hyperglycemia
tachycardia
arrhythmias
Increase myocardial O2 demand
Myocardial ischemia
Lipolysis
Limb and gut ischemia
What is the brand name for norepinephrine?
Levophed
T or F: Norepinephrine has dose-dependent pharmacology.
True
What is the normal dose of norepinephrine and what receptors does that dose act on?
2-10 mcg/min
This dose acts on alpha-1 to induce vasoconstriction therefore increasing systemic vascular resistance
What is the high dose of norepinephrine and what receptors does that dose act on?
> 10 mcg/min
This dose acts on beta-1 in addition to alpha-1 to increase inotropy and chronotropy which increases cardiac output and heart rate.
Out of the 3 inopressors, which is least likely to cause tachycardia?
Norepinephrine
Which inopressor is used for undifferentiated shock?
Norpeinephrine
What is the first line medication for septic shock?
Norepinephrine
What are the 3 adverse effects of norepinephrine?
Limb and gut ischemia
Tachycardia
Arrhythmias
What are 3 side effects that are consistent among all inopressors (dopamine, epi, and NE)?
Limb and gut ischemia, tachycardia, and arrhythmias
What are the 2 vasopressors we need to know?
Phenylephrine and vasopressin
What are the 4 inotropes we need to know?
There are no ‘only’ inotrope medications we need to know for this exam. We need to know inodilators and inopressors specifically.
What is the MOA of phenylephrine?
It is a vasopressor that is selective for alpha-1 receptors on blood vessels resulting in vasoconstriction.
What is the brand name for phenylephrine?
Neosynephrine
T or F: Phenylephrine has dose-dependent pharmacology.
False. Phenylephrine has no dose dependent pharmacology
Phenylephrine only acts on alpha-1 receptors to cause vasoconstriction. In response, what does the heart do?
Due to the increased blood pressure from the vasoconstriction, the heart will slow down due to reflex bradycardia.
What is the main indication for use of the vasopressor phenylephrine?
Patients with tachyarrhythmias
What are the 2 adverse effects of phenylephrine?
Limb and gut ischemia and bradycardia
The vasopressin V1a receptor activation causes potent _______________.
Vasoconstriction
The vasopressin V2 receptor activation causes ________ ___________.
Water retention
When is vasopressin used?
Vasopressin is used in adjunct in catecholamine-refractory therapy. This means that if the inopressors like epi, NE, or dopamine are not working, vasopressin can be added on to allow the body to better response to the catecholamines.
What is the dosing for vasopressin?
Fixed dose of 0.03-0.04 units/minute
What are the 2 adverse effects associated with vasopressin?
Myocardial ischemia and gut ischemia
Which medication is the first-line agent for cardiogenic shock?
Dobutamine
Why is dobutamine the first-line agent for cardiogenic shock?
It is an inodilator meaning it increases stroke volume and cardiac output but decreases preload and afterload.
What is the MOA for dobutamine?
This is an inodilator. It is a synthetic catecholamine that is beta selective (beta 1 and beta 2). It works by increase SV and CO while decrease preload and afterload.
What are the 4 main adverse effects seen with dobutamine?
Tachycardia
Atrial and ventricular arrhythmias
Myocardial ischemia
Hypotension
What is the MOA of milrinone?
This is an inodilator that is a phosphodiesterase-III inhibitor. It works by increasing cAMP levels in beta-1 and beta-2 effector cells. It works by increasing SV, CO and decreasing preload and afterload
T or F: Milrinone is less likely to cause tachycardia compared to dobutamine.
True
When is milrinone used?
Cardiogenic shock
When is milrinone considered for a dose reduction?
Renal failure
What are the 4 adverse effects associated with milrinone?
Thrombocytopenia
hypotension
ventricular arrhythmias
mild tachycardia
What is the dosing for dobutamine?
2-20 mcg/kg/min
What is the dosing for milrinone?
0.3-1.5 mcg/kg/min
