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78 Cards in this Set

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  • Back
What is the formula for constriction of blood vessels?
Pressure = Flow x resistance (MAP) = Cardiac Output (flow) x Peripheral resistance (systemic)
How much cardiac output is the atrial kick responsible for?
Without atrial kick, you only passive motion of blood to veins
How much of the cardiac cycle is systole vs diastole?
systole = 1/3
diastole = 2/3
What are the three phases of ventricular systole?
1. Isometric contraction (isovolumetric contraction)
2. Rapid ventricular ejection
3. Reduced ventricular ejection
What are the four parts of ventricular diastole?
1. Isovolumetric relaxation
2. Period of rapid filling
3. Period of slow filling
4. Atrial systole, which provides the atrial kick
What is cardiac output?
The volume of blood in liters pumped by the heart in 1 minute.
What is the cardiac index?
Measurement of the Cardiac Ouput (CO) adjusted for Body Surface Area (BSA). It is a more precise measurement of the efficiency of the pumping action of the heart.
What is the stroke volume? Stroke volume index?
Stroke volume is the volume ejected with each heartbeat. Stroke volume index is adjusted for BSA.
What determines BP?
Cardiac output and the Systemic Vascular Resistance (SVR), which is the opposition encountered by the Left Ventricle.
What is Pulmonary Vascular Resistance (PVR)?
The resistance to blood flow encountered by the Right Ventricle.
What is Left Ventricular End-Diastolic Pressure a measure of? What is the measure tool?
Left ventricular Pre-load (amt of L Ventricle stretch)
PAWP measures pulmonary capillary pressure and, under normal conditions, measures Left Ventricular Pre-load
Mitral Valve dysfunction, Intracardiac defect or dysrhythmia interferes with this measure
What is CVP?
Central Venous Pressure
Measured in the Right Atrium or the Vena Cava close to the heart
Equates to the Right Ventricular Pre-load or Right Ventricular End-Diastolic Pressure
Tricuspid Valve dysfunction, Intracardiac defect or dysrhythmia interferes with this measure
What is Frank-Starling's law?
Explains the effects of preload and states that the more a myocardial fiber is stretched during filling, the more it shortens during systole and the greater the force of the contraction. As preload increases force generated in the subsequent contraction increases, thus SV and CO increase. The increased myocardial stretch causes greater O2 need of the myocardium. Stretched out sweat pants analogy.
What is after load?
Refers to the forces opposing ventricular ejection, including systemic arterial pressure, the resistance offered by the aortic valve, and the mass/density of the blood being moved.
What is preload?
The volume within the ventricle at the end of diastole.
What are the measures of after load?
SVR and arterial pressure = left ventricular after load.
PVR and pulmonary arterial pressure = right ventricular after load.
Increased after load often results in decreased CO.
Vasodilators will reduce after load
What is contractility? How do you measure it?
The strength of the contraction of the heart. Said to increase when the preload is unchanged but the heart contracts more forcefully. Positive Inotropes increase contractility. Negative inotropes decrease it, i.e., beta blockers, Ca++ channel blockers, alcohol, acidosis.
No direct measures of contractility; measuring CO and PAWP indirectly measures. If preload, HR, and after load remain constant then contractility is changed.
What is the phlebostatic axis?
The point at which the transducer is placed (4th intercostal space and mid-chest).
What are you measuring with an arterial line?
systolic, diastolic and mean BPs
What does a Pulmonary Artery Flow-Directed Catheter measure, i.e. Swan-Ganz?
PA pressure -- PA diastolic pressure and PAWP with balloon inflation (Left Ventricular preload); SvO2; CVP at the right atrium
These measures increase with heart failure and fluid volume overload; decreases with volume depletion
The distal lumen sits in the PA
What is the normal range for SvO2 in the L ventricle? Right atrium?
Left ventricle = 95-99%
Right atrium = 60-75%
What do you test to measure fluid status?
CVP and Wedge pressure
(and lung sounds)
What is normal cardiac output? Cardiac index?
4 - 8 L/min (rough depending on size of patient)
2.5 - 5.0 L/min/m2
What is a normal wedge pressure (PAWP/PCWP)?
8-12 or 10-12
Low PCWP = dehydration
High PCWP = Fluid overload
18-20 = onset of pulmonary congestion
20-25 = moderate
25-30 = severe congestion
>30 pulmonary edema
What is a normal CVP (Right Ventricular preload)
2-6 mmHg
What conditions increase preload? Basic treatments?
-Congestive heart failure
-Hypercoloid (elevated proteins)
-Volume displacement
-ACE inhibitors
Afterload = BP. True?
False. It is a component of BP. SVR is after load

left Ventricular after load = SVR
Right Ventricular after load = PVR (not common in adults)
What is a normal SVR? PVR?
SVR = 800-1200 dynes/sec/cm5
PVR = 200 dynes/sec/cm5
Can you have low BP and have high after load?
Yes due to low cardiac output (Low BP) and vasoconstriction (high SVR); can also have high SVR and be in a hypertensive crisis
What conditions decrease preload? Basic treatments?
- Hypovolemia
- increased intrathoracic pressure
- Cardiac tamponade
- Tachydysrhythmias
- Loss of atrial kick (a-fib)
- Crystalloid solutions (LR, NS)
- Colloid solutions (albumin, plasmanate)
- Blood or blood products
-Adjust vasodilators (decrease nitrates)
What conditions increase afterload? Basic treatments?
- Vasoconstriction
- Aortic Valve Disease
- Hypercoaguability
- Arterial vasodilators
- ACE inhibitors
- Phosphodiesterase inhibitors
- Intraaortic balloon pump
- Pulmonary vasodilators
- O2 to reduce Right ventricular after load (reducing work of lungs)
What conditions decrease afterload? Basic treatments?
- Vasodilation
Treatment: vasopressors to increase afterload
What conditions increase contractility? Basic treatments?
- sympathetic nervous system stimulation
- Beta blockers
- Ca++ channel blockers
What conditions decrease contractility? Basic treatments?
- Myocardial ischemia or infarction
- Cardiomyopathy
- Hypoxemia & acidosis
- Negative inotropes
- Cardiac glycosides (digoxin)
- Sympathomimetics
- Phosphodiesterase inhibitors (milrinone)
- Calcium
- Glucagon
What conditions increase heart rate?
- sympathetic stimulation
- Cardiac glycosides (digoxin)
- beta blockers
- CCBs
- Overdrive pacing
- Vagal maneuvers
What conditions decrease heart rate?
- parasympathetic stim
- Conduction abnormalities
- Sympathomimetics
- Parasympatholytics, ie, atropine
- Pacemaker
What are complications of PA catheters?
- During insertion (tickling SA node, can temp or perm stop working; v-tach from right ventricle; infection)
- During monitoring (movement)
- During removal (make sure not embedded in PA; could result in PE or air embolism
What are the impacts of inotropic medications?
Increase myocardial contractility, primarily
As that happens, following also occurs:
- Ventricular emptying increases
- Filling pressure of the heart decreases
- Stroke volume increases
- Cardiac output increases
- Increases BP
- Improves tissue perfusion
Negative, Increases:
- myocardial O2 demand
- workload of the heart
- vascular resistance
**used for shock and low cardiac output syndromes
What are the classes of inotropic medications?
Cardiac glycosides = digoxin
Sympathomimetics = stimulate adrenergic receptors
- natural catecholamines (epinephrine, dopamine, norepinephrine)
- Synthetic: (dobutamine, neosynephrine, phosphodiesterase inhibitors = milrinone)
What are the drugs most commonly used for cardiogenic shock with hypotension?
Dopamine (moderate dose)
What are the drugs most commonly used for cardiogenic shock, caused by cardiac failure, with normotension?
Dopamine (low dose)
Epinephrine (low dose)
What are the drugs most commonly used for septic shock with hypotension?
Dopamine (low-mod)
What are the most commonly used drugs for hypovolemic shock?
Blood products
What are the most commonly used drugs for shock related to bradycardia?
What is the most commonly used drug for anaphylactic shock?
What is dopamine used for?
Hypotensive arrest
NOT for septic shock
Heart failure (use with caution)
Increase renal perfusion
Correct hemodynamic imbalance in shock syndrome
What receptors are activated by Dopamine?
Alpha (increases with dose)
Beta 1 (peaks and then effect declines high dose)
Beta 2 (low-moderate, not dose-dependent)
What are the cardiovascular effects of dopamine?
- Increases cardiac output (most with low dose, diminishing response with high dose)
- Increases heart rate (most with moderate dose)
- increases SVR (most with high dose)
What receptors are activated by Dobutamine?
- Alpha (NO effect)
- Beta 1 (high activation with all doses)
- Beta 2 (Moderate activation)
What are the cardiovascular effects of Dobutamine?
- Increases Cardiac Output
- Increases heart rate (effect increases with dose)
- DECREASES SVR (reason it is good for pump failure)
Where are alpha receptors located and what is the response to stimulation?
Located on vessels of skin and kidneys
vasoconstriction of peripheral arterioles to shunt blood
Where are beta1 receptors located and what is the response to stimulation?
Located in cardiac tissue
Increase HR, conduction, and contractility
Where are beta2 receptors located and what is the response to stimulation?
Located in vascular and bronchial smooth muscle
Vasodilation of peripheral arterioles
What receptors are activated by epinephrine?
Alpha (response is higher with higher dose)
Beta 1 (response peaks with moderate dose)
Beta 2 (response is moderate with any dose)
What are the cardiovascular effects of epinephrine?
- Increases CO (highest response with moderate dose)
- Increases HR (moderate response with high dose)
- Increases SVR (moderate response with high dose)
What receptors are activated by Norepinephrine?
Alpha (response is higher with higher dose; higher than epinephrine)
Beta 1 (moderate response with any dose)
Beta 2 (No response)
What are the cardiovascular effects of Norepinephrine?
- Increases CO (low response)
- Increases HR (low response)
- Increases SVR (very high response) good for septic shock to reduce vasodilation
What receptors are activated by Phenylephrine?
Alpha (high response)
Beta 1 (No response)
Beta 2 (No response)
What are the cardiovascular effects of Phenylephrine?
- DECREASES CO (low response)
- DECREASES HR (low response)
- Increases SVR (very high response)
Why is dobutamine the best choice for pump failure or with dopamine for MI/shock?
- Primarily beta1 effects
- mild beta2 effects with mild vasodilation
- increases contractility without increasing HR, B/P or SVR
Why is Norepinephrine (levophed) used for septic shock? What are primary adverse effects?
- Increases CO
- Increases SVR
Adverse effects:
- arrhythymias, HTN, chest pain
- anxiety
- respiratory distress (even tho no Beta 2 effect)
What are epinephrine and phenylephrine typically used for?
- Code situation/shock
- Very potent alpha stimulator
- Increases BP without stimulating myocardium
- Increases SVR
** watch peripheral circulation; use heat packs if color/pulses/cap refill are diminshed
What is milrinone typically used for?
- Strictly for pump failure; usually acute exacerbations
- Positive inotrope and vasodilator
- Increases CO (contractility and decreased after load)
** Incompatible with Lasix
How do vasodilators work on after load and preload?
Afterload reduction:
- arterial dilation, results decreased resistance to ventricular ejection; may improve CO without increasing myocardial O2 demand
Preload reduction:
- venous dilation to increase capacitance; results in decreased filling pressure for the failing ventricle
What are the effects of nitroglycerin?
Arterial and venous dilation; at low doses, mainly VENOUS; at high doses, mainly ARTERIAL
Adverse effects: postural hypotension, headache, reflex tachy
***Antagonist to Heparin!!! (if both given together, PTT appears elevated until nitro stopped and then dangerous high PTT)
What are the effects of niprusside (nitride)?
Very potent venous and arterial vasodilator
Used for hypertensive crisis; decrease after load in pulmonary edema and heart failure
Avoid in renal failure - breaks down to thiocyanate (psychosis, tinnitus, coma)
Avoid in liver failure - breaks down to cyanide (almond smell on breath)
** MIX only with D5W, not NS; protect from light
What is Phentolamine (regitine) used for?
alpha adrenergic antagonist used in treatment of dermal necrosis after extravasation
What drugs should ideally be given through a central line?
- dopamine
- epinephrine
- levphed
- neosynephrine
What is shock?
Failure of the circulatory system to maintain adequate perfusion of vital organs
What are the three stages of shock?
1. Compensatory (non-progressive)
- maintain CO, vasoconstriction, decreased urine, tachycardia
2. Reversible (progressive)
3. Irreversible
- Multiple organ damage
- Endotoxin release
What is cardiogenic shock?
shock caused by pump failure, i.e., MI, PE, valve dysfunction, dysrhythmias (filling/emptying defects); occurs when >40% of myocardium is involved
What are the phases of septic shock?
Early or Warm phase: total vasodilation, Low BP, resistant to fluid resuscitation, low urine, tachypnic; expect PA cath to be low <800, CO will be high 8-10 bc so much fluid floating around but too vasodilated to move.

Late or Cold phase: vasoconstriction, hypotension, altered mental status, poor outcomes
What is the defining feature of neurogenic shock?
What are the hemodynamic changes for cardiogenic shock?
HR: Increased
Stroke volume: Decreased
CO: Decreased
SVR: Increased
PAWP: Increased
CVP: Increased
What are the hemodynamic changes for hypovolemic shock?
HR: Increased
Stroke volume: no change or decreased
CO: decreased
SVR: increased
PAWP: decreased
CVP: decreased
What are the hemodynamic changes for septic shock (warm or hyperdynamic)?
HR: Increased
Stroke volume: Increased
CO: Increased
SVR: Decreased
PAWP: decreased
CVP: decreased
What are the hemodynamic changes for septic shock (cold or hypodynamic)?
HR: Increased
Stroke volume: decreased
CO: decreased
SVR: increased
PAWP: increased
CVP: increased
What are the hemodynamic changes for neurogenic shock?
HR: decreased or normal
Stroke volume: no change
CO: decreased
SVR: decreased
PAWP: decreased
CVP: decreased