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What is cardiac output?

Amount of blood pumped from the left ventricle in 1 minute.

Normal: 4-8 lpm
What is stroke volume?

Amount of blood pumped from the left ventricle in a single beat.

Normal: 60-130 ml/beat
What is Starling's Law?
Increased filling volume = Increased muscle stretch = Increased energy = Increased output (if the LV becomes too large Decreased SV)
What is preload?
The stretch on the muscle fibers before contraction
What is afterload?
The sum of the external factors that oppose ejection (tension of the chamber wall and peripheral resistance)
What does CVP reflect?
Measures right atrial mean pressure

During diastole, this pressure reflects the right ventricular and diastolic pressure.  Reflects the amount of blood returning to the heart and the ability of the heart to pump the blood into the arterial system.
What are the normal ranges for CVP?
1-6 mmHg

4-8 cmH20
What can be used to measure CVP and where is it located?
Central line: located in right atrium
Swan-Ganz catheter: proximal lumen
What are 3 factors that affect CVP?
How does contractility affect CVP?
Poor contractility prevents complete emtpying of the right ventricle, causing a rise in end diastolic pressure and a rise in CVP
How does afterload affect CVP?
Afterload= the resistance in pulmonary vessels; the pressure the right ventricle must overcome to deliver blood to pulmonary circulation

*Therefore, a rise in afterload, increases CVP
What can cause a low CVP?
Low CVP can be caused by an inadequate venous return due to low circulating blood volume:
*Hemorrhage (true loss)
*Sepsis (third spacing)
*Anaphylactic shock (vasodilation--blood is shunting to the peripheries)
What is third spacing?
Fluid is gathering in areas it shouldn't be
What can cause a high CVP?
*Poor contractility as in right ventricular infarction
*Failure of the venticle to relax as in constrictive pericarditis
*High afterload as in PE or COPD
*Positive pressure mechanical ventilation--PEEP or CPAP increase intrathoracic pressure which will increase CVP readings
What does PAP measure?
PAP measures the pressure of blood in the pulmonary artery, which affects the afterload pressure of the right ventricle
Normal ranges for PAP?
Systolic: 15-25 mmHg
Diastolic: 8-12 mmHg
What are factors that can affect PAP?
*Pulmonary blood flow
*Pulmonary vascular resistance
What can cause a low PAP?
Low PAP caused from inadequate venous return due to low circulating blood volume:
*Anaphylactic shock
What can cause a high PAP?
*Increased blood volume as in over-infusion of IV fluids
*Left to right intracardiac shunt as in an atrial or ventricular septal defect
*Pulmonary hypertension resulting from hypercapnia, acidemia, or hypoxemia
*PE or obstruction of pulmonary veins
*Mitral valve stenosis
*Left ventricular failure
What are three drugs that can be given to lower PAP?
What does PCWP measure?
Measures left atrial mean pressure and the left ventricular end diastolic pressure
Where and how is PCWP measured?
Located in pulmonary arteries

Balloon at the distal end of the catheter is inflated and it "wedges" in a brach of the pulmonary artery, blocking blood flow from the right side of the heart
Normal ranges of PCWP?
5-15 mmHg
What factors affect PCWP?
*Contractility (poor contractility causes a rise in PCWP because left ventricle doesn't completely empty)
*Afterload (rise in afterload increases PCWP)
What can cause a low PCWP?
Low PCWP caused by low circulating blood volume:
*Over-use of vasodilators
What can cause a high PCWP?
*Left ventricular failure
*Mitral valve stenosis
*Aortic valve stenosis
*Systemic hypertension
*High preload as in over-infusion of IV fluids
*Poor contractility as seen in left vent. infarction, aneurysm, hypoxemia, hypoperfusion of the heart
If there is an elevated PCWP, where does the problem exist?
Problems exist in left heart:
Examples of problems that could cause an elevated PCWP?
*Left atrial myxoma (prolapsing tumor)
*Mitral insufficiency or stenosis
*Left ventricular infarction
*Left ventricular aneurysm
*Fluid overload
*High systemic resistance
*Aortic insufficiency or stenosis
*Coarctation of the aorta
How is the severity of the problem determined with PCWP?
Severity of problem determined by number of elevated pressures:
*Only PCWP elevated--problem is minor
*PCWP & PAP elevated--problem is more severe
If only the PAP is elevated, where does the problem exist?
If only PAP is elevated, problem exists in pulmonary circulation due to pulmonary vasoconstriction or obstruction of flow
Examples of problems that would cause an elevated PAP?
*Allergic reactions
*Pos. pressure ventilation
*Primary pulmonary hypertension
IF CVP is elevated in conjunction with PAP?
Cor pulmonale exists
If only the CVP is elevated, where does the problem exist?
If only CVP is elevated, problem exists in right heart; usually results from tricuspid valve or right ventricular fluid overload or failure
Examples of problems that would cause CVP to rise?
*Right atrial myxoma
*Tricuspid insufficiency or stenosis
*Right vent. infarction
*Constrictive pericarditis
*Cardiac tamponade
*Left to right shunt
*Pulmonary insufficiency
Definition of Swan-Ganz catheter?
Multilumen, balloon-tipped, pulmonary aterial catheter
Purposes of Swan-Ganz catheter?
*Monitor CvP through proximal lumen
*Administer IV fluids through proximal lumen
*Draw blood of mixed venous gases through distal lumen
*Monitor PAP with balloon deflated
*Monitor PCWP with balloon inflated
*Measure Cardiac Output via thermister and themodilution technique
Swan-Ganz catheter insertion sites?
*Jugular vein
*Subclavian vein
*Antecubital vein
*Femoral vein
Potential complications of the Swan-Ganz catheter?
*Hematoma at insertion site
*Large airway obstruction
On a waveform, how do you know the Swan-Ganz catheter is inserted correctly?
You should see the Dicrotic Notch on the waveform.
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