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Exam 3- Hemodynamics
Terms in this set (45)
What is the Frank-Starling Law?
The greater the stretch, the greater force of the next contraction
How does the Frank Starling Law relate to preload?
if there is too little preload (stretch) as in hypovolemia, the heart will not have enough stretch to propel the blood (cardiac output) through the body. If volume increases, the more preload (stretch) the heart will have and will contract with more force
How does pressure in the heart work?
Blood flows from areas of higher pressure to areas of lower pressure
What is the cardiac cycle? AKA systole and diastole.
Both the atria and the ventricles have filling phases (diastole) and contraction phases (systole); During diastole the left and right ventricles receive blood from the atria; During systole the ventricles squeeze blood from the heart to the aorta and the pulmonary artery.
What is the Atrial Kick? What dysrhythmia would mess with is?
Active atrial contraction forces additional volumes of blood into the ventricles; usually 20% of CO is because of atrial kick
What does systolic BP tell us? Diastolic? MAP?
How is MAP calculated?
MAP = 2(diastolic) + 3 all divided by 3
It represents the average systemic arterial pressure during the ENTIRE CARDIAC CYCLE; 70-100 mmHg; MUST BE ABOVE 60 for organs to perfuse
What is cardiac output?
Amount of blood the heart pumps per minute.
Determined by stroke volume and heart rate.
Approximately 70cc with each stroke at an average rate of 72 strokes per minute.
What is the Cardiac Index?
a hemodynamic measure that
relates the cardiac output (CO) to body surface area (BSA)
. This relates heart performance to the
size of the individual
Cardiac index = cardiac output / body surface area
. If the CI falls
below 1.8 L/min/m2
, the patient may be in cardiogenic shock.
What are hemodynamics?
A term to describe intravascular pressure, oxygenation, and blood flow occurring within the cardiovascular system.
What are the goals of hemodynamic monitoring?
Maintain adequate tissue perfusion by assessing the body's response to tissue oxygen demands. Alert the healthcare team of an impending cardiovascular crisis before organ injury occur. Evaluate immediate response to treatment modalities.
How do we measure hemodynamics?
manual blood pressure, arterial blood pressure (used for unstable patients), central venous pressure, left atrial pressure, pulmonary wedge pressure, SVO2, and cardiac output measurement
What are indications for hemodynamic monitoring?
Dehydration; Hemorrhage; GI Bleed; Burns; Surgery; Acute MI; Cardiomyopathy; Shock: all types: septic, cardiogenic, neurogenic, anaphylactic; Congestive Heart Failure
amount of blood filling the ventricle before they contract
also known as "filling pressures"
What is reflected by the PCWP (pulmonary capillary wedge pressure)? What is the only way to get a PCWP?
Left Ventricular Preload (or filling)
The only way we can get a PCWP is if the patient has a pulmonary artery catheter
What is reflected by the CVP (Central Venous Pressure)? How do we get a CVP?
Right ventricular preload (or filling)
We get CVP from central lines
What is Left ventricular end-diastolic VOLUME?
The VOLUME left in the ventricle when the mitral valve closes determines the amount of blood ejected into the systemic circulation; only empties 60-70%...EJECTION FRACTION
What Increases Preload?
Increased circulating volume
Mitral valve insufficiency
Tap vasoconstrictor use
What decreases Preload?
Decrease circulating volume
Mitral valve stenosis
Asynchrony of atria and ventricles
What is Contractility?
the strength of the cardiac muscle to push blood from the ventricles against the systemic vascular resistance/blood pressure of the patient.
What medications influence contractility?
What is Afterload?
the ventricles must pump against in order to eject their volume or
How hard the heart [either side left or right] has to push/pump to get the blood out of the ventricles
What medications affect afterload?
ACE Inhibitors decrease afterload
Levophed increases afterload
What is Systemic Vascular Resistance?
reflects left ventricular afterload
What is Pulmonary Vascular Resistance?
reflects right ventricular afterload
What is the major factor that influences SVR?
major factor that influences SVR is the lumen (diameter) of the vessel
What is Ejection Fraction?
Basic parameter for evaluation of the
of the heart
EF = SV / EDV (end-diastolic volume)
Should be over 50%
What are the most common invasive hemodynamic monitoring devices?
Central venous lines
Swan-Ganz lines/PA lines
What is an Arterial Line? Who is it preferred in?
used to monitor systemic blood pressure/systemic vascular resistance. The radial artery is most commonly used for arterial line placement; USED for MONITORING ONLY, NEVER GIVE MEDS IN THIS; An invasive technique for monitoring arterial blood pressure; Preferred in unstable patients because it is accurate and continuous
What must be done prior to inserting an Arterial line and explain the method. When is this test considered negative?
Allen's Test Procedure
- this makes sure the ulnar artery is patent
Raise the patient's hand and ask them to make a fist. Occlude both radial and ulnar arteries by applying pressure with your fingers. Instruct the patient to clench their fist a few times and take note of blanching or paleness that will occur. Release pressure from the ulnar artery, while maintaining pressure on the radial artery. If the ulnar artery is patent, you will see the hand color return (then release pressure from the radial artery).
If it takes more than 5-10 seconds for color to return after you have released pressure from the ulnar artery, the Allen's Test is considered negative and that radial artery should not be used.
What is the bedside monitor?
amplifier is located inside. The amplifier increases the size of signal
What is the Transducer?
changes the mechanical energy or pressures of pulse into electrical energy; should be level with the phlebostatic axis; this tells us if the A-line is working
What is Central Venous Pressure (right atrial monitoring)?
direct measure of the right atrium pressure;
REFLECTS RIGHT VENTRICULAR DIASTOLIC PRESSURE
; Assess blood volume; reflects preload to the right side of the heart; Assess right ventricular function; Infusion site for large fluid volume; Infusion site for hypertonic solutions
How do we know CVPs are in the correct place?
What is a Swan-Ganz catheter?
Often we do not put these in but occasionally it is the only way to tell us the
pressure in the LEFT side of the heart
; Normally has four ports (can have another proximal lumen for fluids or medication infusion)
What is the anatomy and process of inserting a Swan-Ganz catheter?
A balloon tipped catheter is inserted percutaneously into the subclavian vein. The Swan-Ganz catheter is slowly advanced toward the right atrium.
When it enters the right atrium the balloon is inflated.
The catheter floats back into the pulmonary artery and remains in this position for continuous monitoring.
What is the Phlebostatic Axis?
the anatomical area which the nurse should LEVEL to the stopcock. The phlebostatic axis is located at the 4th intercostal space, mid-axillary line. This is the location of the right atrium. Best practice is to always use a leveling device.
What are the functions of the catheter?
Continuous hemodynamic monitoring, assessing vascular tone, myocardial contractility, and fluid balance. Measures PAP, CVP, and allows hemodynamic calculations. Cardiac output can be determined using thermodilution. Transvenous pacing
What is the problem with a right ventricular waveform?
If the swan falls or gets pulled back into the RV it is considered a swan emergency.
If you see an RV waveform (looks like VT) pull the swan immediately.
If the swan remains in the RV it may cause the patient to go into VT.
What is the PCWP?
PCWP is an indirect measurement of left ventricular end diastolic pressure.
What are possible complications of an catheter inserted?
Increased risk of infections - same as with any central venous lines—use occlusive dressing and Biopatch to prevent
Thrombosis and emboli-- air embolism may occur when the balloon ruptures, clot on end of catheter can result in pulmonary embolism
Catheter wedges permanently—considered an emergency, notify MD immediately, can occur when balloon is left inflated or catheter migrates too far into pulmonary artery (flat PA waveform)...can cause pulmonary infarct after only a few minutes!
Ventricular irritation - occurs when catheter migrates back into RV or is looped through the ventricle, notify MD immediately...can cause VT
What are the nursing implications of catheter care?
Prevent or reduce the potential for complications.
Maintain 300mmHg on bag
(Need to maintain 300 on pressure because the arterial line is a high pressure system!! If we don't have enough pressure it will not maintain)
Maintain continuous flow through tubing
Aseptic dressing change
Sterile caps on openings
Change tubing q 96 hrs.
AT LEAST 5 min hold on discontinued site
What does low RAP indicate?
Low RAP indicates hypovolemia that may be attributed to dehydration, acute blood loss, extreme vasodilation (as in sepsis)
What does high RAP indicate?
High RAP indicates severe vasoconstriction, fluid overload, pulmonary hypertension
What comes first?
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