CC EXAM 1 Hemodynamics Part 1

suniguka's version from 2016-02-10 05:34


Resources: Hemodynamic Monitoring


Question Answer
1. Hemodynamics is Measurement ofpressure, flow, and oxygenation within the cardiovascular system
2. Purpose of hemodynamic monitoringhow well the heart is meeting the needs of the body for blood and oxygenation
b. Helps to diagnose and manageheart failure
c. Helps to guidetherapy


Question Answer
1. Cardiac Output (CO)volume of blood pumped by heart in one minute
CO =heart rate x stroke volume (volume of blood ejected with each heart beat)
Normal value CO4-8 liters/minute
2. Cardiac IndexMeasurement of the CO adjusted for body surface area (BSA)
Normal value CI 2.2-4 liters/min/m2
3. PreloadVolume in the ventricle at the end of diastole
Pressure measurements are an indirect measurement ofvolume
Preload is increased byfluid administration; decreased by diuresis
a. Preload in left side of the heart is measured byLeft Ventricular End-Diastolic Pressure (LVEDP) or Pulmonary Artery Wedge Pressure (PAWP)
Normal value LVEDP/PAWP 6-12 mm Hg
High LVEDP/PAWPleft sided heart failure
Low LVEDP/PAWPdehydration
b. Preload in the right side of the heart (a low pressure system) is measured byCentral Venous Pressure (CVP) or Right Atrial Pressure (RAP)
Normal value CVP/RAP2-8 mm Hg
High CVP/RAPright sided heart failure; volume overload
Low CVP/RAPdehydration
4. AfterloadForces opposing ejection of blood from ventricles
Primarily 3 Afterload Forces 3Systemic blood pressure, Resistance offered by aortic valve, Mass/density of blood to be ejected forward
a. Afterload in the left side of the heart is measured byArterial blood pressure and Systemic Vascular Resistance (SVR)
ABP/SVRtells the nurse the overall state of the system vascular bed (constricted or dilated)
Normal SVR 800-1200 dynes/sec/cm(-5)
High SVR vasoconstricted systemic vascular bed
Low SVR vasodilation
Nursing considerations related to afterloadReducing afterload can improve cardiac output, because it is easier for the heart to eject blood forward if the blood vessels are dilated vs. constricted.
b. Afterload in the right side of the heart is measured by 2Pulmonary Artery Pressure (PAP) and Pulmonary Vascular Resistance (PVR)
Normal PAP 25/4-12 mm Hg (mean 10-20 mm Hg)
Normal PVR <250 dynes/sec/cm(-5)
High PAP/PVR Pulmonary hypertension
5. ContractilityDescribes the strength of cardiac contraction
Positive inotropes improve contractility
Negative inotropes decrease contractility
If preload, heart rate, & afterload remain constant yet CO changescontractility is altered
Heart failuredecreased contractility
Types of Invasive Pressure Monitoring (2)1. Arterial blood pressure (arterial line or “art line”) direct measurement of blood pressure. 2. Pulmonary artery flow-directed catheter (Refer to Figure 66-7 on page 1743 of Lewis)
Pulmonary artery flow-directed catheter measures (5)a. Pulmonary artery pressure measurement, b. Central venous or right atrial pressure measurement, c. LVEDP/PAWP measurement, d. Cardiac output measurement, e. Mixed venous hemoglobin oxygen saturation measurement


Components of Pressure Monitoring System (Pulmonary Artery Catheter or Arterial Line)
(Refer to Figure 66-3 on page 1740 of Lewis)
Question Answer
1. Catheter inserted intoartery (BP measurement) or heart (PA Catheter measurements)
2. Pressure tubing
3. Flush solution in pressure bag
4. Transducer Air/fluid interface that converts pressure measured into graphic/digital printout on bedside monitor
5. Pressure cable going to monitor
6. Stopcocks allow for blood sampling



Principles of Invasive Pressure Monitoring
1. Referencing (Refer to Figure 66-4 on page 1741 of Lewis)
Question Answer
Position the transducer so that theair-fluid interface is at the level of the left atrium this is referred to as the phlebostatic axis
– Phlebostatic Axis PositioningHorizontal line drawn through midchest with Vertical line drawn through 4th ICS at sternum.
– Mark chest with a permanent marker once the axis is found.
– Laser pointer or carpenter’s level should be used tolevel the transducer to the phlebostatic axis.
2. Zeroing (4)This is done during initial set-up of hemodynamic monitoring equipment, after insertion of an arterial line; if cables get disconnected, or any time accuracy of readings is questioned.
To Zero equipmentOpen stopcock to room air, turn off to patient, check that monitor reads “zero”.
3. Dynamic Response Test (Square Wave Test) (Refer to Figure 66-4 in Lewis)Done every 8-12 hours to check that the equipment produces a distortion-free signal.
DRT/Square Wave testThis tells you that the system correctly reflects pressures that are being measured
4. Cardiac Output Measurement (using thermodilution method)5-10 ml. cold water rapidly injected in proximal lumen of PA catheter. Thermistor sensor near distal tip detects the differences in blood temperature. CO mathematically calculated as average of 3-4 measurements with acceptable “curve”.
SVR can be calculated off the CO


Nursing Considerations for Hemodynamic Monitoring
1. Assisting with PA catheter insertion (refer to Figure 66-8 on Page 1743 of Lewis)
Question Answer
a. Catheter insertion is done by the physician and guided by observing thewaveforms on the monitor as the catheter is advanced through the heart to the
pulmonary artery by the flow of blood.
Question Answer
b. The balloon at the tip of the catheter is inflated when the catheter tip is in theright atrium to facilitate insertion
c. Common insertion sites (4)Internal jugular vein, Subclavian vein, Antecubital vein, Femoral vein
Balloon (holds 1-1.5 ml of air) at tip has two purposes1. Allows moving blood to float the catheter forward on insertion. 2. Allows PAWP measurement (“wedge” pressure)
**Once a typical PAWP waveform is observed, the balloon isdeflated and left deflated unless the nurse is measuring PAWP (wedge pressure).


2. Obtaining accurate hemodynamic measurements
Question Answer
a. Position patient supine with HOB elevated 0-60% before PAP/CVP measurements
b. Level transducer to phlebostatic axis
c. Obtainmeasurements at end-expiration
d. Properidentification of waveforms
3. Catheter removal (once trained)
Question Answer
4. Monitoring for complications in Arterial lines
clot formation
cold extremity
Loss of limb


Question Answer
Monitoring for complications in Pulmonary Artery Catheters
Infection; sepsis
Air embolus (balloon rupture)
Pulmonary infarction (overwedging; balloon stays inflated too long)
Ventricular dysrhythmias (insertion or removal) **
Cardiac monitoring must be doneand crash cart available!