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25 Cards in this Set
- Front
- Back
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HEMODYNAMIC MONITORING
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HEMODYNAMIC MONITORING
-Hemodynamic press are transmitted from the intravascular space or cardiac chamber through the catheter and the fluid in the noncompliant pressure tubing to the press transducer -A press transducer senses changes in the fluid column generated by the pressures in the cardiac chambers or vessels being monitored -pressure transducer: converts mechanical energy (pressure) into electrical energy and generates a waveform -monitor:gives a wave form and numeric read out -The patency of the hemodynamic monitoring system is maintained by a continuous infusion of flush solution -The solution is placed in a pressure bag that is inflated to 300mmHg to maintain a constant press through the transducer and flush device -A continuous flow of approximately of 3ml/hr prevents backflow of blood through the catheter and tubing, thereby maintaining system patency and accurate transmission of pressures |
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Equipment necessary to measure hemodynamic pressures include
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Equipment necessary to measure hemodynamic pressures include
-noncompliant pressure tubing, a transducer, an amplifier, and a means of recording or displaying the info collected |
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Optimal use of the monitoring system
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Optimal use of the monitoring system
-Several techniques or mechanical factors may cause inaccuracies of the hemodynamic waveforms and values -Air bubbles or blood in the tubing or transducer system distorts pressure readings -The length of the press tubing is kept to a minimum -Stopcocks are included for sampling of blood and zeroing of the transducer |
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Square wave test
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Square wave test
-Helps identify whether the hemodynamic system is optimized -By activating the fast flush device for 1 or 2 sec, the press waveform on the oscilloscope is replaced by a square wave -Causes of nonoptimized systems include air bubbles, blood, loose connections, cracks, leaks, or soft IV tubing in the system |
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Zeroing and leveling
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Zeroing and leveling
-The pos of the transducer in relation to the pt atria and the sys calibration also affects the accuracy of the hemodynamic values -Before obtaining hemodynamic parameters, the transducer is leveled and zeroed -A transducer placed above the reference point produces falsely low readings -A transducer below the reference point produces falsely high readings -The zero reference point is established at the intersection of the mid-anterior-posterior line and the fourth intercostals space, know as the phlebostatic axis -The HOB may be elevated as much as 40degrees, providing the transducer is releveled after any changes in pt potion -After leveling the transducer, the system is zeroed by turning the stopcock on the transducer off to the pt and open to air -The monitor has a function key that is used to zero the system -When activated, the monitor adjusts the digital reading to zero and indicates that the zeroing procedure was successful |
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Arterial pressure monitoring
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Arterial pressure monitoring
-Is achieved through an intra-arterial catheter connected to the pressure monitoring system -This allows continuous monitoring of the systemic arterial blood pressure and provides vascular access for obtaining blood samples by withdrawing blood from a stopcock in the system -Most common sites for arterial catheter insertions are the radial and femoral arteries -The connecting tubing is assembled and flushed, and the transducer is leveled, zeroed, and calibrated before the catheter is inserted |
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Arterial pressure waveform
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Arterial pressure waveform
-Normal arterial waveform should have a rapid upstroke, a clear dicrotic notch, and a definite end diastole -The initial sharp upstroke of the waveform represents the rapid ejection of blood from the ventricle into the aorta -The dicrotic notch reflects a slight backflow of blood in the aorta, reflecting closure of the aortic valve when the aortic pressure is higher than the left ventricular pressure -Dicrotic notch corresponds with the end of ventricular repolarization and the T wave on the ECG -The value measured at the peak of the waveform is the systolic pressure -The dicrotic notch then indicates the end of ventricular systole and the beginning of diastole -As blood flows to the periphery, the pressure in the arterial system decreases -The lowest point of the waveform is the diastolic pressure -MAP is used to evaluate perfusion of vitally body organs -MAP = (dia x 2) + sys / 3 -Circulation to the extremity in which the arterial line is placed must be monitored frequently |
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Nursing considerations
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-Blood pressures obtained using an arterial catheter are usually 5-20mmHg higher than those obtained using a cuff
-The high and low alarms are set for systolic, diastolic, and mean pressures within 10-20mmHg of the pt typical blood pressure -The system should not be flushed with a syringe -No IV solution of medication should be administered through the arterial pressure monitoring system at any time |
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Central venous pressure monitoring
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Central venous pressure monitoring
-CVP reflects the pressure of blood in the right atrium or vena cava -It provides information about intravascular blood volume, right ventricular end diastolic pressure, and right ventricular function -CVP indirectly reflects left ventricular end diastolic volume and function, because the left and right sides of the heart are linked by the pulmonary vascular bed -Catheter is inserted into and AC, jugular, femoral, or subclavian vein and is threaded into position in the vena cava close to the right atrium -Reflects pressure in the great veins -Single or multi-lumen catheter advanced from peripheral or central vein until tip is in proximal SVC -Clinical uses: To monitor blood volume, RV function, central venous return, Administration of IV meds, fluid, blood, TPN, Blood sampling -Evaluated continuously via pressure transducer (measured in mmHg) or intermittently via water manometer (measured in cm H20) -Normal CVP: 2-6 mmHg |
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Central venous pressure waveform
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-The central venous waveform seen on the monitor reflects the events of cardiac contraction;
-the central venous catheter “sees” these slight variations in pressure that occur during the cardiac cycle and transmits them as a characteristic waveform. -There are three positive waves (a, c, and v) and two negative waves (x and y), and these correlate with different phases of the cardiac cycle and EKG. + a wave: This wave is due to the increased atrial pressure during right atrial contraction. It correlates with the P wave on an EKG. + c wave: This wave is caused by a slight elevation of the tricuspid valve into the right atrium during early ventricular contraction. It correlates with the end of the QRS segment on an EKG. - x descent: This wave is probably caused by the downward movement of the ventricle during systolic contraction. It occurs before the T wave on an EKG. + v wave: This wave arises from the pressure produced when the blood filling the right atrium comes up against a closed tricuspid valve. It occurs as the T wave is ending on an EKG. - y descent: This wave is produced by the tricuspid valve opening in diastole with blood flowing into the right ventricle. It occurs before the P wave on an EKG. |
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Pressure transducer CVP
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Pressure transducer
-The hemodynamic monitoring system components and preparation for CVP monitoring are identical to those described for arterial pressure monitoring Zeroing and leveling -The pos of the transducer in relation to the pt atria and the sys calibration also affects the accuracy of the hemodynamic values -Before obtaining hemodynamic parameters, the transducer is leveled and zeroed -A transducer placed above the reference point produces falsely low readings -A transducer below the reference point produces falsely high readings -The zero reference point is established at the intersection of the mid-anterior-posterior line and the fourth intercostals space, know as the phlebostatic axis -The HOB may be elevated as much as 40degrees, providing the transducer is releveled after any changes in pt potion -After leveling the transducer, the system is zeroed by turning the stopcock on the transducer off to the pt and open to air -The monitor has a function key that is used to zero the system -When activated, the monitor adjusts the digital reading to zero and indicates that the zeroing procedure was successful |
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CVP cont
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-CVP measured by a pressure transducer normally is 0-6mmHg
-Decreased CVP values indicate a hypovolemic state often requiring administration of fluids -A low or decreasing CVP also may be related to vasodilation or diuretic therapy -Right ventricular failure and mechanical ventilation are two of the more common causes of inc CVP -Mechanical ventilation increases intrathoracic pressure, which is transmitted to the pulmonary vasculature, heart, and great vessels -CVP may be increased as well because intrathoracic pressure compresses the pulmonary vessels, creating resistance to blood flow from the right side to the left side of the heart and causing blood to back up in the right ventricle, right atrium, and vena cava |
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CVP cont
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-CVP is elevated because of reduced forward blood flow and the backup of blood and pressure in the right atrium and vena cava
-Right ventricular failure due to coronary artery disease or left ventricular failure is associated with increased CVP values -The inability of the right ventricle to pump blood through the pulmonary vasculature because of injured or infracted myocardium results in increased volume and pressure in the right atrium and vena cava -Left ventricular failure may increase CVP as the pressure of blood volume congests they pulmonary vasculature and impairs flow from the right ventricle, causing right ventricular dilation and subsequent failure -Again the increased pressure is reflected backward to the right atrium and vena cava -Interventions are directed toward facilitating forward blood flow by improving ventricular contractility and reducing the intravascular blood volume |
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Pulmonary Artery Catheter (Swan-Ganz Catheter)
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Pulmonary Artery Catheter (Swan-Ganz Catheter)
-Possible to assess right ventricular function, pulmonary vascular status, and indirectly left ventricular function -Cardiac output, right atrial, right ventricular, and PA pressures as well as PAWP are measured using a PA catheter -A 7.5F thermodilution catheter is the size most commonly used -Lumens contain 2-5 lumens Proximal port or right atrial port: Blue, proximal injectate -Opens approximately 30cm from distal catheter tip -lies in patient’s right atrium -Connects to transducer via pressure tubing -Cardiac output injectate instilled here -Monitors RA pressure, Draw blood samples, Infuse IV meds and fluids (3 way stopcock facilitates) -Inject solution for CO studies -WARNING: if shooting CO studies, don’t put vaso active drugs in this port (fluids will be turned off during CO study) Distal Port: (PA port - yellow) Most important -Opens at catheter tip, lies in patients pulmonary artery (PA) -Connects-to-transducer-via-pressure-tubing Monitored continuously -Monitors PA pressures -Draw blood samples -Monitors PCWP -Draw all SVO2 samples here (mixed venous) -WARNING: Never inject more than 1.5 cc of air, only instill air into this port - never fluids ! |
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Pulmonary Artery Catheter (Swan-Ganz Catheter) cont
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Thermistor port: (Cardiac Output port - square white box)
-Ends approximately 4cm from distal tip -Contains a fine temperature-sensitive wire to measure blood temperature and CO -Connects thermistor wires to bedside CO computer -Should see 3-4 straight gold needles coming out of this port -Keep port covered with red cap Inflation port (balloon port) -Syringe will passively deflate if balloon is intact -Before-transport ask-for-a-current-wedge-tells-if-balloon-is-intact, provides a strip of the wedge, and information on volume status -If balloon ruptures mark the port so it is not used. |
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Swan-Ganz Catheter and CVP
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-The Swan-Ganz catheter (pulmonary artery flotation catheter) was devised by H.J.C. Swan and William Ganz in 1970.
-It has resulted in accurate and quick monitoring of the cardiopulmonary status of patients in a critical care setting. -It provides measurements that can be used as guidelines for treating shock, congestive cardiac failure of any cause, pulmonary edema, and embolism for monitoring patients undergoing cardiac surgery. -The catheter actually identifies specific hemodynamic measurements. These include: -Measurement of right atria pressure (RAP) -Pulmonary artery pressure (PAP) -Pulmonary capillary wedge pressure (PCWP) -Cardiac output (CO) measurement -Sampling of right atrial and pulmonary artery (mixed venous) blood. -Central venous pressures (CVP) have frequently been utilized to measure circulatory status of patients -Although the CVP has been very helpful it does have its limitations. -The CVP readings are only reliable to measure right heart function, systemic venous compliance, and intravascular volume when the patient has no significant cardiopulmonary disease. -The CVP is most valuable in monitoring blood volume and adequacy of central venous return. |
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PA catheter insertion
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PA catheter insertion
-The flush system is connected to the transducer, which is then placed at the zero reference point, leveled, and zeroed -Each lumen of the PA cath is flushed with sterile solution from the flush system -The PA port is then connected to the prepared transducer with pressure tubing, and the other lumens are connected to either a pressure monitoring system or to IV solution -Most common insertion sites are the left or right subclavian veins, internal or external jugular veins or femoral veins -Ventricular arrhythmias are the most common complication during PA catheter insertion |
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Waveform interpretation
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Waveform interpretation
-All hemodynamic pressures and waveforms are generated by pressure changes in the heart caused by the myocardial contraction (systole) and relaxation/filling (diastole) phases of the cardiac cycle There are three categories of hemodynamic waveforms; -atrial including right and left and PA wedge; -ventricular including left and right; and -arterial including PA and systemic aortic -Pneumothorax is a complication of insertion of the PA catheter introducer through the subclavian vein -Ventricular arrhythmias are common during the insertion of a PA catheter |
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Nursing considerations
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-Measurement of all hemodynamic pressures is most accurate when obtained at the end of expiration
-Intrathoracic pressure at end expiration is about equal to atmospheric pressure -Increased PA pressures are associated with left ventricular failure, mechanical ventilation, and pulmonary vascular vasoconstriction -Abnormal PAWP waveforms are most common than abnormal right atrial waveforms because left ventricular dysfunction and mitral valve disease tend to occur more frequently than right ventricular or tricuspid valve disorders -Elevated PAWP frequently is due to left ventricular dysfunction or hypervolemia |
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Parameters
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Parameters
-RA/CVP: 2-6mm Hg -RVP: systolic 15-28mm Hg diastolic 0-8mm Hg -PA: systolic 15-30mm Hg diastolic 5-15mm Hg -PCWP: 8-12mm Hg |
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Cardiac Output (CO), Cardiac Index (CI) Measurements
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Cardiac Outputs, amount of blood ejected by LV per minute = 4-8liters/min
Cardiac Index -the CO in reference to the individual body size or body surface area -more specific way to evaluate CO because it is indexed to the BSA -a method of normalizing CO for everyone; regardless of size; allows us to compare cardiac outputs from different sized individuals -2.5-4liters/min/m2 Techniques for Determining Cardiac Output -Thermodilution: iced or room temperature injection is instilled rapidly through proximal port of PA catheter -this changes the temperature of the patient’s blood and the thermistor picks up this change in temperature -The computer then determines amount of blood passing through and can determine a cardiac output. -For adults, use 10 cc of D5W and quickly inject -Use average of 3 or 4 sequential thermodilution -If using iced injectate don’t touch barrel of syringe |
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Right Atrial Pressure
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-Reflects pressure in right atrium
-Measured through proximal port of PA catheter -Normal RAP :2-6mmHg Clinical Uses: a. Asses RV function b. Asses venous return to right heart (preload status) Decreased RAP :Hypovolemia and Venodilation Increased RAP: -RV failure / RV infarct / Chronic LV failure / Rejection -Hypervolemia / Tricuspid Insufficiency / L - R shunts -Pulmonary HTN / PE / Pulmonary stenosis/COPD -Cardiac tamponade / Constrictive pericarditis -PEEP / Pressure ventilators -Right atrial pressure is equivalent to both the right ventricular pressure in diastole (when the tricuspid valve is open, the right atrium and right ventricle are common chambers) and to the central venous pressure. -Reduced right atrial pressure is generally secondary to hypovolemia. |
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Right Ventricular Pressure (RVP)
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-Reflects RV function
-Normalpressures: a. Systolic: 20-30mmHg b. Diastolic: 0-5mmHg -Not routinely measured at bedside due to irritability of RV, Seen during insertion of PA catheter AbnormalValues: -Increased RV pressure= RV failure / Chronic CHF; Pulmonary HTN / Pulmonic Stenosis / Hypoxemia; Tamponade / Constrictive pericarditis / VSD -If PA cath is in RV it will show sharp pattern -Right Ventricular Pressure (RVP) is an arterial waveform and must have a systolic and diastolic reading -When a PA cath passes through the right ventricle a Anocrotic notch should appear and represents “atrial kick” -Anacrotic notch is a notch on the ascending side of the waveform deflection -Anacrotic notch is found to the left of waveform peak -Atrial kick provides 22%-33% of cardiac output, and hence the urgency in controlling A-fib -If a PA cath is pulled it may irritate the right ventricle and precipitate arrhythmias -Options are to withdraw the cath to the RA/CVP position after the balloon is deflated -A PA cath that has pulled shallow will cause ventricular irritability and will bang around in the ventricles causing arrhythmias, verify the balloon is down and withdraw to a CVP position |
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Pulmonary artery pressure (PAP)
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-Reflects both right and left heart pressures
-Measured through distal port of PA catheter -Divided into 2 phases: Systole and Diastole -PA systolic pressure (PAS): reflects pressure produced by RV -Normal PAS = 20 - 30 mmHg (same as RV systolic) -PA diastolic pressure (PAD): indirectly reflects pressure in LV at end of diastole (LVEDP = preload), thru opening of the mitral valve -Normal PAD = 10 - 15 mmHg (higher than RV diastolic) -PAD = PCWP = LAP = LVEDP (in patients with normal lungs and mitral valve) -Decreased PAP- Hypovolemia and Dampened waveform -Increased PAP- Pulmonary disease (ARDS, COPD), Hypoxia, PE, Pulm HTN, LV failure, MV disease and L - R shunts -when the pulmonic valve opens, blood flows from the RIGHT VENTRICLE (systole) thru PULMONIC VALVE and to PULMONARY ARTERY -Pulmonary artery pressure is equal to right ventricular pressure during systole, while the pulmonary valve is open. -It is increased in the presence of either increased pulmonary vascular resistance or elevated pulmonary flow. -Increased pulmonary vascular resistance is seen in states of chronic lung disease or pulmonary embolism. -Elevated pulmonary flow would be the result of a ventricular septal defect. |
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PCWP
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PCWP
-Since there are no valves between the pulmonary capillaries and the left atrium, and since the pulmonary vascular bed normally has a low resistance, the pulmonary capillary wedge pressure (PCWP) correlates closely with left atrial pressure. -During diastole, with an open, non-stenotic mitral valve, the pulmonary venous bed, left atrium and left ventricle become a common chamber, and PCWP is then also equal to left ventricular diastolic pressure (LVDP). -PA diastolic pressure (PAD): indirectly reflects pressure in LV at end of diastole (LVEDP = preload), thru opening of the mitral valve -PCWP is more indicative of LVEDP further downstream -pulmonary artery wedge pressure PAWP is used to estimate left ventricular end diastolic pressure -left ventricular end diastolic pressure is used to estimate left ventricular end diastolic volume and therefore preload -Measured with balloon inflated at end of expiration -NormalPCWP=4-12mmHg -Inflate balloon sails into distant pulmonary circulation, lodges in small branch of PA and occludes it -Results in cessation of forward blood flow in that balloon- occluded segment of pulm. Circulation -During this occlusion, catheter sensing tip “sees through” pulm. Circulation (no valves) and into the LA = indirect reflection of LAP Decreased PCWP- Hypovolemia and Vasodilator drugs ( afterload reduction) Increased PCWP- LV failure, Mitral valve disease, Tamponade / constrictive pericarditis, Fluid overload (hypervolemia) -Pericardial tamponade – CVP, RV, PAP, PCWP would all come together and reach a common number -When wedging a PA cath you only inflate the balloon with enough air to cause a change in waveform and never more than 1.5ml total -Position changes can cause inadvertent wedging -Inadvertent wedging can occur shortly after initial placement -For an inadvertent wedged PA cath verify the balloon didn’t somehow become inflated, ask the patient to cough forcefully or even perform a valsalva maneuver to see if the pressures can un-wedge the cath -PA waveform who’s morphology is a low amplitude rolling waveform might indicate PCWP wedge or CVP waveform; -A new cath could wedge as a result of the catheter warming to body temp and becoming more flexible and pushing the tip distally |
