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HEMODYNAMIC MONITORING:The Fundamentals
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Goal:
Provide the participant with the basic knowledge required to care for a patient with an arterial line, central venous pressure/right atrial pressure line, and/or a pulmonary artery catheter.
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Objectives: Define hemodynamic monitoring. State indications for hemodynamic monitoring. Identify the correct reference point for leveling &
zeroing the hemodynamic monitoring system. Identify components of normal arterial, right atrial,
pulmonary artery, & pulmonary artery wedge waveforms. Identify factors that can affect the accuracy of the
waveforms. Describe common complications associated with
hemodynamic monitoring. Discuss the nursing care for patients with hemodynamic
monitoring.
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Hemodynamic Monitoring:
The use of a device or instrument to provide physiological measurements in order to more closely and accurately monitor a patient’s condition.
Usually involves the use of an invasive catheter inserted into a body cavity or organ system.
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Hemodynamic Monitoring - Examples:
Intra-arterial pressureCentral venous pressureIntra-cardiac pressures:
Right atrial pressurePulmonary artery pressurePulmonary artery wedge pressure
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Indications:
Intra-arterial:Continuous blood
pressure monitoringBlood sampling
Frequent arterial or venous sampling
Ability to quickly assess the effects of medical interventionsMedications or fluid
Intra-cardiac:Continuous monitoring of
both right & left heart fluid status
Cardiac outputMixed venous blood
samplingAbility to quickly assess
the effects of medical managementMedications or fluid
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Common Components:
Monitoring device:AmplifierOscilloscope
Transducer cableTransducerTransducer holder
Flush system:Pressure bagFluid:
Heparin vs. NS
Pressure tubingCatheterCarpenter’s level
Common System Components:
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Accurate & Reliable Waveforms/Values:
Technical factors:Patient positioning:
Supine Head of bed: 0-45°
Leveling: Eliminates effects of hydrostatic forces on the observed
hemodynamic pressures Ensure air-fluid interface of the transducer is leveled
before zeroing and/or obtaining pressure readings Phlebostatic axis:
Level of left atrium4th ICS & MAL (technically ½ AP diameter)Mark the chest with washable felt pen
Phlebostatic Axis:
Leveling:
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Accurate & Reliable Waveforms/Values:
Technical factors:Zeroing:
Negates the force exerted by the atmosphere (760 mmHg at sea level)
Pressure transducers can be affected by changes in temperature
“Drift” will occur from the zero baseline over time
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Accurate & Reliable Waveforms/Values:
Technical factors:Pressure tubing & transducer system
System free of airLength of tubing; correct tubingSystem connectors tight; stopcocks Luer-lockedAdequate fluid in flush systemFlush solution pressurized to 300 mmHgDynamic response testing
Square wave, fast flush or snap test
Dynamic Response Test:
Figure A – Expected square wave test
Figure B – Overdamped
Figure C – Underdamped
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Accurate & Reliable Waveforms/Values:
Overdamped:Sluggish, artificially rounded & blunted
appearanceSBP erroneously low; DBP erroneously highCauses: large air bubbles in system, too
compliant of tubing, loose/open connectionsOverdamped? Shock states, vasodilation,
aortic stenosis, thrombus on catheter tip, catheter kinked or against vessel wall
Overdamped Waveform:
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Accurate & Reliable Waveforms/Values:
Underdamped or ringing:Overresponsive, exaggerated, artificially
spiked waveformSBP erroneously high; DBP erroneously low Causes: small air bubbles, too long of
tubing, defective transducer Underdamped? Vasoconstriction,
hypertension, atherosclerosis, aortic regurgitation, hyperdynamic states (fever)
Underdamped Waveform:
Intra-arterial Pressure Monitoring
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Blood Pressure Monitoring:
Non-invasive blood pressure:Dependent on blood flow
Invasive, intra-arterial monitoring:Dependent on pressure changesTypically more accurate than NIBPAllows for convenient arterial blood
sampling
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Arterial Line Insertion Sites:
Radial:Most common siteGood collateral circulationAccessibility & ease of maintenanceModified Allen’s test
BrachialFemoralDorsalis Pedis
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Arterial Waveform:
Peak systolic pressure:Generated by left ventricular contractionPeak systole correlates with QRS on ECG
rhythm stripNormal: 100-140 mmHg
Arterial Waveform:
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Arterial Waveform:
Dicrotic notch:Closure of the aortic valveMarks the end of ventricular systole & the
beginning of diastoleDiastole:
Lowest pressure in arterial systemMeasured just before systolic upstrokeNormal: 60-80 mmHg
Arterial Waveform:
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Arterial Waveform:
Catheter location:The more distal the catheter is placed, in
relation to the aorta, the higher the systolic pressure & the lower the diastolic pressure
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Complications:
Infection:LocalizedSystemic
HematomaHemorrhageThrombosis/embolizationIschemiaNerve damage
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Nursing Care: Assess arterial line flush system:
Adequate, appropriate fluid Pressurized to 300 mmHg No air bubbles Connections tight Infection control
Level & zero q shift & PRN Continuously observe arterial waveform quality;
over/underdampened Correlation to NIBP Site care Assess circulation distal to insertion site
Central Venous Pressure&
Right Atrial Pressure
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Central Venous Pressure & Right Atrial Pressure:
Indications:Assessment of intra-vascular volume status:
Preload: the volume or pressure generated at end-diastole
Assess right ventricular function:Follow trends
Secure access; often only IV access available
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Central Venous Pressure & Right Atrial Pressure:
Measured through a catheter tip placed within the right atrium (RAP) or just outside RA in the vena cava (CVP):Single-lumen, double-lumen, triple-lumen
cathetersPulmonary artery catheter
Access Sites:SubclavianInternal jugular veinFemoral vein
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CVP/RAP Pressures:
Normal values:2–6 mmHg
Increased CVP/RAP:HypervolemiaHyperdynamic states (increased cardiac output)Cardiac tamponadeConstrictive pericarditisPulmonary hypertensionHeart failurePulmonary embolusPositive pressure ventilation
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CVP/RAP Pressures:
Normal values:2–6 mmHg
Decreased CVP/RAP:Hypovolemia:
DehydrationHemorrhage
Decreased mean systolic pressureVasodilation (specifically, venodilation):
SepsisVasodilators
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CVP/RAP Waveform:
Waveform Components: “a” wave:
Atrial contraction (atrial kick)Within the PR interval
“x” descent: atrial diastole “c” wave:
Rise in pressure w/ tricuspid valve closureNear the end of the QRS
“v” wave:Passive atrial filling during ventricular systoleFollowing the T wave, within the T-P interval
“y” descent: passive atrial emptying
CVP/RAP Waveform:
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Abnormal Waveforms:
Large “a” waves:Loss of A-V synchrony (Cannon Waves)Tricuspid valve stenosis
Loss of “a” waves:Dysrhythmias resulting in loss of P wave
Giant “v” waves:Tricuspid insufficiencyRight ventricular failure
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Complications:PneumothoraxInfection:
Localized, endocarditis, systemicBleeding/hemorrhageDysrhythmias:
Premature ventricular contractionsVentricular fibrillationHeart block
Thrombus/embolusPerforation of cardiac chamber
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Nursing Care: Assess CVP/RAP line flush system:
Adequate, appropriate fluid Pressurized to 300 mmHg No air bubbles Connections tight Infection control
Level & zero q shift & PRN Continuously observe CVP/RAP waveform quality;
over/underdampened Correlation to clinical picture Site care Assess for complications
Pulmonary Artery Pressure&
Pulmonary Artery Wedge Pressure
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Indications: Assess left & right heart function:
Preload:Right heart: RAPLeft heart: pulmonary artery diastolic & pulmonary artery wedge
pressures Cardiac output: thermodilution Afterload:
Right heart: Pulmonary vascular resistance (PVR)Left heart: Systemic vascular resistance (SVR)
Contractility: Stroke work index (SWI)
Assess response to therapeutic interventions Atrial and ventricular pacing Mixed venous blood gas Continuous venous oxygen saturation
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Clinical Indications:Complicated MIEnd-stage heart failureAcute pulmonary edemaPulmonary embolusAcute respiratory distress syndromeShockAcute renal failureComplex fluid managementCardiac surgeryHigh-risk surgical patients
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PA Pressure Monitoring:
Pulmonary artery catheter:Standard is a #7-French, multi-lumen,
radiopaque catheterMarked in 10-cm incrementsMultiple ports & openings1.5-cc balloon at distal end
Pulmonary Artery Catheter:
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Anatomy of a PA Catheter:
Components:ThermistorBalloon inflation port w/ gate valveProximal injectate portTypically has three infusion ports:
RA infusion port & lumen openingRV infusion port & lumen openingPA distal infusion port & lumen opening
Balloon
Insertion & Placement:
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Insertion:
Access:Right internal jugularLeft Subclavian veinFemoral
Method:Patient positioningPercutaneousVessel dilator & introducer sheath
RA
RV
PA
PAWP
Insertion:
RA
RV
PA
PAWP
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PA Pressures:
Pulmonary artery systolic (PAS):Normal PAS: 15–30 mmHg
Pulmonary artery diastolic (PAD):Normal PAD: 5–16 mmHg
Pulmonary arterial wedge pressure:Normal PAWP: 5–12 mmHg
All pressures measured at end-expiration
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PA Pressures:
Increased PA pressures:Pulmonary hypertensionPulmonary diseaseMitral valve diseaseLeft ventricular failurePulmonary embolus
Decreased PA pressures:HypovolemiaPulmonary artery vasodilation (meds, SIRS, sepsis)
PA Waveform:
PA Waveform Components:
1. PA systolic peak
2. Dicrotic notch:Closure of PA valve
3. PA diastole
4. Anacrotic notch:Opening of PA valve
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Pulmonary Artery Wedge Pressure:
Also: PCWP or PAOPNormal PAWP: 5–12 mmHgIndirect measurement of mean left atrial pressure
(LAP) which is an indirect measure of left ventricular end-diastolic pressure (LVEDP) or left ventricular preload
Normally, PAWP is 1–3 mmHg lower than PADPhysiologically impossible for PAWP to be higher
than the PAD
PA
PAWP
PAWP:
PAWP Balloon Inflation:
PAWP Waveform Components:
“a” wave:Atrial contraction (atrial kick)
“x” descent:Atrial diastole
“c” wave:Closure of mitral valve
“v” wave:Atrial filling
“y” descent:Passive atrial emptying
PAWP Waveform Components:
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Obtaining PAWP:
Continuous, close observation of the ECG and the PAP waveform during procedure
Inflate balloon: Open gate valve after syringe attached Slowly & gently inflate with only enough air to “wedge” the
balloon (typically 1.25-1.5 cc) Wedge for no more than 10-15 seconds or 2-3 respirations If strong resistance is met – do not inflate If no resistance is met or blood in lumen - STOP
Measure PAWP at end-expiration “a” wave method – most accurate
Obtaining PCWP:
Respiratory Variation:
PAPwaveform in a spontaneously
breathing patient
Respiratory Variation:PAWP waveform in a mechanically
ventilated patient
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Monitoring Problems:
Air bubbles in systemBlood in systemThrombus at tip of catheterSpontaneous wedging & overwedgingLoss of pressure tracingPressures that do not match the clinical
picture
Overwedging:
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Complications:
InfectionDysrhythmiasPneumothoraxHematoma & hemorrhageValve rupturePulmonary artery rupturePulmonary infarctPulmonary embolus
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Nursing Care:
Goals of therapyPrevention of infectionPatient positioningAssuring accuracy of dataContinuous waveform monitoringActivity
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Cardiac Output:
Cardiac output:Amount of blood pumped by the heart per
minuteCO = SV x HRFour physiologic factors affect CO:
PreloadAfterloadContractilityHeart rate
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Cardiac Output:
Preload:Load (volume) that stretches the ventricles prior to
contraction:Right heart – CVP/RALeft heart – PAD or PAWP
Afterload:Impedance to the ejection of blood from ventricles:
Depends on: volume & mass of blood ejected; and compliance & size of vascular space into which blood is being ejected
Right heart – PVRLeft heart - SVR
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Cardiac Output:
Contractility:Ability of myocardial tissues to shorten and develop
tension; “squeeze”:Cannot directly measure clinicallyIndirectly: LVSWI or RVSWI
Heart rate
Stroke volume: average volume of blood ejected per cardiac contraction
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Cardiac Output:
Thermodilution:Equipment:
Computer module/monitor w/ softwarePA catheter w/ thermistor & injection set-up
5-10 cc fluid bolus (injectate)Room temperature vs. iced injectateInject smoothly & quickly w/ end-expirationCalibration factors: computation constantPatient positioning
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Cardiac Output:
Normal values:Cardiac Output: 4–6 L/minCardiac Index: 2.5–4 L/min
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References:
Boggs, R. L., & Woolridge-King, M. (Eds.). (1993). AACN procedure manual for critical care (3rd ed.). Philadelphia; Saunders.
Clochesy, J. M., Breu, C., Cardin, S., Whittaker, A. A., & Rudy, E. B. (1996). Critical care nursing (2nd ed.). Philadelphia; Saunders.
Marino, P. L. (1998). The ICU book (2nd ed.). Baltimore; Williams & Wilkins.