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.