Hemodynamic Monitoring
Part 2
PAC insertion & measurements:
PAP, wedge, & cardiac output
MICU Competencies
2006 - 2007
1
Pulmonary Artery Pressure Monitoring
• Balloon tip, indwelling catheter with several
lumens & thermistor placed in the PA
• The PA (distal) & CVP (proximal) ports are
connected to a hemodynamic monitoring
system
• Provides monitoring & measurement of the
pulmonary artery wedge pressures (PAWP),
cardiac outputs, & cardiopulmonary function
2
Indications for PA Monitoring
• Alterations in cardiac output (CO)
• Shock [cardiogenic, hypovolemic, septic]
• Alteration in fluid volume [preload]
• Alteration in tissue perfusion
• Differentiate cardiac &/or pulmonary disease
• Cardiac output measurements
3
Cardiac Output
• Volume pumped by ventricles each minute;
normal = 4 - 8 liters/minute
• Cardiac Output = Heart Rate x Stroke Volume
(CO = HR X SV)
• SV = amount of blood ejected from each
ventricle with each contraction;
normal SV = 50 - 100 ml per contraction
4
Cardiac Index
• Cardiac output (CO) adjusted to body size
• Cardiac index (CI) = CO / body surface area
• Normal CI range = 2.5 to 4.3 L/min/m2
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Low Cardiac Output
• Inadequate ventricular filling
dysrhythmias
hypovolemia
cardiac tamponade
mitral or tricuspid stenosis
constrictive pericarditis
restrictive cardiomyopathy
6
Low Cardiac Output
• Inadequate ventricular emptying
mitral/tricuspid insufficiency
myocardial infarction &/or disease
increased afterload (hypertension)
metabolic disorders (acidosis, hypoxia)
negative inotropic drugs (beta-blockers,
calcium channel blockers)
7
High Cardiac Output
• Increased HR and/or contractility and/or
decreased afterload
– Sepsis
– Anemia
– Pregnancy
– Hyperthyroid crisis
8
Determinants of
Cardiac Output & Stroke Volume
• Preload - Volume or pressure generated in
the ventricles at end diastole
• Afterload – Resistance to ejection of blood
from the ventricles
• Contractility – Force of ventricular ejection;
difficult to measure clinically
9
Clinical Measurement of Preload
• Left ventricular end diastolic pressure =
LVEDP; measures preload in left ventricle
– Pulmonary artery wedge pressure (PAWP) reflects
LVEDP; normal = 8 - 12 mmHg
– If unable to wedge PAC, use PA diastolic
– PA diastolic (PAD); normal = 10 - 15 mmHg
– PAD indirectly reflects left atrial pressure, which
indirectly reflects LVEDP
10
Clinical Measurement of Preload
• Central venous pressure = CVP;
measures preload in the right ventricle
– Normal CVP = 2 – 8 mmHg
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Factors that Affect Preload
• Anything that alters →
– Circulating blood volume
– Blood returning to the heart
– Ventricular filling time
12
Factors that Decrease Preload
Affect right & left ventricles (CVP & Wedge)
• Hypovolemia
• Patient position reducing venous return
• Vasodilatation causing blood to pool
• Reduced venous return due to mechanical
ventilation - high PIP, high levels of PEEP
• Tension pneumothorax
Blood is not returning to the heart to fill the ventricles.13
Factors that Increase Preload
• Intravascular volume overload
• Cardiac tamponade
• Restrictive cardiomyopathies
• Left ventricular dysfunction (↑ PCWP & CVP)
• Right ventricular dysfunction (↑ CVP)
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Afterload
• Afterload is any resistance against which
the ventricle must pump in order to eject its
volume
– Systemic Vascular Resistance (SVR) reflects LV
afterload
• Normal Range = 800-1200 dynes/sec/cm-5
– Pulmonary Vascular Resistance (PVR) reflects
RV afterload
• Normal Range =100-250 dynes/sec/cm-5
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Factors that Affect Afterload
• Volume & mass of blood ejected from the
ventricle
– Inverse relationship between afterload
and CO (↑CO = ↓afterload;
↓CO = ↑afterload)
• Compliance & diameter of the vessels into
which the blood is ejected
• Aortic impedance, peripheral vascular
resistance, and blood viscosity
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Decreased Afterload (↓ SVR)
• Arterial dilatation from drugs such as
nitroprusside, nitroglycerin, calcium
channel blockers, beta blockers
• Shock (septic, anaphylactic, neurogenic)
• Hyperthermia (fever)
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Increased Afterload (↑SVR)
• Accomplished by vasoconstriction
– Hypothermia
– Hypertension
– Alpha agonists (pressors)
• Levophed, Dopamine, Phenylephrine, Epinephrine
– Low CO with hypovolemic or cardiogenic shock
• An effect of obstruction
– Aortic/pulmonic stenosis
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Increased Afterload (↑ PVR)
• Conditions exhibiting increased PVR
– Pulmonary hypertension
– Hypoxia
– End-stage COPD (Cor pulmonale)
– Pulmonary emboli
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Contractility = Inotropy
• Inherent ability of cardiac muscle to contract
• Reflected indirectly by stroke volume index
(SVI) and the stroke work index for each
ventricle (LVSWI & RVSWI)
• Influenced by myocardial oxygenation &
functionality; electrolyte balance; +/inotropes; amounts of preload and afterload
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Factors/Meds Increasing Contractility
Positive Inotropes
• Sympathic stimulation – “fight or flight”
• Dobutamine
• Epinephrine (Adrenalin)
• Norepinephrine (Levophed)
• Amrinone (Inocor)
• Dopamine (5 – 10 mcg/kg/min)
• Calcium; glucagon; caffeine
• Digoxin (only oral inotrope)
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Factors Decreasing Contractility
Negative inotropes
• Acidemia
• Hypoxia
• Beta blockers
• Anti-arrhythmics
22
PACs in the MICU
In 2006, Dr. Wheeler presented the
findings from the Fluid and Catheter
Treatment Trial (FACTT) to nurses in our
MICU. Data from this study indicates a
preference for using the CVP to monitor
fluid status and conservative fluid
management of the patient. Therefore, we
do not frequently see or manage patients
with PAC’s in our MICU.
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PA Catheter Insertion
• Strict sterile technique; threaded through an
introducer
• Common sites are subclavian & jugular
(occasionally femoral)
• PA balloon is inflated & floated through the RA
→ tricuspid valve → RV → the pulmonic valve
→ PA → the wedged position
• Record a continuous strip of the insertion
hemodynamic waveforms at the bedside
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PAC Insertion Waveforms
PAWP=PAOP=PCWP=wedge
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Manual CVP Measurement
• Zero/level CVP stopcock at the
phlebostatic axis
• Record duel channel strip with CVP and
Ao waveforms
• Measure all waveforms at end-expiration
(See slides #30 & 31)
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Manual PA/PCWP Measurement
• Zero/level PA stopcock at phlebostatic axis
• Record duel channel strip with PA and Ao
• PA systolic = 20-30; PA diastolic = 10-15
• Slowly inflate balloon with 1.0 – 1.5 ml air
• KEEP EYES ON MONITOR
• Keep inflated 5 – 10 seconds
• Passively deflate
• Record the return of PA waveform
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Cardiac Output Measurements
• 10ml syringe of room temperature D5W injected
quickly & smoothly via the proximal port
• Thermistor at the tip of the catheter senses the
change in temperature
• Rate of change in blood temperature generates
a cardiac output value
• Minimum of 3 measurements within 10% of
each other averaged for a mean cardiac output
• Confirm on the monitor
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Maintenance, Care & Measurement
•
Sterile technique during tubing & dressing changes
•
Consistent leveling & measurement techniques
•
Measure CVP, PAP, and PCWP at end-expiration
•
Do not over-inflate balloon (only 1.5 ml)
•
Allow balloon to deflate passively
•
Only MDs advance PAC when necessary (i.e. PAC
not wedging)
29
Using End-expiration Reference
• Draw at least 2 vertical lines
• First line = Ao tracing deviates from baseline
• Back up 200 msec (one large box) to draw
second vertical line
• Draw a horizontal line to the left of the
second line indicating
– Systolic and diastolic values for PAP
– Mean of the CVP; mean of the PAWP
See next slide for example
30
The first vertical line would be drawn where the Ao tracing
deviates from baseline
Second vertical line would be drawn where the ↑ is located
See the horizontal line to the left of the arrow
indicating the PAOP
31
(PAOP = PAWP; Paw = Ao)
Keys to Excellent Measurements
• Use only the Ao as a reference for endexpiration. The respiratory waveform is not
accurate!
• To help determine end-expiration for a
non-ventilated patient, remember:
– “Vent = valley” (lower portion of waveform)
– “Patient = peak” (higher portion of waveform)
• PA mean = PAS + 2(PAD)/3
32
Complications from PA catheters
Problem
Pneumothorax
Description/Treatment
Subclavian insertion/chest tube
Infection
Thrombophlebitis
Air embolus
Common complication/antibiotics
Site red, tender/remove PAC
With insertion; loose connections/
prevention; L lateral T-berg position
Cath tip in RV/remove; defib
During insertion/pull back; may
repeat attempt to float
Ventricular dysrhythmias
Catheter knotting/kinking
PA perforation or
infarction
Prolonged or frequent
wedging/watch for bright red blood
return/surgical or no treatment 33
Documentation for PAC
• Record on hemocalculations sheet: HOB;
PEEP; drips; position of PAC (in cm); scale;
interpretation of CVP, PAP, & PCWP; sign
• Stamp sheet “Permanent Chart Document”
• Computation constant in HED as annotation
• Zero calibration every four hours in HED
• See additional data to chart on next slide
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Documentation for PAC
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References & Resources
Burns, S. M. (2004). Continuous airway pressure monitoring. Critical Care Nurse, 24(6),
70-74.
Chulay, M., & Burns, S. M. (2006). AACN Essentials of critical care. McGraw-Hill: New
York.
Edwards. (2006). Pulmonary Artery Catheter Educational Project. http://www.pacep.org
Edwards Lifesciences. (n.d.) Educational videos. www.edwards.com
MICU Routine Practice Guidelines. www.vanderbiltmicu.com
MICU Bedside Resource Books
MICU Education Kits – Pulmonary Artery Catheter (Red cart in conference room)
MICU Preceptors, Help All Nurses, & Charge Nurses
VUMC policies. http://vumcpolicies.mc.vanderbilt.edu
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