Hemodynamic Monitoring Flashcards
What is cardiac output?
Volume of blood in liters pumped by the heart in 1 minute
What is cardiac index?
Measurement of cardiac output adjusted for body surface area
What is the stroke volume?
The volume ejected from the heart with each beat
What is stroke volume index?
Measurement of SV adjusted for BSA (body surface area)
What determines blood pressure?
Cardiac output and the forces opposing blood flow
What is systemic vascular resistance (SVR)?
opposition encountered by the left ventricle
What is pulmonary vascular resistance (PVR)?
Opposition encountered by the right ventricle
What makes up the resistance to blood flow by the vessels?
PVR + SVR
What determines stroke volume?
Preload, afterload, and contractility
What is preload?
The volume within the ventricle at the end of diastole
How is preload measured?
Various pressures are used to estimate the volume
What is the preload of the left ventricle called?
Left ventricular end-diastolic pressure
What is used to measure the left ventricular end-diastolic volume?
Pulmonary artery wedge pressure (PAWP)
What does the pulmonary artery wedge pressure indicate?
It reflects left ventricular end diastole under normal conditions
What is pulmonary artery wedge pressure?
A measurement of pulmonary capillary pressure
When might pulmonary artery wedge pressure NOT reflect left ventricular end-diastolic pressure?
Mitral valve dysfunction, intracardiac defect, dysrhythmias
The value of the pulmonary artery wedge pressure thus reflects the __ of the left ventricle
preload
The value of the pulmonary artery wedge pressure thus reflects the preload of the __ ventricle
left
What does CVP stand for?
Central venous pressure
Where is central venous pressure (CVP) measured?
Right atrium or in the vena cava close to the heart
What does the central venous pressure (CVP) indicate?
Right ventricular preload
How is the preload of the right ventricle measured?
By using the CVP
Right ventricular preload aka
right ventricular end-diastole pressure
When does the central venous pressure (CVP) NOT indicate the right ventricular end-diastolic pressure?
Tricuspid valve dysfunction, intracardiac defects, or dysrhythmias
What does Frank Starling’s law explain?
The effects of preload
What is Frank Starling’s law?
The more a myocardial fiber is stretched during filling, the more it shortens during diastole and the greater the force of the contraction
As preload increased, what happens?
The force generated in the subsequent contraction increases
If preload increases, what happens to stroke volume and cardiac output?
They both increase
The greater the preload, the greater the myocardial __
stretch
The greater the preload, the greater the myocardial __ __
oxygen requirement
What can decrease preload?
Diuresis and vasodilation
What action will increase preload?
Fluid administration
What is afterload?
The forces opposing ventricular ejection
What opposing forces make up afterload? (3)
Systemic arterial pressure
Resistance offered by aortic valve
Mass and density of blood
What two measurements indicate left ventricular afterload?
Systemic vascular resistance
Arterial pressure
What two measurements indicate right ventricular preload?
Pulmonary vascular resistance
Pulmonary arterial pressure
An increase in afterload results in a decreased __ __
cardiac output
What effect does afterload have on myocardial oxygen requirement?
Increased afterload results in need of more oxygen
What drug is often used to reduce afterload?
Milrinone
What is the effect of milrinone?
Vasodilator
What is contractility?
The strength of contraction
When does contractility increase?
When preload is unchanged and the heart contracts more forcefully
Epinephrine __ contractility
increases
Norepinephrine __ contractility
increases
Isoproterenol (Isuprel) __ contractility
increases
Dopamine __ contractility
increases
Dobutamine __ contractility
increases
Digitalis (digoxin) __ contractility
increases
Calcium __ contractility
increases
Milrinone __ contractility
increases
A drug that increases contractility is called a __ __.
positive inotrope
A drug that decreases contractility is called a __ __.
negative inotrope
An increase in contractility results in an increase in myocardial __ __
oxygen demand
Calcium channel blockers __ contractility
decrease
Beta-adrenergic blockers __ contractility
decrease
What acid-base imbalance reduces contractility?
Acidosis
What is contractility measured?
There are no direct clinical measures of contractility
What indirectly measures contractility?
Preload (pulmonary artery wedge pressure) and cardiac output, then graphing the results
A graphing of a patients pulmonary artery wedge pressure and cardiac output measures what?
An indirect measure of contractility
How can one know if contractility has been changed?
Preload, heart rate, and afterload remain the same, but cardiac output increases
What parts of invasive arterial BP monitoring system are disposable?
The catheter, pressure tubing, flush system, and transducer
What does referencing a pressure monitoring equipment mean?
Placing the transducer so that the zero-reference point is at the level of the atria of the heart
What is used for a zero-reference point?
Stopcock nearest the transducer
What is a good way to make sure a transducer is at the level of the atria?
Use an external landmark on the patient called the phlebostatic axis, mark it on the patient’s skin
How is the phlebostatic axis determined?
Draw a horizontal line through the fourth intercostal space along the chest wall and draw a vertical line down from the axilla midway between chest walls, the intersection of the two lines
What should you do after you have found the phlebostatic axis when setting up invasive hemodynamic monitoring?
Mark the spot on the patient, take the transducer to the spot, or ideally mount it on a bedside pole
What is the purpose of zero balancing invasive pressure monitoring equipment?
It confirms that when pressure within the system is zero, the monitor reads zero
How do you zero balance invasive pressure monitoring equipment?
Open the reference stopcock to room air and observe the monitor for a reading of zero
By opening the reference stopcock to room air, is allows the invasive pressure monitoring device to…
use atmospheric pressure as a reference for zero
When is the transducer of invasive pressure monitoring equipment zeroed?
During the initial setup, immediately after insertion of the arterial line, when the transducer has been disconnected from the pressure cable/pressure cable has been disconnected from monitor OR when accuracy of measurement is questioned
What should you ALWAYS do when setting up invasive pressure monitoring equipment?
Follow the manufacturer’s guidelines
What is the normal range for pulmonary artery diastolic pressure (PADP)?
4-12 mmHg
What is the normal range for pulmonary artery wedge pressure (PAWP)?
6-12 mmHg
What is the normal range for left arterial pressure (LAP)?
6-12 mmHg
What is the normal range for right arterial pressure (RAP)?
2-8 mmHg
What is the normal range for central venous pressure (CVP)?
2-8 mmHg
What is the equation for right ventricular end-diastolic volume (preload)?
Stroke volume / Right ventricular ejection fractions (RVEF)
What does RVEF stand for?
Right ventricular ejection fraction
What does right ventricular end-diastolic volume indicate?
Right ventricular preload
What is the normal range for right ventricular end-diastolic volume (preload)?
100-160 mL
How is MAP calculated?
Systolic + 2(diastolic) / 3
diastolic + 1/3(systolic - diastolic)
diastolic + 1/3*(pulse pressure)
How is pulse pressure calculated?
Systolic - diastolic
What is the normal range for pulse pressure?
40-60
What is the normal range for MAP?
70-105 mmHg
What does PAMP stand for?
Pulmonary artery mean pressure
How is pulmonary artery mean pressure (PAMP) measured?
Pulmonary artery systolic pressure (PASP) + 2(PADP) / 3
What is the normal range for pulmonary artery mean pressure (PAMP)?
10-20 mmHg
How is pulmonary vascular resistance (PVR) calculated?
(PAMP - PAWP) * 80 / CO
What is the normal value for pulmonary vascular resistance?
<250 dynes/sec/cm-5
How is pulmonary vascular resistance index (PVRI) measured?
(PAMP - PAWP) * 80 / Cardiac index
What is the normal range for pulmonary vascular resistance index?
160-380 dynes/sec/cm-5
How is systemic vascular resistance (SVR) calculated?
(MAP - CVP) * 80 / CO
What is the normal range for systemic vascular resistance?
800-1200 dynes/sec/cm-5
How is the systemic vascular resistance index (SVRI) calculated?
(MAP - CVP) * 80 / Cardiac index
What is the normal range for systemic vascular resistance index?
1970-2390 dynes/sec/cm-5/m2
How is cardiac index measured?
CO / BSA
What is the normal range for cardiac index?
2.2-4 L/min/m2
What is the normal range for cardiac output?
4-8 L/min
What is the normal range for heart rate?
60-100 bpm
What is the normal range for right ventricle ejection fraction?
40-60%
How is right ventricle ejection fraction (RVEF) calculated?
SV / RVEDV * 100
What is the calculation for stroke volume?
Cardiac output / Heart rate
What is the normal range for stroke volume?
60-150 mL/beat
How is stroke volume index (SVI) calculated?
Cardiac index / heart rate
What is the normal range for stroke volume index?
30-65 mL/beat/m2
How is stroke volume variation (SVV) calculated?
SV max - SV min / SV mean
What is the normal value for stroke volume variation?
<13%
What is stroke volume variation?
A naturally occurring phenomenon in which the arterial pulse pressure falls during inspiration and rises during expiration due to changes in intra-thoracic pressure secondary to negative pressure ventilation (spontaneously breathing)
What is the normal range for arterial hemoglobin O2 saturation?
95-100%
What is the normal range for mixed venous hemoglobin O2 saturation?
60-80%
What is the normal value for venous hemoglobin O2 saturation?
70%
Why should a dynamic response test be performed on invasive pressure monitoring equipment?
Checking that the equipment reproduces without distortion, a signal that changes rapidly
What is another name for a dynamic response test?
Square wave test
How often should a dynamic response test (aka square wave test) be performed?
Every 8-12 hours, when the system is open to air, or you question the accuracy of the measurements
What are possible indications for a patient to have an invasive arterial BP monitor?
Acute hypotension/hypertension
Respiratory failure
Shock
Neurologic injury
Coronary interventional procedures
Continuous infusion of vasoactive drugs (norepi)
Frequent ABG sampling
What type of catheter is typically used to cannulate an artery?
Nontapered Teflon catheter
What arteries are typically used for arterial BP monitoring?
Radial, femoral
What measurements can be obtained from an arterial line?
Systolic, diastolic, and MAP
What measurement from an arterial line is most accurate?
Readings from a printed pressure tracing at the end of expiration
Why should you use measurements from the end of expiration?
To limit the effect of respiratory cycle on arterial blood pressure
What position should you position a patient for initial readings from an arterial line?
Supine, if possible
If you are unable to position a patient supine, what is the next best alternative for arterial blood pressure readings?
Head of bed elevated at 45 degrees is generally equal to supine
When would having the head of the bed elevated to 45 degrees be contraindicated for initial arterial line readings?
If the patient’s BP is extremely sensitive to orthostatic changes
How can the nurse make sure of accurate continuous readings from an arterial line?
Keep the zero-reference stopcock level with the phlebostatic axis
On an arterial pressure tracing, what does the dicrotic notch indicate?
aortic valve closure
List 5 complications of arterial lines
Hemorrhage
Infection
Thrombus formation
Neurovascular impairment
Loss of a limb
If a catheter dislodges or the arterial line disconnects, what is the likely complication?
Hemorrhage
How can you avoid hemorrhaging from the arterial line becoming disconnected or catheter dislodging?
Use Luer-lok connections
Always check the arterial waveform
Activate alarms
How can you avoid infection from arterial lines?
Inspect site for inflammation
Monitor patient for signs of systemic infection
Change pressure tubing, flush bag, and transducer
How often should you change the pressure tubing, flush the bag and transducer of arterial line equipment?
Every 96 hours or according to agency policy
What should the nurse do if they suspect infection of an arterial line?
Notify HCP
Remove the catheter
Replace equipment
How can an arterial line result in circulatory impairment?
Formation of a thrombus around the catheter, release of an embolus, spasm, or occlusion of the circulation by the catheter.
Before an arterial line is inserted into a radial artery, what test should be performed?
An Allen test
What does the Allen test confirm?
Ulnar circulation to the hand is adequate
How do you conduct an Allen test?
Apply pressure to radial and ulnar arteries, ask patient to open and close hand. Hand should blanch. Release pressure. If color does not return in 6 seconds ulnar artery is not adequate
When a patient has an arterial line, what should then nurse assess hourly?
Neurovascular status distal to the insertion site
If the limb of an arterial line is compromised, what might it look like?
Cool, pale, prolonged capillary refill
What symptoms might a patient have is their limb is compromised from an arterial line?
Paresthesia, pain, paralysis
How can a nurse maintain arterial line patency and limit thrombus formation?
Assess the flush system every 1-4 hrs
When the nurse assesses the flush system of an arterial line, what is she checking?
1) Pressure bag inflated to 300 mmHg
2) Flush bag contains fluid
3) System is delivering a continuous slow flush
What should the pressure bag of an arterial line be inflated to?
300 mmHg
How much should the flush system of an arterial line be delivering?
1-3 mL/hr
What does APCO stand for?
Arterial pressure-based cardiac output
What does an arterial pressure-based cardiac output (APCO) calculate?
Continuous cardiac output/continuous cardiac index
What does an arterial pressure-based cardiac output measurement assess?
Patient’s ability to respond to fluids by increasing stroke volume aka preload responsiveness
How does the arterial pressure-based cardiac output (APCO) measurement determine preload responsiveness?
By using SVV (stroke volume variation) or by measuring the percent increase in SV after a fluid bolus
What is stroke volume variation (SVV)?
The variation of the arterial pulsation caused by the heart-lung interaction
In certain patients, stroke volume variation is sensitive indicator of __ __
preload responsiveness
Atrial pressure-based cardiac output (APCO) is only used with __ patients
adult
Atrial pressure-based cardiac output (APCO) cannot be used in patients who are on what type of therapy?
IABP
What is IABP therapy?
Intra-aortic balloon pump therapy
What type of dysrhythmia might the APCO not be able to filter?
Atrial fibrillation
Stroke volume variation is only used with patients who are…
On controlled mechanical ventilation with a fixed respiratory rate and tidal volume
What is arterial pressure?
The force generated by the ejection of blood from the left ventricle into the arterial circulation
Arterial pulse pressure is proportional to __ __
Stroke volume
What does the APCO use to calculate stroke volume?
Arterial waveform characteristics, along with demographic data (age, weight, height, gender)
APCO monitoring is frequently used with a…
central venous oximetry catheter
APCO monitoring combined with central venous oximetry catheter allows for…
Continuous monitoring of central venous o2 saturation and SVR that is derived from the CVP
How is central venous O2 saturation abbreviated?
ScvO2
List 5 contraindications to a pulmonary artery catheterization
Coagulopathy
Endocardial pacemaker
Endocarditis
Mechanical tricuspid or pulmonic valve
Right heart mass (thrombus/tumor)
What are 7 indications for a pulmonary artery catheterization?
Cardiogenic shock
Assessment of response to therapy
Differential diagnosis of pulmonary hypertension
MI with complications
Potentially reversible systolic HF
Severe chronic HF
Transplantation workup
What is a differential diagnosis?
Occurs when your symptoms match more than one condition and additional tests are necessary before making an accurate diagnosis
What is fulminant myocarditis?
Uncommon syndrome characterized by sudden and severe diffuse cardiac inflammation often leading to death resulting from cardiogenic shock, ventricular arrhythmias, or multiorgan system failure
What two measurements increase in patients with heart failure and fluid volume overload?
Pulmonary artery diastolic pressure (PADP)
Pulmonary artery wedge pressure (PAWP)
What is the name of the pulmonary artery flow-directed catheter?
Swan-Ganz
What does the Swan-Ganz measure?
Pulmonary artery pressures, including pulmonary artery wedge pressure
Where is the distal lumen port (catheter tip) of the Swan-Ganz?
Within the pulmonary artery
What is the distal lumen port?
Catheter tip
What is the catheter tip of the Swan-Ganz called?
distal lumen port
What does the Swan-Ganz measure?
pulmonary artery pressures and sample mixed venous blood
The Swan-Ganz has a balloon on the distal lumen port to…
1) allow the catheter to float
2) to meausure PAWP
Why is there a thermometer near the distal tip of the Swan-Ganz?
It monitors core temperature and is used for the thermodilution method of measure cardiac output
What can an advanced technology Swan-Ganz (PA catheter) monitor?
SvO2, CCO, RVED
What are less invasive options than a Swan-Ganz?
APCO monitoring and beside echocardiogram
Where is a PA catheter (Swan-Ganz) inserted?
By HCP at bedside
What conditions may be contraindications to a PA catheter (Swan-Ganz)?
Hypokalemia
Hypomagnesemia
Hypoxemia
Acidosis
Coagulopathy
What are key nursing roles during a PA catheter insertion?
Observe characteristic waveforms on monitor
Watch EKG
Obtain chest x ray
Note and record measurement at exit point
Apply occlusive sterile dressing
What is a measurement of right ventricular preload and reflects fluid volume status?
Central venous pressure (CVP)
Where is a CVP catheter most often placed?
In the internal jugular or subclavian vein
CVP is measured as a…
mean pressure at the end of expiration
What does a high CVP indicate?
Right ventricular failure or volume overload
What does a low CVP indicate?
Hypovolemia
How is a CVP catheter measured?
With a PA catheter using the proximal lumen in the right atrium
What is the reason for measuring the O2 saturation of venous blood in critically ill patients?
It helps to determine the adequacy of tissue oxygenation
What is ScvO2?
Central venous O2 saturation
What is SvO2?
Mixed venous O2 saturation
What do SvcO2 and ScO2 reflect?
The balance among oxygenation of the arterial blood, tissue perfusion, and tissue O2 consumption
What is normal ScvO2 or SvO2?
60-80%
What does a high ScvO2 or SvO2 indicate?
More oxygen supply, less oxygen demand
What conditions might cause a high ScvO2?
Receiving more O2 than needed
Anesthesia
Hypothermia
Sepsis
Why can anesthesia cause a high ScvO2?
Causes sedation and decreased muscle movement
Why can hypothermia cause a high ScvO2?
Decreases metabolic demand
What is an example of high ScvO2 caused by hypothermia?
Cardiopulmonary bypass
How does sepsis cause a high ScvO2?
Decreases the ability of tissues to use oxygen at the cellular level
What does a low ScvO2 or SvO2 mean?
Increased O2 demand
Low hemoglobin
Low arterial saturation
Low cardiac output
What are potential causes of low ScvO2?
Anemia
Bleeding
Hypoxemia
Cardiogenic shock
Increase in metabolic demand, such as muscle movement
What is cardiogenic shock?
When your heart cannot pump enough blood to the brain and vital organs to meet oxygen demand
ScvO2 values are generally slightly __ than SvO2 values
higher
How can the nurse indirectly assess CO and tissue perfusion?
Change in mental status
Strength and quality of peripheral pulses
Capillary refill
Urine output
Skin color and temperature
What does a fall in ScvO2 or SvO2 indicate if arterial oxygenation, CO, and Hgb are unchanged?
Increased O2 consumption or extraction
What could cause an increase in O2 consumption in a patient with a PA catheter?
Increased metabolic rate
Pain
Movement
Fever
Shivering
If the nurse is trying to reposition a patient, their heart rate increases and ScvO2 decreases, what does this mean?
The patient is not tolerating the move well and the nurse should wait to reposition until the ScvO2 returns to normal
What conditions make an accurate SpO2 hard to get?
Hypothermia
IV vasopressor therapy
Hypoperfusion/vasoconstriction
