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Terms in this set (78)
What is the definition of hemodynamics?
Movement of blood
The measurement of the force exerted by the blood as it moves through blood vessels or heart chambers during systole and diastole
Why is BP a crucial measurement?
Integrity of cardiovascular tone
What three factors control BP?
What three things can you measure non-invasively?
Perfusion (finger nail)
What three invasive tools are used in hemodynamic monitoring?
Pulmonary artery catheter
Central venous catheter
The pressure that stretches the ventricular walls at onset of ventricular contraction
The "tank" of fluid feeding the heart
Forcefulness of the heart muscle contracting under a constant load
The strength and rate of cardiac contractions
The load against which the ventricles must contract
The resistance of the vessel to flow from the heart
Number of contractions per minute
Pressure exerted against the vessel walls during systole and diastole
Average amount of pressure exerted by the blood in the vessels
The venous pressure exerted by the blood in the vessels
Pressure in the pulmonary artery
Average amount of pressure exerted in the pulmonary artery
An indirect indication of left atrial pressure
The amount of blood pumped out of left ventricle and into systemic circulation
Amount of blood ejected by the ventricle with every contraction
The volume of blood pumped by the heart in a unit of time divided by the body surface area
3-4 L/min per meter squared
Systemic Vascular Resistance
Pressure against which the heart must push to pump blood to the body
900-1500 Dyne sec/cm -5
Pulmonary Vascular Resistance
Pressure against which the heart must push to pump blood to the lungs
80-250 Dyne sec/cm -5
Indicates contractility of the right ventricular cardiac muscle compared to PVR
7-12 g/meter squared
Indicates contractility of left ventricular cardiac muscle compared to the SVR
40-60 g/meter squared
What is the most important thing to remember when measuring the pressure of a liquid filled closed circuit?
It must be measured at the same level as the point it is being taken for the results to be accurate (Pascal's Principle)
Why is hemodynamics performed?
Intravascular fluid volume
ID sudden changes in pts hemodynamic status
What are the indications for hemodynamic monitoring?
Pts with severe hypotension or hypertension
Pts who may need frequent arterial blood gas assessment
Pts in shock or respiratory failure are candidates for placement of an A-line
What is the pulmonary artery catheter?
Flow-directed, balloon tipped catheter
It has a distal lumen
It has a thermistor
It has a proximal lumen
What is the distal lumen of the pulmonary artery catheter used for?
Measure pulmonary artery pressures
Aspirate mixed venous samples
Continuous monitoring of SvO2
What does the thermistor do on the pulmonary artery catheter?
Temperature sensing device
Used during thermodilution for QT measurements
Measures core temp
A cool solution is added and a computer measures the peak and how long it took for the temp to get back to 70% normal (30% decay)
What is the most important thing to remember about thermodilution?
Cardiac output is inversely proportional to the area under the curve
High cardiac output means a smaller area
The faster the blood flows through the heart the earlier the peak and sharper the drop
What does the proximal lumen used for?
Located in right atrium
Aspirate blood samples
Inject thermal bolus for thermaldilution
What are the indications for a pulmonary artery catheter?
Complex, acute heart disease
Acute, severe pulmonary disease
Shock of all types if severe or prolonged
Severe, multisystem trauma or large area burn
Major system dysfunction undergoing extensive operative procedures
Where is the pulmonary artery catheter inserted?
Subclavian or internal jugular vein
In what order will the tip of the pulmonary artery catheter float through the heart?
Then once balloon is fully inflated cutting off blood flow it will measure the wedge pressure
What are the complications of the pulmonary artery catheter?
Pulmonary artery hemorrhage
Pulmonary infarction (if balloon is left inflated)
Air embolism (if balloon bursts)
What can cause the pulmonary artery pressure to decrease?
Volume of blood ejected by the right ventricle decreases ( afterload of the right ventricle)
Pulmonary vasculature relaxes or dilates
What causes pulmonary artery pressure to increase?
Pulmonary blood flow increases
Pulmonary vascular resistance increases due to: constriction, obstruction, or compression
How do you differentiate between cardiac and non-cardiac pulmonary edema?
Compare PCWP and PAP
Increased PCWP and PAP = cardiac
Normal PCWP and increased PAP = non-cardiac
What causes PCWP to decrease?
Right heart failure (Cor Pulmonale)
Pulmonary hyper tension
What causes PCWP to increase?
Left heart failure (CHF)
mitral valve stenosis
high PEEP effects
What are the possible sites used for arterial catheter?
Radial (site of choice), brachial, femoral, dorsalis pedis, umbilical
What are some common uses for arterial catheter?
Measures systemic artery pressure
Collect arterial blood gas samples
What does the dicrotic notch represent?
Closure of aortic valve during diastole
What does the inotropic phase represent on the arterial waveform?
initial contraction of muscles
What does the volume displacement phase represent on the arterial wavefrom?
Point at which muscle contraction actually causes fluid movement
What are some causes of decreased arterial pressure?
Absolute hypovolemia (blood loss/dehydration)
Relative hypovolemia (shock/vasodilation)
What are some causes of increased arterial pressure?
Improvement in circulatory volume and function
Administration of vasopresors
Define pulse pressure
the difference between arterial systolic and diastolic pressure
systolic - diastolic
What are some causes of decreased pulse pressure?
decreased stroke volume
increased blood vessel compliance (shock)
What are some causes of increased pulse pressure?
increased stroke volume
decreased blood vessel compliance (arteriosclerosis)
What are the three equations for calculation cardiac output?
QT = HR X SV
QT = (130 X BSA)/ [C(a-v)O2 X10]
QT = (VO2)/ [C(a-v)O2 X 10]
How to calculate Cardiac Index
What value of Cardiac Index indicates hypoperfusion?
1.8 - 2.5 L/min/m2
What value of Cardiac Index indicates cardiogenic shock?
less than 1.8 L/min/m2
What increases stroke volume?
drugs that raise cardiac contractility and during early stages of compensated septic shock
What decreases stroke volume?
drugs that lower cardiac contractility and during late stages of decompensated shock
How do you calculate stroke volume?
Why do we use stroke volume index?
to normalize stroke volume measurements among pts of varying body size
SVI = SV/BSA
Normal: 33-47 mL/m2
What effect will a positive inotropic drug have?
increase contractility of the heart
What factors increase: stroke volume, stoke volume index, cardiac output, and cardiac index?
positive inotropic drugs
What factors decrease: stroke volume, stroke volume index, cardiac output, and cardiac index?
Negative inoptropic drugs
hyper inflation of the lungs (MV, CPAP, PEEP)
What will happen to the pressure reading if the transducer is higher than the site of the arterial catheter?
there will be falsely low readings
What will happen to the pressure reading if the transducer is lower than the site of the arterial catheter?
there will be falsely high readings
What are the complications associated with arterial catheters?
What does the central venous catheter measure?
The pressure in the:
BASICALLY: right heart function
What s the purpose of the central venous catheter?
assessment of right ventricular function and intravascular volume status
Administration of fluids, parenteral nutrition, blood, drugs
Emergency route for temporary pacemaker insertion
What are the indications for a Central venous catheter?
to measure central venous pressure
administer fluid, blood, or meds
Aspiration of blood samples
What causes a decrease in CVP?
decreased venous return due to volume loss (absolute or relative hypovolemia)
decrease intrathoracic pressure (spontaneous inspiration)
increased ability of the right heart to move blood
What causes an increase in CVP?
Increased venous return (hypervolemia/volume overload)
Increased intrathroacic pressure (PPV, pneumothorax)
Decreased ability of the right heart to move blood (increased pulmonary vascular resistance or compression around the heart)
When is CVP ideally read?
end of expiration
What are the 5 types of shock?
Define hypovolemic shock
a decrease in the effective circulating blood volume
Define cardiogenic shock
Systemic hypoperfusion due to profound heart failure and/or the ability to meet metabolic needs
Define septic shock
associated with any infectious disease which causes relative hypovolemia
Define neurogenic shock
dysfunction of the sympathetic nervous system resulting in massive peripheral vasodilation and systemic hypoperfusion
Define anaphylactic shock
Systemic reaction causing circulatory failure and biochemical abnormalities
Right heart failure
Normal PAP + PCWP
Increased CVP + PAP
Left heart problem
Increased PCWP +PAP
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