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119 Cards in this Set
- Front
- Back
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we have _________________capillary vessels in the body
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1 billion
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When it comes to blood flow arteries are often referred to?
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conduits
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What happens at the level of the capillaries
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this is where the exchange of gasses and nutrients happen
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what route does the blood take to circulate though the body
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heart-arteries-arterioles-capillaries-venuloes-vein
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in blood flow there are both high resistance and low resistance. if you were looking at a wave form how would you know the difference?
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low resistance- high diastolic
high resistance- low diastolic |
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what are some examples of areas in the body that would have either low or high resistance flow?
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high- brain kidneys thyroid celiac
low- skeletal muscle external cartoid art, SMA (pre-prandial) |
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the longer the vessel the ________ resistance
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higher
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what is the driving force to make blood flow in the body?
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heart and gravity
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doppler is what type of form
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quantative
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color and power are what type of form?
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qualiative
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when blood flows it goes from ____________ pressure to regions of _______________pressure
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high
low |
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if the pressure at both ends of a vessel are equal what will happen
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blood will not flow
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what is blood composed of? how much is there of each component?
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RBC WBC platelets plasma
plasma- 60% of blood cells- 40% of blood |
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RBC make up ___________% of blood cells and contain__________ which transports____________
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99%
hemoglobin oxygen |
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what are the categories of enery blood needs to flow? and what are they?
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kinetic- bloods ability to do work based on motion-pressure energy
potential-pressure energy that is stored in arterial hemodynamics gravitational-stored/potential energy-gravitity pulls the RBC down |
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what are the factors that affect blood flow?
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density of blood
volume flow rate velocity of flow length and diameter of vessl (DVVL) * |
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when the heart contracts and the RBC move it is what type of energy
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kinetic
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during diastole flow in the aorta the RBC have ____________energy
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potential
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when a patient suffers from anemia they have______RBC and ___________resistance while polcythemia has____________RBC and ___________resistance
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low
low high high |
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what does poiseullies law demonstrate a relationship between?
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pressure, volume of flow, resistance
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according to poiseullies law__________is inveresely proportional to the ___________to the 4th power
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resistance
radius |
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what happens when the rbc move against the arterial wall during laminar flow
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cause a loss of pressure and an increase in heat (friction)
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during a stenosis what happens to the pressure and the velocity
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velocitity increases and the pressure will drop
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what area of arterial flow will demonstrate if there is high resistance
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diastolic component of the curve
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what does the continuity rule state
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blood is neither created or destroyed as it flows though a vessel
the volume flow rate is a constant at the proximal and distal portion of a stenosis maintain the volume flow rate the speed/velocity of blood must increase in the stenosis |
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what is the volume flow rate equation
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VFR=flow speed x diameter of vessel
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speed of blood over distance
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V=D/T
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amount of blood flow over time
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F=V/T
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in the human body, how much blood flows in one min
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5L
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what 3 things affect the velocity flow rate in a vessel
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tube length
diameter viscosity |
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if pressure_________then velocity/speed flow rate__________
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increase
increase |
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if flow resistance __________then velocity/speed rate ___________
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increase
decrease |
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if the tube radius increases then the flow resistance___________ and the higher the velocity/speed rate (bigger diameter =less friction)
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decrease
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if the tube length increases what happens to the flow resistance? y?
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it will increase bc the blood cells have more of a chance to rub agaisnt the walls
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there are 3 types of flow what are they and give one example of each
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pusatile flow-arterys
steady flow-capillaries phasic flow-veins |
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what is utilized during triplex imaging
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gray scale image
doppler spectrum color |
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what scale is used to compare doppler shift freq in color
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autocorrelation
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what is the OPTIMUM angle for Doppler spectrum and color doppler
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60 degrees
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what colors are used on the color scale to represent flow and what directon do they represent?
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red/orange/yellow---flow going toward the transducer
blue/violet/indigo--flow going away from transducer |
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___________light has all 3 colors while ________demonstaes no flow
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white
black |
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what 3 things are used to describe the colors seen on a color image? and what are they
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hue-classificaton of color
saturation- it is the mixture of all 3 primary colors (red/blue/green) that turns white luminance/intensity--bightness of hue and saturation present |
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the more white a ccolor has in it means what
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greater saturation which has higher velocites
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what is an indicator to the extent of flow disturbance pressent in the vessl
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luminescence- the brighter it is the more turbulent
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we know that red means blood is coming towards us while blue means blood is flowing away what principle is this?
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bart
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how is turbulent flow demonstarted with color
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it has a mosaic pattern that approaches white
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color uses a pulse packet to send out pulses what are some other names given to the pulse packet?
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ensemble
ensemble length packet size |
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why does color utilize autocorrelation to process information instead of Fast Fourier transform
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slow to process the color flow
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how many pules per scan line are needed for color? how does this affect fr and pulse time
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at least 5 but normally 6-20 pulses per scan line
needs longer transmit pulse time and it will reduce FR |
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how far can the color box be steered
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20 degress to the left or right
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how does autocorrelation work to produce the color image
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takes multiple data samples from different sites and analyzes the data to find the mean frequency, amplitude, and variance of turbulence to display it in color
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when does color ambiguity happen? what does it look like
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happens with the PRF is too low, looks mosaic
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what happens if the sample gate is too large
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spectral widening and window filling on the doppler curve
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what is color aliasing?
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color appears as though there is reverse flow and it usually occurs at the center of a vessel where the velocity is the highest. the lightest shade of one color will fold into the lightest shade of the opposite color such as yellow into blue
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how do u fix color aliasing?
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3 things that can be done
increase PRF increase the range of velocities on the spectrum scale lower the transducer freq |
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what 5 factors does color demonstate>?
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presence of flow
direction of flow speed of flow (mean velocity) character of flow (laminar vs turbulent) global view of anatomy and flow in real time |
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when is color power angio mode of use
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while trying to look at SLOW flow such as to rule out a complete blockage in an artery
great for DEEPER structures |
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what are some advantages and disadvantages of color power
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advantages- no aliasing, not angle dependent,can see flow in occulsions, small vessels, and tortuous vessels
can see slow flow in deep structures disadvantages- no info on velocity, direction or character of flow, highly sensitive to motion (flash artifacts) need cooperative pt low fr all vessels same color can produce false data in lowere PRF setting |
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what is a flash artifact
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created in color power angio mode, shows flow in areas that do not have any flow such as amnoitic fluid
will hafve no flow even on doppler |
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what is a twinkle artifact? what is an example it can be used on
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mix of colors that mimics turbulent flow, has no doppler spectrum. it happens behind strong reflective granular interface sure as a renal or urinary stone
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what is cont wave doppler used for
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segmental pressure, venous testing, evaluating stenotic lesions at deep depths and cardiac
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what are some downfalls of cont wave doppler
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no range or depth resolution
has a zone of sensitivity so flow from more then one vessel can be picked up by the signal narrow bandwidth |
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what is used to process cont doppler? how does it work
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quadrate detection-has two demodulator in the reciever that produces 2 doppler signals that are then mixed with 2 reference signals for the transmitter
after filtering 2 remaining signals differ in phase by 1/4 the cycle period of the reference freq. determines flow direction in cont wave equiptment |
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if your PRF is incorrectly sent out for pulsed doppler you will get___________in your image
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aliasing
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what is the pulsing rate
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note the number of pulses sent per sec also called sampling
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the smaple volume length determines the doppler shift of reutning echoes so what determines the sample volume length
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transmit pulse length
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what is the nyquist limit
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maximum doppler shift which is = to 1/2 the prf
highest doppler freq that can be measured without aliasing |
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if a doppler specturm goes about the nyquist limit there is ___________and if it is below it is __________
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aliasing
unambiguous |
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what is aliasing
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display artifact where there is no stenosis in a an artery. it appears as velocites that are too high to visualize on spectrum
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how is aliasing eliminated
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base line should be shifted down
increase the PRF decrease the transmit freq increase doppler angle (last option) decrease the sample width/sample gate use cont wave doppler |
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what 2 types of systems are there explain
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non imaging-2 crystals where one sends and the other receives. this is utillized in trans cranial
imaging-duplex-combine pulsed doppler system and gray scale |
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what is spectral analysis
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method of looking at rbc moving at any particular point in time. the spectrum plots freq (velocity) on a graph. once a freq shift is detected a dot will be plotted at a specific point in time on the graph
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what does spectral analysis evaluate
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direction
velocity duration characteristics of blood flow |
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what is the FFT what does it stand for
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Fast fourier transform
computerized method of rapidly analyzing a complex signal and displaying the individual components |
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one a doppler spectrum_______is on the y axis and _______x axis
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velocity
time |
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what are two ways that turbulence can show up on doppler spectrum?
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window filling
spectral broadening |
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in the cartoid the ECA has_____________resistance and the ICA__________resistance
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high
low |
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in the internal carotid artery window filling can be present in both turbulent flow and a stenosis. how would u know the difference by looking at the doppler spectrum
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turbulent flow would have partial window filling while a stenosis would have complete window filling
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what is used to evaluate cord flow to check for possible IUGR
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systolic/diastolic ratios (s/d)
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what are the formulas used to figure out both the pulsatile index and the resistance index
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PI= systole max-diastole min
_____________________________ average (mean) RI= systole max-diastole min ______________________________ sys peak |
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normal RI
and PI |
RI= > equal to .7
PI= > equal to 1 |
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what is plug flow? areas?
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speed of flow of blood cells that is constant across the vessel
opening of a vessel mainly aorta clostest to heart distal arteries |
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what is laminar flow? area
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RBC flow smoothly parallel to each other with flow slowing around the walls and the fastest in the center of a vessel
carotid artery ICA/ECA smaller arteries |
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flow that moves in circles
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eddy currents
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what is turbulence
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flow that is random and chaotic in speed and direction. occurs when blood is at high velocity distal to an obstruction or along a rough surface, sharp turn in a vessel or aneurysm
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eddy current are found where
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aneursyms
art bif after a stenosis |
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what is the reynolds #? formula
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predicts the onset of turbulence
r#= ave flow speedxtube diameterx density ___________________________________________ viscosity |
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reynolds number is _________________considered normal flow but if it is____________________turbulent flow
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<1500
>2000 |
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what can increase the reynolds number? decreases it
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flow speed
diameter density decreases: viscosity (resistance of blood to flow) |
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on doppler the angle correct should b between what degrees to get an accurate reading
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45-60 degrees
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what 3 factors affect pulsatile flow
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volume flow rate
pressure velocity |
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where is triphasic blood flow seen
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hepatic veins
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ability of vessel to contract and expand during flow and move blood toward is call what
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compliance
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what is a non compliant vessel
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a vessel with flow reversal
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radius of vessel decreases by 1/2 what will happen to velocity
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increase by 4x the orginal speed
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as flow increases kinetic potential energy_________increases
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losses
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does the volume flow rate change though a stenosis
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no
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describe what the bernoulli effect it. what does it say about blood flowing though a stenosis
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it is the inverse relationship between pressure and velocity
as blood flow though a stenosis.... volume flow rate unchanged velocity increases in the stenosis pressure is less than at either end of it |
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what are the 3 types of stenosis and how are they graded
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severe-70% must be blocked to significantly impair blood flow
critical-more then 70% of vessel blocked occulsion- vessel completly blocked no flow |
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is a vessel completely occuluded what can it do to fix the loss of blood flow?
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collateralization-smaller existing arteries shunt blood past the stenosis making collateral vessels
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velocity of flow will decrease along with flow rate if what happens?
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increase resistance of vessel walls
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fuctions of the veins?
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regulate body temp
control rate of blood return to heart and cardiac output stores 2/3 to 3/4 of bodys total blood volume highway to transport blood out of organ/extremites |
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a _________gradient is needed for venous blood to flow
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pressure
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what happens when a valve becomes incompetent?
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weak valve does not hold blood and it will cause blood to pool creating edema that will set into the extremities
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what is the doppler effect? who created it and when
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technique used to quantify and characterize blood flow patterns
johann christian doppler 1842 |
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the difference between the emitted freq and the returning freq creates a _________
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doppler shift
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spectral analysis is part of the signal processor known as
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doppler shift dectection
spectrum analyzer |
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doppler shift freq range between
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100hz-11000hz
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diagnostic freq range between
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2-10mhz
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who developed FFT? what does it do?
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Baron
separtates and shows freq in a doppler shift of the RBC by breaking down the mixture and range of signals banding them together and displaying them as a function of time in a curve |
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on a doppler curve the....
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vertical axis---doppler shift freq
hortizontal- time brightness of the display=amplitude/power |
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on a doppler curve what does the jagged edges seeon on the curve
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differnt velocities of the returning echoes in flow
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range of doppler shift freq and speeds are demonstrated on the __________
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doppler curve
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what is the doppler equation? what do the symbols mean
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F=2fv cos0
_________ C F-detected freq shift f-transmitted freq v-velocity of RBC C-speed of sound in tissue cos 0 angle between u/s beam and direction of blood flow |
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what does the doppler equation tell us
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the change in freq of a signal as it interacts with a moving structure will give us the doppler shift
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what is the OPTIMUM angle for doppler imaging
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60 degrees
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how far can a doppler beam be steered in linear array
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20 degrees
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when is angle correction useful
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when the angle is off by 5 degrees. this will allow the correct velocity flow speed to be calculated when the angle is not 60 degrees
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what is spectral analysis
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allows us to visualize the range of doppler freq in a signal when doppler shifts are dectected from reflectors moving at different speeds
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what are the primary colors
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red blue green
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