Week 3 - Lesson 1 (Part 9) Flashcards
What does arterial flow reflect? (2)
- Cardiac cycle
2. Flow pattern
On spectral doppler what is on the x axis?
Time
- seconds
On spectral doppler what is on the x axis?
Velocity
What can affect the velocity on the y axis?
PRF
- scale
PSV
Peak systolic velocity
EDV
End diastolic velocity
What is spectral width?
Bandwidth
What is spectral intensity?
Brightness
What is the main parameter for evaluating the severity of carotid stenosis?
Flow velocity
Where is spectral doppler placed on the vessel?
The cursor is placed in the centre of the carotid lumen at an angle of 60° or less
What is useful in the assessment of blood flow at and distal to arterial obstructions?
In evaluating the significance of the occlusive disease
What does doppler spectrum analysis allow?
The accurate detection and quantification of blood flow abnormalities resulting from stenotic lesions
What does stenotic lesions result from? (2)
- A marked disturbance of flow
2. Abnormally high velocities at the site of narrowing
What extend from a stenosis? (2)
- Jet effects
2. Irregular travel of particles in various directions at different velocities and eddy formation
When is the only time you dont put a 60 deg angle on a vessel?
Straight up and down vessel
- eg. distal ICA
What kind of analysis do you get from spectral doppler?
Quantification
- number results
What kind of analysis do you get from power doppler?
Aware of a single taking place
What are effects of arterial stenosis? (4)
- Widening or dispersal of the band of systolic velocity
- Spectral broadening
- loss of clear window below systolic portion - Complete filling in of the spectral tracing
- Reversal of blood flow due to eddies
Where do you place the gate/sample volume in doppler?
In the center of the normal vessel lumen and in the center of a stenotic area
What does a temporal tap help with?
To differentiate between ECA and ICA
How does a temporal tap help differentiate between ICA and ECA?
Because the temporal artery comes off of the ECA and when you tap it the ECA will change and the ICA wont
What is the pressure remaining in the veins after the blood has traversed the arterioles and capillaries for someone in a supine position?
Low
Why is the pressure remaining in the veins after the blood has traversed the arterioles and capillaries for someone in a supine position low?
Because of their relatively large diameters, medium and large veins offer little resistance to flow
Where does blood readily move?
From the small veins to the right atrium
What does phasic changes in venous pressure and blood flow reflect changes in?
The right atrial pressures in response to cardiac activity
- because of alterations of intrathoracic pressure and respiration
What do alterations in venous hemodynamics occur with? (3)
- Changes in posture
- Important consequence of competence or incompetence of venous valves
- Effects of venous obstruction
What are the 3 main components of venous pressure of the lower limbs?
- Hydrostatic (gravitational) pressure
- Residual pressure
- Muscular and respiratory pressure
What is hydrostatic pressure due to?
The height of the venous blood column
What does hydrostatic pressure apply with?
A patient in a standing position
Why does hydrostatic pressure apply to a standing position?
Because flow from the furthest points (feet) must return to the right atrium
What is the main resistance due to in the lower limbs?
Microcirculation
Residual pressure
At the venous end of the capillaries, the venous pressure supplied by the arterial pressure
