Study guide for 18, 19, 20 Flashcards
Movement of fluid from one location to another?
Velocity
Fluid moving with a variable velocity accelerates and decelerates?
Pulsitile flow
Movement of fluid from one location to another that accelerates and decelerates w/ respiration?
Phasic Flow
Flow pattern seen with normal physiological states?
Laminar Flow
Chaotic flow in many directions and speeds?
Turbulent Flow
Frictional loss, blood slide along vessel wall is considered what?
Heat?
Reynolds number, turbulent flow?
> 2,000
What the effects of stenosis are?
change in flow direction ↑ velocity as vessels narrows turbulence downstream from the stenosis pressure gradient across the stenosis loss of pulsatility
Next 5 questions are about hydrostatic pressure?
These are all in supine
Ankle 140mmHg heart 0mmHg 140 mmHg (140 + 0)
Knee ‘’
mid Chest ‘’
Top of head’’
Doppler shift provide info about what?
Velocity
Positive and negative Doppler shift?
Positive
toward transducer
reflected higher than transmitted
arterial
Positive and negative Doppler shift?
Negative
away from transducer
reflected lower than transmitted
venous
Typical range of Doppler shift found in imaging examinations?
Audible
20Hz - 20kHz
If the sample volume is deep, the PRF and Nyquist limit is what?
low, creates aliasing
Phenomenon high velocity is negative?
Aliasing
Five ways to eliminate aliasing?
- adjust scale
- shallower
- ↓ frequency
- Baseline
- Continuous Wave
Large and small sample volumes, which will fill in on Doppler?
Large, spectral broading