Study guide for 18, 19, 20 Flashcards Preview

DMSO Physics 2 > Study guide for 18, 19, 20 > Flashcards

Flashcards in Study guide for 18, 19, 20 Deck (43):
1

Movement of fluid from one location to another?

Velocity

2

Fluid moving with a variable velocity accelerates and decelerates?

Pulsitile flow

3

Movement of fluid from one location to another that accelerates and decelerates w/ respiration?

Phasic Flow

4

Flow pattern seen with normal physiological states?

Laminar Flow

5

Chaotic flow in many directions and speeds?

Turbulent Flow

6

Frictional loss, blood slide along vessel wall is considered what?

Heat?

7

Reynolds number, turbulent flow?

> 2,000

8

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

9

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''

10

Doppler shift provide info about what?

Velocity

11

Positive and negative Doppler shift?

Positive

toward transducer
reflected higher than transmitted
arterial

12

Positive and negative Doppler shift?

Negative

away from transducer
reflected lower than transmitted
venous

13

Typical range of Doppler shift found in imaging examinations?

Audible
20Hz - 20kHz

14

If the sample volume is deep, the PRF and Nyquist limit is what?

low, creates aliasing

15

Phenomenon high velocity is negative?

Aliasing

16

Five ways to eliminate aliasing?

1. adjust scale
2. shallower
3. ↓ frequency
4. Baseline
5. Continuous Wave

17

Large and small sample volumes, which will fill in on Doppler?

Large, spectral broading

18

X and Y axis on Doppler Spectrum?

X

Time

19

X and Y axis on Doppler Spectrum?

Y

Shift or Velocity

20

Doppler shift inversely related to?

speed of sound in the medium

21

What is the basic Doppler system that simple identifies the blood flow of the presence of a frequency shift?

power doppler (MW pg 333)

22

Gray shades on Doppler spectrum related to two things?

amplitude of reflected signal
number of blood cells creating the reflection

23

Doppler Spectrum, high waveform is a high frequency or low?

?
I think this is high freq. because they are directly related (MW pg 308)

24

What is the Doppler Effect?

the change in frequency

25

Difference between speed and velocity?

Speed

magnitude (distance red blood cells travel in 1 second)

26

Difference between speed and velocity?

Velocity

Magnitude and direction

27

Angle w/ Doppler/ No angle?

0⁰: 1.0
90⁰: 0
180⁰: -1.0

28

Primary advantage for a pulse wave Doppler?

select exact location
(range resolution, range specificity)

29

Primary advantage for continuous Doppler?

ability to accurately measure very high velocity

30

Bidirectional, type of processing?

Phase quadrature or quadrature detection

31

FFT used in what type of what?

Is a computer-based technique, is use to process both pulsed and continuous wave Doppler signals

32

Velocities that color flow measures?

mean or average

33

Autocorrelation?

digital technique to analyses color flow Doppler less accurate but faster than FFT

34

Limitation to color flow imaging?

it has range resolution and is subject to aliasing
pg 325 and esp physics pdf

35

Area of integration in Doppler is called?

Sample Volume

36

More accurate velocity measurement
Increased sensitivity low flow

Large Doppler packet advantages and disadvantages?

Advantages

37

More time needed to acquire data
Reduced frame rate
Decreased temporal resolution

Large Doppler packet advantages and disadvantages?

Disadvantages

38

How to measure low flow states?

Power Doppler?

39

Inspiration vs Expiration

Inspiration

Diaphragm ↓
Thoracic pressure ↓
Abdomen pressure ↑
Venous return to the heart ↑
Venous flow in legs ↓

40

Inspiration Vs Expiration

Expiration

Diaphragm ↑
Thoracic pressure ↑
Abdomen pressure ↓
Venous return to the heart ↓
Venous flow in legs ↑

41

Venous pressure is low, pressure in veins?

Low

42

37. What happens to shape of veins when pressure increases?

starts hourglass, then goes oval, then to round

43

Hydrostatic pressure when standing

Ankle 140 mmHg, Far below heart level, 100mmHg , 240mmHg (140 + 100)
Knee, 140mmHG, Somewhat below heart