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TCD > Class 1 > Flashcards

Class 1 Flashcards

1
Q

What does TCD stand for?

A

Transcranial Doppler

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2
Q

What is TCD?

A

It is a non-invasive assessment of the cerebral blood flow in the basal cerebral arteries.

*Most of them will relate to the circle. of wilis*

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3
Q

What is TCD usually used for?

A
  • Baseline
  • Stroke patients
  • Cerebral deficiency
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4
Q

What type of frequency does a TCD use?

A
  • Low frequency lets you penetrate deeper.
  • Skull bone attenuates 90% of your ultrasound beam.
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5
Q

What is the standard probe used for TCD?

A

2 MHZ probe

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6
Q

Ultrasound passes through many_______

A

Cranial “windows”

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7
Q

What type of information does TCD provide?

A

It provides information regarding velocity (mean velocity) and direction of cerebral blood flow.

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8
Q

Who introduced the first ultrasound transtemporal approach?

A

Dr. Rune Aaslid in 1982

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9
Q

Who first published the transorbital approach?

A

Dr. Merrill Spencer in 1984

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10
Q

Who first published the suboccipital approach?

A

Dr. M. Von Reutern in 1986

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11
Q

When was the first commerical TCD unit invented?

A

1983

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12
Q

What is the circle of wilis?

A
  • It is a network of vessels at the base of the brain that distributes flow to all regions of the RT & LT hemispheres of the brain.
    • Primarly from the anterior circulation: ICA supply
    • Primarily from the posterior circulation: Vertebral supply
  • Most important source of cerebral blood supply and collateral circulation.
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13
Q

Where is the circle of wilis located?

A

It is located at the base of the brain.

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14
Q

What percentage of people have a complete circle of wilis?

A

20%

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15
Q

What is the criteria for vessel identifcation?

A
  1. Depth of sample volume
  2. Direction of flow
  3. Traceability of the vessel
  4. Transducer angulation
  5. Spatial relationship of waveform spectra
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16
Q

What direction can the probe only go towards?

A

Towards the probe.

Usually 50 cm/s

Never reverses.

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17
Q

T/F

Every waveform has its own special type of spectral waveform.

A

True

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18
Q

What is the landmark for vessels?

A

MCA

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19
Q

What are some TCD characterisitics?

A
  • Noninvasive
  • Painless
  • Inexpensive
  • Povides instanteous and continuous cerebral blood flow info.
  • Can be used in any hospital enviroment
  • Safe
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20
Q

What are the main accepted clinical application uses for TCD’s?

TCD applications

A
  • Detect/monitor intracranial vasospasm
    • ​main use
  • Detect/monitor intracranial stenoses
  • Confirm the diagnosis of brain death
  • Assist in the detection and mangement of ASD
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21
Q

Other used for TCD include:

A
  • Assess of collateral pathways
  • Assess autoregulation and vasomotor reactivity
  • ICU monitoring (effects of ICP)
  • Surgical montitoring (CEA, CABG)
  • Detecting of emboli (HITS)
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22
Q

What are some TCD intraoperative monitoring applications?

A
  • Carotid endarectomy
  • Carotid stenting
  • Coronary artery bypass surgery
  • Cardiac valve surgery
  • Abdominall aortic aneurysm
  • Liver transplants
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23
Q

What are some pitfalls and trouble spots of using TCD?

A
  • Variations and incomplete circle of willis
    • e.g. Missing ACA and PCA stemming directly from ICA
  • Absent or small windows
    • Approx. 90-95% of the population have a temporal window.
  • Not identifying/finding best temporal window
  • Improper doppler settings
    • e.g. too low/too high gain, too large sample volume, low power
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24
Q

T/F

A TCD exam is extremely user dependent.

A

True.

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25
Q

How should you set up the equipment pior to beginning a TCD exam?

A
  1. Wipe down transducer and cable
  2. Label vessel, adjust depth, power and direction of flow before applying transducer on the patient.
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26
Q

How should you position the patient pior to beginning a TCD exam?

A
  1. Exam can be preformed in a supine or sitting position
  2. DO NOT reposition a patient with a EVD, without nursing assistance
  3. Know the status of the extracranial vessels.
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27
Q

What window is the MCA in?

A

Transtemporal

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28
Q

What is the depth, velocity, and direction associated with the MCA?

A

Depth: 30-60 mm

Velocity: 50 +/- 12

Direction: Towards the probe

29
Q

What window is the MCA/ACA bifurcation?

A

Transtemporal

30
Q

What is the depth, velocity, and direction associated with the MCA/ACA bifurcation?

A

Depth: 55-65 mm

Direction: bidirectional

31
Q

What window is the ACA located in?

A

Transtemporal

32
Q

What is the depth, velocity, and direction associated ACA?

A

Depth: 60-80 mm

Velocity: 50 +/- 11

Direction: away

33
Q

What window is PCA-P1 located in?

A

Transtemporal

34
Q

What is the depth, velocity, and direction associated with PCA-P1?

A

Depth: 60-70 mm

Velocity: 39 +/- 10

Direction: towards

35
Q

In what window is PCA-P2 seen in?

A

Transtemporal

36
Q

What is the depth, velocity, and direction associated with PCA-P2?

A

Depth: 60-70 mm

Velocity:​ 40 +/- 10

Direction: away

37
Q

In what window is the OA located in?

A

Transorbital

38
Q

What is the depth, velocity, and direction associated with the OA?

A

Depth: 40-60 mm

Velocity: 21 +/- 5

Direction: towards

39
Q

In what window is the carotid siphon seen in?

A

Transorbital

40
Q

What is the depth and velocity associated with the carotid siphon?

A

Depth: 60-80 mm

Velocity: 43 +/- 11

41
Q

In what window is the VA seen in?

A

Transforaminal

42
Q

What is the depth, velocity, and direction associated with the VA?

A

Depth: 60-90 mm

Velocity: 38 +/- 10

Direction: away

43
Q

In what window is the BA seen in?

A

Transforaminal

44
Q

What is the depth, velocity, and direction associated with the BA?

A

Depth: 80-1208 mm

Velocity: 41 +/- 10

Direction: away

45
Q

What are the 3 areas of the transtemporal window?

A
  1. Anterior →ACA
  2. Middle→MCA
  3. Posterior→PCA
46
Q

LABEL THESE WINDOWS:

47
Q

T/F:

The MCA is bigger than the basilar artery.

A

False.

The basilar artery is twice the size of the MCA

48
Q

Where is the MCA window?

A

Transtemporal

49
Q

What is the angle used to find the MCA?

A

Anteriorly and posteriorly.

50
Q

What is the depth range of the M1 segment?

51
Q

What is the depth range for the M2 segment?

52
Q

What is the flow direction found in the MCA?

A

Towards the transducer

53
Q

How should you sample the MCA?

A

Sample at 2mm increments

54
Q

Can the MCA change directiosn?

A

No, it will never change direction

55
Q

Where is the MCA/ACA birfucation?

A

Transtemporal window

56
Q

What is the angle used to find the MCA/ACA bifur.?

A

Anteriorly and superiorly

57
Q

What is the segment depth range for the MCA/ACA bifurc.?

58
Q

What is the flow direction for the MCA/ACA bifurc.?

A

Bidirectional

59
Q

ACA flow direction is….

A

Away from the transducer

60
Q

What is the segment depth range for the ACA?

61
Q

What is normal flow direction in the ACA?

A

Away from the transducer.

It CAN chnage direction in the presence of disease.

62
Q

What window is used for the PCA?

A

Transtemporal

63
Q

What angle is used to find the PCA?

A

Posteriorly and inferiorly

64
Q

What is the segment depth range of the PCA?

65
Q

What is the flow direction in the PCA?

A

Bidirectional.

P1→towards

P2→away

It can change direction with presence of disease

66
Q

Normal velocity relationships

A

MCA>ACA>PCA~VA & BA

67
Q

The more shallow you are….

A

The more distal and superfical you are.

68
Q

What is hyperostosis?

A

Hyperostosis is an excessive growth of bone

TCD (5 decks)

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