TCD > Class 1 > Flashcards

Class 1 Flashcards

(68 cards)

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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
How should you set up the equipment pior to beginning a TCD exam?
1. Wipe down transducer and cable 2. Label vessel, adjust depth, power and direction of flow before applying transducer on the patient.
26
How should you position the patient pior to beginning a TCD exam?
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.
27
What window is the MCA in?
Transtemporal
28
What is the depth, velocity, and direction associated with the MCA?
**Depth:** 30-60 mm **Velocity:** 50 +/- 12 **Direction:** Towards the probe
29
What window is the MCA/ACA bifurcation?
Transtemporal
30
What is the depth, velocity, and direction associated with the MCA/ACA bifurcation?
**Depth:** 55-65 mm **Direction:** bidirectional
31
What window is the ACA located in?
Transtemporal
32
What is the depth, velocity, and direction associated ACA?
**Depth:** 60-80 mm **Velocity:** 50 +/- 11 **Direction:** away
33
What window is PCA-P1 located in?
Transtemporal
34
What is the depth, velocity, and direction associated with PCA-P1?
**Depth:** 60-70 mm **Velocity:** 39 +/- 10 **Direction:** towards
35
In what window is PCA-P2 seen in?
Transtemporal
36
What is the depth, velocity, and direction associated with PCA-P2?
**Depth:** 60-70 mm **Velocity:​** 40 +/- 10 **Direction:** away
37
In what window is the OA located in?
Transorbital
38
What is the depth, velocity, and direction associated with the OA?
**Depth:** 40-60 mm **Velocity:** 21 +/- 5 **Direction:** towards
39
In what window is the carotid siphon seen in?
Transorbital
40
What is the depth and velocity associated with the carotid siphon?
**Depth:** 60-80 mm **Velocity:** 43 +/- 11
41
In what window is the VA seen in?
Transforaminal
42
What is the depth, velocity, and direction associated with the VA?
**Depth:** 60-90 mm **Velocity:** 38 +/- 10 **Direction:** away
43
In what window is the BA seen in?
Transforaminal
44
What is the depth, velocity, and direction associated with the BA?
**Depth:** 80-1208 mm **Velocity:** 41 +/- 10 **Direction:** away
45
What are the 3 areas of the transtemporal window?
1. Anterior →ACA 2. Middle→MCA 3. Posterior→PCA
46
LABEL THESE WINDOWS:
47
T/F: The MCA is bigger than the basilar artery.
False. The basilar artery is twice the size of the MCA
48
Where is the MCA window?
Transtemporal
49
What is the angle used to find the MCA?
Anteriorly and posteriorly.
50
What is the depth range of the M1 segment?
40-60 mm
51
What is the depth range for the M2 segment?
30-40 mm
52
What is the flow direction found in the MCA?
Towards the transducer
53
How should you sample the MCA?
Sample at 2mm increments
54
Can the MCA change directiosn?
No, it will never change direction
55
Where is the MCA/ACA birfucation?
Transtemporal window
56
What is the angle used to find the MCA/ACA bifur.?
Anteriorly and superiorly
57
What is the segment depth range for the MCA/ACA bifurc.?
55-65 mm
58
What is the flow direction for the MCA/ACA bifurc.?
Bidirectional
59
ACA flow direction is....
Away from the transducer
60
What is the segment depth range for the ACA?
60-80 mm
61
What is normal flow direction in the ACA?
Away from the transducer. **It CAN chnage direction in the presence of disease.**
62
What window is used for the PCA?
Transtemporal
63
What angle is used to find the PCA?
Posteriorly and inferiorly
64
What is the segment depth range of the PCA?
60-70 mm
65
What is the flow direction in the PCA?
Bidirectional. **P1→towards** **P2→away** ***_It can change direction with presence of disease_***
66
Normal velocity relationships
MCA\>ACA\>PCA~VA & BA
67
The more shallow you are....
The more distal and superfical you are.
68
What is hyperostosis?
Hyperostosis is an excessive growth of bone
TCD
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