TCD wk 1 (test 1)

Question 1

TCD stands for

Answer 1

Transcraniral Doppler

Question 2

What is TCD used for?

Answer 2

Non-invasive testing for cerebral blood flow in basal cerebral arteries.

Question 3

What transducer does TCD use?

Answer 3

2 MHZ

Question 4

Why is a low frequency transducer used for TCD?

Answer 4

To penetrate the thickness of skull bone. 90% of signal is attenuated in bone.

Question 5

TCD passes through

Answer 5

Cranial windows

Question 6

What does TCD give us

Answer 6

Mean velocity and direction of flow.

Question 7

Development of TCD

Answer 7

1982- Aaslid introduced it.
1983-first TCD unit
2002- PMD created

Question 8

PMD/M-Mode

Answer 8

2002, by Moehring.

Simultaneously displays intensity and direction of intracranial blood flow.

Question 9

Circle of Willis

Answer 9

Network of vessels giving flow to brain. 
ANT-POST and RT to LT.
Collateral system.
20% have complete circle.
Base of brain

Question 10

What vessels do we evaluate?

Answer 10

A1, M1, P1.

There are vessels 1-3, but we can’t see #3 since too superficial.

Question 11

Criteria for vessel identification

Answer 11

Vessel depth
Direction of flow
Trace-ability of vessel
Transducer angulation
Spacial relationship of wave

Question 12

Advantages to TCD

Answer 12

Safe
Non-invasive
Inexpensive
Painless
Used in any hospital setting (ICU too)

Question 13

Uses for TCD

Answer 13

Intracranial vasospasm
Intracranial stenoses
Diagnosing brain death
Assess collateral pathways
ICU monitoring
Detection of emboli

Question 14

TCD intraoperative monitoring

Answer 14

Carotid endarterectomy.
Carotid stenting
Carotid bypass
Liver transplants
AAA

Question 15

TCD pitfalls

Answer 15

Lack of/small windows
Variations-incomplete circle
Improper doppler settings
Not using best temporal window

Question 16

TCD exam necessities

Answer 16

Steady hand
Rest on patient, bed, railings
45-60 minutes
Don't rush
User dependent

Question 17

Beginning TCD exam

Answer 17

Wipe probe and cord.
Pre-set settings-vessel, depth, direction, power.
Supine
Positioned at head of bed.
Know vessels
DO NOT adjust EDV beds

Question 18

Typical TCD values

Answer 18

MCA: 30-60 mm T.
MCA/ACA bif: 55-65mm B.
ACA: 60-80mm A.
PCA-P1: 60-70mm T.
PCA-P2: 60-70mm A.
Transtemporal window

Question 19

Transtemporal window

Answer 19

eye-(ACA)(MCA)(PCA)-ear

Question 20

Middle Cerebral Artery (MCA)

Answer 20

Transtemporal.
30-60mm
M1-40-60mm
M2-30-40mm
Anterior-Superior.
Towards-never changes.
*Pre-set 35mm

Question 21

MCA/ACA Bifurcation

Answer 21

Transtemporal.
55-65 mm.
Bidirectional-MCA (T), ACA (A).
Anterior-Superior.

Question 22

Anterior Cerebral Artery (ACA)

Answer 22

Transtemporal.
60-80 mm.
Away, can change with disease.
Anterior-Superior.

Question 23

Posterior Cerebral Artery (PCA)

Answer 23

Transtemporal.
60-70mm.
Bidirectional- P1 (T), P2 (A); can change with disease.
Posterior-Inferior

Question 24

Velocity relationship

Answer 24

MCA>ACA>PCA.

PCA~VA and BA.

Question 25

Hyperostosis

Answer 25

Overgrowth of bone