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What probe is used for transcranial Doppler?
What is important to remember when imaging through transorbital window?
- 1.) Decrease power output
- 2.) Shut eye
When doing compressions of CCA what will you possibly see? (6)
- 1.) No response or reaction
- 2.) Flow increase
- 3.) Flow decrease
- 4.) Reversal of flow
- 5.) To-Fro pattern
- 6.) Total cessation of flow
What is the formula for PI?
PI = PSV - PEDV / Mean velocity
What is the normal PI for TCD?
0.80 to 1.20
What if PI is less than 0.80...
From what two things?
- 1.) stenosis of the supplying artery
- 2.) AVM feeders
What if PI is greater than 1.20...
From what 3 things?
- 1.) Larger aneurysm
- 2.) Increased intracranial pressure
- 3.) Microvascular disease
When vessels dilate what happens to the PI?
What are the four levels of SAH?
- 1.) < 80cm/sec = normal
- 2.) 80-120 cm/sec = moderate spasm
- 3.) 120-140 cm/sec = severe spasm
- 4.) > 140 cm/sec = severe causing lots of damage
What will be seen when TCD used to determine brain death?
Normal- sharp high resistance, low volume, low velocities
Abnormal- Dampened waveform
What are some treatments for AVMs in the intracranial? (2)
- 1.) Radiosurgery
- 2.) Endovascular treatment
What 3 things are sign can be seen with TCD because it has 3 flow abnormalities?
- 1.) increased flow velocity
- 2.) reduced pulsatility
- 3.) reduced responsiveness to CO2
Velocity maps show color changes displayed __________.
Variance maps show color changes displayed ______________.
Color Doppler displays what?
velocities throughout the scan field
Power Doppler estimates the?
strength of the Doppler shift from each location.
What are the advantages of power Doppler? (3)
- 1.) sensitive to slow flow
- 2.) never aliases
- 3.) angle does not effect it
What are the disadvantages of power Doppler? (2)
- 1.) cannot determine direction
- 2.) frame rates drop
What is packet size?
how many sample areas per a line
What is line density?
how many lines in the color box area
Who is responsible for ensuring that diagnostic US machines maintain good safety records?
The American Institute of US in Medicine
What two things do gray-scale US use?
1.) The distance from the echo to the transducer
2.) strength of the echo
what three things does color Doppler use?
1.) Doppler shift information
2.) Time of flight
3.) amplitude information
What is a visible bruit?
a flash of color within the soft tissue caused by the vibration of the vessel caused by severe flow disturbances
What does OPG-GEE detect?
significant stenosis of the end branches of the ICA.
What are two limitations of OPG-GEE?
1.) can't find exact location of stenosis or differentiate stenosis from occlusion.
2.) Hard to find when collaterals are working
What is the first thing you must do before performing an OPG-GEE?
take brachial pressures first
What are 4 contraindications?
- 1.) allergies to local anesthetics
- 2.) eye surgery within the last 6 months
- 3.) a past spontaneous retinal detachment
- 4.) acute or unstable glaucoma
OPG-GEE is done by...
measuring the ophthalmic artery systolic pressure by applying a vacuum to the eye on the sclera (white of the eye).
What systolic pressures equal what vacuum pressures?
<140 mmHg = 300mmHg
>140 mmHg = 500mmHg
When is a problem with the artery detected when there is...
a difference of 5mmHg between eyes
What does TCPo2 stand for?
What does TCPo2 do? (2)
1.) non-invasive monitoring of the oxygen tension in the skin
2.) direct indication of the microvascular function
What is TCPo2 mainly used for? (3)
1.) neonatal use
2.) vascular care
3.) wound care
What are 8 uses of TCPo2?
- 1. Diagnosis of ischemia
- 2. Healing probability
- 3. Suggesting amputation level
- 4. Plastic surgery
- 5. Hyperbaric medicine
- 6. Orthopedic surgery
- 7. successful revascularization
- 8. PVD assessment
How does TCPo2 work?
- 1. Uses polarographic oxygen electrode
- 2. Electrode heats skin to 44-45 degrees Celsius
- 3. Oxygen is consumed by the electrode
- 4. Electrode is calibrated with gas or with a solution of known PO2
What temp should the room be when doing a TCPo2?
What are 4 things a patient should not do before and during a TCPo2 test?
room temp. 70-73 degrees F.
- 1.) no caffeine 30 minutes prior to test
- 2.) no smoking 30 min prior to test
- 3.) no talking during test
- 4.) no excessive movement during test
When doing TCPo2 electrodes not be placed on? (5)
- 1. ulcers
- 2. cellulitis
- 3. skin close to bone
- 4. large superficial vessels
- 5. pulse sites
What is the three values of healing probability for TCPo2?
1. 70-80 mmHg = healing
2. 30-40 mmHg = borderline healing
3. 10-15 mmHg = non-healing
What is the Reynolds Number used for?
What is the values of Reynolds numbers (2)?
used to determine if flow will be laminar or turbulent
- <2000 = no turbulence
- >3000 = turbulence
What is Raynaud's Disease...
Also known as?
Caused from cold or stress.
What is Raynaud's Phenomenon...
Also known as?
- Underlying conditions:
- stenosis, systemic lupus, carpal tunnel
What are the color changes that Raynaud's in fingertips?
White to Blue to Red
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