Quiz 3 Flashcards
Duplex Testing
Direct testing
Can locate focal stenosis
Can NOT evaluate the amount of perfusion(flow to feet)
Limitations due to body habitus
Pressures/Waveforms
Indirect Testing
Can only locate levels of disease
Shows total perfusion including flow from collaterals
Limitations due to calcified vessels & multi-level disease
The reason for vascular symptoms:
they are cause by an area of HYPOTENSION within the limb.
These low pressures are from the presence of occlusive disease & lack of adequate collateral circulation to the affected area. (Bernoulli Effect)
Segmental Pressures
Utilizes the Peak Systolic Pressure (PSP) at different levels to evaluate for pressure gradients. The PSP’s are also divided by a reference pressure (Highest brachial PSP) & create ratios known as Pressure Indices. Always Bilateral
Cuff Sizes
Brachial 12cm
Thigh 12-17 cm
Calf & Ankle 10 cm
“Cuff Artifact”
The width of the cuff should be at least 20% wider than the diameter of the underlying limb. Cuff Artifact is a FALSE abnormally high (cuff is to small) or low (cuff to big) systolic blood pressure reading. More commonly HIGH. Elevated above 1.25*
Toe pressure are usually obtained using a ______ sensor that displays qualitative waveforms.
Photoplethsmography (PPG)
Obtain the segmental pressure of the legs working from _____ to ______.
Distal –> Proximal.
All Doppler signal for this test are obtained using a ____ MHz CWD.
4-8 MHz
Pressure Indices
A way to compare the lower extremity blood pressure to the individuals systemic blood pressure. A ratio obtaied using the limb pressure & dividing them by the higher brachial pressure. High thigh pressures are typically 30 mmHg greater than the brachial with 4 cuff tech. Most utilized is ABI.
Ankle-Brachial Index (ABI)
in a non-diabetic patient a normal ABI is 1.0 or greater. Can be falsely elevated due to calcified media layer of the arteries (diabetic patients). An ABI greater than 1.25 is considered falsely elevated (Cuff Artifact).
Toe-Brachial Index (TBI)
A normal toes pressure is usually 60-80% of the brachial pressure. A normal TBI is .60-.80. Digital arteries are usually spared from calcification there it is the MOST reliable pressure.
ABI Ranges
.8-.55
Likely Claudication.
Foot ulcer healing: Probably to likely
ABI Ranges
.55-.35
Likely Claudication
Rest Pain: Probable
Foot ulcer healing: Unlikely
ABI Ranges
.2 or less
Likely Claudication
Likely Rest Pain
Foot Ulcer Healing: unlikely
Impending Gangrene: Likely
Pressure Gradient
Difference that exceed 20-30 mmHg usually indicate that some occlusive arterial disease is present within the segment having the lower pressure or above it.
Levels of Disease
Aorto-illiac (in flow) - high thigh Fem-Pop Run off (tibial, outflow) Distal small vessel Multi-Level
Pulse Volume Recordings (PVR)
A type of plethsyography that assesses arterial flow within specific segments of the limb. Measures the expansion & contraction of the segment as blood circulates.
Air-Cuff Displacement PVR
most commonly used. measures air displacement caused by arterial inflow. More diagnostic then segmental pressures
PVR Interpretation- Quantative
Normal Amplitudes: Thigh or Ankle > 15mm. Calf > 20mm.
IF the amplitude is lower than these values, it is probably that some disease is present.
PVR Interpretation- Qualitative
Waveform shape- More Important holds more value
3 Components:
Anacrotic Limb - upstroke
Catacrotic Limb- down stroke
Dicrotic Limb/notch- hump. reflective wave
PVR Waveform Catefories
Normal - Cat 1
Mild- Cat 2 - dicrotic notch absent. Maintains amp
Moderate- Cat 3- dicrotic notch absent. loss of amplitude.
Moderately Severe- Cat 4 - amplitude < 5mm
Severe- cat 5 - flat line. no flow
Interpretation Pitfalls:
Non-compressible vessels (Calcified) Cuff Artifact Low cardiac output Multi-level disease Patient cooperation (Motion)
Analog Dopper Waveforms
Obtained by using of a CW Doppler probe. can be assessed during segmental pressure study. used to determine if waveform is triphasic, biphasic, or monophasic.
Doppler tracings should be recorded from the following areas:
CFA SFA POPA PTA DPA
Analog Doppler Waveforms Interpretation:
Should be Triphasic or Biphasic. Pulsatility Index: average CFA 6 to 7. Average POPA 7 to 9. Average PTA 12 to 16. Should increase as you move distal. Less than 4 is highly indicative of presence of arterial occlusive disease.
Delayed upstroke suggest arterial occlusive disease ______ to the area of the Doppler waveform.
distal
A Monophasic waveform suggest arterial occlusive disease ______ to the are of the Doppler waveform.
proximal
Treadmill Testing
used to identify true claudication. ABIs are taken at 1-2 minute intervals for up to 10-20 mins until the pressures in the ankle return to pre-exercise levels. Normal response will be a slight increase in the PSP immediately following exercise.
Treadmill Testing interpretation
the bigger the pressure drop = more severe
The longer the recover time = the more the levels.
>12 mins = Multilevel Disease
Reactive Hyperemia
Performed on patients who are unable to walk on treadmill. Pump to 250 & leave it there for 3-5 mins. Normal response will be a slight decrease in the PSP immediately following cuff release. Pressure drop 50% Multi level
T or F
If the toe has a notch everything has to be normal?
True.
T or F
If disease was coming from the aorta it would effect both legs?
true.
