Doppler Segmental Pressures (LE) Flashcards
Limitations of Doppler Segmental Pressures (LE)?
- Cannot discriminate between stenosis and occlusion, localize area of obstruction, nor discriminate between CFA and external iliac disease.
- Calcified vessels render falsely elevated doppler pressures.
3.Uncompensated CHF may result in decreased ABI. - Artifactually elevated high thigh pressures when narrowing cuff used on thigh.
- Difficult to interpret in presence of multi-level disease.
Pateient prep/positioning for Doppler Segmental Pressures (LE)?
- Patient should rest 20 minutes prior to exam, especially when vascular disease is present.
- Supine, with legs about same level as hear
Why do you want your legs at the level of your heart for Doppler Segmental Pressures?
so that hydrostatic pressure cannot affect the BP measurements
What artifact is caused if the cuff is too tight?
BP is falsely higher
What artifact is caused if the cuff is too loose?
BP is falsely lower
How much larger should the width of the cuff be?
About 20% greater in diameter than limb
How large is a standard thigh cuff?
19 x 40 xm
The four cuff method (bilaterally) includes:
Brachial (upper arm)
High Thigh
Above the knee (AK)
Below the knee (BK) (calf)
Ankle
Three cuff method (bilaterally) includes:
Brachial (upper arm)
One thigh cuff
Below the knee (calf)
Ankle
Size of cuff (not thigh):
12 x 40 cm
What is the difference between the 4 cuff and 3 cuff method?
- Two thigh cuffs (provide proximal and distal pressure measurements) but artifactually elevated BP’s are obtained
- The 3 cuff method utilizes one large thigh cuff (high on the thigh), providing a more accurate pressure reading
How do you optimize doppler signal?
- 8/10 MHz Doppler frequency probe
- Angle probe 45/60 degrees to the skin
- (behind knee may be an angle closer to 90 degrees)
- Angle the probe so blood moves antegrade
The brachial pressure is measured using which artery?
Brachial (upper arm)
The ankle pressure is measured using which artery?
PTA and DPA; (peroneal only if necessary)
The calf pressure is measured using which artery?
PTA or DPA - that had the highest pressure
The above the knee pressure is measured using which artery?
Same as calf
- PTA or DPA - that had the highest pressure
(may have to use popliteal artery if difficult to obtain)
The high thigh pressure is measured using which artery?
same as above the knee
- PTA or DPA - that had the highest pressure
Why must you start at the ankle and move proximally?
To eliminate the possibility of underestimating the systolic pressure measurement
Cuffs should inflate __________ beyond last audible Doppler arterial signals.
20-30mmHg
Inflate the cuff 20-30mmHg higher than what highest pressure?
brachial
Where is the systolic pressure recorded?
The first audible Doppler arterial signal returns
How is the anke/brachial index (ABI) calculated?
by dividing the ankle pressure by the higher of the two brachial pressures
What is another term for ABI?
ankle/arm pressure index (API)
Ankle/Brachial Index
> 1.0 =
normal
Ankle/Brachial Index
> 0.9 - 1.0 =
May be within normal limits
Ankle/Brachial Index
0.8 - 0.9 =
Mild arterial diesase
Ankle/Brachial Index
0.5 - 0.8 =
Claudication (moderate disease)
Ankle/Brachial Index
< 0.5 =
Rest pain (severe arterial disease)
What is an index that is considered incompressible/unreliable?
> 1.3 - 1.5
Segmental pressure drops of >30 mmHg between two consecutive levels suggests:
significant obstruction
A horizon difference of >20-30 mmHg suggests obstructive where?
at or above the level in the leg with the lower pressure
What toe pressures are evident in foot and toe ulcers that failed to heal?
< 30mmHg
What pressures cannot always be relied on for foot ulcer healing?
Ankle pressures
If resting study is normal you perform and exercise study with helps differentiate, determine and contraindicate what?
Differentiate - between true and pseudo-claudication
Determine - presence/absence of collaterals
Contraindications - SOB, severe hypertension, significant cardiac problems, stroke, walking problems
When would a patient walk on a constant load treadmill at a <12% elevation?
After a normal doppler segmental pressures exam
What pressures would be obtained post-exercise doppler?
both ankles (abnormal first), then higher brachial
What speed do you walk with a pos-exercise doppler exam?
1.5 MPH for a maximum of 5 minutes or until symptoms increase to such severity that patient must stop
When are pos-exercise ABI’s obtained:
Immediately (normal: ABI increases)
With drop after exercise when are pressures obtained?
Every two minutes until pre-exercise presssures are attained
What all does the interpretation of Doppler Segmental Pressures (LE) incorporate?
- duration of exercise
- length of time to recover*
- Pressure changes from pre to post exercise
How long does single level disease take to recognize?
2 to 6 minutes for the ABI’s to increase back to resting levels after they dropped to low or unrecordable levels after exercise
How long does muli-level disease take to recognize?
6 - 12 minutes for the ABI’s to increase back to resting levels after they remained low or at unrecordable levels after exercise
What is reactive hyperemia?
An alternative method for stressing the peripheral circulation
When is reactive hyperemia used?
when patients have PVOD in contralateral leg, use a cane of walker, have pulmonary problems; poor cardiac status, or other situations
How is reactive hyperemia performed?
Bilateral thigh cuffs (19x40) inflated to suprasystolic pressure levels (usually 20-30 mmHg) above the higher brachial BP maintaining the pressure 3 to 5 minutes
What does reactive hyperemia produce?
ischemia and vasodilation distal to the occluding cuffs
When are ABI’s obtained during reactive hyperemia?
upon release of cuff occlusion
Normal limbs may show what with reactive hyperemia?
17-34%
What are single level disease pressures with reactive hyperemia?
< 50% drop in ankle pressure
What are muli-level disease pressures with reactive hyperemia?
> 50% ankle pressure drop
