Ankle Brachial index

Question 1

What kind of test is a Ankle Brachial index test?

Answer 1

Non invasive physiologic test that compares the systolic pressure at the ankle to the systolic pressure of the brachial artery

Question 2

What kind of doppler waveform is used with ABI tests?

Answer 2

CW doppler waveforms are recorded to support the pressure data

Question 3

During a ABI test, when an arterial lumen is narrowed to a critical level, what happens?

Answer 3

The distal arterial flow and pressure significantly increase

Question 4

What is the ABI protocol?

Answer 4

1. Wrap cuffs on the ankle and upper arms
2. Should be placed snug and “straight” rather than “angled”

Question 5

How should we place the ankle and arm cuffs for ABI protocols?

Answer 5

0-12 cm bladder (width) 2-3 cm above the medial malleolus

Question 6

How do we obtain the posterior tibial artery signal? 7 step by step

Answer 6

1. Obtain signal posterior to the medial malleolus
2. Angle 45-60 degrees, pointing the probe towards the heart, with enough pressure to keep the probe in place without compressing the artery
3. Record PTA signal
4. Inflate the cuff 20-30 mmHg above the last audible signal
5. Slowly deflate cuff (2-4 mmHg/ second)
6. Systolic pressure is recorded in mmHg at the first audible signal
7. Ensure the doppler pulse continues after the first pulse to confirm it is an actual signal and not an artifact

Question 7

What is the problem with each of these images?

Answer 7

1. Doppler probe is positioned over the artery at 90 degrees X
2. Doppler probe is positioned to far distal to the medial malleolus X
3. Doppler probe is in a good position over the PTA with a good angle and parallel to the long axis of the artery

Question 8

What are we getting here?

Answer 8

Posterior tibial artery

Question 9

When sampling the pedis artery (DPA) we need to avoid sampling to close to the toes why?

Answer 9

You will likely be listening to the plantar arch or digital vessel

Question 10

When sampling the DPA if the signal is dampened, retrograde or absent what do we do?

Answer 10

Move to the anterior ankle area and search for the ATA signal

Question 11

What do we do if we can’t locate the DPA or the ATA signal?

Answer 11

Find the peroneal artery (PerA) slightly anterior to the lateral malleolus

Question 12

What procedure does this represent?

Answer 12

DPA

Question 13

Where doe we obtain the bilateral brachial (BrA) Pressures?

Answer 13

On the radial artery

Question 14

If the brachial pressure differs >20mmHg or if the waveforms are different, what do we examine? Why?

Answer 14

1. The vertebral arteries to check flow direction.
2. Retrograde vertebral flow on the same side as the lower brachial indicates subclavian steal syndrome

Question 15

How do we calculate ABI?

Answer 15

Pedal pressure / Highest brachial pulse

Question 16

In terms of ABI, what is the normal drop from heart to distal lower extremity?

Answer 16

10 mmHg

Question 17

In terms of ABI, corresponding increase in the amplitude of pulses distally, results from what?

Answer 17

Increased peripheral resistance and elastic recoil?

Question 18

In terms of ABI, Normal resting ankle systolic pressures are usually what?

Answer 18

The same or slightly higher than the brachial pressure

Question 19

IF ABI appears abnormal, what should be done?

Answer 19

Higher brachial should be measured again

Question 20

During ABI, At the ankle the PRA usually has higher pressure than what?

Answer 20

The ATA and DPA

Question 21

What is the average ABI supine?

Answer 21

1.1

Question 22

What is the normal ABI normally?

Answer 22

Usually >0.9 but values will differ in each lab

Question 23

Label the chart

Answer 23

Question 24

Falsely high ABIs will occur in patient with what?

Answer 24

Medical calcifications (5-10% too high)

Question 25

ABI's >1.3 toe pressures (PPG) should be done why? And what is the normal toe/ brachial pressure?

Answer 25

1. For accuracy 2. >0.75

Question 26

Systolic pressure is invalid and must rely on what?

Answer 26

Pulse waveforms and toe pressures

Question 27

What are indications that the artery is calcified? 3

Answer 27

1. Doppler signal does not reappear at a clearly defined pressure 2. Pulse amplitude increases with further cuff deflation 3. Artifactually elevated pressure may not correspond with the pulse waveform

Question 28

ABI's >1.3 mmHg occurs when? 2

Answer 28

1. Diabetic patients 2. Patients on steroid therapy for renal disease

Question 29

What is important to understand in terms of level of pressure measurement?

Answer 29

It is determined by cuff position and NOT by the site of doppler interrogation

Question 30

Placing the cuff too high on the calf does what?

Answer 30

Does not give an accurate reading on ankle pressure

Question 31

What are some limitations of ABI? 6

Answer 31

1. **Falsely increased pressures from calcified vessels**, you can rely on a low pressure recording but not a high one 2. **Significant lesions with developed collateral circulation** resulting in normal distal pressures and waveforms at rest 3. **Extensive bandaging** or casts which cannot be removed 4. Areas of **trauma, surgery, ulceration, or graft placement** that the pressure cuff should not compress 5. **Acute DVT** in the lower extremities should not have pressure cuffs inflated over their thrombus 6. Pressure measurements are usually not permitted on **ipsilateral side of mastectomy or AVG/ AVF (arteriovenous graft/ Arteriovenous fistula**

Question 32

In terms of exercise stress testing, what is acceptable for exercising for a symptomatic patient?

Answer 32

Treadmill walking is acceptable for exercising a symptomatic patient with suspected PAD, especially when the ABI is in the normal range

Question 33

Post- exercise ABI's are used to assess what?

Answer 33

Functional impairment

Question 34

Exercise stress testing assesses what?

Answer 34

Whether walking limitations and induced pain is secondary to nonvascular conditions, such as MSK or cardio pulmonary disease

Question 35

What is the protocol for Exercise stress testing? 4

Answer 35

1. Measure pre-exercise BP and ABI's 2. Patient walks on the treadmill at 10% grade and speed of 2 mph for 5 minutes or until claudication or other restrictions occur. 3. Remeasure the BPs and ABIs within the first minute post exercise 4. Measure BPs and ABIs every 2 minutes, until the ankle pressure returns to within 10 mmHg of the baseline pressure or for 6 -12 minutes

Question 36

What are limitations for exercise stress testing? 4

Answer 36

1. Chest pain 2. Arrythmias 3. Post MI/ cardiac procedure and not cleared by cardiologist 4. Hypertension greater than 180 mmHg

Question 37

What would normal ABI stress testing look like?

Answer 37

1. Little or no decrease in ankle BP after 5 minutes of exercise 2. Decrease in post- exercise systolic pressure should be <20% of the resting pressure and should return to baseline within 3 minutes after exercise

Question 38

Filling in the diagnostic criteria post treadmill exercise BP and ABI's and recovery times

Answer 38

Question 39

What does abnormal recovery Exercise stress test look like? 2

Answer 39

1. Immediate decrease from baseline in post-exercise ankle BP indicates significant arterial obstruction 2. Severity of the disease is also related to the distance a patient can walk and the absolute pressure drop