Throughout each examination, the sonographer should:

• Assess and monitor the patient’s physical and mental status, allowing modifications to the procedure plan according to the patient’s clinical status.
• Analyze segmental pressure and waveform findings to ensure that sufficient data is provided to the physician to direct patient management and render a final diagnosis.

Single-Level Lower Extremity Arterial Physiologic Exam

A limited exam includes the measurement of bilateral systolic blood pressures to obtain the ankle brachial index, in combination with either Doppler or plethysmographic waveform analysis at the ankle.

The ankle brachial index (ABI) includes:

• Measurement of bilateral brachial artery systolic pressures and the higher of the two pressures is used to calculate the ABI
• Measurement of bilateral ankle systolic pressures from the distal posterior tibial (PT) artery and distal anterior tibial (AT)/dorsalis pedis (DP) artery and the higher of the two pressures on each side is used to calculate the ABI
• The ankle brachial index (ABI) is calculated by dividing the highest ankle pressure from each limb by the highest brachial pressure
  • The ABI may be affected by arterial calcification
• Additional information regarding the presence of disease may be obtained by recording toe PPG waveforms and toe systolic pressures
  • The toe brachial index (TBI) is calculated by dividing the great toe pressure by the highest brachial pressure

Doppler waveforms are obtained and documented from the:

• Posterior and anterior tibial arteries at the level of the ankle

Plethysmographic waveforms are obtained and documented from the:

• Ankle level
• PVR waveforms are unaffected by intimal calcification
• Toe PPG waveforms (if indicated)

Multi-Level Lower Extremity Arterial Physiologic Exam

A complete exam includes the measurement of bilateral systolic blood pressures to obtain the ankle brachial index, in combination with either Doppler or plethysmographic waveform analysis from at least three levels.

The ankle brachial index (ABI) includes:

• Measurement of bilateral brachial artery systolic pressures and the higher of the two pressures used to calculate the ABI
• Measurement of bilateral ankle systolic pressures from the distal posterior tibial (PT) artery and distal anterior tibial (AT)/dorsalis pedis (DP) artery and the higher of the two pressures on each side is used to calculate the ABI
  • The ankle brachial index (ABI) is calculated by dividing the highest ankle pressure from each limb by the highest brachial pressure
    • The ABI may be affected by arterial calcification
• Additional information regarding the presence of disease is obtained by recording toe PPG waveforms and toe systolic pressures
  • The toe brachial index (TBI) is calculated by dividing the great toe pressure by the highest brachial pressure

Segmental pressures at the thigh, calf and ankle levels are obtained in cases with an abnormal ABI

• Four cuff technique: includes high thigh, low thigh, calf and ankle pressures
• Three cuff technique: includes thigh, calf and ankle pressures

Doppler waveforms are obtained and documented from the:

• Common femoral artery
• Mid superficial femoral artery (when indicated)
• Popliteal artery
• Posterior and anterior tibial arteries at the level of the ankle

*Gain settings should be maximized at each level to display Doppler waveform characteristics

Plethysmographic waveforms are obtained and documented from the:

• Thigh (includes high thigh and low thigh waveforms if using the four cuff method)
• Calf
• Ankle
• Toe PPG waveforms (if indicated)

*Gain setting are optimized to display PVR waveform characteristics, but left unchanged between levels

Lower Extremity Arterial Physiologic Exam with Treadmill Exercise/Stress Testing

If indicated and ordered by a qualified physician, a non-invasive physiologic study at rest and following motorized treadmill stress testing may be performed. Treadmill testing is generally set at a constant speed and grade (e.g., 2 mph, 10% grade) for five minutes, or until symptoms occur and the patient is forced to stop.

Resting exam includes the measurement of bilateral systolic blood pressures to obtain the ankle brachial index, in combination with either Doppler or plethysmographic waveform analysis at the ankle. This is followed by treadmill exercise for five minutes, or until symptoms occur and the patient is forced to stop.

Following treadmill exercise, bilateral ankle pressure measurements are obtained at timed intervals with the patient in a supine position:

• Begin the ankle pressure measurements in the symptomatic limb or limb with the lowest pre-exercise ankle pressure.
• Use the pedal artery that yielded the higher pre-exercise ankle pressure to record the post-exercise ankle pressure.
• Use the brachial artery that yielded the higher pre-exercise pressure to obtain a post-exercise pressure and calculate the ABI.
• Repeat the post-exercise ABI/pressure measurements at one to two minute intervals for up to 10 minutes, or until ankle pressures return to pre-exercise levels.
  • testing results are based on initial ankle pressure decrease and time required for the ankle pressures to return to pre-exercise levels.

When treadmill testing is contra-indicated or not possible, a physiologic study at rest and following other stress maneuvers may be appropriate. These are generally performed for five minutes, or until symptoms occur and the patient is forced to stop. These are not considered equivalent to treadmill testing. Alternatives to treadmill testing include:

• Hall walking (until symptomatic or for 5 minutes)
• Toe raises (until symptomatic or for 50 toe raises)
• Post occlusive reactive hyperemia
  • Requires occlusive pneumatic cuff inflation at the thigh level for three to five minutes or until the patient can no longer tolerate it
• Repeat post-stress ABI/pressure measurements at one to two minute intervals for up to 10 minutes, or until ankle pressures return to pre-exercise levels
  • testing results are based on initial ankle pressure decrease and time required for the ankle pressures to return to pre-stress levels

When exercising any patient, the examiner should be familiar with risk factors and contraindications related to this test and aware that the protocol may need to be modified for individual patients. Contraindications for treadmill exercise/stress testing include:

• ABI less than 0.5
• Non-compressible vessels (ABI > 1.3)
• Chest pain (unless physician present)
• Questionable or unstable cardiac status
• Shortness of breath
• Unsteadiness when walking
• Hypertension (>180mmHg systolic brachial pressure)

Treadmill exercise/stress testing should be discontinued if:

• Patient completes five minutes of exercise or claudication forces patient to stop
• Patient experiences chest, shoulder, neck, jaw, or arm pain
• Patient experiences shortness of breath, fatigue, or faintness