DOPPLER ASSESSMENT AND ANKLE BRACHIAL INDEX ABI Lucy

DOPPLER ASSESSMENT AND ANKLE BRACHIAL INDEX (ABI) Lucy Stopher A/CNS Vascular Surgery

Objectives How to assess pedal pulses Different doppler sounds What is an ABI How to perform an ABI Interpretation of results When is it required Why is an ABI so important

PEDAL PULSES

PALPATING PEDAL PULSES Dorsalis Pedis: To palpate pulse, place fingers just lateral to the extensor tendon of the great toe. If you cannot feel a pulse, move fingers more laterally Posterior Tibial: To palpate pulse, place fingers behind and slightly below the medial malleolus of the ankle. In an obese or edematous ankle, the pulse may be more difficult to feel

PALPATING PEDAL PULSES

TECHNIQUE TO DOPPLER USE If possible palpate the pulse first Place the doppler at a 45 -70 angle over the skin Once you hear a signal manipulate the doppler to try and achieve the best sound

DOPPLER SIGNALS TRIPHASIC: This is represented by three sounds heard very quickly together (duh. . . dum), as the blood runs through a healthy un-diseased artery.

DOPPLER SIGNALS

DOPPLER SIGNALS BIPHASIC: This can be recognised as two sounds heard together (duh, dum. . . duh, dum), this may be because the Doppler probe is not at the optimum angle. Again, it indicates a healthy artery.

DOPPLER SIGNALS MONOPHASIC: A single, almost ‘banging’ sound (. . . dum!. . . ) indicates that the Doppler signal is unable to penetrate a diseased artery.

DOPPLER SIGNALS VENOUS: A wooshing sound with no discernible beat.

PEDAL PULSES: DOCUMENTATION Colour: Pale, pink, red, mottled Warmth: Cool, cold, warm, hot Movement: Full, limited, none Sensation: Do they have neuropathy? Is this normal for them? Pulses: Palpable or on doppler?

WHAT IS AN ABI? ABI stands for ankle brachial index It is the ratio of the systolic ankle pressure to the systolic arm pressure. The systolic pressure of the leg decreases in proportion with the degree of occlusion It indicates the amount of arterial supply reaching the ankle

HOW TO PERFORM AN ABI? Lie the patient down as flat as possible for 20 minutes. This allows the leg muscles to relax and equalises the blood pressure. Assess the systolic blood pressure in each limb with the doppler. Document each systolic blood pressure on the ABI chart or the inpatient notes.

HOW TO PERFORM AN ABI? Choose the higher systolic arm pressure and use that to calculate the result for both legs. Choose the higher ankle pressure and divide by the arm pressure and repeat for the other leg ABI = Higher Ankle Pressure Higher Arm Pressure

HOW TO INTERPRET THE RESULT >1. 2 and so calcify. 0. 9 -1. 2 0. 5 -0. 9 0. 3 -0. 5 <0. 3 non Indicates calcification of the vessels the test is inaccurate – perform toe pressures as the toe vessels do not Normal, compression therapy can be applied as per medical team. Arterial disease causing claudication Arterial disease causing rest pain Arterial disease causing gangrene/ healing wounds

WHEN IS AN ABI REQUIRED Anytime the arterial supply of the legs are in question e. g. non healing foot wounds with no palpable pulse For the diagnosis/management of leg ulcers If a patient has venous insufficiency an ABI is required prior to the application of compression. On admission for ALL vascular patients with a lower limb problem (e. g. not if the patient is having a carotid endarterectomy) For ALL patients post angioplasty +/- stent and post bypass graft/endarterctomy

WHY IS AN ABI SO IMPORTANT? It gives an indication of the lower limb arterial blood supply, without needing to wait for costly scans. It gives an indication of the effectiveness of a procedure such as angioplasty or bypass When the surgeon follows up a patient they can compare the previous ABI to the patients current ABI to assess deterioration

SUMMARY If a patient has a leg or foot wound and you cannot palpate pedal pulses you should perform: Doppler Assessment Ankle brachial index (ABI) An ABI is a cost effective and saves the necessity to wait for scans ABI’s are essential prior to application of compression bandaging