The Diabetic Foot

Circulation testing.

The foot pulses should be palpated. The Dorsalis Pedis artery usually runs down the dorsum of the foot between the first and second metatarsal. The posterior Tibial pulse runs in the groove behind the medial malleolus. Sometimes these pulses are not palpable due to the presence of oedema in the foot, and in such cases it is more useful to listen to the sounds made by an ultrasound Doppler. The definitive test of circulation in the foot is the Ankle Brachial Pressure Index test.

First take the patient's brachial systolic blood pressure by resting the patient as flat as possible and measuring the systolic pressure in each arm. Take the highest value as the systolic pressure. Pump the cuff up to above systolic pressure and release slowly. Use your Doppler probe to listen for the return of flow as you release the cuff. Record the result.
Next, place the cuff on the patient's ankle and pump it up above systolic pressure. Place the probe over the Dorsalis Pedis Artery and listen for the return of the sound as the cuff is deflated.
Next, repeat the test for the Posterior Tibial Artery and record the results
Calculate the Ankle Brachial Pressure Index by dividing the leg systolic pressure by the arm systolic pressure to form a ratio. A useful form to record the results can be downloaded from here. It is in Acrobat format. (See bottom of page for link to download Acrobat reader)	Download Vascular assessment form
For example: If the Arm systolic pressure was 120 and the leg systolic pressure was 80 then the ratio would by 80/120 or 0.67. Note: The Ankle Brachial Presure index can be artificially higher than 1.0 if there is vascular calcification present. If the clinician feels that this is the case, a referral to a vascular clinic should be considered.