Non-invasive Diagnostic Techniques – Instrument Based Diagnostic Techniques

00:01 Welcome back! Continuing the basic vascular medicine course, we’re going to talk about instrument-based diagnostic techniques.

00:10 The learning objectives are first of all: what kind of instrument-based diagnostic techniques exist and also which non-invasive techniques are the most common and, of course, the most accurate.

00:24 So let’s start in this little diagram with the non-invasive techniques. And we’ll move on later to talk about some of the invasive techniques.

00:34 One of the very best tests for the presence of peripheral vascular disease from atherosclerosis – with narrowing of the arteries – is the ankle brachial index. In this, we take blood pressures in the leg and in the arm and make a comparison. Let’s look at this test in a little more detail.

00:58 First, one places the patient lying, or supine, with all extremities and head on the same level on the table. You use a small Doppler ultrasound blood flow detector to find two arteries. You find the dorsalis pedis artery and the posterior tibial artery in the foot and the brachial artery in the arm. You use a blood pressure cuff – a sphygmomanometer – to measure the blood in both areas. This is the simple blood pressure test that we always do on the arm but here we’re also doing it on the leg. First, you measure the systolic – that is the squeeze of the left ventricle: the highest, number one blood pressure – in the left and right arm. And then you measure it in the two foot arteries: the posterior tibial and the dorsalis pedal artery of the foot. And you make a comparison of the two.

02:05 The blood pressures should be approximately equal in both the arm and the leg, or maybe even a little higher in the leg because of some physical characteristics of the arterial system. But the blood pressure in the leg should not be less than the blood pressure in the arm. And when it is less, it implies that there’s an obstruction in the blood flow to the leg. And you can see here mild reductions, moderate reductions and severe reductions in the blood pressure in the leg tell you that there is mild, moderate or severe atherosclerotic obstructive disease in the leg.