Oscillotonometry: A simple non‐invasive method of differentiating proximal arterial obstruction from distal microangiopathy in the vascular assessment of diabetics

In diabetic patients with ischaemic feet a frequent clinical problem is the differentiation between those with distal microangiopathy alone and those with proximal arterial inflow obstruction. Doppler pressure measurement is of assistance but there is a significant subgroup who have proximal obstruction despite the findings of a high ankle systolic pressure. These patients have stiff arterial walls and the Doppler cuff does not compress them normally. If oscillotonometry is performed, a low range of swing suggests an inflow obstruction whereas a high range suggests a good inflow. This differentiation enables suitable patients to be selected for angiography and possible angioplasty or bypass surgery.