Colleagues;

The issue of incompressible vessels raises another issue that has become 
near and dear to me; that is, what are the alternatives available to the 
technologist when ankle pressures are unrelaible or deemed 
"incompressible"? Clearly, the toe pressure is a viable option but 
published studies of the accuracy of this test, are somewhat dubious.

Last year, this laboratory presented a works-in-progress using 
oscillometric pressures to assess periperal arterial pressures. The 
oscillometric method, does not require  vessel closure and 
therefore is capable of obtaining pressures in patients with incompressible 
vessels. Sergio tells me he has been using this technique for years but 
the only published materail was in January 1997 issue of JVS.

Another intersting study is called the "pole test". With this test, one 
needs only a Doppler, tape measure and a reference chart to obtain 
pressures in the ankles (no BP cuff). The pole test, utilizes the 
principles of hydrostatic pressure to determine absolute ankle pressue. 
While listening to a pedal pulse and at the same time  raising the leg of a the 
patient in the supine position, the technologists measures the height of 
the limb at the point the Doppler signal ceases and the length of the 
limb from the inguinal ligament to the pedal signal site. A chart is then 
used to coordinate a point that relates to a pressure. With our limited 
experience so far, we have been impressed with the apparent accuracy of 
this test but plan to perform more formal research. A real benefit of 
this test is that it works well in patients with low ankle pressures (<50 
mmHg). 

In sum, it is practical to arm the vascular technologists with reliable 
alternatives to the traditional Doppler derived ABI's. I look forward to 
hearing about your experience of this common dilema we are are often faced 
with.

Terry Case
University of Vermont