Hi Brook, Sorry it's taken me awhile to "come out" on this issue of 3-4
segmental pressures.
We've tried both the 3 cuff and 4 segmental pressure cuff techniques over the
years, and I'd like to share some observations. First off, you've got to
take a thigh pressure on yourself or have someone do it for you: try both the
3 and 4 cuff techniques. This is an especially enlightening experience with
the large volume- large thigh cuff if you have a slow auto-cuff inflator or a
weak pump hand. Do it. There is a reality considerable gap between what you
find in the literature and what get when you take actually take pressures,
especially with the 4 cuff technique, in regards to this "cuff artifact".
What has been written in stone (sandstone) is that the three cuff technique
cannot differentiate inflow disease (aortoiliac) from femoral-popliteal
disease, whereas that the 4 cuff technique can distinguish disease levels. A
low thigh pressure, with a large (17 cm) thigh cuff, may be due to iliac or
femoral artery disease. A normal thigh pressure, that which is similar to
brachial pressure, rules out significant inflow disease, as long as the
artery walls are not calcified.
In the 4 cuff technique, studies have shown that a normal high thigh pressure
(at least 20 mm Hg above brachial pressure, some say 30 mmHg) rules out
significant aorto-iliac (A-I) disease, and an abnormal high thigh pressure
will predict significant A - I disease. 1 This elevation in high thigh
pressure is due to the cuff artifact which has been discussed. So an abnormal
high thigh pressure is suppose to be due to inflow disease, not SFA disease.
 Reality check: a segmental pressure that is recorded is the pressure which
is occurring underneath (within the circumference of) the cuff segment. The
SFA lies within the high thigh cuff segment and if it's diseased, it may
result in a low high thigh pressure and inflow may be normal. Inflow
disease, of course will also cause the high thigh pressure to be low.
 Studies have supported this observation and shown that a low high thigh
value can be due to superficial femoral artery disease and not necessarily
A-I obstruction. 2 In another study by Flanigan, the negative predictive
value for the 4 cuff style is high for A-I disease, but the positive
predictive valve is low. 3
It has also been my observation that a number of normal patients lack this
elevation in thigh pressure, even with the high thigh cuff placed as proximal
as possible.
So to summarize:
1) For both the 3 and 4 cuff techniques, a normal thigh pressure rules out
significant aorto-iliac disease.
2) An abnormal thigh pressure in both 3 and 4 cuff styles can indicate A-I or
 SFA disease. (to differentiate you should use another test, eg, PVR's
Doppler waveform, Duplex, or dousing rod.)
3) A high thigh pressure that is 20-30 mm Hg above brachial, IN AN OTHERWISE
NORMAL EXAM DISTALLY, is not abnormal.

In our twisted hypoxic logic (maybe the Denver altitude..), we've stopped
taking thigh pressures altogether. ABI with ankle PVR tells you whether
there is (big vessel) disease ( maybe throw in a stroll on the treadmill). A
strong fem pulse and a normal PVR tells you about inflow, calf pressure and
PVR tells you about fem-pop segment, and duplex ( at an expense of time)
resolves any location issues. After you've taken that thigh pressure on
yourself, you might see the appeal of this approach! Good luck.

Rob Daigle.

1.Heintz SE, Bone GE, Slaymaker EE, Hayes AC, Barnes RW: Valueof arterial
pressure measurements in the proximal and distal part of the thigh in
arterial occlusive disease. Surg Gynocol Obstet:146:337-43,1978

2.Kupper CA, et al.: Spectral Analysis of the Femoral Artery for
Identification of Iliac Artery Lesions... Bruit 8: 157-63 June 1984

3. Flanigan DP et al. Utility of wide and narrow blood pressure cuffs in the
hemodynamic assessment of aortoiliac disease.Surg 92: 16-20, 1982