Parks 915-BL Operating & Service Manual page 33

OFFICE TECHNICS FOR VASCULAR TESTING
After the routine history and physical examination
have been completed, the peripheral vessels are
surveyed with the Doppler ultrasonic velocity
detector. The quality of the arterial signals is
evaluated at the common femoral, superficial
femoral, popliteal posterior tibial, and dorsalis
pedis arteries bilaterally. If the vessels are patent,
these signals will be composed of at least two,
and often three, distinct sounds. The first is
high-pitched and is distinctly separated from the
second (Fig 1, A).
When mild proximal arterial stenosis is present,
there is a slight decrease in the frequency of the
first sound and the second sound is no longer
detected (Fig 1, B). As the degree of occlusion
becomes progressively more severe and
collateralization develops, the signal becomes
more monotonous with only small fluctuations
with each heart beat (Fig 1, C). These changes
NORMAL
G r a p h i c r e p r e s e n t a t i o n o f a u d i b l e D o p p l e r u l t r a s o n i c f l o w v e l o c i t y s i g n a l s o b t a i n e d f r o m t h e p o s t e r i o r t i b i a l a r t e r y o f t h r e e
s e p a r a t e p a t i e n t s . A - n o r m a l ; B - o b s t r u c t e d ; C - s e v e r e l y o b s t r u c t e d .
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in the nature of the arterial signal can be
detected easily,
with the instrument.
An objective and reproducible determination of
the extent of the occlusive disease process can
be made by measuring the systolic arterial
pressure at the ankle.
cuffs are placed around the ankle and the arterial
flow signal is monitored in the posterior tibial or
dorsalis pedis artery (Fig 2). The cuff is then
inflated until the arterial signal is no longer
detected. With the probe still in place, the
pressure is gradually lowered in the cuff until
flow signals are audible once again. The point at
which flow is re-established is the systolic
pressure at the level of the cuff. Under normal
circumstances, the systolic pressure in the ankle
should be equal to or above the systolic pressure
in the brachial artery. If the artery is occluded,
FIG I
SCALE - 2 cm = 1 SEC.
SOUTHERN MEDICAL JOURNAL, Vol 68, No. 1
- Hagood et al
after gaining some experience
5
Standard blood pressure
7
OBSTRUCTED