Hi Kelly, you asked a very good question.  Gene Doverspike gave a very good 
answer regarding billing, as I have (cough cough) "heard" that some labs 
were obtaining Duplex Doppler tracings to accompany the ABI's and billing 
BOTH 93922 AND 93926.

From a practical standpoint - yes, you could use your $150,000 duplex 
machine (or even a used $10,000 unit for that matter), but you'd still have 
to pump up the pressure cuff with a hand sphygmomanometer.  That's why most 
vascular labs have a physiologic machine(s)with automatic cuff inflation, 
(and much more) AND Duplex imagers.

From an economic AND clinical standpoint, there is a much better reason for 
having two (physiologic and Duplex) dedicated instruments in the lab:  

1.  From an economic standpoint, it doesn't make much sense to tie up an 
expensive (generally) Duplex machine for ABI's when it could be put to much 
better use doing carotids, veins, aorta's, renals (you get the picture) 
which reimburse much more than ABI's and ankle waveforms (93922).

2.  From clinical standpoint #1, let's say you have decent(but monophasic) 
Doppler waveforms at the ankles, and ABI's in the 1.4 range.  If you're 
using your duplex machine, you may consider doing full duplex bilateral 
(possibly that wasn't on the patient RX, however), or, like many labs, you 
grab your PPG sensors, slap them on the toes, and get a couple of quick toe 
pressures to check your TBI's. (RARELY affected by calcification).

3.  Consider clinical standpoint #2, (which was an actual patient I saw) 
that had normal ABI's at the Left PT and DP and triphasic Doppler tracings 
at both vessels, and very blunted, monophasic Doppler tracings at both 
right ankle arteries, and ABI's of .55 and .57 at the DP and PT.  Pressures 
proximal on the right side returned to normal above the knee, indicating 
popliteal stenosis (verified by Color Duplex to be ~90%).  Oddly, patient  
complained only of occasional claudication.  I obtained PVR waveforms of 
both ankles (oops! can't do that with duplex) which were identical (left 
and right), and bounding biphasic (I had to reduce the sensitivity by a 
factor of three to even see the whole waveforms!).

To cut to the chase - patient did have severe popliteal stenosis.  Dr. was 
going to do bypass surgery until I explained to him that the patient was in 
no danger of losing a toe, let alone his foot.  Upon further questioning, 
patient said he walked 5 miles every day, most days without pain (in the 
hip) which added the missing piece - the patient was EXTREMELY well 
collateralized, something that CW or Duplex Doppler are lousy at showing - 
and only PVR can detect, which is: OVERALL blood flow to a limb segment.

True story - said Dr. bought a dedicated physiologic machine that week
from one of the physiologic manufacturers (I promised I wouldn't say which 
one).  So, that's the reason so many people use dedicated physiologic 
machines - PVR's can be performed bilaterally, and you can get full 
segmental (8) PVR waveforms in less than 5 minutes, with less clinical 
variation between technologists.  Throw in the fact you can do TBI's or toe 
waveforms for the Pods, finger waveforms and pressures for your hand Dr's, 
Thoracic Outlet studies, and did I mention automatic cuff inflation?

(Climbing down from soapbox)

Bill

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