I am not aware of any notable literature on the subject. But certainly infection, inflammation, etc can result is low resistance hyperemic flow.  We see that fairly commonly. The low resistance flow simply tells you there is vasodilatation in the distal vascular bed. It does NOT predict a proximal obstruction!  Now in our typical patient, we do typically see vasodilatation as the result of proximal obstruction. Look at the systolic upstroke / acceleration. That tells you what is going on proximal. Normal upstroke - no proximal obstruction!

I'll tell you a little story.  You brought back a memory from at least 25 years ago that I have never forgotten. I was in the hospital at the time and we had a 50 something y/o male patient in critical care with Vibrio vulnificus. 
For those of you who are unfamiliar -
Vibrio vulnificus is a species of Gram-negative, motile, curved rod-shaped, pathogenic bacteria that can result in a serious human illness, called vibriosis. Vibrio naturally live in certain coastal waters and are present in higher concentrations between May and October when water temperatures are warmer. You can also contract Vibrio by eating raw or undercooked shellfish, particularly oysters. Vibrio vulnificus can cause a skin infection when an open wound is exposed to brackish or salt water. This patient was overall healthy but with a leg wound and ventured into the Gulf of Mexico in July.

Vibrio vulnificus can cause two types of illnesses: 1) wound infections, which may start as redness and swelling at the site of the wound that can spread to affect much of the body, and 2) primary septicemia, a bloodstream infection with symptoms including fever, dangerously low blood pressure, and blistering skin lesions. Sometimes resulting in limb amputation, about 1 in 7 people die. Our patient had the skin infection and was septic as well. 

So, that was the scenario. His leg wounds were progressing so I was called to evaluate.  I do not have any images but I'll always remember he had a low resistance flow throughout similar to what you describe. What was most striking, I identified dozens of small AVF like connections in the lower leg, more like AV malformations. The patient did survive without amputation and I studied him 3 or 4 more times as I remember and over a period of a couple weeks, these AVF's resolved and were no longer present. No one had ever seen anything like it before and many docs did not believe me. 

Happy Friday everyone. Have a good weekend! 

William B Schroedter, BS, RVT, RPhS, FSVU
4120 Woodmere Park Blvd
Suite 8B
Venice, Florida  34293

-----Original Message-----
From: UVM Flownet <[log in to unmask]> On Behalf Of Elaine Erickson
Sent: Thursday, May 9, 2019 10:30 PM
To: [log in to unmask]
Subject: Hyperemia flow

Hi, I  am looking for any published literature that could explain the following. In Dec 2018 patient presented with severe foot infection/would for arterial duplex. Waveforms were consistent monophasic from CFA through pop with flow through diastole, no focal stenosis. Contralateral normal waveforms. Read as possible inflow. Patient refused angiography and opted for follow up ultrasound that was performed today.

Today the patient stated that her wound has significantly improved and that she had no intervention since Decemer 2018. Today's waveforms were multiphasic throughout. The pop area was heavily calcified but there were high velocity and waveform abnormalities detected presumably from the pop but again heavily calcified. I don't  recall the pressures. What happened to the monophasic waveforms from 5 months ago?

I suspect hyperemia from more critical phase of the wound in December could have contributed to monophasic flow due to low resistance in inflamed foot.  I am hoping to find a paper on low resistant lower extremity waveforms for reasons other than proximal obstruction.. I am especially interested in proximal LE waveforms in the presence of distal infection/inflammation. Can anyone please lead me to a source. Thank you.

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