Peripheral Arterial Disease Collateral Arterial Growth Assessment Using Toe Pulse Oximetry

PAD toe pulse oximetry
During my routine AAA stent assessment, the EVAR resident was unable to find a pulse in my right foot. But the foot looks fine, as I struggle to run with peripheral arterial disease, fighting claudication and numb feet. Image source.

My running, and Ironman training, continue, as I adapt to my sport with peripheral arterial disease. This is all described on this blog, along with the six or seven modifications I’ve devised to improve arterial blood flow to and through my foot, and venous return back toward the heart. With some success, I must add.

I attribute my continued ability to compete in Ironman races to the growth of collateral arteries and arterioles, induced by extensive Ironman training, especially running.

PAD toe pulse oximetry
Recent three-mile run, as I fight calf claudication and numb feet. This took a lot of work, along with careful modifications to my run biomechanics.

I received a letter today, from a follower, asking me how I knew I had grown collaterals, if ultrasound failed to detect a pulse in my foot. I suspect the problem lies in the fine nature of the new arterial tree. After a little research, I came across the following article:

Pulse Oximetry Compared with Doppler Ultrasound for Assessment of Collateral Blood Flow to the Hand,” so I reached for my oximeter, purchased due to COVID-19, and applied it to the toes of both my feet, with the following result:

PAD toe pulse oximetry
As you can see, I did, with some difficulty find a pulse, and the O2 saturation was close to the desired 95%, in both feet.

It was hard to get a stable pulse, probably because the device was designed for fingers, not toes. This observation suggests that oximetry is an effective way to assess foot blood perfusion, when routine Doppler Ultrasound is negative.

I then compared this result with my left index finger:

PAD toe pulse oximetry
Normal O2 saturation, and pulse a little high, as I’ve been running around much too soon after a rather large lunch, which is not proprioceptively advisable.

I think this simple tool, costing about $30, could be useful for monitoring the state of your PAD, and responses to efforts to grow a collateral blood supply, or to assess the effectiveness of surgical interventions.

Just a thought.

-kev aka FitOldDog (Yes! I do have medical training!!!)

PAD toe pulse oximetry
MRI scans through the thighs of three guys. Grey is muscle, white is fat, clear ring around the central white spot (bone marrow) is the femoral bone. Note the loss of both muscle and bone mass in the sedentary guy.


  1. After reading your article and also educating myself about PAD I’m very upset to learn that my Dr put me through a fenmoral bypass graft without ever trying stents first And also never explaining that building collateral blood flow. I think it’s time that all the surgeons continue to learn all available possibilities BEFORE putting their patients through unreversed surgery and lessening their life span Thanks for posting this article and continue posting everywhere you possibly can Thanks again and God Bless

    • The same thing happened to my husband who had femoral popliteal bypass surgeries in March and May, 2022. We learned at routine appointment last month that his March fempop is totally blocked again. Mike is only 69 years old and has controlled diabetes with diet and no wounds or resting claudication. Stents were brought up by us but dismissed by surgeon. And we went to Mayo Clinic thinking we were getting the best treatment. We have appt Monday to hear what they want to do.

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Disclaimer: As a veterinarian, I do not provide medical advice for human animals. If you undertake or modify an exercise program, consult your medical advisors before doing so. Undertaking activities pursued by the author does not mean that he endorses your undertaking such activities, which is clearly your decision and responsibility. Be careful and sensible, please.