Palpable Dorsalis Pedis , but unable to doppler

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Specializes in LTC, Med/Surg, Peds, ICU, Tele.

Took care of a patient the other day with PVD affecting his left foot, his admitting diagnosis was 'cold foot'. On a heparin gtt, in a coronary care unit because of his multiple cardiac history. They almost decided to amputate I was told in report, but the foot was beginning to warm up. Was told that neither dorsalis pedis nor posterior tibial pulse could be dopplered.

Went into the room with off going nurse and we looked at the foot. I reached down to palpate and was able to feel faint pulsating of the dorsalis pedis. The foot was fairly warm with that red blanching color. The off going nurse also was able to palpate.

Later in the shift I used the doppler and tried and tried, but could not obtain any pulse on the left foot, but was still able to palpate. Later the cardiac PAC was also able to palpate, yet was unable to doppler.

He was guessing perhaps collateral circulation had developed. Yet, why would a palpable pulse not be able to be dopplered?

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Specializes in Med Surg, LTC, Home Health.
why would a palpable pulse not be able to be dopplered?

It seems logically impossible.

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Only time I recall having that problem was when the pulse was so weak that the pressure of holding the Doppler actually occluded it. Try a loud setting and a really light touch.

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Specializes in ICU/Critical Care.

We get a lot of vascular patients on my unit with the same diagnosis. Try not to press hard with the probe and turn up the volume.

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Specializes in LTC, Med/Surg, Peds, ICU, Tele.

Oh, I didn't press the doppler. I was always taught not to, that there should be a layer of gel between the doppler and the skin. After not getting a doppler pulse by barely pressing, I tried different pressures.

The PA also spent quite a bit of time attempting a doppler but was amazed to be able to palpate a pulse.

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Here are a few quick points

Make sure you are using a high frequency doppler for peripheral vascular not the same one used for OB.

Have the angle of the beam be 60 degrees to allow the best reflectoin of the sound waves off of the RBCs. 90 degrees does not give a good reflection of the doppler shift.

With weak pulses have the doppler floating in gel and not prssing the skin.

Also try to track up to an area that might be deeper to have protection from accidental compression from the doppler.

Jeremy

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Specializes in LTC, Med/Surg, Peds, ICU, Tele.

Uh, I did doppler correctly and I know how to doppler. I wasn't asking for tips on how to doppler. I spent 10 minutes trying every technique of trying to doppler. The right foot was unaffected and easily dopplered.

I was actually asking for a clinical explanation as to why this pulse could be palpated but not dopplered. The cardiac PA suggested that maybe there was some surface collateral circulation that had developed, but the main artery was occluded.

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If a collateral develop you would not be able to feel them. They are small caliber vessels the feed into the native vessle that you are palpatng.

Your patient likley had a low resitive signal wth a blunted monophasic waveform. The peak velocity would have been 10-20. Is your patient diabetic lmb salvage? Was the AT artery occluded, DP, PT what did the angiogram/CT/ultrasound show.

In all honestly you were likley occluding the signal, often when you have palpable pulses they are harder to find with a doppler, if you track more proximal they are easier to find. Also if the vessels are heavily calcified then the doppler may not be able to pass the calcified vessel.

Patients with limb salvage also can develop consistant venous humm due to intrinsic vasodilitation, this will have artifact that can make finding the arterial signal harder to find since the artery is much smaller than the dialted veins.

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Specializes in LTC, Med/Surg, Peds, ICU, Tele.

I'm trying to remember details of this patient. He was not a diabetic but had had some sort of surgery I believe 3 weeks ago on that side of his body. Honestly, I worked 4 12 hour shifts this week and the patient details are starting to run together, I can't remember the details of this guy, but I know he had PVD and no one had been able to doppler pulses on his left leg, he almost had gone for an amputation but the foot was improving on heparin and we were waiting for his INR to get greater than 2.0 in order to send him home on coumadin. He had an extensive cardiac history. The surgeon had come in that day and felt he was improving and wanted to conservatively wait to see if the limb could be salvaged.

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Specializes in SICU, Peds CVICU.

Recently I had a surgical fellow tell me that dopplering is more "for sure" (I'm really tired.. sorry if this isn't 100% professional) because you're picking up the blood flow of the artery. When you palpate you're feeling the movement of the blood, so it can be transmitted from a more proximal area down to where you're trying to feel for the pedal pulse.

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Specializes in CVICU.

You know what's funny? I had this exact same thing happen to me last night... patient with ruptured AAA s/p endograft repair. Could palpate left posterior tib and pedal pulses but couldn't Doppler... foot was warm with good cap refill. Could easily palpate and Doppler the right foot.

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Specializes in LTC, Med/Surg, Peds, ICU, Tele.
You know what's funny? I had this exact same thing happen to me last night... patient with ruptured AAA s/p endograft repair. Could palpate left posterior tib and pedal pulses but couldn't Doppler... foot was warm with good cap refill. Could easily palpate and Doppler the right foot.

Ha! See, I'm NOT hallucinating! :up:

Did you get any explanation?

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