Carotid Flow Time for Volume Responsiveness + “What does the Chris Fox say?” #foamed


You liked Carotid VTI for volume responsiveness?  Well, then you’re going to love this.

This is another concept that is being studied right now…….not proven yet.  But it’s awesome!!  All the ease of finding the carotid, without all the fuss over angle of insonation.
We’ve got Vicki Noble, the lung queen, and Dave Mckenzie, recent graduate of the ultrasound fellowship at Mass General talking about this technique.
Also, as you read above, we have a new segment we’ll occasionally run, especially when it’s a new or controversial topic.  We’ll get The Man, Chris Fox, to give us his thoughts and find out exactly “What does the Fox say”.


Somehow we got invited to teach at smaccGOLD this year….. must have been some sort of mistake. Regardless, we’re taking the opportunity to hop a puddle jumper down under and ultrasound some joeys and wallabies. If you’re worth your weight in Fosters you take yourself over to the their website and register. And if you’re coming, make sure you submit your abstract by Nov 22nd.
As always, come practice it with us live at:
Study up:

6 Comments on “Carotid Flow Time for Volume Responsiveness + “What does the Chris Fox say?” #foamed”

  1. Gavin denton

    If you checked the correct carotid position with a linear probe and marked it, could you then use an uscom supra-sternal doppler for to get the FTC. No calculations required and people less skilled in USS could continue to apply the technique.

    @DentonGavin (Twitter).

  2. Matt Wong

    How should we interpret the results in a patient with aortic valve stenosis or carotid artery disease? And does it matter if you do the left or the right carotid?

    In atrial fibrillation patients I presume we should average a few measurements together?

    -Matt Wong @MatthewLWong

  3. Daniel Dankl

    Hi Mike and Matt!

    First i want to say that i really love your Podcast-very cool-
    So one question about the carotid flow time: did i get it right that the equation with the square root of the cycle time eliminates the heart rate as a factor of flow time? So if i only measure the flow time alone and heart rate changes after leg raise then the flow time will change too and its change is not due to volume is`nt it?


  4. Jeff

    What about looking at diastolic function for this sort of question? I feel like the main issue is whether we can give more fluids to the patient without going past the point of doing harm. Things like IVC measurement and carotid flow time kind of get to that, but what about going to the source–diastolic function. If someone goes from normal to pseudonormal, for example, maybe it’s the time to start looking at pressors.

  5. PB

    The english intensivist Mervyn Singer studied FTC (long time ago…) and is a parameter integrated in USCOM device software. It was evaluated in descending aorta but, mailing with author, LVOT can be used instead of it (or descending aorta with suprasternal view). FTC is inversely related to systemic vascular resistance, so, a low FTC corresponds to a high SVR and vasoconstricted circulation. So, it is low not only only in hypovolemia. Excess vasopressor, low temperature or non vasodilated shock of any cause are other causes. If you are in doubt, make a fluid challenge and if FTC really change probably patient is a fluid responder. Anyway, it is better to put all clinical and echocardiogram in context, not only FTC.

    *Look at FTC evaluation in LVOT flow…patient was a fluid responder.


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