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Old 04-22-2006, 09:28 PM
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Default Blood velocity ---> Blood Pressure ...?

Hello all,

I am working on a senior biomedical engineering project and would like to see if I could get some help here. My project is essentially developing a Doppler based blood pressure measurement device. The thing is, Doppler will give me the velocity profile of the blood flowing. What do you guys think I should do as for my next steps in this? I have been thinking of using maybe the conservation of momentum, so that:

-dP/dx = d*[v*dv/dx] (d=density, v=velocity, P = pressure)

but I'm not sure if that will work. I'm thinking that the P given here is along the streamline, not against the wall. Actually, after typing this out, I'm convinced it's not the pressure exerted on the wall, as theoretically there is no velocity along the wall

So, sorry for the long post. It comes down to this:

I have Velocity, I want pressure against the wall. I'm sure I could get the diameter of the vessel with Doppler as well. So let's say I have velocity and cross-sectional area. Can we get the Force against the wall now?

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Old 05-13-2006, 10:34 PM
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Default Re: Blood velocity ---> Blood Pressure ...?

Just bumping this...
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Old 05-14-2006, 04:02 PM
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Default Re: Blood velocity ---> Blood Pressure ...?

This is beyond my skills.

You might try visiting WebMD at and clicking on the "Boards and Blogs" button.

There you can post to forums visited by doctors and such. Maybe that would help.
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Old 10-15-2006, 07:40 PM
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Default Re: Blood velocity ---> Blood Pressure ...?

If you know the velocity, try calculating the momentum flux Tao(zr)=-mu*(dVr/dz+dVz/dr) where mu=blood viscosity, Vr=blood velocity in the r-direction, Vz=blood velocity in z-direction. You can develop the Vz using navier-stokes equation in cyllindrical coordinates and assume that the Vs that doppler gives you is the average velocity over the entire vein/artery. Basically, once you have Vz, you can calculate the shear stress, torque on the wall of the vein/artery, and the force (pressure) on the arterial wall.
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