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Can You Hear Venous Blood Flow?

11/05/2008 12:33 PM

How could you hear venous blood flow? Dopplers pick up high flow arterial blood. Could you adjust this technology to hear about 7mhz venous low flow blood.?

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#1

Re: Can you hear venous blood flow?

11/05/2008 2:44 PM

7mhz would put you at the bottom of the 40 Meter CW band.

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#7
In reply to #1

Re: Can you hear venous blood flow?

11/06/2008 1:49 AM

7 MHz seems to be to very high value. 7 mHz seems to be too low. I guess 0.7 Hz would be closer to the truth.

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#11
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Re: Can you hear venous blood flow?

11/07/2008 2:40 AM

Hmmm... I had never considered sending code with my blood... Usually I use a vibroplex. Bill

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#2

Re: Can you hear venous blood flow?

11/05/2008 3:24 PM

It's very simple - just hold a seashell up to your ear. The "sound of the ocean" you hear is the blood rushing through your ear.

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#3
In reply to #2

Re: Can you hear venous blood flow?

11/05/2008 6:38 PM

It may be simple to you and I appreciate the input but how can I convert this knowledge to a portable device to find a vein? You just answered a question I have had since I was a child. I am a nurse and I need to hear the bloodflow in order to find a vein. Any suggestions? I have a light devised and the visiblity is good but in order to thread the IV I need to know what angle the vein follows. Thanks for responding.

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#5
In reply to #3

Re: Can you hear venous blood flow?

11/05/2008 11:54 PM

A device which recognizes venous flow in a blood vessel may be on its way to you. I found this info by a Google search for, "finding a vein for IV by sound."

In the adding-insult-to-injury department, being pricked multiple times with a needle while a nurse tries in vain to find a vein ranks pretty high. The problem can be acute with infants and the obese.

Jim Larsen, a researcher at the Georgia Institute of Technology, was in the hospital once and required several blood tests. All the poking caused swelling and inflammation in his arms, which made it increasingly difficult for nurses to find his veins.

"It often took seven or eight tries," Larsen recalls. "It wasn't long before I felt like a pin cushion."

Now Larsen and his colleagues are working on a solution. They're developing a portable device that would find veins.

Simple technology

The vein finder works by using the Doppler effect, a well-known phenomenon also employed to detect rainfall and even find extrasolar planets. The Doppler effect is what makes an ambulance siren change pitch when it passes you. Sound waves are compressed when the ambulance is coming at you, and they are stretched when it drives away, changing the sound's pitch.

By applying a narrowly focused beam of ultrasonic energy at a certain angle, the vein finder uses the Doppler effect to detect moving blood and determines the direction of flow. Arteries carry blood away from the heart, and veins carry it back.

Like a stud finder used by contractors, the vein finder beeps when it detects a target. A nurse would then activate an attached needle.

The sensor has worked in tests on a model that simulates human tissue and blood vessels. Next up are human tests. Later, data processing and electronics have to be miniaturized to create a prototype for field-testing.

Many uses

The researchers envision the thing ultimately being the size of a fat fountain pen that could be used by ambulance services and the military. But it would be welcome in any hospital or nursing home.

Finding veins is especially difficult in dehydrated patients because their blood vessels lack normal volume, said Connell Reynolds, founder of Reynolds Medical Inc., a medical device manufacturer that is sponsoring the work.

"Similarly, because cardiac patients' hearts aren't pumping properly, their veins are hard to locate," Reynolds said. "It's also difficult to find veins in obese people and young children because their vessels are covered by layers of fat."

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#4

Re: Can You Hear Venous Blood Flow?

11/05/2008 11:36 PM

Apparently, cause of the sound we hear when holding a seashell to our ear is open to some debate...

This from "How Things Are Made"...

Do you remember trying this as a kid -- Holding one of the seashells you grabbed as a souvenir up to your ear? It seems like no matter how far away from the ocean you are, you can still hold a seashell up to your ear and hear the roar of the waves rolling onto the shore. The best shells for producing this sound are the large, spiral conch shells.

Some people have suggested that the sound you hear from the seashell is the echoing of your blood rushing through the blood vessels of your ear. That is not the case. If that were true, then the sound would intensify after exercising, since your blood races faster after exercising. However, the sound is the same even after exercising.

Others say that the whooshing sound inside the shell is generated by air flowing through the shell - air flowing through the shell and out creates a noise. You'll notice that the sound is louder when you lift the shell slightly away from your ear than it is when the shell is right against your head. However, this theory doesn't hold true in a soundproof room. In a soundproof room, there is still air, but when you hold the seashell to your ear, there's no sound.

The most likely explanation for the wave-like noise is ambient noise from around you. The seashell that you are holding just slightly above your ear captures this noise, which resonates inside the shell. The size and shape of the shell therefore has some effect on the sound you hear. Different shells sound different because different shells accentuate different frequencies. You don't even need the seashell to hear the noise. You can produce the same "ocean" sound using an empty cup or even by cupping your hand over your ear. Go ahead and try it and vary the distance at which you place the cup near your ear. The level of the sound will vary depending on the angle and distance the cup is from your ear.

Noise from outside the shell also can change the intensity of the sound you hear inside the shell. You can look at the shell as a resonating chamber. When sound from outside enters the shell, it bounces around, thus creating an audible noise. So, the louder the environment you are in, the louder the ocean-like sound will be.

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#8
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Re: Can You Hear Venous Blood Flow?

11/06/2008 5:08 AM

You could easily disprove the blood flow theory by using a microphone.

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#10
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Re: Can You Hear Venous Blood Flow?

11/07/2008 1:30 AM

[You could easily disprove the blood flow theory by using a microphone.

Perhaps, but if a microphone pickup with associated amplifier/sound/oscilloscope system is used, then one introduces extraneous equipment, which may or may not affect the outcome, while still not proving or disproving the theory. My usual ploy is to keep things simple. If a given shell induces sound when held to an ear, but fails to do so in a soundproof room, while all else is equal, then my conclusion is that it is ambient sound caught in the shell that causes sound to be perceived when the shell is against the ear.

But, you have raised an interesting question. Does a seashell still produce sound, if there is no ear to hear it?

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#6

Re: Can You Hear Venous Blood Flow?

11/05/2008 11:54 PM

Hello and welcome to this forum. Your question is a significant challenge and there are people here who will have the collective knowledge to provide an answer.

I spent three years working as lab technician in a cardiovascular research facility. Have actually manufactured doppler sensors for implant on the corronary arteries and then assisted in the implant surgery (as anaesthetist) for the veterinary subjects.

Doppler might work IF you could get enough amplification of the reflected signal and filter out the higher frequency pulsatile signal of any nearby arterial flow then you'd have a start. You might then need to frequency shift the signal into something that was in audible range, or else have some electronic indicator of detection like an LED.

We also fitted electromagnetic transducers (because they had no crosstalk signal with the dopplers) and they were also highly succesful due to the haemoglobin content in the blood. This would probably be of no use, since they have to surround the blood flow.

The advantage that we had was that we could already see our target blood vessel when we were fitting those items.

How did you arrive at 7mhz signal? (You do mean mili hertz?) The doppler signal would be a function of double the velocity of the blood in the vein. From memory (and it's been a very long time) our arterial signal ranged from 1khz to 10khz because we used to listen to it on speakers during experimental protocols, so I would expect the mean return flow to have given a signal around 2khz.

One alternative might be to set the sensitivity of the doppler to only show 7mhz and then all else in field would be null.

Have you considered modulation of the input signal?

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#9

Re: Can You Hear Venous Blood Flow?

11/06/2008 9:27 AM

When I was in college, one of the Dr.'s at the teaching hospital wanted us to build him an all digital device to measure "Impedance plethysmography" of venous blood flow. He had in his possession an analog, 1960's machine that displayed on a small 4" CRT.

We looked at some patents and experimented on some classmates. We found some frequency bands that seemed to respond to venous blood flow and wrote a short lab paper. But in the end we decided we didn't want the liability of building a device to for the Dr. to play with on living patients.

I believe that there are commercial devices available to measure "Impedance plethysmography."

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#12

Re: Can You Hear Venous Blood Flow?

11/07/2008 4:40 PM

I asked my wife about this. She says that she uses Doppler to find veins all the time. Of course ultrasound machines are a bit heavy to drag around with you everytime you want to plug in an IV. She hates it when she has to "go portable" because the patient (at the other end of the hospital) is incapable of being moved.

Sincerely

Bill

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#13
In reply to #12

Re: Can You Hear Venous Blood Flow?

11/07/2008 6:53 PM

Are you talkin about an ultrasound machine? Can she find them with the portable ultrasound?

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#14
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Re: Can You Hear Venous Blood Flow?

11/08/2008 7:28 PM

When she "goes portable", she has to take the big machine from her room with her. I would guess it weighs about 400 pounds.

When I asked her about veins, her reply was "Sure!! I do it every day!!". I would GUESS that a portable machine would have the same capability. She makes it seem as if it is a simple procedure.

Bill

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#15
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Re: Can You Hear Venous Blood Flow?

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