Vascular Doppler Viewer - Low Cost Blood Flow Speed Measure

Status : 1.0.2 BETA

Latest version : 1.0.2 (Feb. 2022)

First release : Dec 2021

Difficulty : Low

Prerequisite : none

Documentation : Read the Help available from the Vascular Doppler Viewer application software

Support : Forum only, no PM

Low-cost devices available on the market allow the monitoring of the heart beat rate. Nowadays, fetal doppler monitors have been widely promoted and can be easily acquired. They are based on continuous HF waves and the frequency shift due to blood motion falls into the audible range. The audio signal enables the heart rate monitoring as well as the detection of vascular pathologies. For the latter ones, an 8-MHz probe is preferred for its capability to examine body surface vessels and for its better insonation angle thanks to a smaller probe's head.

Spectrum analysis of the audio signal can deliver additional data such as the blood speed and the variation of the blood flow during systolic and diastolic periods. The Vascular Doppler Viewer application is aimed to display these additional data.

In no case it can be use to replace a professional medical examination.

DISCLAIMER: *** RISK OF ELECTRICAL SHOCKS AND DEATH ***

=>Safety rules related to electrical devices must be complied and no connection direct or indirect* shall be made between the device and appliances connected to mains (* e.g. when the device is connected to the USB port of a PC powered from the mains).

Persons unskilled, not familiar or unaware of electrical risks are discouraged to get involved. 
This project is provided for training/education and in no case for commercial purposes or medical diagnostics. 
Use of this project information is under the ENTIRE and SOLE RESPONSIBILITY of the USERS. 
It has not been approved for any kind of applications.

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• Fetal Doppler device with 8-MHz
• or 8-MHz Probe only where connector has been replaced with an USB and a 3.5 mm sockets
• Gel (the gel is not an option. Without gel, the ultrasound propagation is very, really poor due to the impedance mismatch between probe-air-skin )

Note : The HEX file below is the setup executable file. Replace .hex with the .exe extension.

If the easiest way is to buy a Fetal Doppler with the 8-MHz probe (~30$), the cheapest one (~10$) is to get a replacement probe only and to change the sockets in order to connect the computer's USB (+5V power supply) and audio inputs.

IMPORTANT : BEFORE ordering the probe only, you must be sure that the probe embedded all the electronics and delivers the audio signal corresponding to the frequency shift.

On the photo above, we have modified a 2-MHz Doppler probe from VCOMIN. The modified probe can be directly connected to the PC without further interface. Nevertheless, we remind you that a 2-MHz probe is dedicated for deep Doppler and is not well suited for general vascular monitoring uses. Moreover, a deep Doppler induces more interference from surrounding vessels.

NOTE : For the audio connector, connect only the probe output that delivers the signal and the common GND.

IMPORTANT : Read the Help available from the Vascular Doppler Viewer application software.

The current software version is ALPHA (means under test and may still have critical bugs).

To begin with, you may use the sample.wav file and read the documentation.

Basically the Vascular Doppler Viewer application makes a spectrum analysis of the Doppler audio signal.

1. The first step is to "calibrate" the Audio Signal for avoiding artifacts.
2. There is a tab named TOOLS that provides 3 screens :
3. The first one is a Signal Scope. You have to adjust the signal using preferably the Doppler device Volume or in case of Doppler probe only, the Audio Input slider. You must absolutely avoid signal overloads.
4. Next step consist of calibrating the Audio Spectrum to get rid of the noise and to maximize the amplitude without clipping.
5. Last step is to choose the frequency range and Scale Factor to adapt the Doppler Waveform to your needs.

They are several parameters you can tune. These are available from the PREFERENCES tab with a short description for each.

Finally there are also some additional features such a printing, audio file saving or patient's database management (common to all our software).

Due to the strong impact of insonation angle, hardware performance, etc. the accuracy of the measure cannot be guarantee. This application gives a visual information in addition to the audio information.