blood pressure monitoring

[lawrence_vs]

good day all,

I am currently carrying out a blood pressure monitor project. basically it uses the oscillometric method to detect the blood pressure. Currently my hardware comprises of a pressure sensor, instrumentation amp, ADC (pic16f877a) and is connected to the pc via rs232. Currently the voltage readings can be obtained using VISA serial and i can see the waveform. What i need to do now is to obtain specific peaks (amplitude of the peaks will be used to calculate the pressure). How the oscillometric method works isthat the amplitude of change of pressure in the inflattable arm cuff is monitored. As air is slowly released, there will be a sudden spike (when the pulse breaks from its obstruction). The amplitude of this spike is useful for the Systolic pressure. As the pressure is further released, there will be a further increase in the pulse amplitudes and would then start to diminish. The diastolic pressure is when the pulses start diminishing so the amplitude level would need to be measured. I would appreciate any help or guidance... or just simply for someone to show me in the right direction...

Thanks...

[Abhinav T]

Hi Lawrence,

Thank you for posting to the National Instruments Discussion Forums.

You can easily detect the peak of an array of X values using the Threshold Peak Detector VI. This provides you with the index of the detected peak from a given set of data. The index can be fed back into an index array to read the actual amplitude.

Hope this helps!

[Nann]

Could you attach some sample data?

[lawrence_vs]

Hi all, Thanks for the replies. I have been looking at the peak detector and threshold peak detector also. But I am a total newbie to labview and its taking a bit of time. ANyway if anyone has any sample VI's using the peak detector that I can go through, I would really appreciate that. Will keep on trying on my side and will update later.

Thanks.

[Nann]

What problem do you have now?  Have you browse the examples shipped with LabVIEW.  The peak detection VIs are quite straightforward.  I don't think you have problems to use them.  But I guess they might not be suitable for your application, if the peak is sharp and asymmetric.  Possibly the wavelet-based peak detection is better for your application.  I don't have a blood pressure signal but an ECG signal.  But it should show you some idea about how the wavelet-based peak detection work well.

BTW, the wavelet-based peak detection VI I used is shipped with the Advanced Signal Processing Toolkit.

[lawrence_vs]

Hi Nann,

Thanks for the example. I will try it after this as soon as I get back. Will update later on how it goes.

Regards,
Lawrence VS