Heart Rate and Blood Pressure Monitor

[Pete.Dunc]

Hi there, this is my first post so be nice

Basically this is a university project I've been thrown in the deep of.  The specification is to produce a heart rate and blood pressure monitor, the heart rate and blood pressure are to be displayed onscreen.  My responsibility is to take our "heart rate" signal and interpret the results to display the value.

I thought LabView would be good for this. 

Although I have completed the "LabView 101" course I have very limited knowledge of data acquisition, obviously there is a plethora of information on this site (2871 articles) I was just looking to be steered in the right direction.

If you would like anymore information don't hesitate to ask.

Peter

[Coq_Rouge]

For about a year ago I built such a monitor with Labview. I measured the invasive blood pressure  and also extract  the heart rate from this signal. I used the peak detection function for this task. I can not send you any program. But feel free to ask me questions regarding this matter.

 If this system are going to be used on humans, it must comply with the IEC 60601. The hardest part is often to make the system IEC 60601 compatible ;). The measuring part is quite simple    

Message Edited by t06afre on 01-30-2009 03:16 PM

Message Edited by t06afre on 01-30-2009 03:17 PM

Message Edited by t06afre on 01-30-2009 03:19 PM

[Pete.Dunc]

---

t06afre wrote:

For about a year ago I built such a monitor with Labview. I measured the invasive blood pressure  and also extract  the heart rate from this signal. I used the peak detection function for this task. I can not send you any program. But feel free to ask me questions regarding this matter.

 If this system are going to be used on humans, it must comply with the IEC 60601. The hardest part is often to make the system IEC 60601 compatible ;). The measuring part is quite simple    

---

Thank you for the quick reply.

This is a group project and gaining the measurement signals will be undertaken by other students.  I'm really concerned with what to use to get these signals "into" the PC.

The information on the IEC 60601 is great thanks again.

[Coq_Rouge]

Hi PjayD

Is your project on the right track, or do you need a life buoy...

[Pete.Dunc]

Good morning

Later this afternoon our group will be presenting our specification and method to a group of lecturers.  This is an informal presentation with the purpose of getting feedback from them on whether or not we're heading in the right direction in terms of planning.  So after that I'll be able to get going properly.

I'll post on here again in a few hours with an update.

Pete

[ROtake]

there are several medical devices in the market that does that. They all already comply with safety regulations. Most of those devices have an analog external signal that you can read using any simple Data Acquisition board or a digital output like serial RS 232 or any other connection. This way, your system is not connected with the patient and you don't have any conerns about safety. You only need to make sure your program makes the right calculations.

[Pete.Dunc]

Sorry I took so long replying!

I've been working through "Learning with LabVIEW 7 Express" by Bishop. 

This has given me a slightly better understanding of the capabilities of the

program.  Now I can start work on the actual project, I'll be updating on

here much more regularly.

The methods by which the heart rate and blood pressure will be obtained

have been finalised so the input signals are now known;

Heart rate -

This will be a square wave which changes voltage level on each heart beat.

Blood pressure -

This will be a continuous voltage trace and the program will require the

ability to pick off two values (for high and low blood pressure); although

these are not the maximum and minimum values of the graph.  The

user will select when readings are taken.

The devices used to gain these signals are still being produced so for

now I'll be simulating the waves in LabVIEW.  I'm having trouble using

the "Simulate Signal" tool.  I add it, set up the parameters for my square

wave and fed it into a Waveform Chart.  I then select run continuously

and only one period of the wave is displayed.  I was expecting a similar

output to feeding a function generator into an oscilloscope.

All help appreciated!

Peter

Message Edited by PjayD on 03-05-2009 09:50 AM

[ROtake]

Blood pressure signals are something like this...

              o o                                    o o

            o     o                                o     o 

          o        o                             o        o        o o

        o            o     oo                o            o    o     o

      o                o o     o           o                oo         o

   o                               o       o                                 o   o 

o                                     o  o                                    oo

So you will need to read the analog signal (if you're using an analog input with a daq card) and split cycles . On each cycle, you will need to detect the max pressure and the minimal pressure of your signal.

One way to implement this is to create a virtual buffer in memory with the data you read from the card and then process all the calculations you need: separate cycles, then measure max and min press on each cycle, then, you can make an average withing the cycles you detect.

The average values will be this way a little delayed, since you will show the values as an average of the last 3 or 4 cycles.

The heart rate, if i understood correctly, you can just read with analog signals. You will probably have a converting factor to tranform voltage reading to heart rate (bpm).

Ricardo

[Coq_Rouge]

Here is an example of arterial blood pressure from a human. As I told you before you shall use peak an valley detection. For determining the diastolic pressure, and systolic blood pressure. The heart rate is related to the time between to systolic or diastolic events. Your plan looks somewhat strange if you ask me.  

[Pete.Dunc]

Thank you both for replying.

I've not made this very clear; the way the project has been split up I have no say in the way which the input signals are obtained, I agree that it seems strange, but it's out of my hands. 

I just have to get the software to work around the inputs so the descriptions in my previous post still stand.

@ROtake -

In order to measure the blood pressure we will be using auscultatory methods (http://en.wikipedia.org/wiki/Blood_pressure#Auscultatory_methods); the guage will be replaced by a pressure transducer to get a voltage.  This is why I was saying the software will need to be able to take two samples when a user selects (when the sounds are heard); I can't just do peak and min, as the cuff is blown up to a higher pressure and released until the sounds occur.  Reading the sound will be done manually, so there's no need to use LabVIEW for that.

@t06afre -

Thank you for the sample, it would be much easier for me if I had a continuous trace of blood pressure being input.  But because of the way 'the group' have decided to tackle the problem, I'm stuck with the situation above.

I think the way we're doing it is not the best by any means, but I've got to work with what's given to me.