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AFE4490 perfusion index (PI),how to calculate?

Qi Fu
Prodigy 250 points
Other Parts Discussed in Thread: AFE4490

Dear all,

I use the afe4490 ic,i have get the DC(ir),AC(ir),DC(r),AC(r) value,but i don't know how to calculate the perfusion index (PI)?

could you help me?give me some suggests.

Formula or method.

Thank you very much.

best regards

mike fu

2014.07.21

  • 0
    TI__Mastermind 49676 points

    Mike,

    Perfusion index is the ratio of the pulsatile blood flow to the non-pulsatile blood flow.

    PI in percent = ( AC / DC ) * 100

    Regards

    Praveen.

  • 0 in reply to Praveen Aroul
    Prodigy 250 points

    hi Praveen.

    Thank you very much.

  • 0 in reply to Qi Fu
    Prodigy 250 points

    hi praveen,

    i had test the method,but i found a question.The PI value is inconsistent result by red and ired.

    for example,

    i set the simulator the amp=5%,

    the pi  value is 5.1% by red light.

    the pi value is 3.1% by ired light.

    amp=10%

    the pi  value is 10.8% by red light.

    the pi value is 6.5% by ired light.

    amp=20%

    the pi  value is 24.9% by red light.

    the pi value is 13.0% by ired light.

    why the pi value is inconsistent  by red and ired?

    Looking forward to your reply.

    best regards

    mike 

    2014.07.21

  • 0 in reply to Qi Fu
    TI__Mastermind 49676 points

    Hello Qi,

    Which simulator did you use for the tests? What are the other simulator settings?

    What did you set for the %SpO2 in the simulator?

    I am guessing to get the %SpO2 set by the user, the amp is changed only for 1 LED else the ratio of ratios will always be 1 and the %SpO2 will always be fixed.

    Can you check with the simulator manufacturer if the amp output will be the same for both the LEDs?

     

    Regards

    Praveen.