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Systems and Methods Utilizing Plethysmographic Data

  • US 20120271554A1
  • Filed: 05/28/2010
  • Published: 10/25/2012
  • Est. Priority Date: 05/29/2009
  • Status: Abandoned Application
First Claim
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1. A method for facilitating detection of changes in blood volume, said method comprising steps of:

  • sampling a plethysmograph (PG) waveform;

    calculating a spectrum for the PG waveform having a cardiac signal and at least one blood volume indicator;

    detecting the cardiac signal or a harmonic thereof within normal cardiac frequencies of the PG waveform spectrum;

    detecting the blood volume indicator;

    determining a signal strength for each of the cardiac signal or the harmonic thereof and the blood volume indicator, wherein at least one of the determined signal strengths is calculated over a range of characteristic frequencies;

    calculating a normalized value for the blood volume indicator by dividing the signal strength of the blood volume indicator by the signal strength of the cardiac signal or the harmonic thereof.

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