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MINUTE VENTILATION SENSOR WITH AUTOMATIC HIGH PASS FILTER ADJUSTMENT

  • US 20040102908A1
  • Filed: 11/27/2002
  • Published: 05/27/2004
  • Est. Priority Date: 11/27/2002
  • Status: Active Grant
First Claim
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1. A minute ventilation sensing device, comprising:

  • excitation current electrodes for imposing a current field in the thoracic cavity;

    an exciter for supplying excitation current between the excitation current electrodes;

    voltage sense electrodes for generating an impedance signal corresponding to a potential difference between two points in the thoracic cavity when the excitation current is applied;

    sampling circuitry for sampling the impedance signal;

    circuitry for filtering the impedance signal samples into a ventilation band to thereby generate a ventilation signal, wherein the filtering circuitry includes a high pass filter with a variable pole frequency for removing a DC component from the impedance signal samples;

    circuitry for calculating a signal variation parameter from a set of impedance signal samples;

    circuitry for adjusting a frequency response of the high pass filter to compensate for changes in the calculated signal variation parameter; and

    , circuitry for deriving a signal proportional to minute ventilation from the ventilation signal.

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