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Variable indication estimator

  • US 10,357,206 B2
  • Filed: 03/06/2018
  • Issued: 07/23/2019
  • Est. Priority Date: 06/05/2000
  • Status: Expired due to Term
First Claim
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1. A pulse oximetry system, the pulse oximetry system comprising:

  • an analog signal conditioning circuit that receives signals corresponding to attenuated red and infrared light transmitted through body tissue of a patient, the analog signal conditioning circuit comprising an analog-to-digital conversion circuit that provides first discrete signal values at a first time and second discrete signal values at a second time;

    a digital-to-analog conversion circuit that provides control signals to emitter current drivers to cause the red and infrared light to transmit through the body tissue; and

    a digital signal processor that;

    receives the first discrete signal values and the second discrete signal values from the analog signal conditioning circuit, the first discrete signal values having a first amount of noise greater than a second amount of noise of the second discrete signal values;

    outputs an emitter control signal to the digital-to-analog conversion circuit;

    calculates first oxygen saturation values based on the first discrete signal values and second oxygen saturation values based on the second discrete signal values, the first and second oxygen saturation values corresponding with oxygen saturation of the patient'"'"'s blood;

    adjusts the first oxygen saturation values to produce first adjusted oxygen saturation values by smoothing the first oxygen saturation values, wherein the digital signal processor determines to use said smoothing based at least in part on the first amount of noise;

    adjusts the second oxygen saturation values to produce second adjusted oxygen saturation values by applying a curve-fit to the second oxygen saturation values, wherein the digital signal processor determines to use the curve-fit based at least in part on the second amount of noise; and

    outputs the first and second adjusted oxygen saturation values to a display.

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