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Oximeter for reliable clinical determination of blood oxygen saturation in a fetus

  • US 5,494,032 A
  • Filed: 05/23/1994
  • Issued: 02/27/1996
  • Est. Priority Date: 07/12/1991
  • Status: Expired due to Term
First Claim
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1. A quantitative analysis instrument for noninvasive measurement of blood oxygen saturation in a fetus, said instrument comprising:

  • a. a source of at least four different wavelengths of light, at least some of said wavelengths being in the range from 500 to 1000 nm;

    b. optical means for introducing said wavelengths into said fetus and for collecting at least a portion of said wavelengths that are reflected back from said fetus;

    c. a device for positioning said optical means relative to said fetus, whereby at least a portion of said wavelengths are introduced into said fetus and said portion of said reflected wavelengths are collected;

    d. at least one detector positioned relative to said optical means for measuring the spectral intensities of said reflected wavelengths during the diastolic portion of the cardiac cycle of said fetus, to obtain a diastolic set of spectral intensities v. wavelengths, and for measuring the spectral intensities of said reflected wavelengths during the systolic portion of said cardiac cycle, to obtain a systolic set of spectral intensities v. wavelengths;

    e. electronics including a microprocessor and memory means for, (i) storing said diastolic set of spectral intensifies v. wavelengths and said systolic set of spectral intensities v. wavelengths;

    (ii) processing said diastolic and systolic sets of spectral intensities to determine a measure of change between said diastolic and systolic sets to obtain a third set of spectral intensifies v. wavelengths, and (iii) processing said third set of spectral intensifies v. wavelengths to determine a measure of oxygen saturation, said memory means including a multivariate algorithm and a multivariate calibration model, said algorithm using at least three variables; and

    f. means, for indicating said determined measure of oxygen saturation.

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