Fetal pulse oximetry
First Claim
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1. A method of determining the oxygen saturation of fetal blood, the method comprisingemitting light of a first wavelength onto the abdominal surface of a pregnant mammal over time;
- emitting light of a second wavelength onto the abdominal surface of the pregnant mammal over time, wherein the second wavelength is different from the first wavelength;
detecting the intensity of light scattered by fetal and maternal arterial blood at the first wavelength and light scattered by fetal and maternal arterial blood at the second wavelength over time, wherein the time of detection is sufficient to record at least one fetal heart beat and at least one maternal heart beat;
converting the detected light into electronic signals;
processing the electronic signals to separate maternal and fetal contributions to the electronic signals;
removing the contributions to the electronic signals generated by maternal arterial blood;
measuring the absorption of light at the first and second wavelengths by fetal arterial blood; and
calculating the oxygen saturation of the fetal arterial blood from the measured absorption of light over time.
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Abstract
A fetal blood pulse oximetry method and apparatus using a first wavelength of light at about 655 to 705 nm and a second wavelength of light at about 820 to 900 nm. Measurements are taken through a mother'"'"'s abdomen. Processing is performed to extract absorption information related to fetal arterial blood with calculation of fetal oxygen saturation from the extracted data.
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Citations
18 Claims
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1. A method of determining the oxygen saturation of fetal blood, the method comprising
emitting light of a first wavelength onto the abdominal surface of a pregnant mammal over time; -
emitting light of a second wavelength onto the abdominal surface of the pregnant mammal over time, wherein the second wavelength is different from the first wavelength;
detecting the intensity of light scattered by fetal and maternal arterial blood at the first wavelength and light scattered by fetal and maternal arterial blood at the second wavelength over time, wherein the time of detection is sufficient to record at least one fetal heart beat and at least one maternal heart beat;
converting the detected light into electronic signals;
processing the electronic signals to separate maternal and fetal contributions to the electronic signals;
removing the contributions to the electronic signals generated by maternal arterial blood;
measuring the absorption of light at the first and second wavelengths by fetal arterial blood; and
calculating the oxygen saturation of the fetal arterial blood from the measured absorption of light over time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A fetal pulse oximeter comprising
a first light source emitting light at a first wavelength; -
a second light source emitting light at a second wavelength, wherein the second wavelength is different from the first wavelength;
one or more photodetectors suitable for detecting light at the first wavelength and light at the second wavelength, the photodetector capable of distinguishing light at the first wavelength from light at the second wavelength;
a probe configured to engage an abdominal surface of a pregnant mammal, the probe coupling the first and second light sources to the photodetector at a substantially fixed position when the probe is engaged to the abdominal surface; and
a processor configured to (1) process the electronic signals generated by the photodetectors in response to detection of light at the first and second wavelengths, (2) remove the contributions to the signals generated by maternal arterial blood, (3) determine the absorption of light at the first and second wavelengths by fetal arterial blood, and (4) calculate the oxygen saturation of the fetal arterial blood from the absorbed light over time. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification