Method and apparatus for in vivo blood constituent analysis
First Claim
1. A method for determining a blood constituent comprising the steps of:
- emitting electromagnetic radiation of at least three wavelengths toward a patient;
detecting a portion of the electromagnetic radiation scattered by the tissue of said patient for each of said at least three wavelengths and generating at least three signals indicative thereof;
determining a blood constituent result from a combination of said at least three signals, said result being equivalent to the sum of (1) a first blood constituent estimate determined using a first set of at least two of said signals and (2) a multiplicative factor multiplied by a difference between said first blood constituent estimate and a second blood constituent estimate, said second blood constituent estimate being determined using a second set of a different combination of at least two of said signals.
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Accused Products
Abstract
The present invention utilizes at least three wavelengths of electromagnetic radiation for determining a blood constituent, such as arterial oxygen saturation, in a patient. The detected radiation scattered by the tissue of the patient is analyzed in a manner that compensates for variations in the detected radiation caused by differences in the scattering of the radiation at different wavelengths. In particular, a result is determined which is equivalent to the sum of a first blood constituent estimate using a first pair of the detected signals, and the difference between the first blood constituent estimate and a second blood constituent estimate, using a different pair of wavelengths, with the difference being multiplied by a multiplicative factor.
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Citations
58 Claims
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1. A method for determining a blood constituent comprising the steps of:
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emitting electromagnetic radiation of at least three wavelengths toward a patient; detecting a portion of the electromagnetic radiation scattered by the tissue of said patient for each of said at least three wavelengths and generating at least three signals indicative thereof; determining a blood constituent result from a combination of said at least three signals, said result being equivalent to the sum of (1) a first blood constituent estimate determined using a first set of at least two of said signals and (2) a multiplicative factor multiplied by a difference between said first blood constituent estimate and a second blood constituent estimate, said second blood constituent estimate being determined using a second set of a different combination of at least two of said signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for determining a blood constituent comprising the steps of:
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emitting electromagnetic radiation of at least three wavelengths toward a patient; detecting a portion of the electromagnetic radiation scattered by the tissue of said patient for each of said at least three wavelengths and generating at least three signals indicative thereof; determining a blood constituent result utilizing at least one coefficient chosen to compensate for variations in detected radiation paths through said patient of said electromagnetic radiation for at least two of said wavelengths. - View Dependent Claims (11, 12, 13)
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14. A method for determining a blood constituent comprising the steps of:
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emitting electromagnetic radiation of at least three wavelengths toward a patient; detecting a portion of the electromagnetic radiation scattered by the tissue of said patient for each of said at least three wavelengths and generating at least three signals indicative thereof; determining a blood constituent result utilizing said at least three signals; and wherein said at least three wavelengths are chosen so that (1) first and second groups of said wavelengths have sufficient sensitivity to changes in said blood constituent so that a ratio of detected values varies by more than double between 0 and 100 percent of said blood constituent, and (2) said first and second groups of wavelengths have different penetrations into said patient with sufficient overlap to provide correlated errors in blood constituent calculations using said first and second groups of wavelengths. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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23. An apparatus for determining a blood constituent comprising:
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at least one emitter configured to emit electromagnetic radiation of at least three wavelengths toward a patient; a detector configured to detect a portion of the electromagnetic radiation scattered by the tissue of said patient for each of said at least three wavelengths and generating at least three signals indicative thereof; means for determining a blood constituent result from a combination of said at least three signals, said result being equivalent to the sum of (1) a first blood constituent estimate determined using a first set of at least two of said signals and (2) a multiplicative factor multiplied by a difference between said first blood constituent estimate and a second blood constituent estimate, said second blood constituent estimate being determined using a second set of a different combination of at least two of said signals. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 35)
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32. An apparatus for determining a blood constituent comprising:
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means for emitting electromagnetic radiation of at least three wavelengths toward a patient; means for detecting a portion of the electromagnetic radiation scattered by the tissue of said patient for each of said at least three wavelengths and generating at least three signals indicative thereof; means for determining a blood constituent result utilizing at least one coefficient chosen to compensate for variations in detected radiation paths through said patient of said electromagnetic radiation for at least two of said wavelengths. - View Dependent Claims (33, 34)
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36. An apparatus for determining a blood constituent comprising:
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means for emitting electromagnetic radiation of at least three wavelengths toward a patient; means for detecting a portion of the electromagnetic radiation scattered by the tissue of said patient for each of said at least three wavelengths and generating at least three signals indicative thereof; means for determining a blood constituent result utilizing said at least three signals; and wherein said at least three wavelengths are chosen so that (1) first and second groups of said wavelengths have sufficient sensitivity to changes in said blood constituent so that a ratio of detected values varies by more than double between 0 and 100 percent of said blood constituent, and (2) said first and second pairs of wavelengths have different penetrations of said patient with sufficient overlap to provide correlated errors in blood constituent calculations using said first and second groups of wavelengths. - View Dependent Claims (37, 38, 39, 40, 41)
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42. An oximeter processor comprising:
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means for receiving, as an input, signals corresponding to a portion of electromagnetic radiation scattered by the tissue of a patient for each of at least three wavelengths of electromagnetic radiation directed toward a patient; and means for determining a blood constituent result from a combination of said at least three signals, said result being equivalent to the sum of (1) a first blood constituent estimate determined using a first set of at least two of said signals and (2) a multiplicative factor multiplied by a difference between said first blood constituent estimate and a second blood constituent estimate, said second blood constituent estimate being determined using a second set of a different combination of at least two of said signals. - View Dependent Claims (43, 44)
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45. An oximeter processor comprising:
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means for receiving as an input signals corresponding to a portion of electromagnetic radiation scattered by the tissue of a patient for each of at least three wavelengths of electromagnetic radiation directed toward a patient; and means for determining a blood constituent result utilizing at least one coefficient chosen to compensate for variations in path lengths through said patient of said electromagnetic radiation for at least two of said wavelengths. - View Dependent Claims (46)
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47. A software program product comprising:
a memory having a program stored thereon, said program being usable by a processing device, said program being configured to receive, as an input, signals corresponding to a portion of the electromagnetic radiation scattered by the tissue of a patient for each of at least three wavelengths of electromagnetic radiation directed toward a patient; and determine a blood constituent result from a combination of said signals, said result being equivalent to the sum of (1) a first blood constituent estimate determined using a first set of at least two of said signals and (2) a multiplicative factor multiplied by a difference between said first blood constituent estimate and a second blood constituent estimate, said second blood constituent estimate being determined using a second set of a different combination of at least two of said signals. - View Dependent Claims (48, 49, 50, 51, 52, 53, 54, 55)
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56. A software program product comprising:
a memory having a program stored thereon, said program being usable by a processing device, said program being configured to receive as an input signals corresponding to a portion of the electromagnetic radiation scattered by the tissue of a patient for each of at least three wavelengths of electromagnetic radiation directed toward a patient; and determine a blood constituent result utilizing at least one coefficient chosen to compensate for variations in path lengths through said patient of said electromagnetic radiation for at least two of said wavelengths. - View Dependent Claims (57, 58)
Specification