EP0555553A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Improved arterial blood monitoring system
Assignee: Datex Ohmeda Inc
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Filing: 1992-12-23
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Granted: —
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Expires: 2012-12-23
Abstract
Abstract This improved arterial blood monitoring system takes advantage of the basic statistical property of arterial blood that arterial blood contains a plurality of dominant absorbers, whose measured light absorption spectra appear as a constant over a short interval of time. The arterial blood characteristics to be measured are empirically related to the changes in the measured light transmission through the plurality of dominant absorbers as a function of the change in arterial blood volume at the probe site. Therefore, by measuring the transmitted light as it varies with arterial pulsation at selected wavelengths of light, the relative amount of these dominant absorbers in the arterial blood can noninvasively be determined. By selecting one wavelength of light around 1270nm, where water has a measurable extinction and a second wavelength at about 810nm, a wavelength that is substantially isobestic to oxygenated and reduced hemoglobin, a direct relationship between the transmitted intensities at these two wavelengths and the arterial hemoglobin concentration will exist and can be calculated. The use of a plurality of wavelengths of light enable the arterial blood monitoring system to concurrently measure a number of characteristics of arterial blood. By selecting wavelengths of light around 660nm, 940nm and 1270nm, the values of total hemoglobin and oxygen saturation of arterial blood can simultaneously be determined. In addition, oxygen content of arterial blood can be calculated from these values of total hemoglobin and oxygen saturation.
Inventors
- 👤 Jonas Alexander Pologe
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 15:01
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/68; A61B5/6801; A61B5/6813; A61B5/6825; A61B5/6826; A61B5/02; A61B5/024; A61B5/02416; A61B5/145; A61B5/1455; A61B5/14551; A61B5/683; A61B5/6838; A61B5/14552
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
116 words
Apparatus for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising: probe means which noninvasively produces data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at first and second predetermined light wavelengths, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; and means responsive to said data, for producing an indication of total hemoglobin concentration in said arterial blood.
Claim 2
Dependent Claim
116 words
Apparatus for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising: probe means which noninvasively produces data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at first and second predetermined light wavelengths, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; and means responsive to said data, for producing an indication of total hemoglobin concentration in said arterial blood.
Claim 3
Dependent Claim
277 words
Apparatus for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising: probe means which noninvasively produces data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at first and second predetermined light wavelengths, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths, including: means for generating a first beam of light at said first predetermined light wavelength, means for generating a second beam of light at said second predetermined light wavelength, means for applying said first and said second beams of light to said arterial blood in said subject, means for measuring a change in light absorption of said first and second beams of light indicative of said change in arterial blood path length in said subject; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; means, responsive to said data, for producing an indication of total hemoglobin concentration in said arterial blood, including: means, responsive to said data, for computing a numerical relationship between said measured change in light absorption of said first and said second beams of light in said arterial blood in said subject, means for defining a correspondence between said computed numerical relationship and said hemoglobin concentration, means, responsive to said defining means and said computed numerical relationship, for determining said total hemoglobin concentration; means, responsive to said producing means, for displaying in human readable form said indication of total hemoglobin concentration in said arterial blood.
Claim 4
Dependent Claim
277 words
Apparatus for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising: probe means which noninvasively produces data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at first and second predetermined light wavelengths, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths, including: means for generating a first beam of light at said first predetermined light wavelength, means for generating a second beam of light at said second predetermined light wavelength, means for applying said first and said second beams of light to said arterial blood in said subject, means for measuring a change in light absorption of said first and second beams of light indicative of said change in arterial blood path length in said subject; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; means, responsive to said data, for producing an indication of total hemoglobin concentration in said arterial blood, including: means, responsive to said data, for computing a numerical relationship between said measured change in light absorption of said first and said second beams of light in said arterial blood in said subject, means for defining a correspondence between said computed numerical relationship and said hemoglobin concentration, means, responsive to said defining means and said computed numerical relationship, for determining said total hemoglobin concentration; means, responsive to said producing means, for displaying in human readable form said indication of total hemoglobin concentration in said arterial blood.
Claim 5
Independent Claim
111 words
A method for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising the steps of: noninvasively producing data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at first and second predetermined light wavelengths, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; and producing an indication of total hemoglobin concentration in said arterial blood.
Claim 6
Independent Claim
111 words
A method for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising the steps of: noninvasively producing data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at first and second predetermined light wavelengths, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; and producing an indication of total hemoglobin concentration in said arterial blood.
Claim 7
Independent Claim
254 words
A method for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising the steps of: noninvasively producing data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at first and second predetermined light wavelengths, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths, including: generating a first beam of light at said first predetermined light wavelength, generating a second beam of light at said second predetermined light wavelength, applying said first and said second beams of light to said arterial blood in said subject, measuring a change in light absorption of said first and second beams of light indicative of said change in arterial blood path length in said subject; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; producing, in response to said data, an indication of total hemoglobin concentration in said arterial blood, including: computing a numerical relationship between said measured change in light absorption of said first and said second beams of light in said arterial blood in said subject, defining a correspondence between said computed numerical relationship and said hemoglobin concentration, determining, in response to said step of defining and said computed numerical relationship, said total hemoglobin concentration; displaying in human readable form said indication of total hemoglobin concentration in said arterial blood.
Claim 8
Independent Claim
254 words
A method for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising the steps of: noninvasively producing data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at first and second predetermined light wavelengths, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths, including: generating a first beam of light at said first predetermined light wavelength, generating a second beam of light at said second predetermined light wavelength, applying said first and said second beams of light to said arterial blood in said subject, measuring a change in light absorption of said first and second beams of light indicative of said change in arterial blood path length in said subject; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; producing, in response to said data, an indication of total hemoglobin concentration in said arterial blood, including: computing a numerical relationship between said measured change in light absorption of said first and said second beams of light in said arterial blood in said subject, defining a correspondence between said computed numerical relationship and said hemoglobin concentration, determining, in response to said step of defining and said computed numerical relationship, said total hemoglobin concentration; displaying in human readable form said indication of total hemoglobin concentration in said arterial blood.
Claim 9
Dependent Claim
130 words
Apparatus for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes a plurality of dominant absorbers, in a subject comprising: probe means, which noninvasively produces data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at a plurality of predetermined light wavelengths, wherein a first and a second dominant absorber of said plurality of dominant absorbers have different extinction coefficients at at least one of a first and a second of said plurality of light wavelengths; wherein said first and second dominant absorbers include water and hemoglobin, which contain at least first and second components; and means responsive to said data for producing an indication of total hemoglobin concentration in said arterial blood.
Claim 10
Dependent Claim
130 words
Apparatus for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes a plurality of dominant absorbers, in a subject comprising: probe means, which noninvasively produces data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at a plurality of predetermined light wavelengths, wherein a first and a second dominant absorber of said plurality of dominant absorbers have different extinction coefficients at at least one of a first and a second of said plurality of light wavelengths; wherein said first and second dominant absorbers include water and hemoglobin, which contain at least first and second components; and means responsive to said data for producing an indication of total hemoglobin concentration in said arterial blood.
Claim 11
Dependent Claim
416 words
Apparatus for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes a plurality of dominant absorbers, in a subject comprising: probe means, which noninvasively produces data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at a plurality of predetermined light wavelengths, wherein a first and a second dominant absorber of said plurality of dominant absorbers have different extinction coefficients at at least one of a first and a second of said plurality of light wavelengths, including: means for generating a first beam of light at said first predetermined light wavelength, means for generating a second beam of light at said second predetermined light wavelength, means for applying said first and said second beams of light to said arterial blood in said subject, means for measuring said change in light absorption of said first and second beams of light indicative of said change in arterial blood path length in said subject; wherein said first and second dominant absorbers include water and hemoglobin, which contain at least first and second components; means responsive to said data for producing an indication of total hemoglobin concentration in said arterial blood, including: means responsive to said data for computing a numerical relationship between said measured change in light absorption of said first and said second beams of light in said arterial blood in said subject, means for defining a correspondence between said computed numerical relationship and said hemoglobin concentration, means, responsive to said defining means and said computed numerical relationship, for determining said total hemoglobin concentration; wherein said probe means further includes: means for generating a third of said plurality of light wavelengths, selected to be absorbed by one of said first and second components at an absorption rate different than at said first and second wavelengths, means for applying said third beam of light to said arterial blood in said subject, means for measuring said change in light absorption of said third beam of light indicative of said change in arterial blood path length in said subject; means, responsive to a measured change in light absorption indicative of said change in arterial blood path length in said subject at said third light wavelength and said determined total hemoglobin concentration, for computing oxygen saturation of said arterial blood in said subject; means, responsive to said producing means, for displaying in human readable form said indication of total hemoglobin concentration in said arterial blood.
Claim 12
Dependent Claim
416 words
Apparatus for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes a plurality of dominant absorbers, in a subject comprising: probe means, which noninvasively produces data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at a plurality of predetermined light wavelengths, wherein a first and a second dominant absorber of said plurality of dominant absorbers have different extinction coefficients at at least one of a first and a second of said plurality of light wavelengths, including: means for generating a first beam of light at said first predetermined light wavelength, means for generating a second beam of light at said second predetermined light wavelength, means for applying said first and said second beams of light to said arterial blood in said subject, means for measuring said change in light absorption of said first and second beams of light indicative of said change in arterial blood path length in said subject; wherein said first and second dominant absorbers include water and hemoglobin, which contain at least first and second components; means responsive to said data for producing an indication of total hemoglobin concentration in said arterial blood, including: means responsive to said data for computing a numerical relationship between said measured change in light absorption of said first and said second beams of light in said arterial blood in said subject, means for defining a correspondence between said computed numerical relationship and said hemoglobin concentration, means, responsive to said defining means and said computed numerical relationship, for determining said total hemoglobin concentration; wherein said probe means further includes: means for generating a third of said plurality of light wavelengths, selected to be absorbed by one of said first and second components at an absorption rate different than at said first and second wavelengths, means for applying said third beam of light to said arterial blood in said subject, means for measuring said change in light absorption of said third beam of light indicative of said change in arterial blood path length in said subject; means, responsive to a measured change in light absorption indicative of said change in arterial blood path length in said subject at said third light wavelength and said determined total hemoglobin concentration, for computing oxygen saturation of said arterial blood in said subject; means, responsive to said producing means, for displaying in human readable form said indication of total hemoglobin concentration in said arterial blood.
Claim 13
Independent Claim
125 words
A method for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes a plurality of dominant absorbers, in a subject comprising the steps of: noninvasively producing data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at a plurality of predetermined light wavelengths, wherein a first and a second dominant absorber of said plurality of dominant absorbers have different extinction coefficients at at least one of a first and a second of said plurality of light wavelengths; wherein said first and second dominant absorbers include water and hemoglobin, which contain at least first and second components; and producing an indication of total hemoglobin concentration in said arterial blood.
Claim 14
Independent Claim
125 words
A method for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes a plurality of dominant absorbers, in a subject comprising the steps of: noninvasively producing data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at a plurality of predetermined light wavelengths, wherein a first and a second dominant absorber of said plurality of dominant absorbers have different extinction coefficients at at least one of a first and a second of said plurality of light wavelengths; wherein said first and second dominant absorbers include water and hemoglobin, which contain at least first and second components; and producing an indication of total hemoglobin concentration in said arterial blood.
Claim 15
Independent Claim
343 words
A method of noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes a plurality of dominant absorbers, in a subject comprising the steps of: noninvasively producing data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at a plurality of predetermined light wavelengths, wherein a first and a second dominant absorber of said plurality of dominant absorbers have different extinction coefficients at at least one of a first and a second of said plurality of light wavelengths, including: generating a first beam of light at said first predetermined light wavelength, generating a second beam of light at said second predetermined light wavelength, applying said first and said second beams of light to said arterial blood in said subject, measuring said change in light absorption of said first and second beams of light indicative of said change in arterial blood path length in said subject; wherein said first and second dominant absorbers include water and hemoglobin, which contain at least first and second components; producing, in response to said data, in indication of total hemoglobin concentration in said arterial blood, including: computing a numerical relationship between said measured change in light absorption of said first and said second beams of light in said arterial blood in said subject, defining a correspondence between said computed numerical relationship and said hemoglobin concentration, determining, in response to said step of defining and said computed numerical relationship, said total hemoglobin concentration; computing, in response to a measured change in light absorption indicative of said change in arterial blood path length in said subject at a third of said plurality of light wavelengths, wherein said third wavelength is selected to be absorbed by one of said first and second components at an absorption rate different than at said first and second wavelengths, and said determined total hemoglobin concentration, oxygen saturation of said arterial blood in said subject; displaying in human readable form said indication of total hemoglobin concentration in said arterial blood.
Claim 16
Independent Claim
343 words
A method of noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes a plurality of dominant absorbers, in a subject comprising the steps of: noninvasively producing data indicative of a change in light absorption as a function of a change in path length in said arterial blood in said subject at a plurality of predetermined light wavelengths, wherein a first and a second dominant absorber of said plurality of dominant absorbers have different extinction coefficients at at least one of a first and a second of said plurality of light wavelengths, including: generating a first beam of light at said first predetermined light wavelength, generating a second beam of light at said second predetermined light wavelength, applying said first and said second beams of light to said arterial blood in said subject, measuring said change in light absorption of said first and second beams of light indicative of said change in arterial blood path length in said subject; wherein said first and second dominant absorbers include water and hemoglobin, which contain at least first and second components; producing, in response to said data, in indication of total hemoglobin concentration in said arterial blood, including: computing a numerical relationship between said measured change in light absorption of said first and said second beams of light in said arterial blood in said subject, defining a correspondence between said computed numerical relationship and said hemoglobin concentration, determining, in response to said step of defining and said computed numerical relationship, said total hemoglobin concentration; computing, in response to a measured change in light absorption indicative of said change in arterial blood path length in said subject at a third of said plurality of light wavelengths, wherein said third wavelength is selected to be absorbed by one of said first and second components at an absorption rate different than at said first and second wavelengths, and said determined total hemoglobin concentration, oxygen saturation of said arterial blood in said subject; displaying in human readable form said indication of total hemoglobin concentration in said arterial blood.
Claim 17
Dependent Claim
172 words
Apparatus for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising: means for generating a first beam of light at a first predetermined light wavelength; means for generating a second beam of light at a second predetermined light wavelength, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths; means for noninvasively applying said first and said second beams of light to said arterial blood in said subject; means for measuring a change in light absorption of said first and second beams of light by said arterial blood indicative of a change in path length in said arterial blood in said subject; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; and means responsive to said measured change in path length in said arterial blood in said subject for producing an indication of total hemoglobin concentration in said arterial blood.
Claim 18
Dependent Claim
172 words
Apparatus for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising: means for generating a first beam of light at a first predetermined light wavelength; means for generating a second beam of light at a second predetermined light wavelength, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths; means for noninvasively applying said first and said second beams of light to said arterial blood in said subject; means for measuring a change in light absorption of said first and second beams of light by said arterial blood indicative of a change in path length in said arterial blood in said subject; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; and means responsive to said measured change in path length in said arterial blood in said subject for producing an indication of total hemoglobin concentration in said arterial blood.
Claim 19
Dependent Claim
368 words
Apparatus for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising: means for generating a first beam of light at a first predetermined light wavelength; means for generating a second beam of light at a second predetermined light wavelength, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths; means for noninvasively applying said first and said second beams of light to said arterial blood in said subject; means for measuring a change in light absorption of said first and second beams of light by said arterial blood indicative of a change in path length in said arterial blood in said subject; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; and means responsive to said measured change in path length in said arterial blood in said subject for producing an indication of total hemoglobin concentration in said arterial blood, including: means responsive to said measured change in path length in said arterial blood in said subject for computing a numerical relationship between said measured change in light absorption of said first and said second beams of light in said arterial blood in said subject, means for defining a correspondence between said computed numerical relationship and said hemoglobin concentration; and means, responsive to said defining means and said computed numerical relationship, for determining said total hemoglobin concentration; means for generating a third beam of light at a third light wavelength which is selected to be absorbed by one of said first and second components at an absorption rate different than at said first and second wavelengths; means for noninvasively applying said third beam of light to said arterial blood in said subject; means for measuring a change in light absorption of said third beam of light by said arterial blood indicative of a change in path length in said arterial blood in said subject; and means, responsive to said measured change in light absorption at said third light wavelength and said determined total hemoglobin concentration, for computing oxygen saturation of said arterial blood in said subject.
Claim 20
Dependent Claim
368 words
Apparatus for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising: means for generating a first beam of light at a first predetermined light wavelength; means for generating a second beam of light at a second predetermined light wavelength, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths; means for noninvasively applying said first and said second beams of light to said arterial blood in said subject; means for measuring a change in light absorption of said first and second beams of light by said arterial blood indicative of a change in path length in said arterial blood in said subject; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; and means responsive to said measured change in path length in said arterial blood in said subject for producing an indication of total hemoglobin concentration in said arterial blood, including: means responsive to said measured change in path length in said arterial blood in said subject for computing a numerical relationship between said measured change in light absorption of said first and said second beams of light in said arterial blood in said subject, means for defining a correspondence between said computed numerical relationship and said hemoglobin concentration; and means, responsive to said defining means and said computed numerical relationship, for determining said total hemoglobin concentration; means for generating a third beam of light at a third light wavelength which is selected to be absorbed by one of said first and second components at an absorption rate different than at said first and second wavelengths; means for noninvasively applying said third beam of light to said arterial blood in said subject; means for measuring a change in light absorption of said third beam of light by said arterial blood indicative of a change in path length in said arterial blood in said subject; and means, responsive to said measured change in light absorption at said third light wavelength and said determined total hemoglobin concentration, for computing oxygen saturation of said arterial blood in said subject.
Claim 21
Independent Claim
167 words
A method for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising the steps of: generating a first beam of light at a first predetermined light wavelength; generating a second beam of light at a second predetermined light wavelength, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths; noninvasively applying said first and said second beams of light to said arterial blood in said subject; measuring a change in light absorption of said first and second beams of light by said arterial blood indicative of a change in path length in said arterial blood in said subject; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; and producing, in response to said measured change in path length in said arterial blood in said subject, an indication of total hemoglobin concentration in said arterial blood.
Claim 22
Independent Claim
167 words
A method for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject comprising the steps of: generating a first beam of light at a first predetermined light wavelength; generating a second beam of light at a second predetermined light wavelength, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths; noninvasively applying said first and said second beams of light to said arterial blood in said subject; measuring a change in light absorption of said first and second beams of light by said arterial blood indicative of a change in path length in said arterial blood in said subject; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; and producing, in response to said measured change in path length in said arterial blood in said subject, an indication of total hemoglobin concentration in said arterial blood.
Claim 23
Independent Claim
337 words
A method for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject Comprising the steps of: generating a first beam of light at a first predetermined light wavelength; generating a second beam of light at a second predetermined light wavelength, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths; noninvasively applying said first and said second beams of light to said arterial blood in said subject; measuring a change in light absorption of said first and second beams of light by said arterial blood indicative of a change in path length in said arterial blood in said subject; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; and producing, in response to said measured change in path length in said arterial blood in said subject, an indication of total hemoglobin concentration in said arterial blood, including: computing a numerical relationship between said measured change in light absorption of said first and said second beams of light in said arterial blood in said subject, defining a correspondence between said computed numerical relationship and said hemoglobin concentration; and determining, in response to said step of defining and said computed numerical relationship, said total hemoglobin concentration; generating a third beam of light at a third light wavelength which is selected to be absorbed by one of said first and second components at an absorption rate different than at said first and second wavelengths; noninvasively applying said third beam of light to said arterial blood in said subject; measuring a change in light absorption of said third beam of light by said arterial blood indicative of a change in path length in said arterial blood in said subject; and computing, in response to said measured change in light absorption at said third light wavelength and said determined total hemoglobin concentration, oxygen saturation of said arterial blood in said subject.
Claim 24
Independent Claim
337 words
A method for noninvasively measuring a concentration of total hemoglobin in arterial blood, which includes first and second dominant absorbers, in a subject Comprising the steps of: generating a first beam of light at a first predetermined light wavelength; generating a second beam of light at a second predetermined light wavelength, wherein said first and second dominant absorbers have different extinction coefficients at at least one of said first and second light wavelengths; noninvasively applying said first and said second beams of light to said arterial blood in said subject; measuring a change in light absorption of said first and second beams of light by said arterial blood indicative of a change in path length in said arterial blood in said subject; wherein said first and second dominant absorbers are water and hemoglobin, which contain oxygenated and deoxygenated components; and producing, in response to said measured change in path length in said arterial blood in said subject, an indication of total hemoglobin concentration in said arterial blood, including: computing a numerical relationship between said measured change in light absorption of said first and said second beams of light in said arterial blood in said subject, defining a correspondence between said computed numerical relationship and said hemoglobin concentration; and determining, in response to said step of defining and said computed numerical relationship, said total hemoglobin concentration; generating a third beam of light at a third light wavelength which is selected to be absorbed by one of said first and second components at an absorption rate different than at said first and second wavelengths; noninvasively applying said third beam of light to said arterial blood in said subject; measuring a change in light absorption of said third beam of light by said arterial blood indicative of a change in path length in said arterial blood in said subject; and computing, in response to said measured change in light absorption at said third light wavelength and said determined total hemoglobin concentration, oxygen saturation of said arterial blood in said subject.
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