US5061632A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capillary tube hemoglobinometer and oximeter
Assignee: The University of Texas System
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Filing: 1989-01-31
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Granted: 1991-10-29
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Expires: 2009-01-31
Abstract
Abstract An oximeter that measures both the total hemoglobin concentration in whole, undiluted blood and the percentage of the hemoglobin saturated with oxygen. The oximeter uses red and infrared light-emitting diodes to illuminate a capillary tube filled with a sample of whole, undiluted blood. Light scattered by the blood travels a short distance down the length of the capillary tube and reaches a photodetector, the output of which is amplified, digitized, and fed to a microprocessor. The microprocessor computes the total hemoglobin concentration as a nonlinear monotonic function of the infrared light intensity. Oxyhemoglobin saturation is computed from the ratio of the logarithms of the intensities of red and infrared light. The invention provides a measurement of oxygen saturation without calibration shifts present in other oximeters due to fluctuations in total hemoglobin concentration. In addition, the present invention is accurate over a wide range of oxygen saturation, and the blood samples are not diluted or hemolyzed and can thus be preserved for further analysis.
Inventors
- 👤 A. P. Shepherd
- 👤 John M. Steinke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:36
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/314; G01N2021/3144; G01N2021/3155; G01N2021/3181
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
162 words
Apparatus for measuring total hemoglobin concentration and percent oxygen saturation in a sample of whole, undiluted blood, comprising: an elongated cuvette for holding a whole undiluted blood sample; means for selectively illuminating said blood sample with infrared light and red light, the infrared light and red light entering the cuvette at predetermined locations along an axis of the cuvette; means associated with said cuvette for sensing infrared light intensity, IR, and red light intensity, R, at a predetermined measuring location along the axis of the cuvette remote from said predetermined locations at which the infrared light and red light enter the cuvette, and for generating signals indicative of IR and R; processing means for receiving said signals and for calculating total hemoglobin (Hb), and percent oxygen saturation, SO2, based on the signals, (Hb) being calculated as a first calibrated function of IR, SO2 being calculated as a second calibrated function of (LogR/LogIR), the second calibrated function being related to the calculated (Hb).
Claim 2
Dependent Claim
162 words
Apparatus for measuring total hemoglobin concentration and percent oxygen saturation in a sample of whole, undiluted blood, comprising: an elongated cuvette for holding a whole undiluted blood sample; means for selectively illuminating said blood sample with infrared light and red light, the infrared light and red light entering the cuvette at predetermined locations along an axis of the cuvette; means associated with said cuvette for sensing infrared light intensity, IR, and red light intensity, R, at a predetermined measuring location along the axis of the cuvette remote from said predetermined locations at which the infrared light and red light enter the cuvette, and for generating signals indicative of IR and R; processing means for receiving said signals and for calculating total hemoglobin (Hb), and percent oxygen saturation, SO2, based on the signals, (Hb) being calculated as a first calibrated function of IR, SO2 being calculated as a second calibrated function of (LogR/LogIR), the second calibrated function being related to the calculated (Hb).
Claim 3
Dependent Claim
27 words
The apparatus of claim 1, further comprising a housing for holding the illuminating means and detecting means, said housing having a bore for selectively retaining the cuvette.
Claim 4
Dependent Claim
36 words
The apparatus of claim 2, wherein the housing comprises a cylindrical block including an axial bore for selectively retaining the cuvette and radial bores for housing the means for selectively illuminating and said means for sensing.
Claim 5
Dependent Claim
47 words
The apparatus of claim 1, wherein the illuminating means comprise: an infrared light source for emitting infrared light oriented substantially perpendicular to a longitudinal axis of the cuvette; and a red light source for emitting red light oriented substantially perpendicular to the longitudinal axis of the cuvette.
Claim 6
Dependent Claim
34 words
The apparatus of claim 4, further comprising means for directing light from the cuvette to the means for sensing substantially as an exit light beam oriented perpendicular to the longitudinal axis of the cuvette.
Claim 7
Dependent Claim
38 words
The apparatus of claim 5, wherein the infrared and red light sources and light directing means are oriented whereby the infrared light and red light are laterally offset at selected angles in relation to the exit light beam.
Claim 8
Dependent Claim
14 words
The apparatus of claim 1, wherein the first calibrated function is a monotonic function.
Claim 9
Dependent Claim
48 words
The apparatus of claim 7, wherein the first calibrated function is a polynomial function approximated by the equation: (Hb)=A.sub.0 =A.sub.1 IR+... +A.sub.n IR.sup.n wherein n is an integer greater than or equal to 2, and A 0 , A 1 , ..., A n are n+1 calibration constants.
Claim 10
Dependent Claim
9 words
The apparatus of claim 8, wherein n is 2.
Claim 11
Dependent Claim
9 words
The apparatus of claim 8, wherein n is 3.
Claim 12
Independent Claim
98 words
A method for measuring total hemoglobin concentration and percent oxygen saturation in a sample of whole, undiluted blood, comprising: selectively scattering infrared and red light through a whole, undiluted blood sample; measuring infrared light intensity, IR, and red light intensity, R, at a predetermined location, such that total hemoglobin concentration, (Hb), is a monotonic function of IR: approximating the monotonic function with a first calibrated equation; calculating (Hb) from IR based on the first calibrated equation; and determining a second calibrated equation for calculating percent oxygen saturation, SO2, as a function of (LogR/LogIR) based on the calculated (Hb).
Claim 13
Independent Claim
98 words
A method for measuring total hemoglobin concentration and percent oxygen saturation in a sample of whole, undiluted blood, comprising: selectively scattering infrared and red light through a whole, undiluted blood sample; measuring infrared light intensity, IR, and red light intensity, R, at a predetermined location, such that total hemoglobin concentration, (Hb), is a monotonic function of IR: approximating the monotonic function with a first calibrated equation; calculating (Hb) from IR based on the first calibrated equation; and determining a second calibrated equation for calculating percent oxygen saturation, SO2, as a function of (LogR/LogIR) based on the calculated (Hb).
Claim 14
Dependent Claim
14 words
The method of claim 11, wherein the first calibrated equation is a polynomial equation.
Claim 15
Dependent Claim
12 words
The method of claim 11, wherein the second calibrated equation is linear.
Claim 16
Dependent Claim
112 words
The method of claim 13, wherein the second calibrated equation is determined by: determining a first intermediate equation representing the logarithm of R divided by the logarithm of IR for 0% oxygen saturated blood, (LogR/LogIR) 0% , as a function of (Hb); determining a second intermediate equation representing the logarithm of R divided by the logarithm of IR for 100% oxygen saturated blood, (LogR/LogIR) 100% , as a function of (Hb); calculating (LogR/LogIR) 0% corresponding to the calculated (Hb) based on the first intermediate equation; calculating (LogR/LogIR) 100% corresponding to the calculated (Hb) based on the second intermediate equation; calculating SO2 from the second calibrated equation, the second calibrated equation being: ##EQU2##
Claim 17
Dependent Claim
42 words
The method of claim 14, wherein the first intermediate equation is: (LogR/LogIR).sub.0% =C.sub.0 +C.sub.1 (Hb)+... +C.sub.n (Hb).sup.n wherein n is an integer greater than or equal to 2 and C 0 , C 1 , ..., C n are n+1 calibration constants.
Claim 18
Dependent Claim
9 words
The method of claim 15, wherein n is 3.
Claim 19
Dependent Claim
42 words
The method of claim 14, wherein the second intermediate equation is: (LogR/LogIR).sub.100% =D.sub.0 +D.sub.1 (Hb)+... +D.sub.n (Hb).sup.n wherein n is an integer greater than or equal to 2 and D 0 , D 1 , ..., D n are n+1 calibration constants.
Claim 20
Dependent Claim
9 words
The method of claim 17, wherein n is 3.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-10-28 | 1995-04-29 | 1995-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-10-28 | 1999-04-29 | 1999-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-10-28 | 2003-04-29 | 2003-10-29 | $7700.00 | Window Closed / Lapsed |