US3905769A
Expired / Lapsed
US
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Method and apparatus for measuring prothrombin time and the like
Assignee: BAGLEY WALLACE E
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Filing: 1974-02-28
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Granted: 1975-09-16
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Expires: 1994-02-28
Abstract
Abstract In a blood coagulation determining apparatus, an electrical signal whose voltage is linearly related to the optical density of a semi-transparent sample is produced by using a generating photocell which generates an output approximately proportional to the sum of a constant and the logarithm of the transmittance of the sample. The voltage of the signal is subtracted electrically from a first variable represented by a selectable voltage. The result of the subtraction is then electrically multiplied by a second variable to produce an output for display and recording on a chart recorder. The apparatus is especially useful in blood clotting measurements wherein the visual or automatic recognition of straight lines in the plot of optical density versus time is important.
Inventors
- 👤 Wallace E Carroll
- 👤 Richard D Jackson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:06
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/48; G01N33/483; G01N33/487; G01N33/49; G01N33/4905; G01N21/00; G01N21/17; G01N21/25; G01N21/27; G01N21/272
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
104 words
A METHOD FOR DETERMINING THE COAGULATION CHARACTERISTICS OF ANALYTICAL BODY FLUID SAMPLES BY MEASURING THE OPTICAL DENSITY OF THE SAMPLES COMPRISING: DIRECTING A LIGHT BEAM FROM A LIGHT SOURCE THROUGH THE ANALYTICAL FLUID SAMPLE, RECEIVING THE LIGHT FROM SAID SOURCE AFTER IT PASES THROUGH THE SAMPLE AND GENERATING AN ELECTRICAL OUTPUT THE AMPLITUDE OF WHICH THROUGHOUT SUBSTANTIALLY THE ENTIRE RANGE OF TRANSMITTANCE OF THE LIGHT FRM THE SOURCE IS APPROXIMATELY PROPORTIONAL TO THE SUM OF A CONSTANT AND THE LOGARITHM OF THE TRANSMITTANCE, AND SUBTRACTING SAID OUTPUT FROM A FIRST VALUE AND MULTIPLYING THE RESULT BY A SECOND VALUE TO OBTAIN A FINAL RESULT.
Claim 2
Independent Claim
104 words
A METHOD FOR DETERMINING THE COAGULATION CHARACTERISTICS OF ANALYTICAL BODY FLUID SAMPLES BY MEASURING THE OPTICAL DENSITY OF THE SAMPLES COMPRISING: DIRECTING A LIGHT BEAM FROM A LIGHT SOURCE THROUGH THE ANALYTICAL FLUID SAMPLE, RECEIVING THE LIGHT FROM SAID SOURCE AFTER IT PASES THROUGH THE SAMPLE AND GENERATING AN ELECTRICAL OUTPUT THE AMPLITUDE OF WHICH THROUGHOUT SUBSTANTIALLY THE ENTIRE RANGE OF TRANSMITTANCE OF THE LIGHT FRM THE SOURCE IS APPROXIMATELY PROPORTIONAL TO THE SUM OF A CONSTANT AND THE LOGARITHM OF THE TRANSMITTANCE, AND SUBTRACTING SAID OUTPUT FROM A FIRST VALUE AND MULTIPLYING THE RESULT BY A SECOND VALUE TO OBTAIN A FINAL RESULT.
Claim 3
Independent Claim
262 words
A method of varying the prothrombin time of a patient''s blood comprising the steps of subjecting a first prepared plasma specimen of the patient''s blood to the steps of adding thrromboplastin reagent to said specimen; directing a light beam from a light source through said first specimen; receiving the light from said source after it passes through the sample and generating an electrical output the amplitude of which throughout substantially the entire range of transmittance of the light from the source is approximately proportional to the sum of a constant and the logarithm of the transmittance; subtracting said output from a first value and multiplying the result by a second value to obtain a prothrombin time for the first specimen; administering an anti-coagulant in a specific amount to the patient; after administration of said anti-coagulant, obtaining a second specimen of the patient''s blood; preparing plasma; adding thromboplastin reagent; directing said light beam through said second specimen; receiving the light from said source after it passes through said second specimen and generating an electrical output the amplitude of which throughout substantially the entire range of transmittance of the light from the source is approximately proportional to the sum of a constant and the logarithm of the transmittance; subtracting said output from said second specimen from a first value and multiplying the result by a second value to obtain a prothrombin time for the second specimen; whereby the anti-coagulant dosage necessaRy to achieve a desired prothrombin time in the patient can be determined from the prothrombin times measured in the first and second specimens.
Claim 4
Independent Claim
262 words
A method of varying the prothrombin time of a patient''s blood comprising the steps of subjecting a first prepared plasma specimen of the patient''s blood to the steps of adding thrromboplastin reagent to said specimen; directing a light beam from a light source through said first specimen; receiving the light from said source after it passes through the sample and generating an electrical output the amplitude of which throughout substantially the entire range of transmittance of the light from the source is approximately proportional to the sum of a constant and the logarithm of the transmittance; subtracting said output from a first value and multiplying the result by a second value to obtain a prothrombin time for the first specimen; administering an anti-coagulant in a specific amount to the patient; after administration of said anti-coagulant, obtaining a second specimen of the patient''s blood; preparing plasma; adding thromboplastin reagent; directing said light beam through said second specimen; receiving the light from said source after it passes through said second specimen and generating an electrical output the amplitude of which throughout substantially the entire range of transmittance of the light from the source is approximately proportional to the sum of a constant and the logarithm of the transmittance; subtracting said output from said second specimen from a first value and multiplying the result by a second value to obtain a prothrombin time for the second specimen; whereby the anti-coagulant dosage necessaRy to achieve a desired prothrombin time in the patient can be determined from the prothrombin times measured in the first and second specimens.
Claim 5
Dependent Claim
104 words
Apparatus for measuring the optical density of a sample as in measuring prothrombin time and the like comprising: a source of light; detection means arranged to receive light from said source after it passes through the sample and generating an electrical output the amplitude of which throughout substantially the entire range of transmittance of the light from the source is approximately proportional to the sum of a constant and the logarithm of the transmittance; and network means for subtracting the output generated by the detection means from a first value and for multiplying the result by a second value to obtain a final result.
Claim 6
Dependent Claim
104 words
Apparatus for measuring the optical density of a sample as in measuring prothrombin time and the like comprising: a source of light; detection means arranged to receive light from said source after it passes through the sample and generating an electrical output the amplitude of which throughout substantially the entire range of transmittance of the light from the source is approximately proportional to the sum of a constant and the logarithm of the transmittance; and network means for subtracting the output generated by the detection means from a first value and for multiplying the result by a second value to obtain a final result.
Claim 7
Dependent Claim
14 words
Apparatus according to claim 3 in which the source of light is a laser.
Claim 8
Dependent Claim
14 words
Apparatus according to claim 3 in which the detection means is a generating photocell.
Claim 9
Dependent Claim
17 words
Apparatus according to claim 3 in which the detection means is a selenium or silicon generating photocell.
Claim 10
Dependent Claim
26 words
Apparatus according to claim 3 in which the network means comprises means for selectably varying said first value and means for selectably varying said second value.
Claim 11
Dependent Claim
110 words
Apparatus according to claim 3 in which the network means comprises a variable voltage D.C. source comprising a constant voltage D.C. source and a first variable resistor connected across said constant voltage source, the variable voltage being derivable from a pair of terminals connected to said first variable resistor including a terminal connected to a movable tap on said resistor, a second variable resistor having a movable tap, and wherein the detection means, the variable voltage D.C. source, and the second variable resistor are connected together in series in a closed loop with the polarities of the detection means and the variable voltage D.C. source in opposition to each other.
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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) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |