US4986964A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Clot retractometer
Assignee: Virginia Commonwealth University
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Filing: 1990-04-19
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Granted: 1991-01-22
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Expires: 2010-04-19
Abstract
Abstract An instrument for measuring the internal force characteristics of a blood sample (12) during clotting has been developed. The blood sample (12) is held between a cup (10) and a plate (16). The plate (16) is connected to a force displacement transducer (22). As the clot forms, platelets contract and exert an inward pulling force on the plate (16). This inward pulling force is sensed by the transducer (22) which outputs a corresponding voltage signal. The voltage signal is amplified (24) and recorded on strip chart paper (28). The voltage signal (32) can be directly translated into force parameters by first calibrating the instrument with standard weights. It has been found that the maximum force measurements are obtained under controlled temperature, ionic strength and calcium concentration conditions which approximate those of the blood while in the body. A particular feature of the invention includes a water jacket (14) which is used to maintain the temperature of the blood sample (12) at 37° C. (body temperature).
Inventors
- 👤 Marcus E. Carr, Jr.
- 👤 Sheryl L. Zekert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 05:53
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/48; G01N33/483; G01N33/487; G01N33/49; G01N33/4905; G01N2203/00; G01N2203/0058; G01N2203/0089
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
145 words
An instrument for measuring the retraction force characteristics of a blood clot, comprising: a means for holding a blood sample between a pair of parallel plates position a fixed distance apart, said means for holding said blood sample comprising a side wall attached to one of said plates which forms an open top cup with said plate, another of said plates fitting within said open top cup and having an outer periphery spaced from said side wall, each of said plates capable of being in contact with said blood sample such that platelets in said blood sample can adhere to each of said plates; and a means for sensing a pulling force exerted on one of said plates pulling said plates towards each other as said blood sample forms a blood clot, said means for sensing producing an electric signal proportional to said pulling force.
Claim 2
Dependent Claim
145 words
An instrument for measuring the retraction force characteristics of a blood clot, comprising: a means for holding a blood sample between a pair of parallel plates position a fixed distance apart, said means for holding said blood sample comprising a side wall attached to one of said plates which forms an open top cup with said plate, another of said plates fitting within said open top cup and having an outer periphery spaced from said side wall, each of said plates capable of being in contact with said blood sample such that platelets in said blood sample can adhere to each of said plates; and a means for sensing a pulling force exerted on one of said plates pulling said plates towards each other as said blood sample forms a blood clot, said means for sensing producing an electric signal proportional to said pulling force.
Claim 3
Dependent Claim
27 words
An instrument as recited in claim 1 further comprising a means for controlling the temperature of said blood sample while it is positioned between said parallel plates.
Claim 4
Dependent Claim
43 words
An instrument as recited in claim 2 wherein said means for controlling the temperature of said blood sample comprises a jacket and a means for passing a heat transfer media through said jacket said jacket surrounding said means for holding said blood sample.
Claim 5
Dependent Claim
24 words
An instrument as recited in claim 1 wherein said means for sensing comprises a force displacement transducer mechanically connected to one of said plates.
Claim 6
Dependent Claim
30 words
An instrument as recited in claim 4 further comprising a means for amplifying an electrical signal from said force displacement transducer and a means for displaying the amplified electrical signal.
Claim 7
Dependent Claim
20 words
An instrument as recited in claim 5 wherein said means for displaying comprises an X-Y plotter and strip chart paper.
Claim 8
Independent Claim
84 words
A method for determining the retraction force characteristics of a blood sample during clotting, comprising the steps of: positioning a blood sample between a pair of parallel plates which are a fixed distance apart which allows platelets in said blood sample to adhere to both of said plates; maintaining the temperature of said blood sample between 35° C. and 39° C.; and monitoring a pulling force exerted on one of said plates pulling said plates towards each other while said blood sample is clotting.
Claim 9
Independent Claim
84 words
A method for determining the retraction force characteristics of a blood sample during clotting, comprising the steps of: positioning a blood sample between a pair of parallel plates which are a fixed distance apart which allows platelets in said blood sample to adhere to both of said plates; maintaining the temperature of said blood sample between 35° C. and 39° C.; and monitoring a pulling force exerted on one of said plates pulling said plates towards each other while said blood sample is clotting.
Claim 10
Dependent Claim
19 words
A method as recited in claim 7 wherein said step of maintaining maintains said temperature at approximately 37° C.
Claim 11
Dependent Claim
31 words
A method as recited in claim 7 further comprising the step of adjusting the calcium concentration of said blood sample to be within the range of five millimolar and twenty millimolar.
Claim 12
Dependent Claim
24 words
A method as recited in claim 9 wherein said step of adjusting the calcium concentration adjusts the calcium concentration to be approximately ten millimolar.
Claim 13
Dependent Claim
31 words
A method as recited in claim 7 further comprising the step of adjusting the ionic strength of said blood sample to be within the range of 0.10 M and 0.20 M.
Claim 14
Dependent Claim
24 words
A method as recited in claim 11 wherein said step of adjusting the ionic strength adjusts the ionic strength to be approximately 0.15 M.
Claim 15
Dependent Claim
32 words
A method as recited in claim 7 further comprising the step of determining the lag phase prior to force development caused by said inward pulling force of said blood sample during clotting.
Claim 16
Dependent Claim
31 words
A method as recited in claim 7 further comprising the step of determining the maximum rate of force development caused by said inward pulling force of said blood sample during clotting.
Claim 17
Dependent Claim
29 words
A method as recited in claim 7 further comprising the step of determining the maximum force generated caused by said inward pulling force of said blood sample during clotting.
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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) | 1994-01-21 | 1994-07-23 | 1995-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-21 | 1998-07-23 | 1999-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-21 | 2002-07-23 | 2003-01-22 | $7700.00 | Window Closed / Lapsed |