Blood coagulation time test apparatus and method

• US 5,372,946 A
• Filed: 01/06/1994
• Issued: 12/13/1994
• Est. Priority Date: 12/10/1992
• Status: Expired due to Term

• Current Assignee: International Technidyne Corporation (Sphingotec GMBH)
• Original Assignee: International Technidyne Corporation (Sphingotec GMBH)
• Inventors: Cusak, Robert, Samo, Robert J., Laduca, Frank M.
• Primary Examiner(s): Redding, David A.
• Application Number:
  US08/178,060
• Time in Patent Office: 341 Days
• Field of Search: 436/46, 436/63, 436/69, 436/807, 436/80.8, 436/149, 436/165, 435/13, 435/287, 435/810, 435/970, 435/291, 422/99, 422/102, 73/54.02, 73/54.26, 73/54.27, 73/54.31, 73/54.35, 356/246
• US Class Current: 436/69
• CPC Class Codes: G01N 33/4905 Determining clotting time of blood by chemical methods G01N33/86, C12Q1/54
• CPC Class Codes: Y10S 436/807 Apparatus included in process claim, e.g. physical support structures

Abstract

The present invention is an apparatus and method for performing a coagulation time test on a sample of blood wherein the blood is deposited in a fluid reservoir and disposable cuvette. Within the cuvette is formed a capillary conduit have at least one restricted region. The cuvette is inserted into a testing machine which engages the cuvette and draws blood from the fluid reservoir into the capillary conduit. The blood is then caused to reciprocally move within the capillary conduit whereby the blood is forced to traverse the restricted region. The testing machine measures the time required each time the blood is caused to traverse the restrict region. When a measured time is a predetermined percentage longer than an immediately preceding time, coagulation is considered to have occured and the overall coagulation time is displayed to the operator.

Claims

1. A cuvette for use with a drive means in determining a clotting time for a blood sample, comprising;

a planar member having at least one enclosed conduit formed therein, said at least one conduit having an open distal end and proximal end and at least one restricted region positioned therebetween, wherein said at least one restricted region has a roughened surface texture that promotes the coagulation of blood flowing therepast, said distal end being selectively engagable with the drive means;

a fluid reservoir for retaining said blood sample whereby a predetermined volume of blood is accessible by said proximal end of said at least one conduit, wherein said predetermined volume of blood is drawn into said at least one conduit and reciprocally moved back and forth across said at least one restricted region by the drive means, said clotting time being determined when said predetermined volume of blood clots and obstructs said at least one restricted region by a predetermined amount.

2. The cuvette according to claim 1, wherein at least one drain conduit is formed within said planar member, said drain conduit being interconnected to said fluid reservoir and engaged by the drive means whereby blood can be removed from said fluid reservoir into said at least one drain conduit after said predetermined volume of blood is drawn into said at least one conduit.

3. The cuvette according to claim 2, wherein said fluid reservoir includes a primary chamber and a secondary chamber, said blood sample being applied to said primary chamber wherein an excess of blood in said primary chamber overflows into said secondary chamber via overflow ports present between said primary chamber and said secondary chamber.

4. The cuvette according to claim 3, wherein said primary chamber has at least one standpipe positioned therein, said at least one standpipe interconnecting with said proximal end of said at least one conduit whereby said at least one standpipe extends upwardly within said primary chamber a predetermined distance below said overflow ports, said at least one drain conduit being interconnected to said primary chamber below said standpipe, whereby said at least one conduit means can draw blood from said primary chamber above said standpipe and below said overflow ports and said at least one drain conduit means can draw blood from said primary chamber below said standpipe.

5. The cuvette according to claim 1, wherein said cuvette is formed from a translucent material.

6. The cuvette according to claim 3, further including an annular cap member, said annular cap member fitting over said fluid reservoir covering said secondary chamber and having a sloped surface that directs said blood sample into said primary chamber, whereby the presence of said cap member over said secondary chamber prevents blood from spilling out of said second chamber as said cuvette is manipulated.

7. The cuvette according to claim 1, further including a stopping means within said fluid reservoir for stopping a discharging end of a syringe at a predetermined point within said fluid reservoir when said blood sample is applied to said fluid reservoir with said syringe.

8. A method of conducting a coagulation time test on a blood sample drawn from a patient, comprising the steps of:

depositing said blood sample into a fluid reservoir;

drawing a predetermined volume of blood from said blood sample into a capillary tube from said fluid reservoir wherein said capillary tube has at least one restricted region formed therein;

reciprocating said predetermined volume of blood from a first position on one side of said restricted region to a second position on an opposite side of said restricted region and back again;

counting the time elapsed each time said predetermined volume of blood reciprocates between said first position and said second position; and

providing an indication to an operator when the time elapsed for one cycle of travel for the blood between said first position and said second position is a predetermined percentage longer then an immediately preceding cycle of travel.

9. The method according to claim 8, further including the step of draining blood from said fluid reservoir into a drain capillary tube after said step of drawing, thereby substantially emptying said fluid reservoir of said blood sample allowing said fluid reservoir to be manipulated without spillage of said blood sample.

10. The method according to claim 8, wherein said fluid reservoir and said capillary tube are contained within a disposable cuvette and further comprising the step of coupling said cuvette to a reciprocating drive means.

11. The method according to claim 8, wherein said restricted region has a roughened surface texture thereby promoting coagulation of said predetermined volume of blood in said roughened region as said predetermined volume of blood is reciprocated across said roughened region.

12. The method according to claim 9, wherein said fluid reservoir, said capillary tube and said drain capillary tube are contained within a disposable cuvette and further comprising the steps of coupling said capillary tube and said drain capillary tube to separate drive means.

13. The method of claim 8, wherein first photoelectric sensor is positioned at said first position and a second photoelectric sensor is positioned at said second position, wherein said first and second photoelectric sensors can detect the presence of said predetermined volume of blood in said capillary tube and wherein said step of counting is performed by a microprocessor coupled to said first and second photoelectric sensor that measures the time interval between the activation of said first and second photoelectric sensors by the reciprocating predetermined volume of blood.

14. The method according to claim 8, further including the step of heating said predetermined volume of blood in said capillary tube to a predetermined temperature.

15. The method according to claim 8, further including detecting if a portion of said predetermined volume of blood has been drawn beyond an acceptable point in said capillary tube and indicating to an operator the presence of said portion beyond said acceptable point.

16. The method according to claim 8, wherein said predetermined percentage is approximately 125 percent.

17. The method according to claim 8, wherein said step of reciprocating includes pneumatically reciprocating said predetermined volume of blood in said capillary tube.