Method and apparatus for measuring blood coagulation time

• US 4,659,550 A
• Filed: 05/20/1982
• Issued: 04/21/1987
• Est. Priority Date: 06/16/1981
• Status: Expired due to Fees

• Current Assignee: Hoffmann-La Roche Incorporated (Roche Holding AG)
• Original Assignee: Hoffmann-La Roche Incorporated (Roche Holding AG)
• Inventors: Schildknecht, Kurt
• Primary Examiner(s): Richman, Barry S.
• Assistant Examiner(s): Gzybowski, Michael
• Application Number:
  US06/379,840
• Time in Patent Office: 1,797 Days
• Field of Search: 356/39, 356/244, 356/246, 366/341, 366/336, 366/337, 422/73, 422/102, 436/66, 436/69, 435/13, 73/64.1
• US Class Current: 422/73
• CPC Class Codes: G01N 33/4905 Determining clotting time of blood by chemical methods G01N33/86, C12Q1/54

Abstract

Method for measuring the coagulation time of a blood sample in which a sample-reagent mixture is formed by introducing the sample and at least one reagent into a cuvette.

To reduce the operating and material costs, the sample-reagent mixture is so moved in a stationary cuvette that the mixture flows back and forth around an edge projecting into the cuvette, whereby a clot forms on this edge.

Claims

1. An apparatus for measuring blood coagulation time comprising:

(a) a cuvette at least a portion of which is made of a translucent material for receiving a blood sample and at least one reagent to thereby form a blood sample-reagent mixture, said cuvette having a bottom and an upper portion, the upper portion having an opening for receiving a blood sample and at least one reagent and a partition which divides the upper portion into two chambers, the partition having opposing faces which intersect at an acute angle to form a sharp, wedge-shaped edge, said edge being situated within the cuvette at a predetermined distance from the bottom of the cuvette to permit unobstructed communication between the two chambers to permit flow of a blood sample-reagent mixture from one chamber to the other around the edge when variable air pressure is applied to the cuvette thereby causing a clot to form on said edge;

(b) means for producing variable air pressure which communicates via an opening with one of the chambers in the upper portion of the cuvette, said air pressure producing means also causing movement of a blood sample-reagent mixture from one of the chambers to the other around the sharp edge of the partition, thereby forming a clot on said edge;

(c) first electro-optical means for detecting a first point of time corresponding to the initial presence of a blood sample-reagent mixture in the cuvette with a first light beam which traverses the cuvette at a level situated above the sharp edge of the partition in relation to the bottom of the cuvette;

(d) second electro-optical means for detecting a second point of time corresponding to the formation of a clot on the sharp edge of the partition with a second light beam which traverses the cuvette along a path which passes generally close to and below the sharp edge of the partition, so that a clot formed on the edge is in that path of the second light beam and is therefore detectable therewith; and

(e) signal processing means electrically connected to the first and the second electro-optical means for measuring the time interval between the first and the second points of time, said interval being representative of the coagulation time of a blood sample.

2. The apparatus of claim 1, wherein the first electro-optical means comprises a first light source and a first light receiver which are arranged in relation to the cuvette so that the first beam of light, which emanates from the first light source, is received by the first light receiver after the first beam of light passes through the cuvette.

3. The apparatus of claim 2, wherein the second electro-optical means comprises a second light source and a second light receiver which are arranged in relation to the cuvette so that the second beam of light, which emanates from the second light source, is received by the second light receiver after the second beam of light passes through the cuvette.

4. An apparatus for measuring blood coagulation time comprising a cuvette for receiving a sample and at least one reagent to thereby form a sample-reagent mixture, said cuvette having an upper part divided into two chambers by a partition therein and having a bottom, the partition having opposing faces and a sharp wedge-shaped edge portion formed by an intersection of such opposing faces of the partition at an acute angle and situated within the cuvette at a predetermined distance from the bottom of the cuvette to permit unobstructed communication between the two chambers to permit flow of a sample-reagent mixture from one chamber to the other around the edge portion when variable air pressure is applied to the cuvette thereby causing a clot to form on said edge portion;

one of the chambers being connected via an opening with means for producing variable air pressure to effect movement of a sample-reagent mixture from one chamber to the other around the edge portion;

a first light source and a first light receiver which are arranged in relation to the cuvette so that a first beam of light emanating from the first light source and received by the first light receiver passes through the cuvette above the edge portion; and

a second light source and a second light receiver which are arranged in relation to the cuvette so that a second beam of light emanating from the second light source and received by the second light receiver passes through the cuvette close to and below the edge portion so that a clot formed on the edge is detected by this beam of light.

5. An apparatus using variable air pressure for measuring blood coagulation time comprising:

(a) a cuvette for receiving a blood sample-reagent mixture, said cuvette including;

(i) a bottom portion; and

(ii) an upper portion having;

(1) an opening for receiving a blood sample-reagent mixture and

(2) a partition which divides the upper portion into two chambers, the partition having opposing faces which intersect at an acute angle to form a sharp, wedge-shaped edge, said edge situated within the cuvette at a predetermined distance from the bottom portion of the cuvette to permit unobstructed communication between the two chambers to permit flow of a blood sample-reagent mixture from one chamber to the other around the edge when variable air pressure is applied to the cuvette thereby causing a clot to form on said edge;

(b) means for producing variable air pressure in the cuvette to effect flow of a blood sample-reagent mixture around the edge of the partition from chamber to chamber;

(c) means for detecting the initial presence of a blood sample-reagent mixture in the cuvette including;

(i) a first light source for transmitting a first beam of light; and

(ii) a first light receiver for receiving the first beam of light, the first light source and first light receiver located in relation to the cuvette for the first light beam to pass through a blood sample-reagent mixture in the cuvette above the edge of the partition in relation to the bottom of the cuvette, such that there is detected a change in absorptance value measured with the first light beam due to the initial presence of a blood sample-reagent mixture in the cuvette; and

(d) means for detecting the formation of a clot on the edge of the partition including;

(i) a second light source for transmitting a second beam of light; and

(ii) a second light receiver for receiving the second beam of light, the second light source and second light receiver located in relation to the cuvette for the second light beam to pass through the cuvette adjacent the edge of the partition, such that there is detected a change in absorptance value measured with the second light beam due to the formation of a clot.

6. An apparatus for measuring blood coagulation time comprising:

(a) a cuvette at least a portion of which is made of a translucent material for receiving a blood sample and at least one reagent to thereby form a blood sample-reagent mixture, said cuvette having a bottom and an upper portion, the upper portion having an opening for receiving a blood sample and at least one reagent and a partition which divides the upper portion into two chambers, the partition having opposing faces which intersect at an acute angle to form a sharp, wedge-shaped edge, said edge being situated within the cuvette at a predetermined distance from the bottom of the cuvette to permit unobstructed communication between the two chambers to permit flow of a blood sample-reagent mixture from one chamber to the other around the edge when variable air pressure is applied to the cuvette thereby causing a clot to form on said edge;

(b) means comprising a vibrating membrane for producing variable air pressure which communicates via an opening with one of the chambers in the upper portion of the cuvette, said air pressure producing means causing movement of a blood sample-reagent mixture from one chamber to the other around the sharp edge of the partition;

(c) first electro-optical means for detecting a first point of time corresponding to the initial presence of a blood sample-reagent mixture in the cuvette with a first light beam which traverses the cuvette at a level situated above the sharp edge of the partition in relation to the bottom of the cuvette;

(d) second electro-optical means for detecting a second point of time corresponding to the formation of a clot on the sharp edge of the partition with a second light beam which traverses the cuvette along a path which passes generally close to and below the sharp edge of the partition, so that a clot formed on the edge is in the path of the second light beam and is therefore detectable therewith; and

(e) signal processing means electrically connected to the first and the second electro-optical means for measuring the time interval between the first and the second points of time, said interval being representative of the coagulation time of a blood sample.

7. The apparatus of claim 6, wherein the first electro-optical means comprises a first light source and a first light receiver which are arranged in relation to the cuvette so that the first beam of light, which emanates from the first light source, is received by the first light receiver after the first beam of light passes through the cuvette.

8. The apparatus of claim 7, wherein the second electro-optical means comprises a second light source and a second light receiver which are arranged in relation to the cuvette so that the second beam of light, which emanates from the second light source, is received by the second light receiver after the second beam of light passes through the cuvette.