Method and apparatus for determining coagulation times

• US 4,034,601 A
• Filed: 04/12/1976
• Issued: 07/12/1977
• Est. Priority Date: 08/27/1974
• Status: Expired due to Term

• Current Assignee: Baxter Diagnostics Incorporated (Baxter International Inc.)
• Original Assignee: American Hospital Supply Corp. (Baxter International Inc.)
• Inventors: Geiger, Mario Theodore
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Roskos, Joseph W.
• Application Number:
  US05/675,936
• Time in Patent Office: 456 Days
• Field of Search: 73/64.1, 356/36, 356/39, 23/230 B
• US Class Current: 73/64.43
• CPC Class Codes: G01N 33/4905 Determining clotting time of blood by chemical methods G01N33/86, C12Q1/56
• CPC Class Codes: G04F 8/00 Apparatus for measuring unknown time intervals by electromechanical means

Abstract

A method and apparatus for determining coagulation times in such clinical laboratory procedures as prothrombin times tests, activated partial thromboplastin time tests, fibrinogen determinations, factor assays for specific blood coagulation factors, and the like. A fibrous filament is drawn at a predetermined rate through a small body of liquid to be tested and the interval, from the time a suitable coagulating agent is mixed with the liquid to the time the body of liquid clings to the filament and moves with it, is precisely measured as a direct indication of actual coagulation time. The liquid body is supported upon a non-wettable inclined surface bordered by walls defining a well for receiving the liquid and a pathway for its movement. Particularly effective results are achieved by utilizing a pair of spaced filaments moving at precisely the same rate, the filaments being bridged by a web or mass of clotted liquid when coagulation occurs. A photodetector senses movement of the clot and a timer automatically measures the time between coagulant addition and clot formation. After clot detection occurs, an arm lifts the paired filaments from the well while at the same time directing the advancing filaments through slots to strip coagulum therefrom, then lifts the filaments out of the slots to permit fresh filament sections to move into place, and finally lowers the fresh sections onto a clean inclined surface for another coagulation test. Means are also disclosed for gently agitating the coagulating agent or agents prior to admixture with the test liquid, for insuring proper suspension of the reactants, and for reducing risks of infection and cross contamination during use of the apparatus.

Claims

1. A method for determining the coagulation time for a body of fluid, supported on a non-wettable surface, following the intermixing of a coagulation agent with said fluid, comprising the steps of

drawing a filament through said fluid body at a predetermined rate, and detecting when said body clings to said filament and commences to move therewith along and upon said surface, the interval between intermixing of said fluid and agent and the commencement of movement of said body bearing a direct relation to the actual coagulation time of said fluid.

2. The method of claim 1 in which said filament is fibrous, at least some of the fibers thereof having end portions projecting outwardly from said filament.

3. The method of claim 1 wherein there is the further step of measuring the time interval between the intermixing of said fluid and agent and the commencement of movement of said body along said surface.

4. The method of claim 1 in which said surface is generally smooth.

5. The method of claim 1 in which said detecting step includes detecting the interruption of a beam of light by said body upon movement thereof by said filament.

6. A method for determining the coagulation time of a fluid following the addition of a coagulating agent thereto, comprising the steps of

supporting a body of said fluid upon a non-wettable surface, introducing a coagulating agent into said body to initiate a coagulation reaction, simultaneously drawing a filament at a predetermined velocity through said body, and detecting when said body clings to said filament and commences to move therewith along and upon said surface.

7. The method of claim 6 wherein said filament is fibrous, at least some of the fibers thereof having end portions projecting outwardly from said filament.

8. The method of claim 6 wherein there is the further step of measuring the time interval between the intermixing of said fluid and agent and the commencement of movement of said body along said surface.

9. The method of claim 6 in which said detecting step is performed photoelectrically.

10. The method of claim 9 in which said photoelectric detection includes the interruption of a beam of light by said body as the same commences to move with said filament.

11. An apparatus for determining the coagulation time of a fluid following the intermixing of that fluid with a coagulating agent, said apparatus having a non-wettable surface having a portion for supporting a liquid body consisting essentially of a mixture of said fluid and agent, said surface also providing a pathway leading from said supporting portion, a filament, means supporting said filament for movement along a line extending over said supporting portion and along said pathway, and means coacting with said first-mentioned means for longitudinally moving said filament at a predetermined rate.

12. The apparatus of claim 11 in which means are provided for detecting when said body clings to said filament and commences to move along and upon said pathway.

13. The apparatus of claim 11 in which said filament is fibrous, at least some of the fibers thereof having end portions projecting outwardly from said filament.

14. The apparatus of claim 12 in which said detecting means includes a light source for directing a beam towards said pathway, and a photocell for detecting the interruption of said beam by said body as the same commences movement along said pathway.