COAGULATION TIMING APPARATUS, AND METHOD

• US 3,658,480 A
• Filed: 04/13/1970
• Issued: 04/25/1972
• Est. Priority Date: 04/13/1970
• Status: Expired due to Term

• Current Assignee: Eugene J. Weatherby, Gerald J. Kane
• Original Assignee: Eugene J. Weatherby, Gerald J. Kane
• Inventors: Kane, Gerald J., Weatherby, Eugene J.
• Primary Examiner(s): Wolk, Morris O.
• Assistant Examiner(s): Reese, R. M.
• Application Number:
  US05/027,582
• Time in Patent Office: 743 Days
• Field of Search: 23/23B,253 73/64.1 356/39
• US Class Current: 436/69
• CPC Class Codes: G01N 33/4905 Determining clotting time of blood by chemical methods G01N33/86, C12Q1/54

Abstract

Apparatus for determining various blood coagulation times removes inaccuracies of prior apparatus by blanking first derivative signal for part of the coagulation time and then only comparing a component of said signal to a preset level to determine the clotting time.

Claims

2. Apparatus for determining coagulation time of blood plasma in accordance with claim 1 wherein said means responsive to the output signal of said difference amplifier comprises means for generating a signal to stop a timer.

3. Apparatus for determining coagulation time of blood in accordance with claim 1 wherein said means for holding said component below said comparison signal comprises a blanking circuit and switch for holding said component at ground potential.

4. Apparatus for determining coagulation time of blood in accordance with claim 3 wherein said means for holding said component below said comparison signal value for a preset amount of time and then releasing said signal includes a timer, said timer being set to time out and release said component of a signal after initial disturbances in the differentiated signal have ceased.

5. Apparatus for determining coagulation time of blood plasma in accordance with claim 1 wherein said means for generating a comparison signal includes means for adjusting the comparison signal value as a function of time.

6. Apparatus for determining coagulation time of blood plasma in accordance with claim 5 wherein said means for generating a comparison signal includes means for presetting the comparison value depending upon the type of reagent mixed with the blood plasma at the commencement of the timing period.

7. A method for determining coagulation time of blood plasma comprising the steps of passing light through a mixture of blood plasma and reagent, sensing the light so passed through the blood plasma and reagent, transducing the light so sensed into an electric signal, differentiating said electric signal, sensing a time changing component of said signal, comparing said component of said signal to a comparison signal, and measuring the time it takes for the value of said component of said differentiated siGnal to exceed said comparison signal.

8. A method for determining coagulation time of blood plasma in accordance with claim 7 including the steps of successively changing the comparison signal as a function of time.

9. Apparatus for determining coagulation time of blood plasma comprising a source of light, a transducer responsive to said light, means for positioning said plasma between said source and said transducer, differentiating means for differentiating the signal output of said transducer, amplifying means for amplifying the differentiated signal, a difference amplifier, means for generating a comparison signal, said comparison signal being coupled into said difference amplifier, means for coupling a time changing component of the amplified differential signal into said difference amplifier, and means to indicate coagulation time, said means to indicate coagulation time being responsive to the output signal of said difference amplifier when the value of said component exceeds the value of the comparison signal.

10. A method for determining coagulation time of blood plasma comprising the steps of passing light through a mixture of blood plasma and reagent, sensing the light energy so passed through the blood plasma and reagent, transducing the light so sensed into an electric signal, differentiating said signal, sensing a time changing component of said signal, and determining the coagulation time of the blood plasma by sensing when said time changing component of said signal exceeds a predetermined value.