US 5,314,826 A · Platelet activation and function evaluation technique

Abstract

The intensity of initial agitation of blood and an activating reagent affects the contribution of platelets to clotting in an activated clotting time (ACT) test. An improved ACT test accommodates the effects of platelet activation by incorporating a platelet activation phase. In the platelet activation phase an activating reagent is mixed with a sample of blood to be tested at a controlled point in time followed by gently agitating the mixture in such a manner and for a period of time sufficient to establish a predetermined and predictable contribution to the ACT from platelet activation. The platelet activation phase is followed by a clotting test phase of the ACT test. A platelet functionality test provides information regarding the functionality of platelets in a sample of blood. The platelet functionality test uses two simultaneous ACT tests, one with a platelet activation phase which normally achieves a relatively high rate of contribution from platelet activation to clotting, the other with a platelet activation phase which normally achieves a relatively lower rate of contribution from platelet activation to clotting. The difference between the ACTs of the two ACT tests is indicative of the platelet functionality of the sample of blood.

Claims44

Dependent claims

A method for performing an activated clotting time test on a sample of blood containing platelets, comprising the steps of:

combining at a single predetermined point in time an activating reagent and the sample of blood to be tested to form a test mixture at the start of the activated clotting time test;
controllably activating the platelets of the sample during a first phase of the test by manipulating the test mixture to a predetermined degree immediately following the combining of the reagent and the sample to achieve a predetermined rate of contribution from platelet activation to the activated clotting time test;
continuing the activated clotting time test during a second phase of the test by manipulating the test mixture to a predetermined degree difference from the predetermined degree in the first phase immediately after achieving the predetermined rate of contribution;
terminating the activated clotting time test upon detecting a predetermined change in a property of the test mixture during the second phase which occurs as a result of the predetermined rate of contribution from platelet activation achieved during the first phase;
and
calculating the activated clotting time in specific relation to and by accounting for the predetermined rate of contribution from the platelet activation during the test.

3 more elements

A method for performing an activated clotting time test on a sample of blood containing platelets using a plunger sensor apparatus, said apparatus comprising at least one test cell and a plunger assembly within said test cell, said method comprising the steps of:

dispensing a sample of blood into the test cell;
feeding an activating reagent into the sample of blood to form a test mixture;
reciprocating the plunger assembly in the test mixture at a first predetermined rate for a predetermined period of time by alternately lifting the plunger assembly and allowing the plunger assembly to descent through the test mixture, the first predetermined rate of reciprocating the plunger assembly during the predetermined time period achieving a predetermined rate of contribution from platelet activation to the activated clotting time;
immediately after expiration of the predetermined period of time, reciprocating the plunger assembly in the test mixture at a second predetermined rate by alternately lifting the plunger assembly and allowing the plunger assembly to descend through the test mixture, the second predetermined rate being different than the first predetermined rate;
detecting a point in time at which a predetermined property of the test mixture changes by a predetermined expected amount by sensing the descent of the plunger assembly, the predetermined property affecting the activated clotting time test;
measuring an elapsed time from the beginning of the step of feeding the reagent to the point in time at which the property of the test mixture changes by the predetermined expected amount;
and
calculating the activated clotting time of the sample of blood based on the elapsed time in specific relation to and by accounting for the predetermined rate of contribution from the platelet activation to the activated clotting time during the test.

5 more elements

An apparatus for performing a platelet functionality test on blood containing platelets using a plunger sensor technique, said apparatus comprising a cartridge having first and second test cells and first and second plunger assemblies in the first and second test cells, respectively, each test cell further containing an activating reagent, said apparatus further comprising:

dispensing means for dispensing first and second samples of the blood into the first and second test cells;
first reagent drive means for combining the activating reagent with the first sample to form a first test mixture in the first test cell;
first plunger lifting means for reciprocating the first plunger assembly in the first test mixture at a first predetermined rate for a first predetermined period of time by alternately lifting the plunger assembly and allowing the plunger assembly to descend through the first test mixture, and for reciprocating the first plunger assembly in the first test mixture at a second predetermined rate after the expiration of the first predetermined time period by alternately lifting the plunger assembly and allowing the plunger assembly to descend through the first test mixture, the first predetermined rate of reciprocating the plunger assembly during the first predetermined time period achieving a predetermined rate of contribution to clotting of the sample from platelet activation;
detection means for detecting a point in time at which a property of the first sample changes by a predetermined amount to slow the descent of the first plunger assembly by a predetermined amount, the predetermined property relating to the functionality of the platelets in the first sample;
means for measuring a first elapsed time from a point in time at which the activating reagent is combined with the first sample to the point in time at which the descent of the first plunger assembly is slowed by the predetermined amount;
second reagent drive means for combining the activating reagent with the second sample to form a second test mixture in the second test cell;
second plunger lifting means for reciprocating the second plunger assembly in the second test mixture at a third predetermined rate for a second predetermined period of time by alternately lifting the plunger assembly and allowing the plunger assembly to descend through the second test mixture, and for reciprocating the second plunger assembly in the second test mixture at a fourth predetermined rate after the expiration of the second predetermined time period by alternately lifting the plunger assembly and allowing the plunger assembly to descend through the second test mixture, the third predetermined rate of reciprocating the plunger assembly during the second predetermined time period achieving a predetermined rate of contribution to clotting of the second sample from platelet activation;
detection means for detecting the point in time at which a property of the second sample changes by a predetermined amount to slow the descent of the second plunger assembly by a predetermined amount, the predetermined property relating to the functionality of the platelets in the second sample;
means for measuring a second elapsed time from a point in time at which the activating reagent is combined with the second sample to the point in time at which the descent of the second plunger assembly is slowed by the predetermined amount;
the first and second plunger reciprocating means operating simultaneously, the first rate and the third rate of reciprocating the first and second plunger assemblies being different;
and
display means for displaying information related to the first and second elapsed times by which to evaluate the platelet functionality of the blood.

9 more elements

Dependencies are inferred from the claim text.

Platelet activation and function evaluation technique

Life of this patent

Platelet activation and function evaluation technique

Life of this patent

Abstract

Claims44