Activated Clotting Time Is Test That Is Used To Monitor The Effectiveness Of High Dose Heparin Therapy
The MAX-ACT Activated Clotting Time (ACT) test is intended for use in the performance of the activated clotting time test
medical and surgical procedures. MAX-ACT test tubes can be used
in conjunction with the Actalyke instrument, the Actalyke MINI and the
Actalyke XL. MAX-ACT test tubes can also be used in conjunction with
Hemochron® instruments.
SUMMARY
During extracorporeal circulation (ECC) procedures such as cardiopulmonary bypass (CPB), the patient's blood flows through an extracorporeal circuit. The non-biological surfaces of the bypass circuit are known to have a strong procoagulant effect on the blood. To offset this biological response, anticoagulants are routinely administered. The most commonly used anticoagulant is heparin, and it is usually given in high concentrations during periods of extracorporeal circulation. During procedures involving intense heparinization, the ACT and other endpoint-based coagulation assays are frequently used to monitor heparin effect, heparin concentration, and other coagulation parameters.
Blood clot formation is a complex process. The clotting proteins, or factors, circulate normally in an inactive state as precursors to coagulation. In principle, a series of reactions occurs that in turn acts to catalyze the next reaction, hence the common term "Coagulation Cascade". During the reaction process, these proteins and the resulting fibrin mass itself are unstable and water-soluble. In addition, in the presence of anticoagulants and/or diluted amounts of the coagulation proteins, clotting becomes delayed or prolonged. Eventually, however, fibrin (the foundation of a blood clot) will be formed when fibrinogen, one of the clotting proteins, is cleaved.
Biological Improvements: The MAX-ACT Test
For years, it has been assumed that the science behind an ACT test was
relatively simple. The premise has been: place an activator in the tube, add
the blood sample, and a clot will form. In actuality the formation of the clot is simple, but getting the clot to form within a certain timeframe, location, and strength is not as predictable.
The novel, patented MAX-ACT test represents a new approach to ACT formulation with the goal of standardizing contact activation for enhanced
testing reliability. The original handheld ACT described a technique in which the ACT tube was inverted and mixed at least once every 30
seconds throughout the testing period.
Activated Clotting Time - This documented mixing interval continually "re-exposed" the blood sample to the large amounts of glass of the tube walls. The MAX-ACT uses a new formulation to recapture the original premise of the test by including glass beads as an additional activator thus offering constant blood exposure to glass.
Further, the additional activators speed up the clotting cascade via the simultaneous activation of Factor XII (Hageman Factor). Various commercial preparations of activators such as diatomaceous earth (celite), kaolin, glass-beads, and silica will not initiate Factor XII similarly. In principle, reagent that better activates the clotting cascade (either through quantity or quality of the activator) yields shorter, more reproducible clotting times for all specimens tested throughout the range of the test.
This is especially important in CPB where conditions such as hemodilution lower
the amount of Factor XII in the blood. Since coagulation is an enzymatic reaction, dependent upon the temperature of the reaction environment, the
hypothermic conditions encountered in CPB also come into play.
To overcome the aforementioned variables that affect the blood specimen, it is logical to "oversaturate" and vary the type of Factor XII activation. It is imperative to oversaturate Factor XII at the onset of the reaction to guarantee that the eventual prothrombin to thrombin conversion is maximized, thus reducing extraneous testing variables for enhanced reliability
About the Author:
Activated Clotting Time - Helena Laboratories is a clinical laboratory instrument and reagent manufacturer. Our clients include major medical centers, small hospitals, large reference laboratories and small private doctor's laboratories.
Contact Details:
HELENA Laboratories
Beaumont, Texas,
USA
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Categories: Business
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