Lesson 3-6

Rapid

Hemostasis Tests

Rapid Hemostasis Tests

• Activated Clotting Time Plus (ACT+)

• Heparin management test (HMT)

• FDP and D-Dimer tests

Use of Rapid Hemostasis Tests

• Monitor heparin therapy

• Identify – Disseminated

Intravascular Coagulation (DIC)– Deep vein thrombosis (DVT)– Pulmonary embolism

Activated Coagulation Time (ACT)

• The ACT test evaluates coagulation status.

The ACT responds linearly to heparin level

changes and responds to wider ranges of

heparin concentrations than does the APTT.

• The ACT, however, assays overall

coagulation activity. Therefore, prolonged

values may not be exclusively the result

of heparin.

Normal

• ACT: 70–120 seconds

• Therapeutic range: 180–240 seconds

• (two times normal range)

Heparin Therapy

• Action of heparin– Inhibits Factors IX, X, XI, and XII– Inhibits platelet release factor

• Used to prevent thrombosis

Tests for Heparin Effectiveness

• ACT+

• APTT

Disseminated Intravascular Coagulation

• Widespread thrombosis and hemorrhage

• Due to:– Crush injuries– Certain infections

• Coagulation factors and platelets become depleted

Deep Vein Thrombosis and Pulmonary Embolism

• DVT– Caused by slow blood flow– Thrombi form in lower extremities

• Pulmonary Embolism– Complication of DVT– Thrombus dislodges and travels to lungs– Life threatening

FDP and XDP• Fibrinogen/fibrin degradation products • Crosslinked fibrin derivatives

When fibrin is split by plasmin, positive tests for fibrin degradation (split) products, identified by the letters X, Y, D, and E, are produced. These products have an anticoagulant action and inhibit clotting when they are present in excess in the circulation. Increased levels of FDPs may occur with a variety of pathologic processes in which clot formation and lysis occur.This test is done to establish the diagnosis of DIC and other thromboembolic disorders.

FDP and XDP

FDP and XDP

• Formation– Plasmin cleaves fibrin and fibrinogen– Cleavage of stable clot forms XDP– D-dimer, another name for XDP

Reference Values • Negative at 1:4 dilution or <10 µg/mL (<10 mg/L)

Increased FSP and FDP are associated with DIC and are seen in:Venous thrombosisPrimary fibrinolysisThoracic and cradiac surgery or renal transplantationAcute myocardial infarctionPE CarcinomaLiver disease

FDP and XDP

• Tests for FDP and XDP (D-dimer)– Manual latex agglutination tests– Instrumentation