ACTIVATED CLOTTING TIME
(ACT)

Sample type:

blood sample

Uses:

ACT is the most widely used measure of anticoagulation with heparin (and neutralization of heparin with protamine) during extracorporeal circulation.

Precautions:

No specific precautions

Interfering factor:

• The response of ACT to heparin varies from individual to individual and with heparin potency.

• Medications that inhibit platelet function (aspirin, NSAIDs) may affect ACT.

• Underlying coagulopathies (antithrombin III deficiency, clotting factor deficiencies, DIC) must be excluded.

Pre-analytical errors:

Sample Collection:

• Foaming of the sample (air bubbles)

• Hemolysis

• Clotted or partially clotted blood

Unacceptable Sample Types:

• Sample collected into a pre-heparinized syringe

• Sample contamination with tissue thromboplastin

Corrective action :

• Avoid air bubbles

• Discard hemolized sapmle

• Avoid contamination

Post analytical errors:

• Check instrument settings

• Assure that all preventive maintenance has been done

Corrective action:

• Assure that the prescribed preventive maintenance for the instrument is performed

Reference range:

70-120 seconds

Therapeutic range:

180-240 seconds