Activated clotting time

Test/Range/Collection

Activated clotting time, whole blood (ACT)

70–180 sec (method-specific)

$$

Obtain blood in a plastic syringe without anticoagulant. Test should be performed immediately at patient’s bedside. A clean venipuncture is required.

A special vacutainer tube containing activator (eg, celite, kaolin) is also available.

Physiologic Basis

ACT is a point-of-care test used to monitor high-dose heparin as an anticoagulant during cardiac surgery (extracorporeal circulation), angioplasty, and hemodialysis. It is also used to determine the dose of protamine sulfate to reverse the heparin effect on completion of the procedure.

ACT is also used to monitor heparin or direct thrombin inhibitor in patients with lupus anticoagulant.

Interpretation

Prolonged in: Heparin therapy, direct thrombin inhibitor therapy, severe deficiency of clotting factors (except factors VII and XIII), functional platelet disorders.

In general, the accepted goal during cardiopulmonary bypass surgery is 400–500 sec. For carotid artery stenting, the optimal ACT is 250–300 sec.

Comments

ACT is the choice of test when heparin levels are too high (eg, > 1.0 U/mL heparin) to allow monitoring with PTT and/or when a rapid result is necessary to monitor treatment.

Because different methodologies and a number of variables (eg, platelet count and function, hypothermia, hemodilution, and certain drugs like aprotinin) may affect the ACT, the ACT test is not yet standardized. Reproducibility of prolonged ACTs may be poor.

Finley A et al. Review article: heparin sensitivity and resistance: management during cardiopulmonary bypass. Anesth Analg 2013;116:1210.  [PMID: 23408671]

McNair E et al. Bivalirudin as an adjunctive anticoagulant to heparin in the treatment of heparin resistance during cardiopulmonary bypass-assisted cardiac surgery. Perfusion 2016;31:189.  [PMID: 25934498]

Sniecinski RM et al. Anticoagulation management associated with extracorporeal circulation. Best Pract Res Clin Anaesthesiol 2015;29:189.  [PMID: 26060030]

Activated clotting time is a sample topic from the Guide to Diagnostic Tests.

To view other topics, please or purchase a subscription.

Anesthesia Central is an all-in-one web and mobile solution for treating patients before, during, and after surgery. This collection of drug, procedures and test information is derived from Davis’s Drug, MGH Clinical Anesthesia Procedures, Pocket Guide to Diagnostic Tests, and MEDLINE Journals. Learn more.

Citation

* When formatting your citation, note that all book, journal, and database titles should be italicized* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Activated clotting time ID - 619152 Y1 - 2017 PB - Guide to Diagnostic Tests UR - https://anesth.unboundmedicine.com/anesthesia/view/GDT/619152/all/Activated_clotting_time ER -