activated clotting time
Also written as: ACT — Activated Clotting Time
Point-of-care coagulation test used to monitor heparin anticoagulation during cardiopulmonary bypass.
Full Definition
A bedside coagulation assay that measures the time required for whole blood to clot after activation with a contact activator such as diatomaceous earth or kaolin. ACT is the primary method for monitoring anticoagulation during cardiopulmonary bypass, with target values typically >400-480 seconds depending on institutional protocols. The test provides rapid results allowing for real-time adjustment of heparin dosing and is essential for safe conduct of cardiac surgery requiring extracorporeal circulation.
Usage
Usage note: Always specify target range and actual values; commonly abbreviated as ACT.
In Context
- "The activated clotting time was 468 seconds, confirming adequate anticoagulation for bypass initiation." — Perfusion record
- "Additional heparin was administered when the activated clotting time fell below target at 380 seconds." — Anesthesia note