Activated clotting time (ACT) testing: analysis of reproducibility

Area of Science:

• Cardiovascular Surgery
• Hematology
• Medical Device Evaluation

Background:

• Activated Clotting Time (ACT) is the standard for heparin monitoring in cardiac surgery.
• Current precision standards (10% CV) may not reflect modern test performance.
• Recent precision data for ACT testing is limited.

Purpose of the Study:

• To evaluate the precision of Hemochron FTCA510 (celite) and KACT (kaolin) ACT test tubes.
• To determine if ACT test variability meets or exceeds the 10% CV standard.
• To assess ACT test reliability in laboratory and clinical settings.

Main Methods:

• Retrospective analysis of laboratory and clinical data for Hemochron ACT tests.
• Evaluation of reproducibility using multiple lots of control plasma and fresh heparinized blood.
• Analysis of coefficient of variation (CV) across various heparin concentrations and clinical samples.

Main Results:

• Both celite and kaolin ACT tests showed average CVs significantly below 10% in laboratory studies (e.g., celite 5.4% normal, 4.0% abnormal; kaolin 4.5% normal, 3.8% abnormal).
• Precision was even higher with fresh whole blood compared to control plasma.
• Clinical evaluation demonstrated minimal differences in paired ACT values (average 1.8% difference).

Conclusions:

• Hemochron ACT test tubes (celite and kaolin) exhibit precision significantly better than the 10% CV standard.
• These ACT tests provide reliable heparin anticoagulation monitoring for cardiac surgery.
• The study validates the accuracy and consistency of Hemochron ACT testing in real-world clinical use.