Activated clotting time (ACT) measuring devices used simultaneously do not produce correlating ACT values

Introduction

The lack of a 'gold standard' activated clotting time (ACT) measuring device gives rise to the broad range of ACT measuring devices currently on the market. The present study focused on the inter-device and intra-device differences (for example, reproducibility of ACT measurement) in four different ACT measuring systems.

Methods

(1) Hemochron celite tubes, (2) Aktalyke celite tubes, (3) Actalyke ACT-Max tubes and (4) Hemochron Junior low-range (LR) or high-range (HR) cartridges were simultaneously filled with blood drawn (n = 3,997) at baseline, at 3 minutes following administration of heparin (300 IU/kg), 5 minutes after starting cardiopulmonary bypass (CPB), every 30 minutes during CPB and thereafter at 15 minutes following protamine administration.

Results

The ACT values measured simultaneously using four different ACT measuring devices did not correlate with each other at any measurement time. Reproducibility of ACT measurement (for example, intra-device difference) was, in descending order, best for Hemochron Junior, Actalyke ACT-Max, Hemochron celite and Aktalyke celite.

Conclusion

The Hemochron Junior ACT measuring device showed the smallest intra-device measuring error. No correlation, however, could be established between ACT values measured with the four devices tested.