ACT measurement: The biased gold standard of measuring heparin anticoagulation in cardiac surgery



Introduction: In cardiac surgery anticoagulation is usually achieved by administration of heparin. For nearly 50 years the activated clotting time (ACT) has been known as a practicable method to measure this effect [1]. Despite its widespread use, a degree of uncertainty remains concerning its validity and repeatability. Furthermore, ACT measurements can vary based on the measurement method [2]. A smaller trial suggests that there is no statistically significant difference in ACT measurement using the same system [3]. Taking two samples from the same patient at the same time and measuring withthe same Hemochron Response® machine, we compared repeatability of ACT measurements. 

Methods: In this retrospective observational study, we compared duplicate ACT values in patients undergoing cardiac surgery in our institution between January 2010 and May 2012. We used Bland-Altman analysis to look for differences between the two measurements. 

Results: 11569 pairs of duplicate ACT measurements were analysed. Mean bias was –19.5 s (P < 0.05), 95% confidence interval was –20.6 s to 18.3 s. 2,540 pairs (22.0%) varied by more than 10%, 1,831 (15.8%) by more than 20%. 

Discussion: In our institution, a substantial proportion of ACT measurements taken at the same moment from the same patient vary significantly. This disagreement should be considered when defining target areas for anticoagulation to ensure patient safety. 

Hattersley PG. Activated coagulation time of whole blood. JAMA 1966; 196:436-440. [2] Thenappan T, Swamy R, Shah A, et al. Interchangeability of activated clotting time values across different point-of-care systems. Am J Cardiol 2012; 109:1379-1382. [3] Bosch YP, Ganushchak YM, de Yong DS. Comparison of ACT point-of-care measurements: repeatability and agreement. Perfusion 2006; 21: 27-31.
Originele taal-2English
StatusPublished - jun-2013
Evenement28th Annual Meeting of the European Association of Cardiothoracic Anaesthesiologists () - Barcelona, Spain
Duur: 6-jun-20138-jun-2013
Congresnummer: 28


Conference28th Annual Meeting of the European Association of Cardiothoracic Anaesthesiologists ()
Verkorte titelEACTA
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