A Comparison of Activated Partial Thromboplastin Time and Activated Coagulation Time for Anticoagulation Monitoring during Extracorporeal Membrane Oxygenation Therapy

Background Unfractionated heparin is used to prevent coagulation activation in patients undergoing extracorporeal membrane oxygenation (ECMO) support. We designed this study to determine the preferable indicator for anticoagulation monitoring. Methods We conducted a retrospective study and divided the patients into an activated coagulation time (ACT)-target group and an activated partial thromboplastin time (aPTT)-target group. The correlations between ACT, aPTT, and the heparin dose were explored. Results Thirty-six patients were included (19 aPTT-target and 17 ACT-target patients); a total of 555 matched pairs of ACT/aPTT results were obtained. The correlation between the ACT and aPTT measurements was Spearman's Rank Correlation Coefficient ( rs ) = 0.518 in all 555 pairs. The Bland-Altman plot showed data points outside the displayed range (51.2-127.7), suggesting that the agreement between ACT and aPTT was poor. The aPTT group had fewer heparin dose changes (2.12 +/- 0.68 vs. 2.57 +/- 0.64, p = 0.05) and a lower cumulative heparin dose (317.6 +/- 108.5 vs. 396.3 +/- 144.3, p = 0.00) per day than the ACT group. There was no difference in serious bleeding (9 vs . 5; p = 0.171) or embolism events (3 vs. 3; p = 1.0) or in the red blood cell and fresh frozen plasma transfusion volumes between the ACT- and aPTT-target groups. Similarly, there was no significant difference in the ECMO duration (9 [4-15] days vs . 4 [3-14] days; p = 0.124) or length of ICU hospitalization (17 [5-32] days vs . 13 [4-21] days; p = 0.451) between the groups. Conclusion The correlation between ACT and aPTT and the heparin dose was poor. The aPTT group had fewer daily heparin dose changes and a lower cumulative heparin dose per day than the ACT group, with no more bleeding and thrombotic events. Therefore, we recommend aPTT rather than ACT to adjust heparin dose in the absence of better monitoring indicators.