Activated clotting time test alone is inadequate to optimize therapeutic heparin dosage adjustment during post-cardiopulmonary resuscitational extracorporeal membrane oxygenation (e-CPR)

Background: We conducted an observational study to evaluate the relationship between activated clotting time (ACT) and activated partial thromboplastin time (aPTT) tests, anticipating the possibility that the ACT will become a substitute test for the aPTT in post-CPR extracorporeal membrane oxygenation (e-CPR). Patients and Methods: Three hundred and fifteen paired ACT and aPTT samples were derived from 60 in-hospital e-CPR patients and were divided into three groups according to the observed ACT value: low level (ACT<170 s, Group A), intended target level (ACT 170-210 s Group B) and high level (ACT>210 s, Group C). The relationship of aPTT in each group was analyzed. Results: The mean ACT and aPTT values were 189.39 48.27 s (IQR, 163-202) and 71.85 +/- 45.32 s (IQR, 44.5-81.8), respectively. Although the observed mean ACT value of 189.39 s was similar to the intended mean target value of 190 s (p=0.823), the observed mean aPTT value (71.85 s) was significantly lower than the predicted mean target value (77.5 s, p=0.027). Despite the mean ACT values being significantly different in each group (p<0.0001), the mean aPTT values were not statistically different between Groups A and B (p = 0.317). Of the Group B samples (n = 139), only 31 samples (22.3%) met the optimal therapeutic aPTT range. Pearson's correlation coefficient for Group B showed only a weak correlation between ACT and aPTT (r=0.177; p=0.037). Conclusions: Our study demonstrates that the ACT test alone does not seem to be enough to optimize therapeutic heparin dosage adjustment during e-CPR.