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Anticoagulation Monitoring Modalities in Extracorporeal Life Support Patients: A Single Center Experience
*Abdel Ghanie Abu-Samra¹, *David Chu¹, *Joseph Sweeney², *Cynthia Devers², *Corey E Ventetuolo¹, Christopher S Muratore^2
1Rhode Island Hospital Alpert Medical School of BrownUniversity, Providence, RI;²Hasbro Children's Hospital / Rhode Island Hospital Alpert Medical School of BrownUniversity, Providence, RI

Rationale: Extracorporeal life support (ECLS) requires systemic anticoagulation and is associated with bleeding and thrombotic complications. Several heparin monitoring modalities are available including the activated clotting time (ACT), activated partial thromboplastin time (aPTT), and the anti-factor Xa (antiXa) assay. The ideal lab test for monitoring in adults on ECLS remains controversial. Methods: We performed a retrospective review of adult ECLS patients at Rhode Island Hospital in order to assess the correlation between ACT, aPTT, and antiXa levels. We measure aPTT and antiXa levels (Hemosil heparin, Instrumentation laboratories, Bedford, MA) twice daily, including hourly point-of-care (POC) ACT monitoring. Results: Median (IQR) weight was 86.0 kg (78.5-101.8) and median (IQR) heparin dose was 17.5 units/kg/hr (15.8-19.8). The median (IQR) ACT was 195.0 seconds (184.3-209.3), aPTT was 92.5 seconds (78.3 - 129.0), and antiXa level was 0.42 U/mL(0.32 - 0.56). When ACTs were within goal range (180 - 220), the correlation with aPTT and antiXa was poor (Pearson’s correlation coefficient [r]=0.2, p=0.41 and r=0.1, p=0.67, respectively). When antiXa levels were low (<0.3 U/mL), the correlation with ACT was 0.1 (p =0.8) and aPTT was 0.2 (p = 0.44). For therapeutic values of antiXa (0.3-0.7 U/mL), the correlation with ACT was 0.12 (p = 0.64) and aPTT was 0.32 (p = 0.21); ACT and aPTT were also poorly correlated with each other when antiXa levels were in the therapeutic range (r = 0.25; p = 0.33). Conclusion: In this preliminary study, there was poor correlation between these three assays in common use for monitoring anticoagulation in ECLS. In addition to traditional POC testing, routine monitoring of heparin activity may be important to reduce complications in adults supported with ECLS.

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