Heparin – anticoagulant in order to prevent blood clotting and major bleeding during use of the ECMO [14]
- Accelerates the natural anticoagulant antithrombin’s ability to inhibit coagulation [16]
ACT – activated clotting time is the most common way to monitor heparin levels [14]
- Quick results, can be performed multiple times a day [17]
- Results can be affected by: anticoagulation deficiencies (e.g. anemia) and hypothermia [16]
TEG – viscoelastic test that monitors data for many aspects of the blood clotting process, including initial fibrin formation [16]
- Limited by the amount of high sheer stress it places on the biological elements of hemostasis [14]
- Test is very detailed.
- Not as well known [14]
aPTT – plasma assay that tests for the activated partial thromboplastin time; monitors UFH [14]
- Varies too much between laboratories & is easily influenced by other health factors [15]
- Does not account for cellular component of the blood [17]
Anti-Xa – anticoagulant assay that monitors UFH-AT complex levels in the blood after heparin is added [18]
- Requires less blood than and is more accurate than other three tests [19]
- Only trained professionals can perform the test
- Not readily available [20]
Image Source: https://practical-haemostasis.com/Screening%20Tests/aptt.html
Sources:
[14]: Chlebowski, M.M., Baltagi, S., Carlson, M. et al. Clinical controversies in anticoagulation monitoring and antithrombin supplementation for ECMO. Crit Care 24, 19 (2020). https://doi.org/10.1186/s13054-020-2726-9
[15]: Mulder, M. et al. “ECMO and anticoagulation : a comprehensive review.” (2018). https://nvic.nl/sites/nvic.nl/files/pdf/review_22.pdf
[16]: Colman, E., et al., Evaluation of a heparin monitoring protocol for extracorporeal membrane oxygenation and review of the literature. Journal of Thoracic Disease, 2019. 11(8): p. 3325-3335.
[17] Panigada, M., et al., Thromboelastography-based anticoagulation management during extracorporeal membrane oxygenation: a safety and feasibility pilot study. Annals of intensive care, 2018. 8(1): p. 1-9.
[18] Cho, H.J., et al., Anticoagulation Therapy during Extracorporeal Membrane Oxygenator Support in Pediatric Patients. Chonnam Med J, 2017. 53(2): p. 110-117.
[19] Nguyen, T., M. Musick, and J. Teruya, Anticoagulation monitoring during extracorporeal membrane oxygenation: is anti-factor Xa assay (heparin level) a better test? Pediatric critical care medicine, 2014. 15(2): p. 178-179.
[20] Bolliger, D., M. Maurer, and K.A. Tanaka, Toward Optimal Anticoagulation Monitoring During Cardiopulmonary Bypass: It Is Still A Tough “ACT”. Journal of cardiothoracic and vascular anesthesia, 2020. 34(11): p. 2928-2930.