Longitudinal measurement of whole blood viscoelastic properties throughout the course of extracorporeal membrane oxygenation in COVID-19 patients with severe acute respiratory distress syndrome

Background : Venovenous (vv)-extracorporeal membrane oxygenation (ECMO) support is used as rescue therapy in COVID-19 patients with severe acute respiratory distress syndrome (ARDS). However, COVID-19 is associated with a hypercoagulable state with high rates of thrombosis. Whether ECMO implantation exacerbates COVID-19-associated coagulopathy is unknown. Aims : To perform a longitudinal evaluation of whole blood viscoelastic properties throughout the course of vv-ECMO in COVID-19 ARDS patients. Methods : 20 COVID-19 patients undergoing vv-ECMO were included in this prospective study. Blood was sampled before ECMO implantation and then 24 h and 7 days after ECMO implantation. SEER Sonorheometry was performed on a Quantra ® hemostasis analyzer with the QPlus ® Cartridge (HemoSonics LLC). All patients received UFH to a target anti-Xa activity of 0.3-0.5 IU/mL. Results : The median age was 48 (42-58) years, with a median body mass index of 30.5 (28.2-38.5) Kg/m2, and 15 (71%) patients were men. The median SAPSII and SOFA scores on admission were 52.5 (44.3-65.5) and 12.0 (8.5-15.8), respectively. Baseline clot times (CT) and baseline clot times with heparinase (CTH) were within the normal range [median 150 (127-178) s and 129 (118-151) s, respectively] and did not vary throughout the course of ECMO. COVID-19 patients exhibited markedly increased baseline values of clot stiffness [CS, median 49.9 (35.5-69.2 hPA)], fibrinogen contribution to CS [FCS, median 12.80 (6.20-20.10) hPA] and platelet contribution to CS [PCS, median 38.5 (28.7-52.4) hPA]. CS, FCS and PCS decreased from baseline to day 7. CT significantly correlated with aPTT ( r = 0.75, P < 0.0001), FCS with fibrinogen levels ( r = 0.81, P < 0.0001) and PCS with platelet count ( r = 0.85, P < 0.0001) but result delivery was much faster with the Quantra ® analyzer compared to conventional tests (∼15 versus ∼60 min). Conclusions : COVID-19 patients with ARDS exhibited a pronounced baseline procoagulant state that partially resolved over the first 7 days of ECMO support.