Study Design and Parameters

This is a single-center, retrospective study performed with institutional review board (IRB) approval (New York University Langone Health IRB# S20-00611). Inclusion criteria included adults aged 18 years or older with reverse transcriptase-polymerase chain reaction confirmed COVID-19 infection with severe hypoxemia defined by the arterial partial pressure of oxygen–to–fraction of inspired oxygen ratio (P/F ratio) of less than 150 mm Hg or a pH less than 7.23 with a partial pressure of arterial carbon dioxide (PaCO₂) exceeding 60 mm Hg, refractory to conventional medical therapy. Exclusion criteria included patients older than 65 years of age, undergoing active cardiopulmonary resuscitation, those with confirmed neurologic injury, known malignancy with poor prognosis, and multisystem organ failure with the exception of acute kidney injury during the current hospitalization.²¹

Patients’ demographics, baseline characteristics, and laboratory data, including pre-cannulation sequential organ failure assessment score (SOFA), vasoactive inotropic score (VIS), maximum pre-cannulation ventilator support and arterial blood gas were collected. Postcannulation daily values were collected for creatinine, liver function tests, hemoglobin, white blood cell count, platelets, fibrinogen, anti-factor Xa, and partial thromboplastin time (aPTT). Daily inflammatory markers collected included C-reactive protein (CRP), D-dimer, erythrocyte sedimentation rate, ferritin, lactate dehydrogenase level (LDH), and pro-calcitonin.

Therapeutic anticoagulation was initiated for all patients on extracorporeal support with a continuous heparin drip with a goal anti-factor Xa level greater than 0.15 IU/mL and a partial thromboplastin time of less than 70 seconds. All data were collected retrospectively from the review of patients’ electronic medical records. Given the retrospective nature of this study, patient consent was waived.