Prophylactic Versus Therapeutic Dose Anticoagulation In COVID-19 Infection at the Time of Admission To Critical Care Units

Inclusion Criteria: * Age \>18 years old * positive reverse transcription-polymerase chain reaction (rRT-PCR) test for the qualitative detection of nucleic acid from SARS-CoV-2 in upper and lower respiratory specimens. * Intensive care unit (ICU) patient or Step-down unit (SDU) patient on invasive mechanical ventilation, BiPAP, 100% non-rebreather mask, or high flow oxygen or supplemental oxygen of at least 4 liters per minute nasal cannula. * peak d-dimer levels exceeding 1,000 mcg/mL at any time during admission. Exclusion Criteria: * Hospital length of stay less than 5 days. * Hemorrhage before ICU/SDU admission. * Treatment with an anticoagulant other than low molecular weight heparin or unfractionated heparin. * Constant treatment with the same dose of anticoagulant for less than 5 days.