PLAT and COVID-19: In a pilot open-label RCT, 46 critically ill patients with COVID-19 with elevated D-dimer > 3000 ng/mL and PaO2/FiO2 ratios < 100 were randomized to receive either recombinant tissue plasminogen activators (rt-PA) (followed by intravenous UFH) or prophylactic anticoagulation with UFH.