inclusion criteria: we will include adult patients ages 18-75 years old with known or suspected covid-19 infection with a pao2/fio2 ratio < 150 or inferred pao2/fio2 ratio from spo2 if abg is unavailable (table) persisting for > 4 hours despite optimal mechanical ventilation management according to each institution's ventilation protocols, and a neurological exam without focal signs or new deficits at time of enrollment (if patient is on paralytics, patient has been aroused sufficiently to allow a neurological examination to exclude new focal deficits or has mri/ct scan in the last 4.5 hours with no evidence of stroke. finally, patients must be on the ventilator for <=10 days to be eligible. based on experience with critically ill patients, longer ventilation time may be associated with increased risk of bleeding. patients will be enrolled based on clinical features, without consideration of language (using hospital interpreters and translated consent), race/ethnicity, or gender. a neurological exam or ct/mri scan to demonstrate no evidence of an acute stroke is needed due to a recent case-report of large-vessel stroke as a presenting feature of covid-19 in young individuals.

inclusion criteria: we will include adult patients ages 18-75 years old with known or suspected covid-19 infection with a pao2/fio2 ratio < 150 or inferred pao2/fio2 ratio from spo2 if abg is unavailable (table) persisting for > 4 hours despite optimal mechanical ventilation management according to each institution's ventilation protocols, and a neurological exam without focal signs or new deficits at time of enrollment (if patient is on paralytics, patient has been aroused sufficiently to allow a neurological examination to exclude new focal deficits or has mri/ct scan in the last 4.5 hours with no evidence of stroke. finally, patients must be on the ventilator for <=10 days to be eligible. based on experience with critically ill patients, longer ventilation time may be associated with increased risk of bleeding. patients will be enrolled based on clinical features, without consideration of language (using hospital interpreters and translated consent), race/ethnicity, or gender. a neurological exam or ct/mri scan to demonstrate no evidence of an acute stroke is needed due to a recent case-report of large-vessel stroke as a presenting feature of covid-19 in young individuals.