* weight under 50kg * contraindication to anticoagulation in the opinion of the treating clinician including * overt bleeding * platelet count \<50,000 * bleeding academic research consortium (barc) major bleeding in the past 30 days * gastrointestinal (gi) bleeding within 3 months * history of intracranial hemorrhage * ischemic stroke within the past 2 weeks * craniotomy/major neurosurgery within the past 30 days * cardiothoracic surgery within the past 30 days * intra-abdominal surgery within 30 days prior to enrollment * head or spinal trauma in the last months * history of uncorrected cerebral aneurysm or arteriovenous malformation (avm) * intracranial malignancy * presence of an epidural or spinal catheter * recent major surgery within the last 14 days * decrease in hemoglobin \>3 g/dl over the last 24 hours * allergic reaction to anticoagulants (e.g. heparin induced thrombocytopenia) as documented in the electronic health records. extracorporeal membrane oxygenation (ecmo) support or other mechanical circulatory support. * severe chronic liver dysfunction (history of portosystemic hypertension (htn), esophageal varices, or child-pugh class c or above or similar model for end-stage liver disease (meld) scores), abnormality in liver function tests (aspartate aminotransferase (ast), alanine aminotransferase (alt), bilirubin) 5 times greater than upper normal limit. * a history of congenital bleeding diatheses or anatomical anomaly that predisposes to hemorrhage (e.g. hemophilia, hereditary hemorrhagic telangiectasia) * treating physician preference for therapeutic anticoagulation * enrollment in other concurrent trials related to anticoagulant or antiplatelet therapy * existing treatment with therapeutic anticoagulation during the previous 7 days of hospitalization prior to icu admission (e.g. for venous thromboembolism (vte), atrial fibrillation, mechanical valve, etc). * do-not-resuscitate (dnr) /do-not-intubate (dni) or comfort measures only (cmo) orders prior to randomization.

* weight under 50kg * contraindication to anticoagulation in the opinion of the treating clinician including * overt bleeding * platelet count \<50,000 * bleeding academic research consortium (barc) major bleeding in the past 30 days * gastrointestinal (gi) bleeding within 3 months * history of intracranial hemorrhage * ischemic stroke within the past 2 weeks * craniotomy/major neurosurgery within the past 30 days * cardiothoracic surgery within the past 30 days * intra-abdominal surgery within 30 days prior to enrollment * head or spinal trauma in the last months * history of uncorrected cerebral aneurysm or arteriovenous malformation (avm) * intracranial malignancy * presence of an epidural or spinal catheter * recent major surgery within the last 14 days * decrease in hemoglobin \>3 g/dl over the last 24 hours * allergic reaction to anticoagulants (e.g. heparin induced thrombocytopenia) as documented in the electronic health records. extracorporeal membrane oxygenation (ecmo) support or other mechanical circulatory support. * severe chronic liver dysfunction (history of portosystemic hypertension (htn), esophageal varices, or child-pugh class c or above or similar model for end-stage liver disease (meld) scores), abnormality in liver function tests (aspartate aminotransferase (ast), alanine aminotransferase (alt), bilirubin) 5 times greater than upper normal limit. * a history of congenital bleeding diatheses or anatomical anomaly that predisposes to hemorrhage (e.g. hemophilia, hereditary hemorrhagic telangiectasia) * treating physician preference for therapeutic anticoagulation * enrollment in other concurrent trials related to anticoagulant or antiplatelet therapy * existing treatment with therapeutic anticoagulation during the previous 7 days of hospitalization prior to icu admission (e.g. for venous thromboembolism (vte), atrial fibrillation, mechanical valve, etc). * do-not-resuscitate (dnr) /do-not-intubate (dni) or comfort measures only (cmo) orders prior to randomization.

- weight under 50kg - contraindication to anticoagulation in the opinion of the treating clinician including - overt bleeding - platelet count <50,000 - bleeding academic research consortium (barc) major bleeding in the past 30 days - gastrointestinal (gi) bleeding within 3 months - history of intracranial hemorrhage - ischemic stroke within the past 2 weeks - craniotomy/major neurosurgery within the past 30 days - cardiothoracic surgery within the past 30 days - intra-abdominal surgery within 30 days prior to enrollment - head or spinal trauma in the last months - history of uncorrected cerebral aneurysm or arteriovenous malformation (avm) - intracranial malignancy - presence of an epidural or spinal catheter - recent major surgery within the last 14 days - decrease in hemoglobin >3 g/dl over the last 24 hours - allergic reaction to anticoagulants (e.g. heparin induced thrombocytopenia) as documented in the electronic health records. extracorporeal membrane oxygenation (ecmo) support or other mechanical circulatory support. - severe chronic liver dysfunction (history of portosystemic hypertension (htn), esophageal varices, or child-pugh class c or above or similar model for end-stage liver disease (meld) scores), abnormality in liver function tests (aspartate aminotransferase (ast), alanine aminotransferase (alt), bilirubin) 5 times greater than upper normal limit. - a history of congenital bleeding diatheses or anatomical anomaly that predisposes to hemorrhage (e.g. hemophilia, hereditary hemorrhagic telangiectasia) - treating physician preference for therapeutic anticoagulation - enrollment in other concurrent trials related to anticoagulant or antiplatelet therapy - existing treatment with therapeutic anticoagulation during the previous 7 days of hospitalization prior to icu admission (e.g. for venous thromboembolism (vte), atrial fibrillation, mechanical valve, etc). - do-not-resuscitate (dnr) /do-not-intubate (dni) or comfort measures only (cmo) orders prior to randomization.

- weight under 50kg - contraindication to anticoagulation in the opinion of the treating clinician including - overt bleeding - platelet count <50,000 - bleeding academic research consortium (barc) major bleeding in the past 30 days - gastrointestinal (gi) bleeding within 3 months - history of intracranial hemorrhage - ischemic stroke within the past 2 weeks - craniotomy/major neurosurgery within the past 30 days - cardiothoracic surgery within the past 30 days - intra-abdominal surgery within 30 days prior to enrollment - head or spinal trauma in the last months - history of uncorrected cerebral aneurysm or arteriovenous malformation (avm) - intracranial malignancy - presence of an epidural or spinal catheter - recent major surgery within the last 14 days - decrease in hemoglobin >3 g/dl over the last 24 hours - allergic reaction to anticoagulants (e.g. heparin induced thrombocytopenia) as documented in the electronic health records. extracorporeal membrane oxygenation (ecmo) support or other mechanical circulatory support. - severe chronic liver dysfunction (history of portosystemic hypertension (htn), esophageal varices, or child-pugh class c or above or similar model for end-stage liver disease (meld) scores), abnormality in liver function tests (aspartate aminotransferase (ast), alanine aminotransferase (alt), bilirubin) 5 times greater than upper normal limit. - a history of congenital bleeding diatheses or anatomical anomaly that predisposes to hemorrhage (e.g. hemophilia, hereditary hemorrhagic telangiectasia) - treating physician preference for therapeutic anticoagulation - enrollment in other concurrent trials related to anticoagulant or antiplatelet therapy - existing treatment with therapeutic anticoagulation during the previous 7 days of hospitalization prior to icu admission (e.g. for venous thromboembolism (vte), atrial fibrillation, mechanical valve, etc). - do-not-resuscitate (dnr) /do-not-intubate (dni) or comfort measures only (cmo) orders prior to randomization.