patients admitted to an icu and receiving organ support (i.e. high flow nasal oxygen, receiving non-invasive or invasive mechanical ventilation, or are requiring vasopressor/inotrope) patients for whom the intent is to not use pharmacologic thromboprophylaxis active bleeding risk factors for bleeding, including: intracranial surgery or stroke within 3 months; history of intracerebral arteriovenous malformation; cerebral aneurysm or mass lesions of the central nervous system; intracranial malignancy history of intracranial bleeding history of bleeding diatheses (e.g., hemophilia) history of gastrointestinal bleeding within previous 3 months thrombolysis within the previous 7 days presence of an epidural or spinal catheter recent major surgery <14 days uncontrolled hypertension (sbp >200 mmhg, dbp >120 mmhg) other physician-perceived contraindications to anticoagulation platelet count <50 x10^9/l, inr >2.0, or baseline aptt >50 (if available per soc testing) hemoglobin <80 g/l (to minimize the likelihood of requiring red blood cell transfusion if potential bleeding were to occur) acute or subacute bacterial endocarditis history of heparin induced thrombocytopenia (hit) or other heparin allergy including hypersensitivity current use of dual antiplatelet therapy patients with an independent indication for therapeutic anticoagulation patients in whom imminent demise is anticipated and there is no commitment to active ongoing intervention anticipated transfer to another hospital that is not a study site within 72 hours enrollment in other trials related to anticoagulation or antiplatelet therapy

patients admitted to an icu and receiving organ support (i.e. high flow nasal oxygen, receiving non-invasive or invasive mechanical ventilation, or are requiring vasopressor/inotrope) patients for whom the intent is to not use pharmacologic thromboprophylaxis active bleeding risk factors for bleeding, including: intracranial surgery or stroke within 3 months; history of intracerebral arteriovenous malformation; cerebral aneurysm or mass lesions of the central nervous system; intracranial malignancy history of intracranial bleeding history of bleeding diatheses (e.g., hemophilia) history of gastrointestinal bleeding within previous 3 months thrombolysis within the previous 7 days presence of an epidural or spinal catheter recent major surgery <14 days uncontrolled hypertension (sbp >200 mmhg, dbp >120 mmhg) other physician-perceived contraindications to anticoagulation platelet count <50 x10^9/l, inr >2.0, or baseline aptt >50 (if available per soc testing) hemoglobin <80 g/l (to minimize the likelihood of requiring red blood cell transfusion if potential bleeding were to occur) acute or subacute bacterial endocarditis history of heparin induced thrombocytopenia (hit) or other heparin allergy including hypersensitivity current use of dual antiplatelet therapy patients with an independent indication for therapeutic anticoagulation patients in whom imminent demise is anticipated and there is no commitment to active ongoing intervention anticipated transfer to another hospital that is not a study site within 72 hours enrollment in other trials related to anticoagulation or antiplatelet therapy

1. patients admitted to an icu and receiving organ support (i.e. high flow nasal oxygen, receiving non-invasive or invasive mechanical ventilation, or are requiring vasopressor/inotrope) 2. patients for whom the intent is to not use pharmacologic thromboprophylaxis 3. active bleeding 4. risk factors for bleeding, including: 1. intracranial surgery or stroke within 3 months; 2. history of intracerebral arteriovenous malformation; 3. cerebral aneurysm or mass lesions of the central nervous system; 4. intracranial malignancy 5. history of intracranial bleeding 6. history of bleeding diatheses (e.g., hemophilia) 7. history of gastrointestinal bleeding within previous 3 months 8. thrombolysis within the previous 7 days 9. presence of an epidural or spinal catheter 10. recent major surgery <14 days 11. uncontrolled hypertension (sbp >200 mmhg, dbp >120 mmhg) 12. other physician-perceived contraindications to anticoagulation 5. platelet count <50 x10^9/l, inr >2.0, or baseline aptt >50 (if available per soc testing) 6. hemoglobin <80 g/l (to minimize the likelihood of requiring red blood cell transfusion if potential bleeding were to occur) 7. acute or subacute bacterial endocarditis 8. history of heparin induced thrombocytopenia (hit) or other heparin allergy including hypersensitivity 9. current use of dual antiplatelet therapy 10. patients with an independent indication for therapeutic anticoagulation 11. patients in whom imminent demise is anticipated and there is no commitment to active ongoing intervention 12. anticipated transfer to another hospital that is not a study site within 72 hours 13. enrollment in other trials related to anticoagulation or antiplatelet therapy

1. patients admitted to an icu and receiving organ support (i.e. high flow nasal oxygen, receiving non-invasive or invasive mechanical ventilation, or are requiring vasopressor/inotrope) 2. patients for whom the intent is to not use pharmacologic thromboprophylaxis 3. active bleeding 4. risk factors for bleeding, including: 1. intracranial surgery or stroke within 3 months; 2. history of intracerebral arteriovenous malformation; 3. cerebral aneurysm or mass lesions of the central nervous system; 4. intracranial malignancy 5. history of intracranial bleeding 6. history of bleeding diatheses (e.g., hemophilia) 7. history of gastrointestinal bleeding within previous 3 months 8. thrombolysis within the previous 7 days 9. presence of an epidural or spinal catheter 10. recent major surgery <14 days 11. uncontrolled hypertension (sbp >200 mmhg, dbp >120 mmhg) 12. other physician-perceived contraindications to anticoagulation 5. platelet count <50 x10^9/l, inr >2.0, or baseline aptt >50 (if available per soc testing) 6. hemoglobin <80 g/l (to minimize the likelihood of requiring red blood cell transfusion if potential bleeding were to occur) 7. acute or subacute bacterial endocarditis 8. history of heparin induced thrombocytopenia (hit) or other heparin allergy including hypersensitivity 9. current use of dual antiplatelet therapy 10. patients with an independent indication for therapeutic anticoagulation 11. patients in whom imminent demise is anticipated and there is no commitment to active ongoing intervention 12. anticipated transfer to another hospital that is not a study site within 72 hours 13. enrollment in other trials related to anticoagulation or antiplatelet therapy

1. requirement for chronic mechanical ventilation via tracheostomy prior to hospitalization 2. patients for whom the intent is to not use pharmacologic thromboprophylaxis 3. active bleeding 4. risk factors for bleeding, including: 1. intracranial surgery or stroke within 3 months; 2. history of intracerebral arteriovenous malformation; 3. cerebral aneurysm or mass lesions of the central nervous system; 4. intracranial malignancy 5. history of intracranial bleeding 6. history of bleeding diatheses (e.g., hemophilia) 7. history of gastrointestinal bleeding within previous 3 months 8. thrombolysis within the previous 7 days 9. presence of an epidural or spinal catheter 10. recent major surgery <14 days 11. uncontrolled hypertension (sbp >200 mmhg, dbp >120 mmhg) 12. other physician-perceived contraindications to anticoagulation 5. platelet count <50 x10^9/l, inr >2.0, or baseline aptt >50 6. hemoglobin <80 g/l (to minimize the likelihood of requiring red blood cell transfusion if potential bleeding were to occur) 7. acute or subacute bacterial endocarditis 8. history of heparin induced thrombocytopenia (hit) or other heparin allergy including hypersensitivity 9. current use of dual antiplatelet therapy 10. patients with an independent indication for therapeutic anticoagulation 11. patients in whom imminent demise is anticipated and there is no commitment to active ongoing intervention 12. anticipated transfer to another hospital that is not a study site within 72 hours 13. enrollment in other trials related to anticoagulation or antiplatelet therapy

1. requirement for chronic mechanical ventilation via tracheostomy prior to hospitalization 2. patients for whom the intent is to not use pharmacologic thromboprophylaxis 3. active bleeding 4. risk factors for bleeding, including: 1. intracranial surgery or stroke within 3 months; 2. history of intracerebral arteriovenous malformation; 3. cerebral aneurysm or mass lesions of the central nervous system; 4. intracranial malignancy 5. history of intracranial bleeding 6. history of bleeding diatheses (e.g., hemophilia) 7. history of gastrointestinal bleeding within previous 3 months 8. thrombolysis within the previous 7 days 9. presence of an epidural or spinal catheter 10. recent major surgery <14 days 11. uncontrolled hypertension (sbp >200 mmhg, dbp >120 mmhg) 12. other physician-perceived contraindications to anticoagulation 5. platelet count <50 x10^9/l, inr >2.0, or baseline aptt >50 6. hemoglobin <80 g/l (to minimize the likelihood of requiring red blood cell transfusion if potential bleeding were to occur) 7. acute or subacute bacterial endocarditis 8. history of heparin induced thrombocytopenia (hit) or other heparin allergy including hypersensitivity 9. current use of dual antiplatelet therapy 10. patients with an independent indication for therapeutic anticoagulation 11. patients in whom imminent demise is anticipated and there is no commitment to active ongoing intervention 12. anticipated transfer to another hospital that is not a study site within 72 hours 13. enrollment in other trials related to anticoagulation or antiplatelet therapy

1. receiving invasive mechanical ventilation 2. patients for whom the intent is to not use pharmacologic thromboprophylaxis 3. active bleeding 4. risk factors for bleeding, including: 1. intracranial surgery or stroke within 3 months; 2. history of intracerebral arteriovenous malformation; 3. cerebral aneurysm or mass lesions of the central nervous system; 4. intracranial malignancy 5. history of intracranial bleeding 6. history of bleeding diatheses (e.g., hemophilia) 7. history of gastrointestinal bleeding within previous 3 months 8. thrombolysis within the previous 7 days 9. presence of an epidural or spinal catheter 10. recent major surgery <14 days 11. uncontrolled hypertension (sbp >200 mmhg, dbp >120 mmhg) 12. other physician-perceived contraindications to anticoagulation 5. platelet count <50 x10^9/l, inr >2.0, or baseline aptt >50 6. hemoglobin <80 g/l (to minimize the likelihood of requiring red blood cell transfusion if potential bleeding were to occur) 7. acute or subacute bacterial endocarditis 8. history of heparin induced thrombocytopenia (hit) or other heparin allergy including hypersensitivity 9. current use of dual antiplatelet therapy 10. patients with an independent indication for therapeutic anticoagulation 11. patients in whom imminent demise is anticipated and there is no commitment to active ongoing intervention 12. pregnancy 13. anticipated transfer to another hospital that is not a study site within 72 hours 14. enrollment in other trials related to anticoagulation or antiplatelet therapy

1. receiving invasive mechanical ventilation 2. patients for whom the intent is to not use pharmacologic thromboprophylaxis 3. active bleeding 4. risk factors for bleeding, including: 1. intracranial surgery or stroke within 3 months; 2. history of intracerebral arteriovenous malformation; 3. cerebral aneurysm or mass lesions of the central nervous system; 4. intracranial malignancy 5. history of intracranial bleeding 6. history of bleeding diatheses (e.g., hemophilia) 7. history of gastrointestinal bleeding within previous 3 months 8. thrombolysis within the previous 7 days 9. presence of an epidural or spinal catheter 10. recent major surgery <14 days 11. uncontrolled hypertension (sbp >200 mmhg, dbp >120 mmhg) 12. other physician-perceived contraindications to anticoagulation 5. platelet count <50 x10^9/l, inr >2.0, or baseline aptt >50 6. hemoglobin <80 g/l (to minimize the likelihood of requiring red blood cell transfusion if potential bleeding were to occur) 7. acute or subacute bacterial endocarditis 8. history of heparin induced thrombocytopenia (hit) or other heparin allergy including hypersensitivity 9. current use of dual antiplatelet therapy 10. patients with an independent indication for therapeutic anticoagulation 11. patients in whom imminent demise is anticipated and there is no commitment to active ongoing intervention 12. pregnancy 13. anticipated transfer to another hospital that is not a study site within 72 hours 14. enrollment in other trials related to anticoagulation or antiplatelet therapy