evaluation of the efficacy and safety of D-dimer adjusted heparin versus therapeutic dose heparin in patients with COVID-19 Pneumonia.

The following will be done for enrolled patients:

1. Data collection: name, age, sex, special habits of medical importance (i.e. smoking, drug abuse), comorbid conditions.

2. Clinical examination Vital data Local chest examination

3. Measurement of oxygen saturation using pulse oximeter

4. Laboratory investigations:

   Complete blood count with differential count Liver and kidney functions D-dimer level Coagulation profile

5. Radiology work up ( Chest X-ray-High resolution computed tomography of the chest- computed tomography of the chest with pulmonary angiography as needed)

6. Sepsis-induced coagulopathy score (SIC score)

7. Sequential organ failure score (SOFA score)

8. Patients will receive treatment according to the hospital guidelines for different disease stratification severity

Inclusion Criteria:

• All adult (>18 years) patients from both sexes with COVID-19 pneumonia with positive nucleic acid test for severe acute respiratory syndrome Coronavirus (SARS-CoV-2) hospitalized either in the ward or intensive care unit

Exclusion Criteria:

• Patients with absolute contraindication of pharmacological thromboprophylaxis and/ anticoagulation
• Congenital hemorrhagic disorders
• Hypersensitivity to heparin
• Personal history of heparin-induced thrombocytopenia
• Active major bleeding or conditions predisposing to major bleeding. Major bleeding is defined as fulfilling any one of these three criteria: a) occurs in a critical area or organ (e.g.intracranial, intraspinal, intraocular, retroperitoneal, intra-articular or pericardial, intra-uterine or intramuscular with compartment syndrome), b) causes a fall in haemoglobin level (Hb) of ≥2g/dL in a 24h period, or c) leads to transfusion of 2 or more units of whole blood or red blood cells (13).
• Suspected or confirmed bacterial endocarditis
• Ongoing or planned therapeutic anticoagulation for any other indication
• Platelet count <50,000/μL within the past 24 hours or Hb level <8g/dL
• Prothrombin time (PT) ≥2 seconds above the upper limit of age-appropriate local reference range within the past 24 hours
• Activated partial thromboplastin time (aPTT) ≥4 seconds above the upper limit of age-appropriate local reference range within the past 24 hours
• Fibrinogen <2.0 g/L
• Severe renal impairment (CrCl<30 mL/min) or acute kidney injury
• Use of dual antiplatelet therapy
• Pregnancy
• Unwillingness to consent