Background
Patients are at high risk of VTE as they have:
- Acute infection / inflammatory disorder
- Immobility expected for at least 3 days
They require thromboprophylaxis unless they have a risk factor for bleeding.
Contraindication to thromboprophylaxis
- Active bleeding
- Platelets <50
- Acquired bleeding disorder (e.g. liver disease)
- Untreated inherited bleeding disorder(haemophilia/vWD)
- LP/epidural/spinal anaesthesia expected in the next 12 hours or epidural catheter removed in the past 4 hours
- Acute stroke
- Uncontrolled hypertension(>230/120 mmHg)
Dose
| Actual body weight | Tinzaparin | Anti-Xa monitoring |
|---|---|---|
| Creat. clearance >20ml/min | ||
| <50kg | 3500 units OD | No need for anti-Xa monitoring |
| 50-90kg | 4500 units OD | |
| 91-130kg | 8000 units OD | |
| 131-170kg | 12000 units OD | |
| >175Kg | 75 units/Kg OD | |
| Creat. clearance <20ml/min | ||
| <50kg | 2500 units OD | Check anti-Xa level after 3-5 days to ensure not accumulating. Sample needs to be taken 4 hours post dose. Please perform Mon-Fri. Liaise with coagulation laboratory prior to sending. Anti-Xa target 02.-0.5 IU/ml2 |
| 50-90kg | 3500 units OD | |
| 91-130kg | 4500 units OD | |
| 131-170kg | 8000 units OD | |
| >170kg | 1200 units OD | |
Current anticoagulation
If the patient is already on anticoagulation:
- AF or VTE >90 days ago - no change in anticoagulation strategy
- VTE<90 days ago - change to Tinzaparin 175 units/kg OD
Mechanical thromboprophylaxis
- If no contraindications, patients should wear graduated compression stockings
- Completely immobilised patients would benefit from intermittent pneumatic compression in addition to pharmacological thromboprophylaxis
Please note
- Patients with COVID-19 can develop abnormal coagulation but bleeding is rare. Prolongation of PT/APTT is not a contraindication to thromboprophylaxis as long as fibrinogen ≥1g/L
- Venous thromboembolic events can occur despite thromboprophylaxis and should be considered in the deteriorating patient