In this section
| Day | APTT (9-10am) target | Heparin dose | IF INR | Warfarin dose given at 5pm |
| 1 Start | 2-3 ratio | As per APTT | < 1.4 | 10 mg |
| 2 | – | As per APTT |
< 1.8 |
10 mg |
| 1.8 | 1 mg | |||
| > 1.8 | 0.5 mg | |||
| 3 | 2-3 ratio | As per APTT | <2.0 | 10 mg |
| 2.0-2.3 | 5 mg | |||
| 2.4-2.7 | 4 mg | |||
| 2.8-3.1 | 3 mg | |||
| 3.2-3.4 | 2 mg | |||
| 3.5-4.0 | 1 mg | |||
| >4.0 | NIL | |||
| 4 | – | Stop heparin | Predicted maintenance | |
| >8 mg | ||||
| <1.4 | 8 mg | |||
| 1.4 | 7.5 mg | |||
| 1.5 | 7 mg | |||
| 1.6-1.7 | 6.5 mg | |||
| 1.8 | 6 mg | |||
| 1.9 | 5.5 mg | |||
| 2.0-2.1 | 5 mg | |||
| 2.2-2.3 | 4.5 mg | |||
| 2.4-2.6 | 4 mg | |||
| 2.7-3.0 | 3.5 mg | |||
| 3.1-3.5 | 3 | |||
| 3.6-4.0 | ||||
| Nil then 2 mg | ||||
| 4.1-4.5 | ||||
| >4.5 | Nil for two days and then 1mg |
(Last reviewed July 2024)