Dose adjustment
Anti-Xa therapeutic range: While O’Meara study suggests 0.4 – 0.8 IU/ml, range of 0.3 – 0.7 unit/mL is adequate for most indications, and most commonly used. Table 1 is a modified regimen of O’Meara study,3 which was performed in ECMO patients where very tight anticoagulation is required, managed by staff very experience in managing anticoagulation for ECMO circuits; hence, the repeat boluses were recommended by O’Meara et. al. when anti-Xa was below the target range. Repeat boluses is not required in the majority of non-ECMO patients. Regarding dose adjustment for anti-Xa >1, advice from the haematologist should be sought as the anti-Xa can be very high and simply reducing the infusion rate may not be appropriate.3 (ANMF haematology expert group opinion)
The frequency of testing at 2 hourly intervals is the practice in ECMO circuits but not indicated for routine anti-coagulation for non-ECMO patients. Testing too early & too frequently, lends to inappropriate dose adjustments. Testing 6 hours after starting infusion and dose changes is adequate as a general guide, and to check with the haematologist on further monitoring. (ANMF haematology expert group opinion)
Dose adjustments using APTT monitoring have been adapted from the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines 2012,1 which were based on paediatric data from a prospective cohort study.22 (LOE IV GOR D)
For consistency, using APTT monitoring, testing 6 hours after starting infusion and dose changes is suggested as a general guide, and to check with the haematologist. (ANMF haematology expert group opinion)
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