Monitoring DTI Challenges Table
In case of inappropriate DTI dose/aPTT relationship, order diluted thrombin time (DTT) and/or ecarin chromogenic assay (ECA)
  aPTT < target range aPTT in target range aPTT > target range
       
DTT/ECA < target range Increase DTI dose. Increase DTI dose.

Refer to DTT/ECA target only.

Search for other causes of prolonged aPTT:
  • F VII, F IX, fibrinogen deficiency (>> consider repletion)
  • F XII deficiency (common, no increased bleeding risk)
  • Lupus anticoagulant, antiphospholipid antibodies (increased risk for thrombosis).
DTT/ECA in target range

Consider hypercoagulable state.

No change in DTI dose.

Continue dTT/ECT guided anticoagulation.
DTT/ECA > target range

Continue dTT/ECT guided anticoagulation.

Consider confounders of aPTT: high FVIII levels, thrombocytosis

Consider repeating labs.

Consider hypercoagulable state.

Decrease DTI dose.