The VA Northeast Ohio Healthcare System introduced a new nurse-driven anti–factor Xa (anti-Xa) protocol for monitoring unfractionated heparin to replace the previous activated partial thromboplastin time protocol.


To design, implement, and evaluate the efficacy of the anti-Xa monitoring protocol.


An interdisciplinary team of providers collaborated to develop and implement a nurse-driven, facility-wide anti–factor Xa protocol for monitoring unfractionated heparin therapy. The effectiveness of this protocol was evaluated by retrospective analysis.


We reviewed 100 medical records for compliance with the new anti-Xa monitoring protocol. We then evaluated 178 patients whose anticoagulation was monitored with the anti-Xa assay to determine the time to therapeutic range. We found that 80% of patients receiving the anti-Xa protocol achieved therapeutic anticoagulation within 24 hours, as compared with 54% of patients receiving the activated partial thromboplastin time protocol (P < .001). Protocol conversion also yielded a decrease in blood draws, dose adjustments, and potential calculation errors.


Monitoring intravenous heparin therapy with the anti-Xa assay rather than activated partial thromboplastin time resulted in a shorter time to therapeutic anticoagulation, longer maintenance of therapeutic levels, and fewer laboratory tests and heparin dosage changes. We believe the current practice of monitoring heparin treatment with activated partial thromboplastin time assays should be reexamined.

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