Inpatient Monitoring of Unfractionated Heparin

Unfractionated heparin (UFH) is the most widely used intravenous (IV) anticoagulant for treating and preventing thromboembolic disease (e.g., blood clots ). UFH must be closely monitored and adjusted in the hospital. There are two assays used to monitor UFH: 1) the activated partial thromboplastin time (PTT) and 2) the chromogenic anti-factor Xa assay (anti-Xa). This study aims to compare PTT and anti-Xa methods for monitoring UFH in a pragmatic, randomized controlled trial to determine which helps patients reach a therapeutic anticoagulation range faster.

Inclusion Criteria: * Patients at Vanderbilt University Hospital age 18 years and older who are admitted as observation or inpatients for whom intravenous unfractionated heparin (monitored via the PTT nurse-managed protocol) is ordered. * Baseline PTT value is ≥0 and ≤ 36.0 seconds * Baseline heparin level anti-Xa assay value is ≥0 and ≤0.3 Exclusion Criteria: * Indication for anticoagulation is extracorporeal membrane oxygenation or cerebrovascular ischemic event. * Provider determines patient is not appropriate for the study.