• Adam Smith, Eileen M Stock, Nathan Fewel, Michael Rose, and Carrie L Griffiths.
• Central Texas Veterans Health Care System, Department of Veterans Affairs, 1901 Veterans Memorial Dr., Temple, TX, 76504, USA, adam.s.smith@utah.edu.
• J. Thromb. Thrombolysis. 2014 May 1;37(4):419-26.

AbstractUnfractionated heparin is widely used as anticoagulant therapy for thrombotic disease. However, determining appropriate dosing by intravenous infusion is highly variable in practice. Multiple standardized protocols have been adopted, including a weight-based nomogram entailing a loading dose of 80 U/kg, followed by an initial infusion rate of 18 U/kg/h. In some instances, 18 U/kg/h has resulted in supratherapeutic activated partial thromboplastin time (aPTT). This study aimed to determine if an initial heparin infusion rate of 14 U/kg/h per a high-dose protocol achieved therapeutic anticoagulation more rapidly than 18 U/kg/h. A retrospective chart review performed at a Veterans Health Administration facility located in the southwestern U.S. identified 129 patients hospitalized from January 2009 to August 2011 receiving a high-dose protocol for heparin with an initial infusion rate of 14 or 18 U/kg/h. The proportion of patients achieving subtherapeutic, at goal, or supratherapeutic aPTT on two subsequent mornings was determined. Time to reach therapeutic aPTT was assessed with a multivariable generalized linear model. Patients provided 18 U/kg/h for heparin anticoagulation therapy experienced elevated aPTT values initially. Also, these patients generally took 1.41 times longer to reach therapeutic aPTT than patients receiving 14 U/kg/h [estimate = 0.34, 95% CI 0.11, 0.57; p < 0.01]. Larger body mass index led to increased time to reach therapeutic anticoagulation. This study's results suggest that patients may benefit from receiving an initial heparin infusion rate of 14 U/kg/h over 18 U/kg/h. Decreasing the time to therapeutic aPTT may further help reduce workload from monitoring and dose titrations.

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