title: Evaluation of initial heparin infusion rates for a high-dose protocol.
abstract: Unfractionated 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.
authors.affiliation: Central Texas Veterans Health Care System, Department of Veterans Affairs, 1901 Veterans Memorial Dr., Temple, TX, 76504, USA, adam.s.smith@utah.edu.
authors.forename: Adam
authors.initials: A
authors.lastname: Smith
authors.forename: Eileen M
authors.initials: EM
authors.lastname: Stock
authors.forename: Nathan
authors.initials: N
authors.lastname: Fewel
authors.forename: Michael
authors.initials: M
authors.lastname: Rose
authors.forename: Carrie L
authors.initials: CL
authors.lastname: Griffiths
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006493:Heparin / Q000008:administration & dosage*; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time / Q000379:methods; D012189:Retrospective Studies; D013927:Thrombosis / Q000097:blood* / Q000188:drug therapy*
chemical_list: D000925:Anticoagulants; D006493:Heparin
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