title: Error in body weight estimation leads to inadequate parenteral anticoagulation.
abstract: Parenteral anticoagulation is a cornerstone in the management of venous and arterial thrombosis. Unfractionated heparin has a wide dose/response relationship, requiring frequent and troublesome laboratorial follow-up. Because of all these factors, low-molecular-weight heparin use has been increasing. Inadequate dosage has been pointed out as a potential problem because the use of subjectively estimated weight instead of real measured weight is common practice in the emergency department (ED). To evaluate the impact of inadequate weight estimation on enoxaparin dosage, we investigated the adequacy of anticoagulation of patients in a tertiary ED where subjective weight estimation is common practice. We obtained the estimated, informed, and measured weight of 28 patients in need of parenteral anticoagulation. Basal and steady-state (after the second subcutaneous shot of enoxaparin) anti-Xa activity was obtained as a measure of adequate anticoagulation. The patients were divided into 2 groups according the anticoagulation adequacy. From the 28 patients enrolled, 75% (group 1, n = 21) received at least 0.9 mg/kg per dose BID and 25% (group 2, n = 7) received less than 0.9 mg/kg per dose BID of enoxaparin. Only 4 (14.3%) of all patients had anti-Xa activity less than the inferior limit of the therapeutic range (<0.5 UI/mL), all of them from group 2. In conclusion, when weight estimation was used to determine the enoxaparin dosage, 25% of the patients were inadequately anticoagulated (anti-Xa activity <0.5 UI/mL) during the initial crucial phase of treatment.
authors.affiliation: Cardiology Division of Clinical Hospital of the University of São Paulo, Ribeirão Preto School of Medicine, Brazil.
authors.forename: Leon Gustavo
authors.initials: LG
authors.lastname: dos Reis Macedo
authors.forename: Luciana
authors.initials: L
authors.lastname: de Oliveira
authors.forename: Maria Carolina
authors.initials: MC
authors.lastname: Pintão
authors.forename: Andrea Aparecida
authors.initials: AA
authors.lastname: Garcia
authors.forename: Antônio
authors.initials: A
authors.lastname: Pazin-Filho
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage*; D001835:Body Weight; D016009:Chi-Square Distribution; D004636:Emergency Service, Hospital; D017984:Enoxaparin / Q000008:administration & dosage*; D005260:Female; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage*; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D013927:Thrombosis / Q000188:drug therapy*
chemical_list: D000925:Anticoagulants; D017984:Enoxaparin; D006495:Heparin, Low-Molecular-Weight