title: Urinary excretion as an input variable in volume kinetic analysis of Ringer's solution.
abstract: The disposition of fluid given by i.v. infusion can be studied by fitting one-volume and two-volume kinetic models to the fractioned dilution of blood haemoglobin and serum albumin concentrations over time. However, the two-volume model is sometimes associated with a high standard error in estimating the size of the secondary (peripheral) body fluid space, V2. To examine if a fixed elimination rate constant (kr) determined by urinary excretion can be used to make the model more stable, we infused Ringer's acetate 25 ml kg-1 over 30 min in 15 male volunteers (mean age 35 yr). A fixed kr increased the total residual error when curve-fitting was applied according to the one-volume model. The two-volume model was improved when there was a strong within-patient covariance between kr and V2 (r2 < or = -0.98). The size of V2 was 10 litre when the fixed and model-generated values of kr agreed fully.
authors.affiliation: Karolinska Institute, Department of Anaesthesia, Söder Hospital, Stockholm, Sweden.
authors.forename: R G
authors.initials: RG
authors.lastname: Hahn
authors.forename: D
authors.initials: D
authors.lastname: Drobin
mesh_terms: D000328:Adult; D005440:Fluid Therapy; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007262:Infusions, Intravenous; D007552:Isotonic Solutions / Q000493:pharmacokinetics*; D008297:Male; D008954:Models, Biological; D012709:Serum Albumin / Q000378:metabolism; D014556:Urine
chemical_list: D006454:Hemoglobins; D007552:Isotonic Solutions; C028570:Ringer's acetate; D012709:Serum Albumin