Prescribing Hemodialysis Using a Weekly Urea Mass Balance Model

• Published in: Blood purification Vol. 9; no. 5-6; pp. 271 - 284
• Main Authors: Leypoldt, John K., Kablitz, Carl, Gregory, Martin C., Senekjian, Harry O., Cheung, Alfred K.
• Format: Journal Article
• Language: English
• Published: Basel, Switzerland Karger 1991
• Subjects: Adult; Aged; Aged, 80 and over; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Blood Urea Nitrogen; Body Fluid Compartments; Emergency and intensive care: renal failure. Dialysis management; Female; Humans; Intensive care medicine; Kidney Failure, Chronic - metabolism; Kidney Failure, Chronic - therapy; Kinetics; Male; Medical sciences; Middle Aged; Models, Theoretical; Original Paper; Proteins - metabolism; Renal Dialysis; Urea - metabolism; Adequacy of hemodialysis; Urea kinetic modeling; Protein catabolism; Proteins; Extrarenal dialysis; Urea; Urinary system disease; Hemodialysis; Catabolism; Calculating method; Resuscitation
• ISSN: 0253-5068; 1421-9735
• DOI: 10.1159/000170025

Prescribing hemodialysis by monitoring only predialysis BUN concentrations is not sufficient to guarantee adequate therapy. Results from the National Cooperative Dialysis Study have suggested that hemodialysis therapy is adequate if the protein catabolic rate is maintained greater than 1 g/day/kg body weight and simultaneously if sufficient hemodialysis is prescribed to maintain either a time-averaged BUN concentration (TACurea) less than 50 mg/dl or a value of Kt/V greater than unity. In the present study mathematical relationships were derived from a weekly urea mass balance model that permit an evaluation of TACurea and of protein catabolism via the urea generation rate (G) without the need for conventional urea kinetic modeling. The parameters TACurea and G were simply calculated from a midweek predialysis BUN concentration (BUNMw) by:TACurea = 0.7 BUNMw G =0.7BUNMw(Kr+Kdτ/T) where Kr, Kd,τ and T denote residual renal urea clearance, dialyzer urea clearance, number of minutes of hemodialysis per week, and number of minutes total in a week, respectively. Clinical results from 139 modeling sessions on 91 patients demonstrated that TACurea and G derived from urea kinetic modeling correlated highly with those calculated from the above equations (r = 0.96 and 0.94, respectively). It is concluded that individualized hemodialysis prescription and adequacy of therapy can be assessed by monitoring TACurea and G by calculation from a weekly urea mass balance model.