title: Assessment of the length of each hemodialysis session by on-line dialysate urea monitoring.
abstract: Hemodialysis (HD) prescription is usually based on the periodical measurement of the Kt/V achieved in a midweek dialysis session. The purpose of the study was to assess the duration of each HD session to achieve a target dose of dialysis. This allowed to determine whether a given dialysis session may be considered representative of the other HD sessions. Seventy-two HD sessions were studied in 4 stable patients, who were randomly dialyzed during 3 consecutive periods, each lasting 2 weeks, using a different blood flow rate (Qb) in each period: 400, 300 or 200 ml/min. All HD were prolonged to achieve an on-line dialysate urea monitor (UM) Kt/V of 1.2. The UM Kt/V was compared with the Kt/V calculated using pre-HD, post-HD and rebound (45 min post-HD) plasma water urea concentrations. Comparison of the duration of the second midweek dialysis session with the length of the other HD showed 95% concordance intervals (+/-2 SD) of +/-21.08 min for Qb 400, +/-26.88 min for Qb 300 and +/-37.02 min for Qb 200 ml/min. The 95% concordance intervals for whole body urea clearance were +/-32.0, +/-20.36 and +/-15.62 ml/min for Qb 400, 300 and 200 ml/min, respectively. No differences were observed between UM Kt/V and blood-based double-pool Kt/V obtained by the second-generation Daugirdas (1.18 +/- 0.08) and Garred (1.19 +/- 0.08) Kt/V formulas. In conclusion, a great variability was observed between different HD sessions with regard to the whole body urea clearance and the time required to attain a target Kt/V even when the HD characteristics remained constant. The length of every HD required to achieve a target dose of dialysis can be assessed by on-line dialysate urea monitoring.
authors.affiliation: Department of Nephrology, Reina Sofia University Hospital, Avda Menendez Pidal s/n, E-14004 Cordoba, Spain. ghernandez@nexo.es
authors.forename: G
authors.initials: G
authors.lastname: Hernandez-Herrera
authors.forename: A
authors.initials: A
authors.lastname: Martin-Malo
authors.forename: M
authors.initials: M
authors.lastname: Rodriguez
authors.forename: P
authors.initials: P
authors.lastname: Aljama
mesh_terms: D000368:Aged; D015312:Hemodialysis Solutions / Q000737:chemistry*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D006435:Renal Dialysis / Q000295:instrumentation / Q000379:methods*; D014508:Urea / Q000032:analysis* / Q000097:blood
chemical_list: D015312:Hemodialysis Solutions; D014508:Urea