title: Fractional urea clearance in continuous ambulatory peritoneal dialysis: effects of volume disturbances.
abstract: The effects of volume disturbances on the KT/V were investigated prospectively in 133 consecutive urea clearance studies on patients on continuous ambulatory peritoneal dialysis (CAPD). Four subjects (group A) had fluid loss (actual weight < dry weight), 57 (group B) were studied on the basis of their dry weight, 58 (group C) had moderate fluid excess (0.5% of dry weight), and 14 patients (group D) had severe fluid excess (> 5% of dry weight). The KT/V was calculated on the basis of dry weight and actual weight with V obtained from the Watson anthropometric formulae which were applied either uncorrected or with a correction for changes in body water from dry weight conditions. The groups compared by variance analysis. The following weekly KT/V estimates were obtained: (1) using dry weight V: group A 1.81 +/- 0.17, group B 2.0 +/- 0.59, group C 1.79 +/- 0.46, group D 1.85 +/- 0.37 (no difference between groups); (2) using uncorrected actual weight V: group A 1.85 +/- 0.15, group B 2.05 +/- 0.59, group C 1.77 +/- 0.45, group D 1.78 +/- 0.37 (group B had a higher KT/V than group C, p < 0.05), and (3) using corrected actual weight V: group A 1.93 +/- 0.14, group B 2.05 +/- 0.59, group C 1.70 +/- 0.43, group D 1.63 +/- 0.36, (group B had a higher KT/V than either group C or group D, both at p < 0.01). In CAPD, fluid deficit is rare and causes a small increase in KT/V, whereas fluid retention is frequent and causes a decrease in KT/V. This decrease is pronounced in patients with severe fluid excess. The uncorrected Watson formulae underestimate V and, consequently, overestimate KT/V in CAPD patients with fluid excess.
authors.affiliation: Renal Section (111 C) Veterans Administration Medical Center, Albuquerque, NM 87108, USA.
authors.forename: A H
authors.initials: AH
authors.lastname: Tzamaloukas
authors.forename: G H
authors.initials: GH
authors.lastname: Murata
authors.forename: A
authors.initials: A
authors.lastname: Dimitriadis
authors.forename: S
authors.initials: S
authors.lastname: Voukiklari
authors.forename: S
authors.initials: S
authors.lastname: Antoniou
authors.forename: D
authors.initials: D
authors.lastname: Malhotra
authors.forename: J
authors.initials: J
authors.lastname: Kakavas
authors.forename: N V
authors.initials: NV
authors.lastname: Dombros
authors.forename: N
authors.initials: N
authors.lastname: Nicolopoulou
authors.forename: E V
authors.initials: EV
authors.lastname: Balaskas
mesh_terms: D000368:Aged; D001834:Body Water / Q000502:physiology*; D001835:Body Weight / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010531:Peritoneal Dialysis, Continuous Ambulatory; D011446:Prospective Studies; D014508:Urea / Q000378:metabolism*
chemical_list: D014508:Urea