title: Relationship between interdialytic weight gain and acid-base status in hemodialysis by bicarbonate.
abstract: The aim of this study was to determine the relationship between interdialytic weight gain and acid-base balance pre- and posthemodialysis in uremic patients undergoing hemodialysis with a high bicarbonate dialysate (39 mmol/L). To this end we studied 8 stable uremic patients on regular hemodialysis thrice weekly who had stable hematocrit values for at least 3 months, similar clinical characteristics including dry weight but widely varying interdialytic weight gain. Arterial line blood samples were collected anaerobically in heparinized syringes pre- and posthemodialysis in 4 consecutive hemodialysis sessions for the determination of pH, Paco2, and HCO3. Prehemodialysis values (mean +/- SD) were pH = 7.34 +/- 0.03, Paco2 = 36.43 +/- 1.4, and Hco3 = 20.1 +/- 1.55. Posthemodialysis values were pH= 7.47 +/- 0.02, Paco2 = 38.72 +/- 2.0, and HCO3 = 27.73 +/- 1.72. In other words, patients were moderately acidemic prior to and moderately alkalemic after the hemodialysis session. Of note, a significant negative correlation was revealed between the interdialytic weight gain and the values of prehemodialysis blood pH (r = -0.721, p < 0.001) and HCO3 (r = -0.836, p < 0.001) and posthemodialysis pH (r = -0.533, p < 0.001), Paco2 (r = -0.623, p < 0.001) and HCO3 (r = -0.815, p < 0.001), suggesting an important role of the interdialytic weight gain on acid-base equilibrium of uremic patients undergoing hemodialysis. Thus, patients with high interdialytic weight gains may require higher bicarbonate concentrations to achieve normal acid-base status whereas patients with low interdialyic weight gains may require lower bicarbonate concentrations to prevent alkalemia at the end of dialysis.
authors.affiliation: Department of Nephrology, Aretaieon University Hospital, Athens, Greece.
authors.forename: B
authors.initials: B
authors.lastname: Agroyannis
authors.forename: C
authors.initials: C
authors.lastname: Fourtounas
authors.forename: H
authors.initials: H
authors.lastname: Tzanatos
authors.forename: A
authors.initials: A
authors.lastname: Dalamangas
authors.forename: D V
authors.initials: DV
authors.lastname: Vlahakos
mesh_terms: D000136:Acid-Base Equilibrium; D000138:Acidosis / Q000503:physiopathology; D000368:Aged; D006801:Humans; D008875:Middle Aged; D006435:Renal Dialysis; D014511:Uremia / Q000503:physiopathology / Q000628:therapy*; D015430:Weight Gain