High sodium bicarbonate and acetate hemodialysis: Double-blind crossover comparison of hemodynamic and ventilatory effects

Abstract

The superiority of bicarbonate dialysis (Bi HD) over acetate dialysis (Ac HD) using a high sodium dialysate has not been established to our knowledge. We compared to Bi HD to Ac HD over 6 weeks each in ten stable patients using a double-blind crossover design and a dialysate sodium concentration of 140 mEq/liter. The dialyzer, delivery system, and disalysate constituents were identical except for the substitution of Bi or Ac. Interdialytic weight gain, pre- and post-HD blood pressures, and heart rates were also comparable in the two protocols. Beginning of the week pre-HD serum Bi was greater during Bi HD than Ac HD (19.1 +/- 0.9 vs. 15.1 +/- 0.8 mEq/liter, P less than 0.001); post-HD Bi values were also higher during Bi HD. Similarly, pre-HD pH was also greater with Bi HD 7.40 +/- 0.012 vs. 7.35 +/- 0.001 U, P less than 0.01). The number of adverse symptoms and signs were similar during each protocol (2.0 +/- 0.65 for Bi HD vs. 2.5 +/- 0.5 for Ac HD episodes/patient/6 weeks, NS). However, fewer therapeutic interventions were required during the Bi HD protocol (1.5 +/- 0.43 vs. 3.1 +/- 0.6 treatments/patient/6 weeks, P less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

The Arterial Oxygen Extraction Tension and Oxygen Compensation Factor during Acetate and Bicarbonate Dialysis

“…A higher HCOj concentration in plasma during bicarbonate dialysis might have induced a respiratory compensation for the metabolic alkalosis, producing hypoventi lation and an increment in arterial pCOi. These suggestions are supported by the inves tigation of Henrich et al [8], Thus, in this regard bicarbonate dialysis did not seem to be of any advantage over acetate in controlling dialysis-induced hypoxemia [2. 7.9, 10], Oxy gen delivery to the peripheral tissue depends on the oxygen affinity of hemoglobin.…”

Blood Pressure, Ventilation and Lipid Imbalance during Hemodialysis: Effect of Dialysate Composition

“…112], and a greater tolerance to ultrafiltration [14,19,26,46,101] as com pared to acetate dialysis, except in acute renal failure [51]. Similarly, bicarbonate dialysis has been reported to be associated with a lower incidence of symptomatic postural hy potension in patients with autonomic insuffi ciency dialysed with a low Na+ concentration ( 133 mcq/1) in the dialysate [95], It should be noted, however, that during acetate and bi carbonate dialysis with a high dialysate Na+ concentration (140 nteq/1), there was no dif ference in the supine or upright blood pres sure response of individuals with [95] or without [27] autonomic insufficiency.…”

“…57a]. However, such a mechanism does not appear to be an impor tant mediator of the drop in pOi for the fol lowing reasons: (1) hypoxemia can be tempo rally dissociated from the changes in sys temic pH [14,15] and (2) hemodialysis with bicarbonate-containing dialysate can be asso ciated with either hypoventilation and hyp oxemia [27,54,62,94,103] or no change in ventilation and pC>2 [3,41,56,60] despite comparable degrees of systemic alkalosis. Such discordant responses suggest additional factors dependent on the dialysate composi tion or delivery system (vide infra).…”

“…the decrease in serum osmolality brought about by the process of diffusion could lead to a further loss of intravascular fluid (IVF) by causing the latter to redistrib ute into the interstitial and intracellular com partments [21][22][23][24][25], The latter course of events would therefore tend to oppose the process of refilling or replenishment of the IVF by interstitial fluid which is expected to occur as the plasma oncotic pressure rises [21][22][23][24][25]. Under certain conditions, however, such an intravascular volume replenishing process can be favorably influenced by var ious other factors, such as the state of extra cellular fluid volume prior to dialysis, the tonicity or sodium concentration of the dialysate and the degree of variation in plasma osmolality [25][26][27][28][29]104], In this regard, an expanded extracellular fluid volume prior to hemodialysis [25], bicarbonate dialysate [ 112], a high dialysate Na concentration [21][22][23][24][25][26][27]104], or a stable plasma osmolality and oncotic pressure [28,29,104] will tend to minimi7.c transcompartmental fluid shifts or enhance the intravascular refilling process, thereby ameliorating the reduction in preload or cardiac output. Symptomatic hypotension would, therefore, tend to occur less fre quently under those conditions [18][19][20][21][22][23][24][25][26...…”

Hemodynamic Stability during Different Forms of Dialysis Therapy: A Pathogenetic Analysis

“…Concerning plasma osmolality in relation to the dialysate sodium concentration, many authors have shown that the blood pressure stability during UF+HD is improved with higher dialysate sodium concentrations, espe cially in acetate-buffered dialysis [62][63][64], As was already mentioned, the improved hemo dynamic stability at higher dialysate sodium concentrations is probably mainly the result of a better preservation of plasma volume [ 16. 18].…”