Effects of lactate-buffered and lactate-free dialysate in CAVHD patients with and without liver dysfunction

Background. Continuous modalities of renal replacement deplete patients of bicarbonate, which is traditionally replaced indirectly by lactate in dialy sate or replacement fluids. We have compared a new lactate-free dialysate ( unbuffered dialysate with separate bicarbonate replacement of dialytic bica rbonate loss) with standard lactate-buffered dialysate in terms of acid-bas e control, lactate accumulation, and hemodynamic stability in patients unde rgoing continuous renal replacement therapy in an intensive care unit. Methods. A nonrandomized crossover cohort study involving 54 patients with multi-organ failure (of whom 19 had significant hepatic dysfunction) was pe rformed. All patients completed 24-hour continuous hemodiafiltration agains t both lactate-buffered and lactate-free dialysate. Arterial pH, blood gase s, bicarbonate, and lactate, veno us sodium, blood pressure, and inotrope r equirements were measured before and at six hourly intervals during the fir st 24 hours of dialysis against each dialysate. Results. Lactate-free dialysate provided more rapid control of acidosis tha n lactate buffered with less total administration of buffer than that given during the lactate-buffered period (total mmol bicarbonate vs, total mmol lactate + bicarbonate). Lactate accumulation was slight in both periods, bu t was higher during lactate-buffered continuous venovenous hemodiafiltratio n (CVVHD). The mean arterial pressure rose during lactate-free dialysis wit h decreased inotrope doses and fell during lactate-buffered dialysis with i ncreased inotrope requirement. Results in patients with liver dysfunction w ere not significantly different from those without it. Conclusions. Over the time scale of 24 hours, lactate derived from continuo us dialysis circuits is efficiently cleared from the blood of most patients with multi-organ failure, but with less effect on systemic acidosis than i s produced by equivalent amounts of bicarbonate.