HEMODIALYSIS WITH ACETATE, DL-LACTATE AND BICARBONATE - A HEMODYNAMICAND GASOMETRIC STUDY

Using invasive techniques we have studied various hemodynamic and gaso metric parameters in the course of hemodialysis (HD) with different bu ffers in an animal model. HD sessions of 180 minutes at zero ultrafilt ration were carried out on three groups of eight uremic dogs each, und er anesthesia and constant mechanical ventilation. The three groups di ffered only in the buffer used: acetate (Group AC), equal proportions of DL-lactate and acetate (Group AC+LA), and bicarbonate (Group BC). N o hemodynamic changes were seen in Group BC. In the AC and AC+LA group s we observed on minute 1 a decrease of the mean blood pressure (MBP) and of the systemic vascular resistances (SVR). These parameters retur ned to baseline values within the first 30 minutes in Group AC+LA. In Group AC the SVR also returned to baseline values after the minute 30, but the MBP remained below baseline throughout the study period, toge ther with cardiac index and left ventricular stroke work index decreas es. Only in Group AC did we see a flattening of the ventricular functi on curves. Only in this Group was there a decrease of the arterial oxy gen pressure (PaO2) with an associated increase of the alveolo-arteria l and arterio-venous O-2 differences. The O-2 consumption was not modi fied in any of the groups. Acetate as a single buffer induces hemodyna mic instability through peripheral vasodilation and reduction of myoca rdial contractility. The myocardial depression induced by acetate, in its turn, causes a reduction in PaO2. The mixed acetate+lactate buffer is hemodynamically better tolerated than acetate as single buffer, as it induces only vasodilation.