New reinfusate composition in high UF haemodiafiltration: electrolyte solution combined with bicarbonate

When high-permeability membranes are employed, high UF should be used in order to obtain optimal uraemic toxin removal and to avoid backfiltration. A high UF requires the infusion of an electrolyte solution including Ca2+ and Mg2+ which cannot be associated with bicarbonate in prepackaged solutions because of the risk of precipitation; therefore acetate or lactate are used as buffers. This study evaluated whether bicarbonate can be infused together with an electrolyte solution in high UF HDF, and if so, the clinical advantages that could be obtained by substituting acetate with bicarbonate in the reinfusate. In 12 patients on postdilutional high UF (121 +/- 10 ml/min) HDF (Qb 400, Qd 500 ml/min, dialysate containing Na, 141 +/- 2; K, 2.5; Ca, 3.5; Mg, 0.7; Cl, 111 +/- 2; acetate, 3; bicarbonate, 34 mEq/l; TMP 400 mmHg), an acid bag (Na, 128; K, 4; Ca, 7; Mg, 2; Cl, 141; acetate, 8 mEq/l), and a basic bag (Na, 150; HCO3, 80; Cl, 70 mEq/l), each containing 2 litres, were simultaneously infused through a Y connection. The final composition of reinfusate at the drip-chamber, combined with the above dialysate, allowed a negative intradialytic mass balance for Na, K, Mg and a positive one for Ca, acetate, to maintain prepostdialytic plasma values of these ions as well as bicarbonate close to normal limits. Furthermore, in five high-risk patients, clinical data were evaluated on high UF HDF, infusing a solution containing either acetate or bicarbonate, and an improvement of vascular stability was observed with the bicarbonate reinfusate.(ABSTRACT TRUNCATED AT 250 WORDS)