Bicarbonate buffered dialysate and replacement solutions for CRRT: effect of crystallization on the measured levels of electrolytes and buffer
© The Author(s) 2001
Published: 26 June 2001
The aim of this study was to investigate the impact of the addition of calcium to bicarbonate solutions for CRRT. We tested single bag (SB; bicarbonate and calcium mixed 24 h before testing) and double bag (DB) solutions (mixed immediately before), with and without the addition of 4 mEq/l acetate. Prescribed calcium varied from 0-5 mEq/l. In all test solutions prepared with calcium 5 mEq/l there was a decrease in the measured calcium concentration. SB solutions presented lower concentrations of calcium, compared with DB solutions. When the prescribed calcium concentration was increased, there was a parallel increase in calcium deficit (prescribed-measured). The prescribed calcium showed a negative correlation with sodium and potassium and a positive correlation with pCO2. We also found a positive correlation between calcium deficit and pCO2 (r = +0.59; P < 0.001). The crystallization, as measured by the weight of the crystals, was greater in the SB solutions when compared to the DB solutions (17.7 ± 7.0 mg versus 9.1 ± 1.8 mg, n = 14; P = 0.01). The crystallization correlated with the measured concentration of calcium (r = -0.62; P = 0.02), and pCO2 (r = +0.75; P = 0.002). We also observed a negative correlation between the pH, and the pCO2 (r = -0.82; P < 0.001). Our results suggest that the use of bicarbonate solutions containing calcium as replacement fluids for CRRT is a potentially unsafe procedure.