Automated peritoneal dialysis with 'on-line'-prepared bicarbonate-buffereddialysate: technique and first clinical experiences

Background. Automated peritoneal dialysis (APD) has the possibility of incr easing the dialysis efficacy by using higher fill volumes, frequent dialysa te exchanges, and tidal techniques. It is then possible to treat patients a dequately without residual renal function. The drawbacks of the required hi gh amounts of dialysis solution of up to 30 litres per session are the high costs of lactate-based dialysate bags and difficulties for the patients in handling these bags. So far, bicarbonate-based peritoneal dialysate, which may be more biocompatible, is only available for CAPD in double-chamber ba gs. In APD this could be overcome by 'on-line' preparation of bicarbonate-b uffered dialysate using advanced technologies originally designed for on-li ne preparation of substitution fluid for haemofiltration. Methods. Four patients without residual renal function were treated with AP D five times weekly in a crossover study design. Patients received standard lactate-based (35 mmol/l) treatment (25 litres per session each) in weeks 1 and 3. In week 2 on-line-produced bicarbonate-buffered (37 mmol/l) dialys ate was used. This dialysate was prepared by an AK 100 Ultra haemodialysis machine. The machine was modified for adding glucose from a 50% concentrate to the desired concentration of 1.7%. Electrolytes, pH, pCO(2), and dialys is efficacy parameters were measured. Microbiological testing was carefully performed. Results. Creatinine clearances, Kt/V, and pCO(2) did not vary between the d ifferent treatment phases, whereas the pH showed a distinct increase during the bicarbonate phase. Repeated determinations of endotoxins and culturing showed no contamination of the dialysate. The composition of the produced dialysate was reproducible with respect to pH, pCO(2), sodium, calcium and bicarbonate, whereas the glucose concentration varied by +/-20%. Conclusions. On-line preparation of PD fluid with the AK 100 Ultra is easy and safe to handle. APD with dialysate containing 37 mmol/l bicarbonate pro vides improved acid-base balance and possibly improved biocompatibility, an d may lead to a significant cost reduction. Further development in order to provide smaller machines and more precise ways of achieving a desired dial ysate glucose concentration is necessary.