P1116IS DIALYSIS ADEQUACY AMELIORATED AFTER INCREASING DIALYSATE FLOW RATE IN CHRONIC HEMODIALYSIS? - ONE YEAR FOLLOW-UP

Abstract

Abstract Background and Aims Hemodialysis (HD) adequacy, as measured by single pool (sp) Kt/V and urea reduction rate (URR), has been reported to be ameliorated after increasing dialysate flow rate (DFR). However, this is a matter of controversy as no benefit has been observed with dialyzers incorporating features to enhance dialysate flow distribution. We investigated the effect of increasing DFR on dialysis adequacy and on various laboratory parameters. Method Twenty-three patients, M/F=20/3, aged 65(44-89) years, dialyzed thrice weekly for 50(6-274) months, using polysulfone low flux dialyzers, participated in an annual randomized cross-over study. Patients were dialyzed with DFR of 500 ml/min and 700 ml/min for 6 consecutive months respectively, according to their usual dialysis prescription and with ultrafiltration volumes according to clinical need. Blood was sampled before and at the end of midweek sessions at the beginning of the first, 7th and 13rd month for urea, creatinine, potassium, sodium, albumin, total Ca and phosphate (sP). URR, spKt/V, corrected for albumin Ca(sCa) and sCa x sP product (CaxP) values were calculated. Results Under both 500 and 700 ml/min DFRs used, the expected post-dialysis alterations were found: decreased values in serum urea (respectively 161,5±38,0 to 49,9±20.1-p<0,001 and 140,3±30 to 56,0±20.4 mg/dl-p<0,001), creatinine (respectively 10,2±2 to 3.9±1,2-p<0,001 and 10,2±3,3 to 4,1±1,6 mg/dl-p<0,001), potassium (respectively 5,2±0,7 to 3,7±0,3 mM-p<0,001 and 5,3±0,6 to 3,9±0,3mM-p<0,001) and phosphate (respectively 5,4±1,7 to 2,9±0,6-p<0,001 and 5,7±1,6 to 2,6±0,6 mg/dl-p<0,001); increased values in serum albumin (respectively 4,3±0,4 to 4,7±0,4 g/dl-p=0,001 and 4,2±0,3 to 4,7±0,4 g/dl-p<0,001) and sCa (9,1±0,7 to 11,3±0,9 mg/dl-p<0,001 and 8,7±0,6 to 9,9±0,7 mg/dl-p<0,001). After increasing DFR from 500 to 700 ml/min we observed no reductions in pre-dialysis serum urea and creatinine levels or URR (68,6±8,1% to 69,9±7,9%-p=NS) and Kt/V (1,41±0,4 to 1,42±0,3-p=NS) values. However, under DFR of 700ml/min post-dialysis sCa, sP and sCa x sP product values were always lower compared with those under DFR of 500 ml/min (respectively 9,9±0.7 vs 10,8±0.8 mg/dl-p<0,001, 2,6±0,6 vs 2,9±0,6 mg/dl-p=0,02 and 25,6±6,2 vs 30,9±6,7 mg2/dl2-p<0,001). Conclusion DFR increase from 500 to 700 ml/min did not lead to favorable effects on dialysis adequacy but resulted in post-dialysis amelioration of serum calcium and phosphate levels and may be useful in cases of hypercalcemia, hyperphosphatemia and calcifications. DFR increase utility needs further investigation in patients with disorders of calcium-phosphate metabolism.