Post-dialysis Solutes Rebound: Comparison of Two Protocols for Hemodialysis

The blood urea concentration is artificially low immediately following high-efficiency dialysis. Post-dialysis urea rebound correlates with hemodialysis efficiency, and is inversely correlated with dialysis treatment time. We evaluated the effect of variation in the length of hemodialysis treatment on urea, creatinine and other solutes rebound. We used two protocols for hemodialysis, using 500-ml dialysate/min and similar dialyzed blood volume. Protocol A: hemodialysis with blood flow of 300 ml/min for four hours; protocol B: hemodialysis with blood flow of 400 ml/min for three hours. Fifteen stable anuric patients with end- stage renal disease (ESRD) were hemodialysed using each protocol, three sessions a week, for a period of two weeks. The mean dialyzed blood volume in protocol A and B was 66 +/- 4 and 67 +/- 4.8 liters/session, respectively. The mean blood flow in protocol A was 286 +/- 22 ml/min, and in protocol B was 395.3 +/- 13 ml/min. The mean urea pre and immediately post dialysis in patient using protocol A was 20.5 +/- 5.4 and 5.55 +/- 2.2 mmol/L, respectively. While in protocol B it was 19.8 +/- 4.6 and 6 +/- 1.68 mmol/L. The mean urea, one hour post dialysis, in protocol A was 6.51 +/- 1.9 Vs 8.04 +/- 2.6 mmol/L in protocol B (P value < 0.003). The percent rebound of mean blood urea concentration in protocol A and B one hour post dialysis was 17.3% vs 34%, respectively. Predialysis creatinine in protocol A and B was 894 +/- 156.8 vs 907.9 +/- 163 umol/L, respectively (P= 0.4). The immediately post-dialysis creatinine in protocol A and B, was 317+/- 98.4 vs 331 +/- 72.0 micromol/L (P = 0.4), while one hour later it was 398.6 +/- 104.0 vs 442.6 +/- 107.2 micromol/L, respectively (P value < 0.007). The percent rebound of creatinine was 25.6% in protocol A vs 33.5% in protocol B. These results show significant difference between the two protocols, and confirm increased rebound of urea and creatinine one hour post dialysis with shorter time of dialysis treatment.