Clinical impact of residual function in haemodialysis.

The term residual renal function (RRF) refers to the small renal function activity persisting in patients affected by chronic renal failure in the uraemic phase. It is associated with better clinical features as well as better laboratory values (1). Nevertheless, RRF usually decreases with variable rates over time; in particular peritoneal dialysis is associated with a better preservation of RRF than haemodialysis.

Residual renal function and post dialysis urea rebound.

Kt/v is used to estimate haemodialysis prescription and treatment adequacy and usually does not include evaluation of urea rebound. In addition urea clearance provided by the presence of residual renal function (RRF) is additive to dialytic urea clearance. Rebound is a phenomenon involving other molecules such as creatinine and phosphorus. The aim of this study was to investigate the role of RRF on post dialysis urea, creatinine and phosphorus rebounds. We investigated 7 patients with RRF (group 1) and 7 uraemic anuric patients (group 2). Urea rebound was lower in group 1 than group 2: 9.5 +/- 4% vs 18 +/- 7% (p = 0.04). Creatinine rebound and phosphorus rebound were similar in both groups 15.2 +/- 9% group 1 vs 14.6 +/- 5% group 2 (p = NS) and 16.7 +/- 7% group 1 vs 20 +/- 7% group 2 (p = NS) respectively. Our data suggest Kt/v calculated without considering rebound overestimates haemodialysis efficacy.

Clinical impact of residual renal function on patients starting dialysis treatment.

We describe our clinical experience of monitoring residual renal function of patients on regular dialysis treatment as residual renal function can play an important role in the management of patients undergoing regular dialysis. With active residual renal function it is possible to delay the start of haemodialytic programmes. In managing dialysis treatments, it is important to maintain residual renal function by preventing hypotensive events. It is known that in acute renal failure intradialytic hypotension is able to reduce the recovery of renal function. Out patient follow-up plays an important role for these patients. This paper will also discuss the use of biocompatible membranes during dialysis. The outcome is that they are not associated with better maintenance of residual renal function.

Haemodialysis in acute renal failure.

Haemodialysis in acute renal failure differs from chronic uraemia. We describe our clinical experience comparing tolerance to dialysis and dialysis efficacy of bicarbonate haemodialysis in comparison to haemofiltration. Both provide adequate treatment for ARF, Kt/v 0.6 +/- 0.1, URR 56% in bicarbonate haemodialysis compared to Kt/v 0.4 +/- 0.06, URR 60% in haemofiltration. Clinical outcome was the same in both groups, in particular the overall survival was satisfactory at about 70%. These results are likely to reflect close control of these patients by nursing staff committed to haemodialysis in acute renal failure.