02 - Nefrologia 21-4 - Editorial non-oliguric

In the pre-RRT era, many patients with oliguric ARF died of hyperkalaemia or fluid overload. With the advent of RRT, it quickly became apparent that these complications could be averted or treated by the initiation of RRT1. However, just as in chronic renal failure, precise indications for initiation of RRT have never been established2. In the modern era, it is conventional to initiate RRT when oliguria persists after correction of reversible factors such as hypovolaemia, hypoxia and hypotension. How long one should wait after these factors have been corrected remains uncertain, and for many physicians, the decision to initiate RRT depends on the perceived likelihood, or otherwise, that renal function will return rapidly, and the presence or absence of complications of ARF such as hyperkalaemia, fluid overload, or severe metabolic acidosis. No adequate randomised controlled trial (RCT) of initiation of dialysis in ARF has been performed but, in oliguric ARF, the ‘time window’ before onset of severe complications is usually short (of the order of 1 or 2 days) and it seems unlikely that the precise timing is crucial. In non-oliguric ARF, this ‘time window’ may be much longer, and many more patients may recover renal function without RRT, or die of causes unrelated to ARF. A careful evaluation of the indications for RRT is therefore much more important in nonoliguric ARF to avoid unnecessary use of RRT, with its attendant potential complications, and to avoid unnecessary transfer of patients to centres providing RRT.