Acid–base balance in acute renal failure and renal replacement therapy

The approach to acid–base balance based on the concept of strong ions, initially proposed by Stewart, is briefly overviewed. The anion gap and the strong anion gap are both discussed. Comments are made on the strong ion difference of fluids administered to patients and their impact on acid–base status will be commented. Renal failure patients have an altered acid–base balance; most commonly, a mixed type of metabolic acidosis (hyperchloraemic, and of a high anion gap) is observed. The consequences of renal metabolic acidosis are described. Finally, the impact of renal replacement therapy on acid–base balance is exposed; different modalities of renal replacement are considered in regard to their alkalinizing performance.