Acid-base balance in dialysis patients

Acid-base balance in dialysis patients is achieved by a unique interaction between the patient and the particular mode of renal replacement therapy. The prevailing serum HCO3- in these patients is determined not only by endogenous acid production but also by the nature of the dialysis prescription and, in particular, by the bicarbonate (or lactate) concentration of the bath solution. Despite the technical advances in dialysis therapy, pre-dialysis serum HCO3- remains lower than normal in most patients receiving hemodialysis and in many patients receiving peritoneal dialysis. A central question is whether even a mild degree of acidosis increases morbidity and mortality in patients with end-stage renal disease. This article reviews the nature of the acid-base equilibrium achieved in patients receiving hemodialysis or peritoneal dialysis, addresses the question of whether correction of acidosis is beneficial, and reviews the techniques for increasing serum HCO3- in these patients. Based on the information available, it is clear that the patient with a serum HCO3- less than 19 mEq/L should be assessed to determine the cause of the low value and steps undertaken to correct the acidosis. Whether patients with steady-state values between 19 and 24 mEq/L require specific attention remains an issue for further investigation.