Treatment of Metabolic Alkalosis in Renal Failure

The renal failure patient with metabolic alkalosis presents a unique therapeutic challenge, He will most likely have become alkalotic because of vomiting, gastric aspiration, excess administration of bicarbonate or its precursors, or treatment with calcium carbonate. More unusually he may become alkalotic while receiving magnesium or aluminum hydroxide along with sodium polystyrene sulfonate resin for the treatment of hyperkalemia (1). In any event, mild alkalosis is often corrected by removing the initiating cause, and the concomitant renal failure tends to bring about acidosis anyway. In some cases, an inhibitor of gastric secretion such as cimetidine or ranitidine may be usefully given, not to correct already existing alkalosis, but to prevent further losses of gastric acid (2). Normal saline can be given to dehydrated patients who can tolerate fluid administration. When alkalosis becomes severe, usually at a pH above 7.6 or a serum bicarbonate concentration higher than 40 to 45 mmoles/L, more aggressive treatment is required (3). At these levels, according to one surgical study, mortality increases considerably from 41% at a blood pH of 7.56 to 80% at a pH of 7.70 (4). Severe alkalosis depresses the central nervous system and increases neuromuscular excitability. It causes hypokalemia, provokes cardiac arrhythmias, and enhances digitalis intoxication. Alkalosis also increases binding of oxygen to hemoglobin, preventing the release of oxygen to peripheral tissues. The compensatory respiratory depression further decreases tissue oxygenation (5,6). How then should such aggressive treatment be carried out? It goes without saying that certain measures are ineffective or contraindicated in renal failure. For example, in the absence of normal renal function acetazolamide is ineffective. Potassium chloride, in the presence of renal failure, cannot be readily given unless there is accompanying hypokalemia. Neither should arginine hydrochloride be given, because the The International Journal Of Artificial Organs / Vol. 10/ n 5, 1987/ pp. 284-286