DYSKALEMIAS IN PERITONEAL DIALYSIS: their causes and treatments

Despite general physicist principles applied in peritoneal dialysis and hemodialysis are the same ones, the rate of potassium removal is markedly slower in the former (1). Peritoneal clearance for potassium averages about 17 ml/minute for intermittent peritoneal dialysis (IPD), and approximately 7 ml/minute for continuous ambulatory peritoneal dialysis (CAPD). These values are between those for urea and creatinine clearances. Interestingly, during the first hour of a dwell, potassium clearance is higher (24 ml/minute) than that of the remaining period and the most probable explanation for these high values is the release of potassium from the cells that line the peritoneal cavity. This release may be promoted by the initial low pH and / or by the hyperosmolality of the instilled dialysate (2). Standard peritoneal dialysis solutions contain no potassium (3,4). In patients with severe hyperkalemia and total body potassium excess, peritoneal dialysis is inefficient to remove adequate amounts of potassium and, therefore, hemodialysis is recomended to treat such emergency (1). In IPD, as in hemodialysis, during the first one to two hours, there is a more rapid fall in plasma potassium concentration which is due chiefly to a shift of potassium into the cells (1). Subsequently potassium concentration decreases as the result primarily of potassium removal. During intermitten