Longitudinal comparison of intermittent versus continuous ambulatory peritoneal dialysis, in the same patients.

Twelve patients who had been on intermittent peritoneal dialysis (IPD) for an average of 18.3 months each, were switched to continuous ambulatory peritoneal dialysis (CAPD). CAPD experience is now 118 patient months (average 9.8 months per patient), and ten patients remain on CAPD. Serum chemistries reflected the change to continuous dialysis with a fall in serum creatinine, potassium, uric acid, phosphate, and BUN. The total CO2 rose markedly, indicating prevention of the recurrent metabolic acidosis experienced in IPD. Serum phosphate fell significantly into the normal range. Serum calcium rose slightly in six patients and significantly in three others. Serum alkaline phosphatase activity rose in seven patients, without development of clinical evidence of bone disease. Mean hematocrit values were higher in most patients of CAPD, but fell again after one year. The transient nature of the rise in hematocrit suggests that improved volume control, as reflected in blood pressure changes, may play a role in the frequently reported increase in hematocrit on CAPD. Despite an increase in peritonitis rate (one infection per 5.9 patient months on CAPD, versus one per 12.2 patient months on IPD), CAPD offers several distinct advantages over IPD, especially in control of uremic acidosis, phosphate retention, blood pressure and fluid management, as well as an overall improvement in physical and psychosocial well-being.