CAPD: Developments during Changing Times

Editor: Since its first clinical application and the introduction of exchangeable bags in 1976, there have been many decisive steps that have further contributed to the development of continuous ambulatory peritoneal dialysis (CAPD). These steps include technical improvements such as closed systems, or Y-set techniques, and the flush-before-fill principle, as well as more biocompatible dialysis solutions. The image of CAPD has also changed: instead of being regarded as a competitive treatment concept, it has become an integrative or complementary treatment. When analyzing CAPD treatment in our peritoneal dialysis center and comparing treatments from the 1990s with CAPD treatments from the year 2000 and on, we wanted to discern differences in demographic data, treatment duration, residual renal function, infection rate, and clinical parameters. We decided to make the cut at the year 2000 because the switch to multichambered bags with biocompatible dialysis solutions took place during that year. A total of 120 patients on CAPD from 1990 to 2005 were studied retrospectively in the renal outpatient clinic of Heidelberg. Of these patients, 67 were treated before the year 2000 and 53 after the year 2000. All patients were using the double-bag system with the Y-set. Comparisons of the two patient groups showed that the distributions of male and female patients and original renal diseases were approximately the same. The average age of patients that started treatment after the year 2000 was 49.0 years; they were, on average, 5 years older than those treated before the year 2000 (44.0 years, p = 0.03). At the commencement of treatment, the volume of residual diuresis was significantly higher in patients treated from the year 2000 on than in those treated before the year 2000 (1580 vs 1082 mL) but, during the further course of treatment, relative loss of residual renal function and decrease in residual diuresis did not differ between the two patient groups. In contrast to these findings, the data showed a significant decrease in the incidences of peritonitis (the time span of peritonitis-free intervals rose from 20.0 months to 47.6 months) and exit-site infection (the average time span between exit-site infections increased from 23.0 to 33.9 months). Diastolic blood pressure was significantly lower in the patient group treated more recently (81 vs 86 mmHg) but, when comparing systolic blood pressure, no significant difference was observed in the two patient groups. Hemoglobin levels measured at the commencement of treatment were higher (10.9 vs 10.0 g/dL, p > 0.0003), serum creatinine was lower (6.2 vs 8.9 mg/dL, p > 0.0001), and urea tended to be lower (125.7 vs 137.6 mg/dL, NS) in patients treated after the year 2000. The data show that the average age of CAPD patients has increased. This trend has been observed worldwide and has been described in various publications (1,2). Possibly, there will be an increased tendency to consider patients suffering from chronic cardiac insufficiency suitable for the usually better tolerated CAPD treatment as well. Probably, after the year 2000, an increased number of patients with a high volume of residual diuresis received CAPD treatment. In contrast to other observations (3), our observations did not support the conclusion that the biocompatible dialysis solutions used during the years 2000 and on contributed to better maintenance of residual diuresis. The significantly decreased incidence of peritonitis and exit-site infections in the patient group treated more recently can probably be attributed to the use of biocompatible dialysis solutions, which result in a clearly reduced number of glucose degradation products, the unfavorable effects of which on peritoneal mesothelial cells have been proven on various occasions (3,4). The better blood pressure values and higher hemoglobin values in the more recent patient group suggest that treatment has improved, which is probably due to the new treatment guidelines. The lower creatinine level in patients treated from the year 2000 and on is an argument in favor of starting renal replacement therapy at an early stage of the disease (5).