Why the double-bag system still remains the best technique for peritoneal fluid exchange in continuous ambulatory peritoneal dialysis.

Since March 1979 (the Italian-French-Spanish meeting in Turin), we have been using the double-bag system for peritoneal fluid exchange in patients on continuous ambulatory peritoneal dialysis (CAPD). This technique, subsequently followed by many others because of the advantages to the patients, still represents the best tool in bag-exchange procedure, because it satisfies the following characteristics: single luer-lock connection; flush-before-fill; simple, safe, and aseptic manipulation; short training period; no carrying bag; good patient acceptance; and low incidence of exogenous peritonitis. In 13 years with 237 patients selected for double-bag treatment, we have observed an incidence of 1 episode of peritonitis every 26.6 patient-months. Few clinical CAPD-related complications like hypotension and alterations of Ca-P metabolism were observed, probably as a result of more personalized peritoneal fluid with high Na+ (136 mEq/L) and Ca2+ (3.5 mEqL) concentrations. In the meantime, we have also had available plasticizer-free bags, which eliminated one of the main risk factors in peritoneal sclerosis. The utilization of the plasticizer-free double-bag system, currently adopted by numerous other centers, still remains the best option from a clinical and psychological viewpoint of the patients on CAPD.