The self-locating catheter: clinical experience and follow-up.

BACKGROUND: The self-locating catheter invented by Nicola Di Paolo has been used increasingly in Italy and elsewhere since 1994, with about a thousand patients currently implanted every year. Twelve grams of tungsten inserted into the tip of the conventional Tenckhoff catheter during extrusion does not significantly change its form, but suffices to keep the tip firmly in the Douglas cavity. OBJECTIVE: The aim of the present study was to confirm our preliminary results in a large population of peritoneal dialysis patients. SETTING: 16 Italian nephrology departments. RESULTS: In addition to confirming the validity of the new catheter, the present results show that patients with the new catheter have fewer episodes of peritonitis, tunnel infection, cuff extrusion, catheter malfunction, obstruction, and leakage. CONCLUSION: The present multicenter control study confirms preliminary results and demonstrates that complications of peritoneal dialysis, such as cuff extrusion, infection, peritonitis, early leakage, and obstruction, are statistically less frequent in patients with self-locating catheters than in patients with classic Tenckhoff catheters.

Crystallization inhibitors in the pathophysiology and treatment of nephrolithiasis.

It is currently agreed that stone formation in the urinary tract requires supersaturation with respect to a given solid phase. However, this principle fully applies only to stones other than calcium-containing stones, in which case compounds acting as inhibitors are postulated to naturally occur in urine. Stone formation would therefore ensue from an imbalance between promoters and inhibitors. The saturation state can be estimated by means of computer model systems based on ab initio calculations, which account for the main soluble complexes formed in urine between relevant cations and anions. This estimates the overall promoting potential of urine. However, in the case of calcium nephrolithiasis, supersaturation does not make a clear-cut separation between normal subjects and patients. Several studies in the last two decades have identified many inhibitors of calcium oxalate and calcium phosphate crystallization, which are classified into the ionic and macromolecular. They have been shown to act on kinetics by interfering with nucleation, growth and aggregation of crystals. Unfortunately, except for citrate, none of the newly discovered substances has been definitely characterized in its molecular composition and structure, type and potency of inhibition, differences in concentration and structure between stone-forming and non stone-forming subjects. Citrate exhibits a dual action in urine, opposing crystal formation by both thermodynamic and kinetic mechanisms. At present it is the only natural inhibitor which can be measured in urine, quantitated as to inhibitory activity and used in medical treatment.

Cost analysis of blood purification in intensive care units: continuous versus intermittent hemodiafiltration.

BACKGROUND: We implemented a program for continuous renal replacement therapies (CRRT) in intensive care units (ICU) based on the cooperative work of dialysis and ICU personnel. Our aim was to report the main details of this program and compare its cost with that of intermittent hemodiafiltration (IHDF). METHODS: The study referred to 181 ICU patients with renal failure. We considered the costs of both technical devices and assisting personnel. CRRT was performed as continuous veno-venous hemodiafiltration (CVVHDF) (24 hr daily); dialysis and ICU nurses shared surveillance. Only dialysis nurses performed IHDF (as acetate-free biofiltration, 4 hr daily) in the ICU. RESULTS: The daily cost of CRRT was Euro 276.70; of which 79% was for devices and 21% was for human resources. Nurse surveillance required 141 min per day, ICU nurses supplied 55% (77 min) and dialysis nurses 45% (64 min). On average, CRRT surveillance required less than 1 min/nurse/hr for both dialysis and ICU nurses. The daily cost of 4-hr IHDF sessions of was Euro 247.83, of which 44% was for technical devices and 56% was for human resources. CONCLUSIONS: The cooperation between dialysis and ICUs improved the use of human resources and allowed us to supply CRRT to all critically ill patients with acute renal failure. The expenditure for CRRT was 12% higher than that for IHDF, due to the cost of technical devices.