L. Capotondo

Morphology of the Peritoneal Membrane during Continuous Ambulatory Peritoneal Dialysis

In the last 3 years we performed 52 peritoneal biopsies (PB) in 31 patients on continuous ambulatory peritoneal dialysis (CAPD). Samples of the parietal peritoneum were obtained either during insertion of the catheter or while it was being repositioned or removed. PB was performed in 13 patients before initiating CAPD and in 27 after 7-49 months of CAPD while 7 had PB during peritonitis, and, again, in 5 of these cases, PB was repeated after 1-4 months for light, electron transmission, and scanning electron microscopy. BP after CAPD showed that mesothelial cells were irregularly spaced, and at times we observed alterations in the cellular structure. Rarely were these cells degenerating, while rarefaction and in many cases complete absence of microvilli were observed. In some cases the submesothelial layers showed rarefaction of the connective tissue and sclerosis. During peritonitis, PB showed more alterations with marked degeneration and in some cases necrosis of the mesothelium and alterations of connective tissue. PB performed some months after peritonitis showed only a partial regression of these alterations and sclerotic patches, and no microvilli were noted in the mesothelium.

Phosphatidylcholine and Peritoneal Transport during Peritoneal Dialysis

Peritoneal effluent of patients on chronic ambulatory peritoneal dialysis (CAPD) contains a surface-active material (SAM) made up of phospholipids and showing phosphatidylcholine on thin-layer chromatography. This substance drastically lowers surface tension, helps to repel water and has a lubricating effect. The presence of stratified phosphatidylcholine on the peritoneum might narrow the stagnant dialysate fluid layer and situations which can alter the quantity or composition of SAM may affect peritoneal transport and also, perhaps, the formation of adherences. This led us to verify, experimentally, the presence of phospholipids in basal conditions, after CAPD and during peritonitis and to check if addition of phosphatidylcholine to dialysis liquid is able to modify water transport in patients with low ultrafiltration and peritonitis. Phospholipids in the dialysis effluent of patients who have been on CAPD for a long time are lower than observed in the first days of peritoneal dialysis. A more drastic, significant decrease in phospholipids was observed in patients with low ultrafiltration and in patients with peritonitis. Mean ultrafiltration significantly increases in patients with low ultrafiltration and in those with peritonitis during dialysis exchanges containing phosphatidylcholine (50 mg/l) indicating that the latter is able to restore normal physiological conditions.

Bleeding Tendency of Chronic Uremia Improved by Vascular Factor

Complex hemostatic changes in uremic patients are characterized by platelet distress and prolonged bleeding time. Dialysis corrects platelet function and improves the bleeding time but introduces a tendency to thrombophilia. The uremic patient is thus an excellent model for the evaluation of hemostatic drugs. VUEFFE (VF) is a new hemostatic agent which reduces bleeding time without modifying clotting parameters. Changes in hemostasis and coagulation were studied in 42 hemorrhagic uremic subjects in dialysis or on conservative management. The patients were divided into two groups, one of which was given oral VF and the other oral placebo. 84% of those receiving VF ceased bleeding within 15 days (compared to 25% for placebo) and there was a significant reduction in bleeding time. The drug can be given orally or parenterally, is well tolerated and without side effects, making it suitable for administration to hemorrhagic uremic patients.

THE SELF-LOCATING PERITONEAL CATHETER: FIFTEEN YEARS OF EXPERIENCE

504 During the past 30 years, many attempts have been made to modify the Tenckhoff peritoneal catheter in order to improve its function and efficiency (1–3). The catheter is a serious issue in peritoneal dialysis because it creates a communication between the abdominal cavity and the outside world, thus exposing patients to potentially severe complications, some of which can be reduced using new connection systems (4–6). Nevertheless, these complications tend to limit the use of peritoneal dialysis, although it is more physiological than hemodialysis. It is therefore logical to try and improve the function and biocompatibility of peritoneal catheters (6). Peritoneal catheters often become dislocated, leading to malfunction and need for replacement since it is usually not possible to restore them to their correct position. In 1995, with the aim of preventing this complication, the Nephrology Department of the University Hospital of Siena designed a new catheter, similar to the Tenckhoff catheter in form but with a 12-g high specific weight tungsten cylinder incorporated in the abdominal extremity. We call this new catheter the “self-locating peritoneal catheter” (SLPC) (7,8). Our catheter maintains the original form and internal diameter of the Tenckhoff catheter for most of its length, but the external diameter increases in the last 2 cm, where we do not find the usual perforations. This new catheter has some important physical characteristics: