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.

Effect of hypertriglyceridemia correction by omega-3 fatty acids on peritoneal transport in continuous ambulatory peritoneal dialysis patients.

Lipid abnormalities, both hypercholesterolemia and particularly hypertriglyceridemia (hyperTg), are common in long-term continuous ambulatory peritoneal dialysis (CAPD) patients. Hyperviscosity and rheological alterations have been proposed as major hemodynamic problems in hyperTg patients. The aim of this study was to evaluate whether a hyperTg correction by employing omega-3 fatty acids (omega-3) affects peritoneal transport. Six hyperTg (> 700 mg/dL) CAPD patients were treated with 2-3 g/day of omega-3 until normal Tg values were achieved. The assessment of peritoneal dialysis efficacy was performed by evaluating the peritoneal equilibration test (PET) before omega-3 supplementation, when normal Tg levels were reached, and 3 weeks after stopping therapy when hyperTg returned. When normal Tg levels were reached, a small but significant improvement of urea and creatinine D/P was noted: 0.85 +/- 0.05 versus 0.93 +/- 0.03 (p < 0.05) and 0.78 +/- 0.03 versus 0.86 +/- 0.05 (p < 0.05), respectively, with negative correlation between D/P of urea and Tg. These preliminary data demonstrate that a hyperTg correction with omega-3 may induce an increase in peritoneal transport of small molecules in CAPD.

Peritoneal sclerosis: role of plasticizers in stimulating interleukin-1 production.

The role of plasticizers (PLS) in inducing water flow inhibition and peritoneal sclerosis has been demonstrated in both in vivo and in vitro studies. Interleukin-1 (IL-1) has been shown to be a regulator of fibroblast proliferation as well as collagenase production. The aim of this study was to evaluate the role of PLS in stimulating mononuclear cell IL-1 secretion. Two cultures containing 10(3) cells/mL were obtained from 14 healthy subjects. One was used as the control, and the other was mixed with diethylhexylphthalate (DEHP) to reach a final concentration of 2.8 x 10(-3) M. After 4 hours the samples were centrifuged, and the supernatants were tested by radioimmunoassay for IL-1 alpha and IL-1 beta. The results showed a significant increase in both IL-1 alpha and IL-1 beta production in DEHP-stimulated cells in comparison to the controls: 42.6 +/- 15.4 versus 29.3 +/- 10 ng/L (p < 0.015) for IL-1 alpha, and 153.6 +/- 55 versus 113.6 +/- 32 ng/L (p < 0.03) for IL-1 beta In conclusion, PLS added to mononuclear cells were able to induce IL-1 secretion. This mechanism could be responsible, at least in part, for the development of peritoneal sclerosis. Thus the employment of plasticizer-free bags should be elective in peritoneal dialysis.

Combined hemodialysis-hemoperfusion in the treatment of secondary hyperparathyroidism of uremic patients.

Hyperparathyroidism and its related symptoms such as bone pain, soft-tissue calcifications and pruritus often get worse during dialysis treatment. We have treated 12 cases among 170 patients on regular dialysis by using coated charcoal (150 g/cartridge) in combination with standard hemodialysis. During a 6-month treatment period, without changing medical therapy and diet regime, the patients reported a marked relief from pruritus. Parathyroid hormone (PTH) levels changed from 552 +/- 86 to 364 +/- 62 pg/ml (p less than 0.001) compared to the pretreatment period, Plasma PO4(3-) changed in the same period from 6.9 +/- 1.8 to 4.6 +/- 1.5 mg/dl (p less than 0.005). The results obtained indicate a relationship between PTH, serum plasma PO4(3-) levels and pruritus. The mechanism which may be involved is that hemoperfusion removes PTH excess by absorption. Our treatment reducing PTH levels resulted in a marked relief from pruritus and other symptoms, suggesting that patients in this condition, before undergoing surgical parathyroidectomy, may be usefully treated with this therapeutic modality.

On-line bioelectric impedance during haemodialysis: monitoring of body fluids and cell membrane status.

We have measured by a computed integrated system (BIA 109, RJL AKERN) the changes of bio-impedance (BI) deriving from a tetrapolar system working on 800 microA, 50 kHz current, in 23 haemodialysed patients. Resistance (R) and reactance (Xc) have been continuously monitored during haemodialysis in each patient. Resistance was strictly inversely correlated to the decrease of body weight (r = 0.82). Also, Xc increased almost constantly. In most of the patients the increase of Xc was proportionally greater than R, resulting in an increase of phase angle (PA). However, Xc showed a transient decrease in response to seven severe symptomatic hypotensive episodes, whereas R maintained the increasing trend, causing a sharp reduction of phase angle. As Xc is an expression of storage of electrical charge by the cells acting as condensers, and phase angle quantifies the active capacitive component in relation to passive electrical resistance, these parameters may be important to evaluate cell membrane function. In fact, the univocal increase of R, Xc and phase angle observed during normal unevenful haemodialysis probably indicates improvement of cellular activities due to the depurative treatment. On the contrary, the transient reduction of Xc and phase angle observed during hypotensive crises may be an expression of cellular distress because of a too rapid ultrafiltration.

Effect of intravenous supplementation of a new essential amino acid formulation in hemodialysis patients.

Protein energy undernutrition (PEU) and abnormalities of amino acid (AA) metabolism are common in maintenance hemodialysis patients (MHP). A new EAA formulation (BS695), enriched with valine and threonine, containing some histidine, and low in phenylalanine and methionine was recently developed. We randomly supplemented 11 MHP with this solution (treated group, TG) and 10 MHP with a standard AA solution containing both essential and non-essential AA (control group, CG). Both groups received 3.65 g of nitrogen, i.v. three times per week during hemodialysis for six months. During treatment, dietary intake remained stable in both groups. Before treatment, after three and six months of treatment, and six months after the end of treatment, we determined routine blood chemistries, anthropometry, serum protein levels (albumin, transferrin), delayed cutaneous sensitivity (Multi-test), protein catabolic rate (PCR), plasma AA content and motor nerve conduction velocity (MNCV). Before treatment PEU, predominantly of marasmic type, was common. After treatment anthropometry and immune response were unchanged in both groups; PCR increased more in CG than in TG; serum albumin levels decreased significantly only in CG; MNCV improved in TG and worsened in CG. These preliminary results suggest that this new EAA formulation may have beneficial effects on some nutrition related abnormalities of MHP. Better results might occur with long-term AA supplementation, particularly if it is associated with a higher energy intake.