[From the Mailing List SIN: professional risks for the nephrologists: clinical risk and risk management]. / Dalla Mailing-List soci SIN (ML-SIN). Eventi indesiderati nei Centri Dialisi: Rischio clinico e risk management nel sistema sanitario.

An extensive debate on bacteraemias due to aquatic bacteria has recently developed in the Mailing List SIN. This topic was analyzed in two previous issues where the epidemics observed in two Dialysis Centers have been presented and discussed. The two experiences had in common the difficulty in identifying the source of contamination in industrial products commercialized as ''sterile''. In one case, the source of the epidemic could not be identified, in the other one it was discovered only incidentally thanks to a notice of the supplier company of the contaminated material. This underlines the importance of defining specific operating protocols in case of hospital epidemics and stresses the issues related to the professional risk and the potential legal implications.

Prediction of the progression of renal failure in adult and in pediatric patients with malignant focal glomerulosclerosis.

A retrospective analysis of the progression of renal failure was performed in 6 children and 5 adults with idiopathic nephrotic syndrome unresponsive to steroids and immunosuppressants and with histological findings of focal glomerulosclerosis. We analyzed the linear regression of Ccr and of their logarithmic transformation vs time (months) starting from the time when the first abnormal value was observed (t = 0). The regression analysis was performed at three different times, when Ccr was: 30-20, 20-25 and 10-15 ml/min/1.73 sqm. Extrapolation of each of these lines on the x axis predicted when renal function would be zero. The difference in months, between the predicted and actual time of starting dialysis was prediction error. "r" values were always elevated and statistically significant for both linear and logarithmic regression; there was a large intersubject variability in the rate of loss of renal function but the mean prediction error at various levels of Ccr was within limits clinically acceptable. Moreover its magnitude did not significantly decrease by prolonging the time of observation. This indicates that in this disease the decay of Ccr enters a track which proceeds linearly or logarithmically after the onset of renal failure and no major deviation from the predicted line is to be expected. The good predictability in our study may be attributed to the fact that our patients were homogeneous for a number of factors which may be relevant to progression of the disease. It confirms the view supported by Gretz et al. [1983] that there is a need for stratification of patients in large cohort studies on the predictability of loss of renal function.

Prescription and assessment of tidal peritoneal dialysis delivery with a specific equilibration test.

OBJECTIVE: To propose a simplified equilibration test specific for tidal peritoneal dialysis (TPD) that will overcome the inconveniences of the measurement of TPD peritoneal solute clearances through whole dialysate collection. This will enable the prediction of peritoneal creatinine and urea clearances, the suitability of patients for TPD, and routine assessment of TPD delivery. DESIGN: In a prospective study, patients had a standardized TPD run, and dialysate-to-plasma (D/P) ratios for creatinine and urea were calculated at various TPD and peritoneal equilibration test (PET) time points and on total TPD dialysate. Solute clearances were estimated and measured, and correlation coefficients were obtained among all these variables. SETTING: Dialysis unit of a pediatric nephrology department and patients' homes. PATIENTS: Eleven pediatric patients with end-stage renal disease in stable clinical conditions treated with TPD. INTERVENTIONS: Dialysate and blood sample collections. MAIN OUTCOME MEASURES: D/P ratios for creatinine and urea at the fifth and seventh TPD exchanges, at 15-, 30-, 60-, and 120-minute PET times, and on total TPD dialysate and TPD peritoneal creatinine and urea clearances. RESULTS: Correlation coefficients between PET-derived and total TPD dialysate-derived D/P ratios, and those between PET-derived and measured creatinine and urea clearances were more significant at the 120-minute PET time point compared with the other PET time points. Best correlations were obtained at the fifth and seventh TPD exchanges. D/P ratios for creatinine and urea of the fifth and seventh TPD exchanges correlated significantly with the D/P ratios calculated from total TPD dialysate. A significant correlation was also found between peritoneal creatinine and urea clearances on total dialysate volume (measured clearances) and those derived from the dialysate collection of the fifth and seventh TPD exchanges (estimated clearances)--that based on the seventh exchange being slightly more significant. Moreover, the estimated clearances derived from the seventh exchange were within 10% of the measured value in 90.9% of patients both for creatinine and urea. CONCLUSION: The significant correlation between measured and estimated peritoneal creatinine and urea clearances and the low percentage of underestimates of measured clearances obtained using the seventh TPD exchange-derived indices confirm the accuracy of the D/P ratios for creatinine and urea derived from any exchange after the fifth (preferably the seventh) of a standardized TPD run in estimating peritoneal creatinine and urea clearances. This method could represent a simple and accurate means for prescribing TPD and routinely assessing TPD delivery.

Evaluation of the peritoneal equilibration test in children on chronic peritoneal dialysis.

The peritoneal equilibration test (PET) is routinely performed in adults treated with chronic peritoneal dialysis to assess the peritoneal transport rate and to optimize treatment prescription. Only a few and not well-standardized studies on the PET have been reported in children. Twenty-six PET's were performed in 16 children, mean age 10.9 +/- 4.9 years, mean body weight (BW) 26.8 +/- 11.9 kg, treated with nightly intermittent peritoneal dialysis (NIPD). The PET was performed according to Twardowski. Forty mL/kg BW of 2.27% glucose solution were infused at a rate of 10 mL/kg BW every 2 minutes. In the simplified test, dialysate samples were taken at dwell times 0, 2 and 4 hours for glucose and creatinine. A blood sample was taken after a 2-hour dwell time for the same parameters. The standard PET (8 patients) consisted of dialysate samples at 0, 15, 30, 60, 120, and 240 minutes and blood samples at 0 and 240 minutes. Mean D/P ratio for corrected creatinine and D/D0 ratio for glucose at 2 hours were 51.6 +/- 11.6 and 50.4 +/- 9, respectively; at 4 hours 69.6 +/- 12 and 34.4 +/- 9.8, respectively. There was good correlation between D/P creatinine and D/D0 glucose at 4 hours (p < 0.0001). Patients were classified as high (3 cases), high-average (5), low-average (6), and low (2) transporters. A statistically significant difference was found between the curves obtained by the simplified PET and those of the standard PET in the first hour (r = 0.66; p < 0.05). In conclusion, the PET, modified for use in children, gave reliable and reproducible results.(ABSTRACT TRUNCATED AT 250 WORDS)

Two years of experience with a new device system: a multicenter study.

Peritonitis is a crucial complication of peritoneal dialysis. Over the last few years, new device systems have been developed to reduce episodes of peritonitis caused by exogenous contamination. Remarkable improvement has been obtained by modifying the original connection between the catheter and the bag with the introduction of the Y-set. The aims of this study were to test the reliability and simple use of a double-bag system without disinfectant in-line (Gemini, Gambro) and to evaluate the incidence of peritonitis in a 2-year period of follow-up. In a group of 167 patients, enrolled in 14 dialysis units in Italy, with a follow-up of 2433 patient-months, we observed 82 episodes of peritonitis in 52 patients, with a cumulative incidence of 1 episode every 29.7 patient-months. At 12 months the percentage of patients peritonitis-free was 69.7%, and at 24 months it was 62.8%. The training to complete the bag exchange, assessed by patient and nursing staff, was defined as "easy" in 61% of the cases and "difficult" in only 12% of the cases. The percentage of patients requiring a partner was 23%. For patients this device system presents easy handling in terms of the bag exchange, and it may prevent peritonitis.

A new test for tidal peritoneal dialysis prescription.

Prediction of suitability of patients for tidal peritoneal dialysis (TPD) treatment based on the peritoneal equilibration test (PET) may be hypothetically subject to errors, due to the difference between the long equilibration times of the PET and the short dwell times currently utilized during TPD. Eleven patients, mean age 12.4 +/- 3.3 years, mean body weight 34.2 +/- 15kg, had both a standardized TPD run (initial fill volume 40 mL/kg, tidal volume 50%, dwell time 10 min, treatment time 8 h) and a PET performed. D/P ratios for creatinine and urea were calculated at the 5th and 7th TPD exchanges (approximating equilibration time of the TPD run), at the time points of the PET and on the total TPD dialysate volume. D/P ratios for creatinine and urea of the 5th and, even more, the 7th TPD exchange, and D/P ratios obtained from total TPD dialysate were significantly correlated overall (r = 0.96, p < 0.0001 for 5th D/P creatinine and urea; r = 0.98, p < 0.0001 for 7th D/P creatinine and urea). Correlation coefficients between PET-derived and total TPD dialysate-derived D/P ratios were generally poor or only modest. Thus, it is possible to predict TPD clearance, and consequently the suitability of patients for TPD, knowing the D/P ratios for creatinine and urea at the 7th TPD exchange of a standardized TPD run. Our data could represent a new reliable test for TPD prescription.

Flow cytometric study of immunocompetent cell phenotypes and phagocytosis in CAPD effluent.

The immunocompetent cells from peritoneal effluent in 22 stable CAPD patients were studied for surface phenotype distribution and for phagocytic properties by flow cytometry. The following monoclonal antibody couples were employed with direct dual color immunofluorescence: HLA-DR/CD 4, CD 8/CD 11c, Leu 7/CD 16, CD 14/CD 13, and Anti-Leucocyte/CD33. The phagocytic properties of peritoneal macrophages and polymorphs (PMN) were evaluated by the ingestion of 2.02 microns O fluoresceinated microspheres. The same analyses were also performed in peripheral blood. A FACStar laser-operated flow cytometer was employed. A remarkable heterogeneity of CAPD fluid cells was demonstrated, even in the absence of any obvious infection, suggesting the possible occurrence of aborted inflammatory processes. Activated T helper cells, T suppressors (CD8+/CD11+) and Fc gamma+ cells prevailed among lymphocytes, whereas variable amounts of monocytes and PMNs were present. The phagocytic activity of CAPD fluid phagocytes ranged from very depressed to normal values, whereas it was only moderately reduced in blood, suggesting local blocking phenomena, possibly due to interfering metabolites. Flow cytometry is the method of choice for a rapid and accurate analysis of phenotypic and functional properties of cells recovered from various body fluids. This study may be helpful in evaluating local immune response mechanisms in CAPD patients.

Dialysis delivery in children on nightly intermittent and tidal peritoneal dialysis.

To achieve more adequate dialysis in a shorter treatment time, seven children, characterized as high/high average (H/HA, 5 patients) and low/low average (L/LA, 2 patients) transporters according to the peritoneal equilibration test, were treated with tidal peritoneal dialysis (TPD) for 13.7 +/- 5.7 months, after being treated with nightly intermittent peritoneal dialysis (NIPD) for a similar period. We determined the TPD prescription necessary to provide improved clearances compared with NIPD within the same or less treatment time. Dialysis flow rate was significantly higher in TPD than NIPD, due to a reduction of dwell time and an increase in the number of exchanges. Peritoneal and total clearances of urea and creatinine were higher, whereas serum creatinine and urea nitrogen levels were lower and treatment duration shorter during TPD than NIPD, notwithstanding a decrease of residual renal function. Moreover, a mean time-averaged blood urea nitrogen level as low as 48.5 +/- 11.6 mg/dl was achieved during TPD. The improvement was more significant in H/HA than in L/LA patients.

[Immunohistological aspects of nephropathy with minimal lesions]. / Aspetti immunoistologici della nefropatia a lesioni minime.

Renal biopsies from 32 patients, whose light microscopy showed a pattern of minimal changes nephropathy, have been submitted to immunohistological examination. On the basis of immunofluorescence pattern we separated the cases into three groups: the first group (12 cases) was characterized by absence of any glomerular deposit. The second group (9 cases) showed focal and segmental deposits of IgM and sometimes C3 on capillary walls. In the third group (11 cases) we observed slight deposits of IgM and sometimes C3 "comma like" over glomerular structures in all glomeruli. The site of these last deposits was sometimes mesangium and sometimes the capillary walls. The results of immunohistological examinations gave no information about the pathogenetic mechanisms of minimal changes nephropathy. We observed that the patients enclosed in the second group had a worse clinical prognosis, compared with the other two groups.

Use of urea kinetic model and haemofiltration to improve nitrogen balance in haemodialysed children.

To improve nitrogen balance and nutritional status, 10 paediatric patients (11.2 +/- 2.7 years; 28.5 +/- 5.1 kg) on regular haemodialysis (HD) for 25.3 +/- 1.2 months were treated with haemofiltration (HF) for 12.2 +/- 3.4 months. HF was prescribed using a urea kinetic model to ensure a pre-treatment blood urea nitrogen (BUN) of 130 mg/100ml. Urea generation rate (Gu) and protein catabolic rate (PCR) were computed by urea kinetics. Protein and calorie intake was assessed in the children on an unrestricted diet by analysis of 10 days' dietary records obtained every two months. During HF treatment a significant decrease of Gu and PCR was obtained and nitrogen balance increased in all the children.

Nitrogen balance: an adequate treatment prescription index for children on haemofiltration.

We studied 12 children (10.6 +/- 2.5 years; 21 +/- 4.8 kg body weight) with end-stage renal disease on chronic haemofiltration prescribed using a urea kinetic model. After 12 months, urea generation rate, protein catabolic rate and nitrogen balance were assessed in each patient. Pre-treatment BUN was adequate in all 12 patients but in three nitrogen balance and growth rate were unsatisfactory. These three children were studied for a second year in which plasma water cleared/week was increased; during this year a significant increase in nitrogen balance and growth rate was obtained.