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.

Comparison of patient hospitalization in chronic peritoneal dialysis and hemodialysis: a pediatric multicenter study.

Patient hospitalization was compared in 207 pediatric patients (age < or = 15 years at the start of dialysis) on chronic peritoneal dialysis (CPD) (127 patients) or center hemodialysis (HD) (80 patients), treated in 17 dialysis centers during the period 1989 to 1994, and followed up for at least three months. The hospitalization rate was expressed as hospital days per patient-month, and was calculated on the overall period of treatment and separately for the first and second year. Since the age at start of dialysis markedly differed between CPD (8.2 +/- 4.7 years) and HD (11.2 +/- 2.9 years) patients (with no HD patient younger than five years), results are separately presented in three patient groups: CPD patients aged < 5 years (A); CPD patients aged five to 15 years (B); HD patients (C). The duration of hospitalization was subdivided according to the following different causes: routine (monitoring of dialysis adequacy), complications of the modality, patient primary renal disease, and other causes. The results are presented in Table 1. A statistically significant difference in total days hospitalized was found between each of the two groups of CPD patients and the HD patients; the results for hospitalization for dialysis-related complications were higher in the group of younger children on CPD, while the difference between the two age-matched groups of patients on CPD and HD was not significant.

Changes in body composition assessed by bioimpedance analysis in the first 6 months of chronic peritoneal dialysis.

Dietary protein restriction, progressive loss of renal adaptive capacity, and uremic toxicity may contribute to the development of malnutrition and water retention in severe chronic renal failure (CRF). Malnutrition is also common in children treated with chronic peritoneal dialysis (CPD). It is not clear how the start of CPD influences body composition of children with CRF. We used a bioimpedance analysis device (BIA 101S Akern) to measure resistance and reactance in 7 children, with residual creatinine clearance of about 5 mL/min/1.73 m2 at the start of CPD (t0) and repeated the test 6 months later (t1). Distance (D), which is considered a reliable index of hydration and nutrition, was obtained from resistance (R) and reactance (Xc) by calculating phase angle (PA). BIA values of our patients were compared with those of healthy children of the same statural age from a series of 551 controls. There was an overall improvement of Xc, PA, and D after 6 months of CPD. In some cases D did not normalize, which indicates that some children with CRF on a restricted protein diet may present changes of body composition that are only partially reversed by short-term CPD. The present indications for the start of CPD should probably be reassessed, at least in some cases, to prevent malnutrition.

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.

Clinical experience in the treatment of infants with chronic peritoneal dialysis.

Chronic peritoneal dialysis (CPD) is the first treatment modality for most infants with end-stage renal failure; this group of patients shows peculiar clinical and technical problems. We present the data from a National Registry on 22 children starting CPD under one year of age, representing 11.6% of the total population of the Registry (189 patients). Mean weight at start of CPD was 6.1 +/- 1.8 kg and duration of dialysis was 22.1 +/- 15.5 months. During the follow-up period, 9 patients were transplanted, 1 was shifted to hemodialysis, and 4 died. Patient survival was 89.1% and 82.2% at 1 and 2 years (97.9% and 96.5% in the group of 167 older children); technique survival results were 89.1% at 1 year and 77.1% at 2 years (vs 92.5% and 85.7%, respectively). The incidence of peritonitis was 1 episode every 15.6 CPD-months (1:16.1 in the older children). Catheter-related complications occurred more frequently in infants (1:11.8 vs 1:17 episode:CPD-months), even if this difference was not statistically significant. Statural growth was on average -0.29 +/- 0.66 SD/year with a significant improvement between the first (-0.50 +/- 0.79) and the second (+0.23 +/- 0.77) year of CPD. Our data confirm that infants represent a higher risk group and that they can be treated satisfactorily with CPD while awaiting renal transplantation.

[Management of acute renal failure in hospital practice]. / La gestione dell'insufficienza renale acuta nella pratica ospedaliera.

The incidence of ARF in pediatric population varies according to the definition of the syndrome. If the diagnosis is based on a decrease of glomerular filtration rate (GFR), possibly accompanied by a decrease of urinary output and the sudden change of renal function indexes, then the number of patients which can be considered affected by ARF in hospital practice is high, as it comprises all the cases with functional impairment of renal function. The availability of tables with normal values of serum creatinine for different gender and age and the knowledge of the minimal urine output compatible with the normality allows a precise diagnosis of ARF. The differential diagnosis of ARF must take into account prerenal, renal and postrenal causes. Prerenal and renal ARF may be sometimes difficult to differentiate. Indexes such as sodium fractional excretion, utilizing urinary to plasma ratios of sodium and creatinine, can be helpful: values less than 1 indicate prerenal ARF, more than 2 renal ARF. The management of ARF is dependent on the causes of ARF. Prerenal ARF is normally treated by measures of volume expansion and/or removal of the underlying cause. Renal ARF requires an accurate control of water and electrolyte balance and of nutritional status and the prevention or treatment of numerous complications, which may worsen the course of the syndrome. Indications to dialysis must be evaluated every day and an assessment of nutritional status performed. All the factors which may cause hypercatabolism, such as infections, hemorrhage, low calorie intake, must be recognized and treated. This approach allows a better control of serum urea, potassium, phosphate and acidosis. Nutrition must be implemented and an adequate protein and calorie intake must be obtained, through spontaneous oral route and, whenever required, enteral and parenteral nutrition. In conclusion, patients with mild-degree, mostly of prerenal origin, ARF represent a common finding in hospital practice. Identification and prompt treatment of the underlying cause is the best prevention of acute tubular necrosis. Patients with ARF of renal origin require, in particular, daily nutritional assessment and dietary treatment to delay the onset of dialysis.

[Indications for recombinant growth hormone (rhGH) treatment in kidney diseases]. / Indicazioni al trattamento con ormone della crescita ricombinante (rhGH) nelle malattie renali.

Growth retardation is one of the major problem in children with chronic and terminal renal failure. The growth hormone-insulin-like growth factor axis is altered in uraemia, resulting in peripheral resistance. This insensitivity seems to be overcome in an experimental study by supraphysiological doses of recombinant human growth hormone (rhGH). Several clinical studies have confirmed that rhGH increases growth velocity in children with chronic renal failure with and without dialysis and after renal transplant, without significant side-effects. The improvement of growth is more marked in prepubertal patients and during the first year of rhGH treatment. Also in our experience prepubertal children showed an increase of height standard deviation score and growth velocity during rhGH treatment; the pubertal patients failed to improve their statural growth. GH, as the prototype of an anabolic hormone, has also great potential in improving catabolic conditions of various origin, particularly those due to renal failure. RhGH can improve nitrogen balance and the nutritional parameters with an increase of muscle mass and a decrease of fat mass. Prospectively, rhGH could be utilized to improve the hypercatabolic condition of acute renal failure. The following analysis will discuss the recent studies employing rhGH in renal diseases and will attempt to give some guide lines to rhGH treatment in these illnesses.

[Treatment of corticoid-resistant nephrotic syndrome: a still unresolved problem]. / Il trattamento della sindrome nefrosica corticoresistente: un problema tuttora aperto.

The nephrotic syndrome persists unchanged after the initial course of steroid therapy in 15 to 20% of patients. In such cases, the severity of the condition lies essentially in the risk of developing end-stage renal failure. This occurs in one third to one half of the cases. Furthermore, some of these children are at risk for recurrence of their original disease in the transplanted kidney. The course of steroid resistant nephrotic syndrome (SRNS) is usually punctuated by the need for numerous hospitalizations for mobilization of edema and treatment of infection. The treatment of patients with SRNS presents a major problem in the field of pediatric nephrology. Immunosuppressive agents may be efficient in some of steroid-resistant patients, inducing remission of proteinuria and protecting renal function. Unfortunately, all these agents have a low therapeutic index. Thus, in deciding whether, how, and when to use immunomodulating drugs, the nephrologist should be aware of their potential side effects, of the results that may be obtained and of the possible strategies for maximizing their therapeutic index.

[Epiphyseal chondroblastoma. Clinical and anatomo-radiographic aspects]. / Il condroblastoma epifisario. Considerazioni cliniche ed anatomo-radiografiche.

The clinical radiological and anatomohistological features of fourteen cases of epiphyseal chondroblastoma are described. The seat, origin, and evolution of the tumor are discussed. The diagnosis of the epiphyseal localization is easy, but there are same problems in the differential diagnosis of the epiphyseal-metaphyseal of metaphyseal forms.

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.

Dietary prescription based on estimated nitrogen balance during peritoneal dialysis.

Protein and energy requirements of children on automated peritoneal dialysis (APD) have still not been sufficiently well defined, although their adequacy is important to maintain a positive nitrogen (N) balance and prevent malnutrition. We carried out 42 studies to estimate N balance in 31 children over 3 years on APD for 19.8+/-15.7 months. Twenty metabolic studies were performed in patients dialysed for less than 1 year (7.2+/-3.3 months) and 22 in patients treated for more than 1 year (31.3+/-13.6 months). The mean estimated N balance of all metabolic studies was 57.5+/-62.8 mg/kg per day. In only 21 of 42 studies was N balance estimated to be over 50 mg/kg per day, which is considered adequate to meet N requirements for all metabolic needs and growth of uremic children. Estimated N balance correlated significantly with dietary protein intake (r=0.671, P=0.0001) and total energy intake (r=0.489, P=0.001). Using the equations of correlation, the values of dietary protein intake [=144% recommended dietary allowance (RDA)] and total energy intake (89% RDA) required to obtain an estimated N balance >50 mg/kg per day were calculated. Significantly lower estimated N balance values were obtained in the studies performed on patients on APD for over 1 year (36.09+/-54.02 mg/kg per day) than in patients treated for less than 1 year (81.11+/-64.70 mg/kg per day). In conclusion, based on the values of estimated N balance, we were able to establish adequate dietary protein and energy requirements for children on APD.

Models to assess nitrogen losses in pediatric patients on chronic peritoneal dialysis.

To develop models to estimate nitrogen (N) losses of children on chronic peritoneal dialysis (CPD) from easily measurable indexes and laboratory tests, we measured the N content and all nitrogenous compounds in dialysate (D), urine (U), and feces over 3 days in 19 pediatric patients on CPD. Total measured N losses (TNm) were 5.56+/-2.26 g/day (69.9+/-11.1% in dialysate, 16.3+/-10.6% in urine, and 13.6+/-4.6% in feces). Correlation coefficients between measured dialysate and urinary N losses and the single nitrogenous compounds indicated values of over 0.9 only for urea in dialysate and urine; fecal N losses correlated well with body surface area (BSA). Taking into account these correlations, we developed a univariate additive model and three multivariate models to predict total estimated N losses (TNe). The best prediction of TNm was obtained with model 3, which considered not only urea output in dialysate and urine but also dialysate protein loss and BSA: TNe (g/day)=0.03+/-1.138 UN urea+0.99 DN urea+1.18 BSA+0.965 DN protein. A confirmatory analysis performed on a second group of 23 pediatric patients on CPD, using all four models, showed a higher percentage of studies with a relative difference between TNm and TNe less than 10% for model 3 than for the other models. Thus, N losses of pediatric patients on CPD can be estimated from measured urea and protein losses in dialysate and urea loss in urine, together with BSA.