Hemodialysis in children: principles and practice.

Hemodialysis has benefited from major progress over the last decade, improvements in technology and in clinical management. The morbidity over the sessions have decreased, seizures being exceptional, hypotensive episodes or headaches rare and pain related to the fistula puncture is effectively prevented by xylocaine ointment. The development of urea kinetic modeling allows the calculation of the dialysis dose Kt/V, and an indirect assessment of the protein intake. Even if the validity of these parameters are questioned their analyse provides an assessment and therefore is a "good thing." The patient also benefited from the technological revolution. The newer machines provide for precise control of ultrafiltration volumetrically assessed, buffered bicarbonate became a standard technique, biocompatible and highly efficient membranes and specific material available for infants have been developed. More recently the concept of ultrapure dialysate, ie, free of microbiological contamination, germs and endotoxins was developed, as was the availability of continuous blood volume monitoring during the session. The hemodiafiltration modality especially with the on line concept, because of all the advantages, should not be limited only to patients at risk.

Normal statural growth in 2 infants on chronic peritoneal dialysis: anecdotal or whole management-related.

AIMS: Growth retardation is usual in children on chronic peritoneal dialysis (CPD). Despite attention to many contributing factors (nutrition, dialysis dose, hemoglobin level, adynamic bone disease, hyperparathyroidism or rickets, growth hormone resistance, etc.), normal growth is rarely obtained in infants on CPD. MATERIALS AND METHODS: We had the chance to observe normal growth over a 1 year period in 2 consecutively treated infants on CPD. Louise (renal hypodysplasia) required CPD at the age of 1 month: creatinine 430 micromol/l; oliguric, creatinine clearance lower than 5 ml/min/1.73 m2. Nutrition was achieved orally with human milk during the first 6 months of life. Tidal peritoneal dialysis allowed a high dialysis dose Kt/V urea 3.8/week and Kcreatinine 105 l/week/1.73 m2. Hemoglobin was maintained over 13 g/dl and low levels of vitamin D analogue were prescribed to avoid adynamic bone disease. At the age of 1 year her height was 75 cm. i.e. in the normal range for age. Madeline (renal hypodysplasia) commenced on CPD at the age of 6 weeks and managed similarly. Her height at 1 year of age was 74 cm. RESULTS: In our 20 years of experience with children on dialysis, these 2 cases of normal statural growth for age at 1 year warrant discussion. As well as nutritional support, the new and recent therapeutic options in our team were: firstly, to avoid high doses of activated vitamin D to control PTH, as high doses are able to induce both a risk of adynamic bone disease and a direct bone cartilage toxicity: secondly, to maintain normal hemoglobin level; and thirdly, to deliver a high dialysis dose (urea, creatinine clearance) based on an individually adapted prescription. CONCLUSION: We feel this management approach is necessary to achieve optimal statural growth in children on chronic peritoneal dialysis. But this management concept only based on clinical anecdotal observations needs further evaluation before its use in clinical guidelines.

The optimal approach to peritoneal dialysis prescription in children.

OBJECTIVE: To describe the optimal approach to peritoneal dialysis (PD) prescription in children. DESIGN: Review of the available literature. RESULTS: Unlike the situation in adults, the main method used for PD in children is automated peritoneal dialysis (APD). The prone position, while resting, permits the dialysis prescription to use a higher fill volume (IPV), as in continuous ambulatory peritoneal dialysis (CAPD), and is also probably more effective than PD in an upright position. However, because APD is limited to 10 hours, the dialytic effectiveness of nocturnal APD should avoid two potential risks: (1) use of too high an IPV per exchange, inducing lymphatic reabsorption, a factor in unsuitable water and sodium balance [Fischbach M. Peritoneal dialysis prescription for neonates. Perit Dial Int. 1996; 16(Suppl):S52-4]; and (2) use of too short a dwell time per exchange, limiting the purification of creatinine and phosphate despite an apparently adequate urea purification (Malhotra C, Murota GH, Tzamaloukas AH. Creatinine clearance and urea clearance in PD: What to do in case of discrepancy. Perit Dial Int. 1997; 17:532-5).

Impact of increased intraperitoneal fill volume on tolerance and dialysis effectiveness in children.

The known relationship between peritoneal fill volume (IVP) and dialysis efficiency favors the use of an optimal IVP to enhance peritoneal dialysis (PD). Therefore, we have studied the effects of an increased IVP in consecutive stages [800, 1400, and 2000 mL/m2 of body surface area (BSA), respectively] in 8 children on chronic PD (mean age: 9 years 6 months; range: 2-16 years). Each prescribed IVP was maintained for 60 minutes of dwell time, allowing a short peritoneal equilibration test. Tolerance was assessed clinically and by intraperitoneal pressure (IPP) measurements at the end of each dwell test. Determination of dialysate-to-plasma ratios, and calculation of mass transfer area coefficients (K0A) using the Henderson method for urea, creatinine, and phosphate, were used to assess the impact of an increased IVP on dialytic efficiency. Increasing IVP from 800 to 1400 and thereafter to 2000 mL/m2 induced an IPP increment, respectively, from 8.4 +/- 1.4 cm (of water) to 12.1 +/- 1.4 cm and thereafter to 18.3 +/- 1.4 cm, with a positive strong linear correlation (r = 0.92; P = 0.001; IPP = 1.46 +/- 8.17(-3) IVP). In the same manner increasing IVP induced K0A increments for urea of 10.6 +/- 1.2 mL/min per m2 to 15.3 +/- 1.6 mL/min per m2 and 17.1 +/- 1.9 mL/min per m2; for creatinine of 7.9 +/- 0.09 mL/min per m2 to 11.2 +/- 0.18 mL/min per m2, and 12.3 +/- 0.21 mL/min per m2; and for phosphate of 5.2 +/- 0.08 mL/min per m2 to 6.7 +/- 0.09 mL/min per m2 and 6.6 +/- 0.07 mL/min per m2, respectively. When K0A values were normalized to the values achieved at the IVP of 1400 mL/m2, the K0A gain obtained increasing IVP from 1400 to 2000 mL/m2 was only significant for urea, peaked for creatinine, and even slowly decreased for phosphate. Moreover, a fill volume over 1400 mL/m2, which appears to be the optimal volume in terms of dialysis efficiency, was only barely tolerated with clinical signs of discomfort and an increased IPP. Therefore, in our opinion, the maximal IVP in children over the age of 2 years should be nearly 1400 mL/m2, both in terms of abdominal tolerance and in terms of urea, creatinine, and phosphate peritoneal membrane purification capacities.