| Abstract|| |
Continuous peritoneal dialysis (CPD) in children has been an important mode of renal replacement therapy (RRT) since 1978. Continuous ambulatory peritoneal dialysis (CAPD) was used initially in children and then, in infants. Automated peritoneal dialysis (APD) was introduced in the eighties. Currently. CPD is the predominant mode of RRT in children, and 3/4 of these patients are managed with APD. Certain events have evolved with time, such as: a) growth and nutrition; b) renal osteodystrophy; c) anemia; and d) training. Complications from CPD continue to be a challenge and include: a) peritonitis; b) hernias and c) stress. Future directions in pediatric CAPD are: a) applying techniques to measure dialysis adequacy; b) improvement in dialysis solutions, such as pH, osmolality and different osmotic agents; c) additives to the dialysis fluid, such as hormones, growth factors; d) improvements in catheters and cyclers; and e) strategies to reduce peritonitis rates. There are challenges for CPD in the future; however, it appears to be the most practical and cost-effective dialysis therapy for children with end-stage renal disease.
Keywords: Continuous peritoneal dialysis, Children, Growth, Peritonitis.
|How to cite this article:|
Balfe J W. Continuous Peritoneal Dialysis in Children: Past, Present and Future. Saudi J Kidney Dis Transpl 1997;8:279-84
|How to cite this URL:|
Balfe J W. Continuous Peritoneal Dialysis in Children: Past, Present and Future. Saudi J Kidney Dis Transpl [serial online] 1997 [cited 2020 Aug 14];8:279-84. Available from: http://www.sjkdt.org/text.asp?1997/8/3/279/39355
| Introduction|| |
The purpose of this paper is to describe how CAPD in children evolved, where we are now, and what can be projected for the future. It is well known that CAPD was conceptualized and first used by Popovich and Moncrief in 1976  . Peritonitis was a problem because they only had glass bottles. However, Oreopoulos, using plastic dialysis bags, demonstrated that CAPD could be used with acceptable peritonitis rates  . Because our pediatric hospital was near to that of Professor Oreopoulos, we were made aware of this exciting dialysis technique shortly after its discovery.
At our hospital, we first used chronic peritoneal dialysis during the late 1960s on children awaiting renal transplantation. Our first renal transplantation was performed in 1969. Specifically, the type of peritoneal dialysis used for the children was intermittent peritoneal dialysis (CIPD). Every week, the child would receive intermittent peritoneal dialysis (IPD) for a 24-hour period, using one hour exchanges and using a temporary catheter (Trocath, McGaw). However, because of the sudden popularity of hemodialysis, all our patients were switched to that mode of therapy.
In 1978, we had a number of children on hemodialysis in whom we had exhausted their vascular access sites. We were fortunate to be able to have them trained for CAPD in Prof. Oreopoulos's unit. Our first, and the first ever pediatric patient on CAPD was reported  . We then started our own CAPD program which was also applied to small children, since vascular access was problematic in that group. CAPD was welcomed by us, and gradually by many pediatric dialysis units around the world because of its ease of use for all children, especially the small child. In the 1980s, automated peritoneal dialysis equipment became available. It was enthusiastically accepted by pediatric nephrologists because it had become apparent to everyone that the technique of CAPD for children was quite burdensome to many of the families. Now, in many pediatric nephrology centers around the world, chronic peritoneal dialysis (CPD) has become the dialytic mode of choice, and within these programs, automated peritoneal dialysis (APD) is preferred. In order to discuss the evolution of CPD in children, focus will be placed on selected topics.
| Growth and Nutrition|| |
Poor growth is usually observed in a child with chronic renal failure (CRF). This occurs in spite of attempts to provide optimal nutrition. The initiation of peritoneal dialysis is frequently accompanied by improved growth. We observed acceptable growth velocity in infants on CAPD who received optimal nutrition from tube feeding  . Growth in the pre-pubertal children was poor. However, in the post-pubertal children, with their endocrine induced growth spurt, growth was considered acceptable. Unfortunately, it appears the best result that one can anticipate from CPD is maintenance of growth velocity. CPD will not produce accelerated growth, and thus children with growth failure will remain small. In spite of a successful renal transplant, the short stature usually persists.
Good nutrition is mandatory for growth. Peritoneal dialysis per se can cause anorexia, and this leads to poor dietary intake. This is felt to be related to an elevated blood glucose and/or abdominal fullness from the dialysate. Because of the high incidence of protein calorie malnutrition in CAPD patients, many programs prescribe tube feeding, either nasogastric or gastric. Vigilant assessment of the patient, ideally by a renal dietitian, is important. Nutritional assessment of the adult CAPD patient can be difficult. Dietary food records, subjective global assessment (SGA), percent lean body mass, and plasma albumin levels are used  . Although a reduced plasma albumin is a known mortality risk factor  , it cannot be considered diagnostic of protein malnutrition since changes in albumin concentration has many causes, such as changes in protein synthesis or catabolism, protein losses in the dialysate, redistribution, changes in the state of the patient's hydration or different assay methodology. In children, growth is the ideal marker of adequate nutrition and dialysis. It is important to measure serially and accurately the child's height, dry weight, and head circumferences (for the child < 3 years of age). Fat and muscle mass are assessed anthropometrically (skin-fold thickness, mean arm muscle circumference). We reported the incidence of hypoalbuminema in children receiving CPD to be 43%  . Patients are prescribed generous intakes of protein, preferably of high biological value. Infants should receive 2.5-4.0 gm/kg/day; toddlers and children 2.02.5 gm/kg/day; and, adolescents 1.5 gm/kg/day. Intraperitoneal amino acids have been used in adults  and children  .
Because CPD and renal transplant will not correct serious growth failure (< -2 SD), many centers are using recombinant human growth hormone (rhGH). Two randomized control trials have shown good results , . Unfortunately, growth induced by rhGH is not as effective for children receiving dialysis  . However, the response to rhGH may be better in children on peritoneal than those on hemodialysis  .
| Renal Osteodystrophy|| |
Healthy bones are a pre-requisite for good growth. When we initially assessed our CAPD patients, growth was best in those with no renal osteodystrophy  . It is important to give supplemental vitamin D to CAPD patients. Patients who received supplemental 1-alpha hydroxy D3 (1 alphaOH-D3) had significantly less renal osteodystrophy and had less secondary hyperparathyroidism  . Intraperitoneal calcitriol has been used on patients managed by CAPD  . Some of our children were refractory to appropriate or high doses of 1-alpha hydroxy D3 and showed a good response to intraperitoneal calcitriol. This type of therapy we feel, is analogous to intravenous pulse calcitriol therapy, which is effective against tertiary hyperparathyroidism  . Salusky. et al has written extensively on renal osteodystrophy in children, and cautions against over aggressive vitamin D treatment, a possible cause of adynamic bone disease  .
| Anemia|| |
In the early days of our program, most of the patients had anemia. A frequent reason for hospitalization was for blood transfusion. The introduction of recombinant human erythropoietin (rHuEPO) has dramatically changed this occurrence. We initially treat our CPD patients with thrice weekly subcutaneous rHuEPO. Once their hemoglobin concentration is stable, they are switched to twice weekly dosing. Because some children find the injection painful, children can be given the rHuEPO intraperitoneally  . The pharmacokinetics of intraperitoneal rHuEPO has been studied  . Others have demonstrated that once weekly rHuEPO can be effective , .
| Training|| |
It used to take two weeks of hospitalization to train a family on the CAPD technique. They were taught the physiology of the peritoneum and the signs, symptoms, and antibiotic treatment of peritonitis. When cyclers became available, it required three days to train these already expert families. Nowadays, with the switch to ambulatory care, we train the families in 7-10 days, on an out-patient basis. It is convenient to have a functioning catheter prior to commencing training. It is important to train a backup person(s) to do the procedures and preferably, this should be the other parent or caregiver.
| Complications|| |
This continues to be the major problem in CPD. The incidence of peritonitis in our unit at the onset of the program (1978) was one episode per 10.8 treatment months. The major pathogens are gram positive organisms, namely, Staphylococcus aureus and S. epidermidis. Unfortunately, our results have failed to improve, with the 1995 incidence being one episode per 10.8 patient months, appreciating that most of these children would have been on continuous cyclic peritoneal dialysis (CCPD). The peritonitis rate from a large cohort of North American pediatric centers (NAPRTCS)  is one episode every 8.2 patient-months. The peritonitis rates are higher in children, especially infants, as compared to adults  . The diagnostic triad for CAPD peritonitis of cloudy fluid (WBC > 100 x 106), neutrophils in effluent > 50%, and abdominal pain, may need to be altered because of APD. We continue to use continuous dosing with intraperitoneal cefazolin (load 500 mg/L, maintenance 250 mg/L) and tobramycin (load 1.7 mg/Kg, maintenance 8 mg/L). Over the past few years, there has been a tendency to use vancomycin. However, because of the emergence of vancomycin resistant organisms, physicians have reverted back to the usual proven antibiotics. The most recent treatment recommendations have been published  . A clean exit-site is important in the prevention of peritonitis. Similar bacteria that cause peritonitis cause exit-site infections. For an exit-site infection, we prescribe oral cephalexin or cloxacillin, plus daily exit-site care with providone and sterile gauze dressing (2x2).
Hernias were a major problem at the onset of our program. They were most frequently inguinal and the incidence was higher in young males  . The major cause is increased intra-abdominal pressure. Fortunately, there are fewer hernias reported now and this is most likely related to the increased use of APD wherein the patient is supine and therefore has a reduced intra-abdominal pressure.
Although CAPD was embraced by the pediatric nephrologic community, it did place a tremendous burden on the family, especially the primary caregiver, usually the mother. The children had anorexia, and thus meal time was long and laborious. This latter problem was partially alleviated by tube feeding. Many families required relief every 4-6 weeks, wherein the child was admitted to a 'respite care' facility for a week. APD has reduced this burden and we see fewer over-stressed families. The use of a skilled social worker is invaluable to help the families cope with the medical challenges yet, guide their child through the normal stages of separation and individualization  .
| Future Directions for Pediatric CPD|| |
For some time in CPD, in children and adults alike, the dialysis prescription has been somewhat arbitrary. For the adult patient, 2 liters of dialysis fluid was prescribed four times per day. This has shown to be woefully inadequate dialysis for some adults (> 80 kg body weight). For children, the exchange volume and the number of exchanges varies from center to center. Dialysis is now quantified by using two tests: a) KT/V urea (weekly urea clearance/total body water), and b) weekly creatinine clearance/body surface area. The adult literature suggests that one should aim at a KT/V > 2.0 and a creatinine clearance of 50-60 L/wk/1.73 m2  . Careful attention should be directed toward the expected decline in renal function, and appropriate adjustment made to the dialysis prescription. Routine measurement of these indices is being done in many pediatric dialysis units  . It is imperative to provide the children with optimal dialysis.
Hypertonic dialysis solutions using glucose with an acid pH are the routine of the day. The ideal solution would be isotonic with a neutral pH. It is reasonable to expect in the near future, solutions with a neutral pH from the use of true bicarbonate and having glucose replaced with a glucose polymer. Dialysis fluid containing 1.1% amino acids (Nutrineal) are currently being used  . Further research is required to demonstrate that this therapy is cost effective.
The peritoneal route for drug administration has been used for years. More recently, the effectiveness of intra peritoneal delivery of erythropoietin, insulin, calcitriol, and growth hormone has been shown. This new route of drug delivery has been interesting. However, one must be cautions about every new substance given intra peritoneally, as the consequences, such as sclerosing peritonitis can be devastating  .
There is a need for truly pediatric, dialysis catheters in the small patient. Current catheters are made of silicon rubber and newer materials should be able to prevent the accumulation of a biofilm. The current cyclers are a real improvement. They are small and easy to use. The cycler of the future may provide one with the option to provide tailor-made electrolyte concentrations or additives, and be able to purify tap water by a built-in reverse osmosis system. Cost and need will dictate future directions.
Why are the peritonitis rates much higher in children? Research is urgently needed to answer this question. Peritonitis is still the greatest complication for CPD in children and adults. Prevention of the staphylococcus carrier state needs to be better understood.
The revolution in molecular biology cannot ignore the peritoneum. The mesothelial cell appears to be appropriate for gene therapy. It can be engineered to produce EPO, vitamin D, and growth hormone.
The future for CPD in children presents many challenges. However, the potential to provide optimal renal replacement therapy for many children at a reasonable cost is achievable. It is important to maintain children, while on dialysis, with excellent health so they are ready for a renal transplant.
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J Williamson Balfe
Division of Nephrology, The Hospital for Sick Children, 555 University Avenue, Rm. 5109 Toronto, Ontario, M5G IX8