PD: The dialysis modality of choice for pediatric ESRD patients
Continued improvements in medical technology and health care delivery systems have ushered in a change in the spectrum of childhood diseases. Geographic areas with access to current medical technologies have noted a shift from infectious diseases to chronic systemic ailments. Among these chronic conditions, a significant increase in the prevalence rate of chronic kidney disease (CKD) among children has been reported. Children who progress to ESRD or CKD Stage V require renal replacement therapy in the form of PD, HD, or renal transplant, preemptively if possible. In most children, the modality of PD is preferred over HD in order to avoid the problems associated with vascular access, anticoagulation, and hemodynamic instability7, 8. Yet this preference does not always translate into consistent data. In 2006, USRDS reported at five years post-initiation of ESRD treatment, 12% of children remained on HD compared with 4.1% on PD ( over 80% had received a transplant)5. Multi-factorial issues surround the initial choice and continuance of a particular renal replacement therapy. Education of the healthcare team and patient, access to systems necessary to support the chosen modality and overall patient health play critical roles across the ESRD disease management cycle.
When PD is decided upon, automated PD (APD) also known as continuous cycling peritoneal dialysis (CCPD) is frequently used in children principally to facilitate school attendance and social activities. CCPD allows greater flexibility in the number and volume of exchanges during the night without taxing the patients' time. (link to AREP PD modalities webpage). Recent innovative applications of computer technology within the cycler machine and simplified operator interfaces allow for adaptable and individualized dialysis prescriptions that meet clinical needs and make disease management and patient surveillance less complicated.
Access to the peritoneal membrane
The main function of a PD catheter is to permit consistent bidirectional flow of dialysate without extraordinary effort or undue discomfort. Catheter function depends upon its design, implantation site, and the configuration of the system used to perform dialysis exchanges. General consensus of catheter types for pediatric care is lacking, however; the tendency is to follow best practices as established in the adult PD population. The double cuff, swan neck, and downward exit have each demonstrated successful outcomes. The issue of cuff extrusion can be reduced by following established recommendations for cuff placement6,11. Proper orientation of the catheter is critical in pediatric patients. In infants, there may not be enough room above the diaper for a downward facing exit site, therefore the site is typically upward facing. In adolescents, the catheter is placed laterally. Consideration must also be given to other apparati such as gastrostomy tubes or vesicostomies in such cases the catheter is preferentially placed in the right lower quadrant away from the G tube site12. Presternal catheters may be useful to avoid issues in infants with diapers, ostomies, and abdominal wall weakness. Since omental catheter occlusion is more common in children than in adults, partial omentectomy or omental tacking to epigastrum or lateral abdominal wall is performed in many children6,11,12 .
Exit site care
After the initial placement of the PD catheter, exemplary exit site care is especially crucial30. Routine sterile technique and thorough hand washing with antibacterial soap are considered best practices. Hydrogen peroxide should only be used to soften excessive crust. Iodine solutions are popular in hospital settings where many infants are receiving long term care. Limiting the use of iodine solutions will assist in decreasing skin irritations and decreasing iodine absorption which has been observed to result in thyroid function abnormalities38, 39. In children, the PD catheter may only have one cuff. Therefore, catheter stabilization is critical. Children do not have fully developed abdominal musculature and the catheter can easily be pulled out. Catheter stabilization support mechanisms such as pediatric belts and stockinettes assist with immobilization of the catheter. Stockinettes are particularly useful in infants. Finally, gauze dressings are preferred to occlusive types.
Exit site infections
Exit site infections are associated with increased morbidity, treatment failure and PD catheter removal39. Meticulous exit-site care limits the presence of causative organisms thereby reducing exit site infection occurrence. An infected exit site is often erythematous, indurated and tender. It may bleed or exude pus. In most cases, the causative organism can be determined from a swab culture of the site. If left untreated, the exit site infection can extend into the tunnel and eventually cause peritonitis38. Treatment of exit site infections30,40 is dependent upon presenting signs and symptoms. Intensified local care or treatment with a topical antibiotic cream may be sufficient treatment in the absence of purulence, tenderness, and edema. In the presence of erythema alone, topical treatment with hypertonic saline compresses or mupirocin 2% ointment is usually sufficient. Avoid getting cytotoxic agents such as povidone-iodine or hydrogen peroxide into the sinus. Mupirocin ointment should not be used with polyurethane catheters because the polyethylene glycol in the ointment will degrade the catheter. Treatment is more problematic and more prone to failure when there is purulent drainage40. Topical antibiotic therapy is not appropriate for acute or chronic infections. Changing the cleansing agent is common, but experts have opposing views on whether to switch to a stronger agent, or a less irritating one. Therapy for purulent exit site infection should be based on the results of Gram stain, culture and sensitivities. If the infection has not resolved after treatment for 2 weeks, a surgical approach may be necessary. The major risk factor for exit site infection is nasal carriage of Staphylococcus. Persistently positive nasal cultures are associated with a threefold to fourfold increased risk of Staphylococcal exit site infection. Eradication of nasal carriage is logical to prevent these infections.
Peritonitis
Peritonitis may occur more frequently in children. Reports in the 1990’s indicated higher rates in children than in adults, but more recent reports show similar rates41. It is important to note that “abdominal pain and fever in children are too non-specific to predict peritonitis in the absence of elevated dialysate leukocyte count42.” Peritonitis remains one of the most important limitations to the delivery of continuous ambulatory peritoneal dialysis (CAPD). Contamination of the peritoneum, from endogenous or exogenous sources, is responsible for most peritonitis episodes. Patients usually present with a cloudy bag, although other causes should be distinguished: Culture-positive infectious peritonitis, infectious peritonitis with sterile cultures, chemical peritonitis, eosinophilia of the effluent, hemoperitoneum, malignancy (rare), chylous effluent (rare), specimen taken from “dry” abdomen. Clinical suspicion of peritonitis should be followed rapidly by microbiological examination and empirical treatment. Microbiological confirmation allows for subsequent treatment based on sensitivities. Other interventions such as catheter removal may be appropriate in some patients. Peritonitis may be further prevented by adequate exit-site care, hygienic methods, and techniques to minimize early contamination of the exit site. Mupirocin as previously mentioned may also have a role in preventing infections caused by Staphylococcus aureus42. The current approach to the treatment of peritonitis relies primarily on the intraperitoneal administration of antibiotics. A key development is the publication of the Consensus Guidelines for the Treatment of Peritonitis in Pediatric Patients Receiving Peritoneal Dialysis by an international committee of physicians and nurses under the auspices of the International Society of Peritoneal Dialysis. These guidelines include recommendations for empiric antibiotic therapy, treatment of gram-positive, gram-negative, and fungal peritonitis as well as indications for catheter removal and replacement. Empiric therapy algorithms for peritonitis have been published by Piraino B, et al.40 and Warady BA, et al.42 in Peritoneal Dialysis International and are available at www.pdiconnect.com.
Hernia development
Inguinal, exit site, umbilical, and prior abdominal incision sites are common sites for hernia development43, 44. Of these, umbilical and inguinal hernias are the most common types that occur with PD. The risk of a hernia formation can be reduced by avoiding constipation, heavy lifting, high-volume PD fills; and activities that increase pressure in the abdomen. Most herniae present as painless swelling. When pain appears, a complication must be considered. Incarceration and strangulation of bowel may occur with any kind of hernia, but is more frequent with smaller herniae. There is no evidence that abdominal binding or wearing a corset will decrease incidence of hernia development. Traditional surgical techniques are used to repair the hernia, including reinforcement of the abdominal wall whenever necessary.
Catheter malfunction
Reduced dialysate drainage is most often due to omental trapping of the peritoneal catheter. Constipation, intraperitoneal adhesions, fibrin, blood clots, and catheter migration are common reasons for catheter malfunction.
Cardiovascular disease
The burden of cardiac disease is significant in the pediatric ESRD population, most notably 33% of pediatric ESRD patient deaths are attributed to cardiovascular causes45. ESRD has a particularly large influence on the cardiovascular system in children, as indicated by the more than a 700-fold increased risk of cardiac death in affected individuals compared with healthy children of the same age45. High systolic blood pressure and elevated serum concentrations of intact parathyroid hormone, calcium and phosphate, as well as long-term dialysis, seem to be important risk factors for cardiovascular disease in pediatric patients with ESRD46.
Special considerations when utilizing PD in pediatric patients:
Infants and very young children have special dialysis needs. Increased fluid intake, required for adequate growth, and the resultant waste products formed from metabolism, often dictate greater ultrafiltration (UF) for adequate fluid balance16. Assessment of appropriate fluid balance is typically monitored through daily weights and through weighing of diapers. Other medical considerations include hyperglycemia, hyponatremia, and hypothermia associated with PD. Hyperglycemia may occur from absorption of glucose containing solutions with resultant insulin administration. Hyponatremia is common in very young children due to losses from dialysate or due to disease states which cause tubular dysfunction and polyuria17. Hypothermia and hypotension, due to dialysate and dialysis tubing that has not been warmed, are potentially preventable18. Some frequently used methods to warm the dialysate (with manual systems) include: utilizing bag warmers, placing heating pads around the bags, or if the infant is in an isolette, placing the equipment in the isolette, if no contraindications are noted19,20.
Contraindications to PD in pediatric patients:
Contraindications to the use of PD in children are categorized according to absolute and relative contraindications. Absolute contraindications include abdominal wall defects such as omphalocele, gastroschisis and bladder extrophy as well as diaphragmatic hernia, obliterated peritoneal cavity and peritoneal membrane failure. Relative contraindications include inadequate living situation for home dialysis, lack of appropriate caregiver, recent abdominal surgery, or imminent living-related donor transplantation8.
References:
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40. Piraino B, et al. ISPD Guidelines/Recommendations. Peritoneal dialysis-related infections recommendations:2005 update. Perit Dial Int 25:107-131, 2005
41. Tranaeus A. Peritonitis in Paediatric Continuous Peritoneal Dialysis. In: Fine RN, Alexander SR, Warady BA, eds. CAPD/CCPD in Children, 2nd ed. Boston/Drodrecht/London: Kluwer Academic Publishers. 1998:301-347
42. Warady BA, et al. Consensus guidelines for the treatment of peritonitis in pediatric patients receiving peritoneal dialysis. Perit Dial Int 20:610-624, 2000
43. Garcia-Urena MA, Rodriguez CR, Vega Ruiz V, Carnero Fernandez FJ, Fernandez-Ruiz E, Vazquez Gallego JM, Velasco Garcia M. Prevalence and management of hernias in peritoneal dialysis patients. Perit Dial Int 26:178-182, 2006
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