Peritoneal dialysis in children: Pathophysiological approaches, prescription and management of complications for adequate treatment.

Abstract

Peritoneal dialysis (PD) is the most commonly used renal replacement therapy in children worldwide. It utilizes the peritoneal membrane as a semi-permeable surface for the exchange of solutes and water between the dialysate and peritoneal capillaries. There are two main modalities: continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD), the latter being performed at home using a cycler.
Pediatric prescriptions must be individualized based on body surface area, intraperitoneal pressure (IPP), and specific dialysis needsPD is generally well tolerated and offers several advantages, such as better preservation of residual diuresis, the possibility of home-based treatment, and the continuity of schooling. It also doesn’t require anticoagulation. However, it may lead to mechanical complications (hernias, leaks, pain) and infectious ones (peritonitis, catheter-related infections),some times more frequent than in adults.
Placement of an appropriate catheter (e.g., Tenckhoff) under sterile conditions with antibiotic prophylaxis is crucial for effective and safe treatment. The adequation of dialysis take into acount the choice of dialysis solution (glucose, icodextrin, bicarbonate or lactate buffer) and prescription parameters (volume, dwell time, number of cycles) should aim to optimize clearance while preserving peritoneal membrane function, but also maintain normal child weight and height growth. PD is the technique of choice in pediatrics, PD remains a flexible, effective, and suitable alternative, especially for young children or when access to hemodialysis is limited.

INTRODUCTION

Peritoneal dialysis (PD) is the most widely used extra-renal replacement therapy in children worldwide, particularly in younger children and in low- and middle-income countries[1].

In Europe, PD is the initial treatment modality for stage 5 Chronic Kidney Disease (CKD) in 40% of cases, according to the ESPN/ERA-EDTA registry. The principle of PD lies in the use of the peritoneal membrane as a filter membrane[2].

THE PERITONEUM

The peritoneum is a membrane made up of two layers: the parietal layer and the visceral layer, which are joined by the mesos. The peritoneal membrane is made up of mesothelium, interstitium, and capillaries (Figure 1).

The peritoneal cavity is the space between the two sheets. Under physiological conditions, this “virtual” space contains less than 100 mL of a liquid formed from plasma ultrafiltrate. This effluent contains few cells (fewer than 50 cells/mL) and no neutrophils in the absence of infection[3]. This is a “functional” anatomical contact and exchange surface measuring 0.5 to 2 m2[4]. In children, the prescription of peritoneal dialysis must be individually adapted, taking into account the body surface area (expressed in mL/m²) to determine the intraperitoneal filling volume (IPF). In fact, anatomical peritoneal surface area is age-invariant if expressed per unit of body surface area [5,6].

PD exchange principle

During PD in both adults and children, the capillaries of the peritoneal surface are recruited (only 20% are perfused at rest). The abdominal pressure resulting from dialysate infusion is known as intraperitoneal pressure (IPP). Transperitoneal exchanges take place via several mechanisms, with the peritoneal membrane behaving like a semi-permeable membrane; it allows diffusion, absorption, and convection.

A mathematical model with three pore types, proposed by B. Rippe, models the transports established during PD[7]. The histological equivalent of small and large pores has not been established. This model is illustrated inFigure 1.

Figure 1.Illustration schematizing the exchange model across the various pores of the peritoneal membrane according to Rippe B.

Ultra-small pores (transcellular transport via type 1 aquaporins) are mainly responsible for osmotic gradient-mediated free water transport (usually glucose), playing a vital role at the start of the cycle, when the crystalloid gradient is strong. They are responsible for 40–50% of ultrafiltration (UF). Small pores transfer water by diffusion and convection (50–60% of overall UF), as well as water coupled with solutes (urea, creatinine, sodium, etc.). Large pores allow macromolecules to pass through.

H2O: water, R: radius, nm: nanometer

INDICATIONS AND CONTRAINDICATIONS FOR PD IN CHILDREN

It is recommended to start a replacement technique in children with an estimated glomerular filtration rate (eGFR) of less than 10 mL/min/1.73 m2, or when the child presents uremic symptoms refractory to medical treatment[2]. PD is then the technique of choice, particularly in infants, due to the absence of appropriate extra body circuits dedicated to them in chronic hemodialysis[8]. PD can be used from birth, including in premature infants[9].

However, no study has shown that one dialysis modality is superior to another in terms of survival[10]. Thus, the choice of dialysis modality depends on the convictions and possibilities of the teams in charge of the child and the choice of the family.

Advantages of PD

This is a gentle, physiological dialysis method that ensures good hemodynamic tolerance and preserves residual diuresis. Unlike hemodialysis, it does not require anticoagulation. PD also helps to maintain vascular capital, an essential factor in these young patients, who are likely to undergo several renal replacement therapies over the course of their lives. PD is carried out at home, which limits “hospital constraints.” This technique is also preferable when the family is far from the dialysis center. Nocturnal PD enables schooling to be maintained. Compared with non-intensive hemodialysis techniques, daily PD also reduces water restriction and dietary constraints. In order to optimize staturo-weight growth in children with chronic renal failure, enteral nutritional support is often necessary to cover the caloric needs required according to the child’s age[11]. In addition, children with chronic renal failure are treated with daily injections of growth hormone to optimize statural growth[12].

Disadvantages of PD

The technique can nevertheless represent a significant burden for the family, leading to difficulties with adherence in adolescents who may find the dialysis time too long. Studies on the quality of life of families of children undergoing peritoneal dialysis highlight a significant impact on their well-being[13], with a high prevalence of anxiety-depressive disorders among parents[14]. Chronic PD also leads to alterations in the peritoneal membrane. Chronic PD induces submesothelial fibrosis and neoangiogenesis, clinically reflected in altered membrane transport[15].

PD is contraindicated in children with pathologies that affect the integrity of the peritoneal membrane or cavity, such as omphalocele, bladder exstrophy, diaphragmatic hernia, laparoschisis, or obliterated peritoneal cavity. The presence of ileostomies and colostomies, significant organomegaly, living situations unsuitable for home dialysis, lack of appropriate caregiver support, and recent abdominal surgery may lead to discussion of the first-line indication for PD[16].

PRESCRIBING PD IN PRACTICE

There are several stages in the process once the indication for PD has been established, the family’s commitment to the project has been ascertained, and the feasibility of the procedure has been verified.

The practitioner will first select the catheter and ensure that it is in place and functioning properly. The PD modality

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