Complications of Peritoneal Dialysis Part I: Mechanical Complications

Peritoneal dialysis (PD) is a form of KRT that offers flexibility and autonomy to patients with ESKD. It is associated with lower costs compared with hemodialysis in many countries. However, it can be associated with unexpected interruptions to or discontinuation of therapy. Timely diagnosis and resolution are required to minimize preventable modality change to hemodialysis. This review covers mechanical complications, including leaks, PD hydrothorax, hernias, dialysate flow problems, PD-related pain, and changes in respiratory mechanics. Most mechanical complications occur early, either as a result of PD catheter insertion or the introduction of dialysate and consequent increased intra-abdominal pressure. Late mechanical complications can also occur and may require different treatment.

Epidemiology of peritoneal dialysis outcomes

Peritoneal dialysis (PD) is an important home-based treatment for kidney failure and accounts for 11% of all dialysis and 9% of all kidney replacement therapy globally. Although PD is available in 81% of countries, this provision ranges from 96% in high-income countries to 32% in low-income countries. Compared with haemodialysis, PD has numerous potential advantages, including a simpler technique, greater feasibility of use in remote communities, generally lower cost, lesser need for trained staff, fewer management challenges during natural disasters, possibly better survival in the first few years, greater ability to travel, fewer dietary restrictions, better preservation of residual kidney function, greater treatment satisfaction, better quality of life, better outcomes following subsequent kidney transplantation, delayed need for vascular access (especially in small children), reduced need for erythropoiesis-stimulating agents, and lower risk of blood-borne virus infections and of SARS-CoV-2 infection. PD outcomes have been improving over time but with great variability, driven by individual and system-level inequities and by centre effects; this variation is exacerbated by a lack of standardized outcome definitions. Potential strategies for outcome improvement include enhanced standardization, monitoring and reporting of PD outcomes, and the implementation of continuous quality improvement programmes and of PD-specific interventions, such as incremental PD, the use of biocompatible PD solutions and remote PD monitoring.

The use of peritoneal dialysis (PD) can be advantageous compared with haemodialysis treatment, although several barriers limit its broad implementation. This review examines the epidemiology of peritoneal dialysis (PD) outcomes, including clinical, patient-reported and surrogate PD outcomes.

Peritoneal dialysis (PD) has distinct advantages compared with haemodialysis, including the convenience of home treatment, improved quality of life, technical simplicity, lesser need for trained staff, greater cost-effectiveness in most countries, improved equity of access to dialysis in resource-limited settings, and improved survival, particularly in the first few years of initiating therapy.

Important barriers can hamper PD utilization in low-income settings, including the high costs of PD fluids (owing to the inability to manufacture them locally and the exorbitant costs of their import), limited workforce availability and a practice culture that limits optimal PD use, often leading to suboptimal outcomes.

PD outcomes are highly variable around the world owing in part to the use of variable outcome definitions, a heterogeneous practice culture, the lack of standardized monitoring and reporting of quality indicators, and kidney failure care gaps (including health care workforce shortages, inadequate health care financing, suboptimal governance and a lack of good health care information systems).

Key outcomes include not only clinical outcomes (typically defined as medical outcomes based on clinician assessment or diagnosis) — for example, PD-related infections, technique survival, mechanical complications, hospitalizations and PD-related mortality — but also patient-reported outcomes. These outcomes are directly reported by patients and focus on how they function or feel, typically in relation to quality of life or symptoms; patient-reported outcomes are used less frequently than clinical outcomes in day-to-day routine care.

A Randomized Controlled Trial of a Bicarbonate and a Bicarbonate/Lactate-Containing Dialysis Solution in Capd

Objective

To evaluate the safety and efficacy of bicarbonate and bicarbonate/lactate-based PD fluids.

Design

A randomly allocated prospective controlled trial lasting eight weeks.

Setting

Five renal units in Europe.

Patients

Individuals who have been treated by CAPD for at least three months and who have had at least one month's therapy with 40 mmol/L lactate PD fluid. Those with recent infection, diabetes or other serious illness are excluded. Forty-seven individuals have entered the study so far.

Interventions

Patients are randomly allocated to three groups. Group 1 receive 40 mmol/L lactate dialysate, Group 2 are given 38 mmol/L bicarbonate fluid and Group 3 are tested with a 25 mmol/L bicarbonate and 15 mmol/L lactate dialysate.

Outcome measures

The primary outcome measure is the plasma bicarbonate level. Adverse events and ease of use of the two-chambered bags used by Groups 2 and 3 are also being assessed.

Results

To date, plasma bicarbonate levels have been the same in all treatment groups up to the end of the trial period. There are no differences in serum lactate levels. No side effects are attributable to the test fluids. The patients have managed the two-chambered bags successfully.

Conclusion

This trial is still ongoing, but to date, neutral bicarbonate based fluids have been as effective as lactate dialysate in treating uremic acidosis.

The Impact of Peritonitis on Peritoneal and Systemic Acid-Base Status of Patients on Continuous Ambulatory Peritoneal Dialysis

Objective

To assess the possible effects of peritonitis on peritoneal and systemic acid-base status.

Design

pH, pCO2, lactate, and total leukocyte and differential count were simultaneously determined in the overnight dwell peritoneal dialysis effluent (PDE) and arterial blood in noninfected patients (controls) and on days 1, 3, and 5 from the onset of peritonitis.

Setting

University multidisciplinary dialysis program.

Patients

Prospective analysis of 63 peritonitis episodes occurring in 30 adult CAPD patients in a single center.

Results

In controls, mean (±SD) acid-base parameters were pH 7.41 ±0.05, pCO2 43.5±2.6 mm Hg, lactate 2.5±1.5 mmol/L in the PDE, and pH 7.43±0.04, PaCO2 36.8±3.8 mm Hg, lactate 1.4±0.7 mmol/L in the blood. In sterile (n=6), gram-positive (n=34), and Staphylococcus aureus (n=9) peritonitis PDE pH's on day 1 were, respectively, 7. 29±0.07, 7. 32±0.07, and 7.30±0.08 (p<0.05 vs control). In gram -negative peritonitis (n=14) PDE pH was 7.21 ±0.08 (p<0.05 vs all other groups). A two-to-threefold increase in PDE lactate was observed in all peritonitis groups, but a rise in pCO2 was only seen in gram -negative peritonitis. Acid-base profile of PDE had returned to control values by day 3 in sterile, gram -positive and Staphylococcus aureus peritonitis and by day 5 in gramnegative peritonitis. Despite a slight increase in plasma lactate on the first day of peritonitis, arterial blood pH was not affected by peritonitis.

Conclusion

PDE pH is decreased in continuous ambulatory peritoneal dialysis (CAPD) peritonitis, even in the absence of bacterial growth. In gram-negative peritonitis, PDE acidosis is more pronounced and prolonged, and pCO2 is markedly increased. Arterial blood pH is not affected by peritonitis.

The Choice of Dialysis Solutions in Pediatric Chronic Peritoneal Dialysis: Guidelines by AnAD HOCEuropean Committee

Objective

To provide guidelines on choosing dialysis solutions for children on chronic peritoneal dialysis (PD).

Setting

European Paediatric Peritoneal Dialysis Working Group.

Data Source

Literature on the application of PD solutions in children ( Evidence), and discussions within the group ( Opinion).

Conclusions

Glucose is the standard osmotic agent for PD in children ( Evidence). The lowest glucose concentration needed should be used ( Opinion). Low calcium solution (1.25 mmol/L) should be applied, wherever possible, with careful monitoring of parathyroid hormone levels ( Opinion). The use of amino acid-containing dialysis fluids can be considered in malnourished children, although aggressive enteral nutrition is preferred ( Opinion). There is insufficient evidence documenting the efficacy of intraperitoneally administered amino acids ( Evidence). When ultrafiltration and/or solute removal are insufficient, poly-glucose solutions are a welcome addition to the treatment of children on nocturnal intermittent PD ( Evidence). However, in the absence of any reported long-term experience with children, their use must be closely monitored ( Opinion). Bicarbonate would appear to be the preferred buffer for PD in children, but more in vivo studies are required before it replaces the present lactate-containing solutions ( Evidence/Opinion).

A Randomized Clinical Trial with a 0.6% Amino Acid/1.4% Glycerol Peritoneal Dialysis Solution

Background

Glucose is an accepted osmotic agent for peritoneal dialysis (PD) although it has several drawbacks. Some of these drawbacks have been addressed by the introduction of solutions with low glucose degradation products and physiological pH in dual-chambered bags. Despite this achievement, there is a need for alternative osmotic agents. This randomized clinical trial analyzes 3-month's clinical experience with a mixture of 0.6% amino acids and 1.4% glycerol.

Methods

The study was performed at the renal units of the University Hospitals Ghent, Belgium, and Utrecht, The Netherlands. Stable PD patients were randomized for either protocol A (test solution, n = 5) or protocol B (control regimen, n = 5). In both protocols, there was a run-in phase of 1 month with a dialysis regimen of 2 × 2 L 2.27% glucose solution (Dianeal; Baxter, Nivelles, Belgium), 1 × 2 L Extraneal (Baxter), and 1 × 2 L glucose solution (Dianeal). After this month-long run-in period, patients in group A received during 3 months 2 × 2 L amino acid/glycerol solution, 1 × 2 L Extraneal, and at least 1 × 2 L of a classic glucose solution.

Results

Glucose absorption decreased in the test group during the test phase (from 84.2 ± 8.7 to 11.7 ± 11.6 g/24 hours, p = 0.001). Dialysate levels of cancer antigen 125 (CA125) increased in the test group, from 17.5 ± 11.0 to 32.4 ± 4.6 units/L ( p = 0.04), whereas, in the control group, the levels remained stable (15.5 ± 8.7 and 14.9 ± 9.8 units/L respectively, p = 0.4). There were no differences in serum urea, serum bicarbonate, serum osmolarity, serum albumin, or parameters related to skin-fold thickness or serum glycerol levels between control and test solutions. No differences were observed in obtained ultrafiltration after a 4-hour dwell with 2.27% glucose or the test solution, both measured at week 4 of the run-in period and week 12 of the test period.

Conclusion

This study demonstrated that the use of a new 0.6% amino acid/1.4% glycerol-containing dialysis solution is safe and well tolerated. Glucose load was reduced significantly and dialysate CA125 levels improved significantly. Ultrafiltration was comparable with that of a 2.27% glucose solution. All these factors, in combination with the potential nutritional benefits, can contribute to a beneficial impact on the success of the PD technique. Further long-term studies in larger patient groups are warranted to explore the potential of this promising new solution.

Clinical Evaluation of a Peritoneal Dialysis Solution with 33 mmol/L Bicarbonate

Objective

To evaluate the efficacy and safety of a new peritoneal dialysis solution with 33 mmol/L bicarbonate.

Design

In an acute, prospective, randomized crossover study, 8 patients were randomized in two groups of 4. On the first study day, the first group performed two consecutive 4-hour exchanges with a dialysis solution containing 35 mmol/L lactate: the first exchange with 13.6 g/L and the second with 38.6 g/L dextrose. On the second study day, the same type of exchanges were performed with bicarbonate. The second group underwent the same treatment, but used bicarbonate solutions on the first day and control solutions on the second study day. Thirty-three patients participated in a 2-month prospective and randomized study. After a 4-week baseline period using solutions containing 40 mmol/L lactate, the patients were dialyzed with either 33 mmol/L bicarbonate solutions or 40 mmol/L lactate solutions.

Setting

Peritoneal dialysis units at the University Hospital of Brescia and the Niguarda Hospital of Milan, Italy.

Results

Acute study: Control and bicarbonate solutions had similar effects on blood chemistries and peritoneal transport. Chronic study: Mean venous bicarbonate concentrations remained unchanged in the control group (26.6 -27.2 mmol/L), but decreased significantly in the bicarbonate group from 28.8 mmol/L at the start of the study to 23.0 mmol/L after 2 months of bicarbonate administration. Other biochemical parameters remained unchanged.

Conclusion

A peritoneal dialysis solution with a bicarbonate level of 33 mmol/L does not adequately correct uremic acidosis.

Effect of Different Buffers on the Biocompatibility of Capd Solutions

Commercially available solutions for continuous ambulatory peritoneal dialysis (CAPO) affect the viability and function of the cells in the peritoneal cavity. The low biocompatibility of the solutions may be caused by a low pH, hyperosmolality, high glucose content, and lack of potassium, glutamine, and other components essential for normal cellular functions. The nature of the buffer employed is also important for the cytotoxicity of the solutions. Lactate, the most frequently used buffer, has been shown to inhibit cellular functions important for the peritoneal defense system including phagocytosis, bacterial killing, and secretion of cytokines. It is generally believed that the cytotoxicity of lactate is caused by lowering of intracellular pH and impairment of metabolism due to changed redox potentials. However, the cytotoxicity of lactate is highly dependent upon the pH of the solutions, indicating that passive or active diffusion across the cell membrane is determining the effects of lactate. Bicarbonate has been heavily advocated as an alternative buffer because it is the most important naturally occurring buffer in plasma and it enables a pH of approximately 7.4 in the solutions. However, due to sedimentation of calcium carbonate (CaCO3) and production of toxic glucose metabolites it is difficult to prepare and store bicarbonate-based solutions. Moreover, investigations have revealed that even bicarbonate-based solutions are not optimal regarding biocompatibility, presumably due to a paradoxical intracellular acidification caused by influx of carbon dioxide (CO2). More recently, the effect of other buffers such as pyruvate and histidine have been examined. Especially pyruvate is a promising new buffer candidate.

Conventional CAPD solutions based on lactate have been shown to impair a wide variety of cell functions important for the peritoneal host defense. Apart from the influence of hyperosmolality, high glucose concentration, lack of potassium, glutamine, and other factors, this seems to be due to the combination of low pH and high lactate concentration. Presumably, lactate carries protons across the membrane, which results in intracellular acidification and increased intracellular lactate concentration, both of which may impair cell metabolism and function.

Bicarbonate-based solutions are less toxic than lactate-based solutions -primarily attributable to the higher pH. However, experiments performed by our group have indicated that bicarbonate concentrations that are too high may also affect cell function, and that a solution containing both bicarbonate and lactate may be superior. However, further studies are needed to fully elucidate this problem.

Pyruvate seems to be a promising new buffer candidate with lower toxicity than lactate solutions at identical pH and glucose content. Comparison of pyruvate, lactate, and bicarbonate solutions regarding cytotoxicity and especially intracellular acidification will hopefully shed new light on the toxic properties of these solutions.

No Significant Differences in Peritoneal Fluid Handling in Children Using pH-Neutral or Acidic Solutions

Objectives

Differences in peritoneal fluid handling in the acute setting can be expected if children are converted to pH-neutral dialysis solutions because conventional acidic solutions exert toxic effects on peritoneal mesothelial cells and microcirculation. Peritoneal fluid kinetics was therefore investigated with both types of solutions in a group of children.

Design

Peritoneal equilibration tests (PETs) were performed in 12 patients [mean age 70 months, mean time on peritoneal dialysis (PD) 18 months] using a pH-neutral PD fluid (Physioneal 3.86%; Baxter Ltd, Castlebar, Ireland) and dextran 70 as a volume marker. The results of these PETs were compared to those of a historic group of 12 children (mean age 75 months, mean time on PD 17 months).

Setting

Pediatric dialysis unit in a tertiary institute.

Patients

Stable pediatric PD patients.

Main Outcome Measures

Transcapillary ultrafiltration (TCUF) and marker clearance, dialysate-to-plasma (D/P) ratios for urea and creatinine, and Dt/D0ratio for glucose.

Results

TCUF and lymphatic absorption were not different between the two groups. There was also no significant difference in small solute clearance measured by D/P ratio for urea and creatinine and Dt/D0ratio for glucose.

Conclusion

Peritoneal fluid kinetics is not significantly altered if pH-neutral dialysis solutions are applied compared to acidic solutions. An altered TCUF, as is hypothetically possible using an acidic solution, was not established.

Effect of peritoneal dialysis fluid composition on peritoneal area available for exchange in children

BACKGROUND

Although conventional peritoneal dialysis fluids (PDFs), such as Dianeal, are non-physiological in composition, new PDFs including Physioneal have a more neutral pH, are at least partially buffered with bicarbonate and, most importantly, contain low concentrations of glucose degradation products (GDPs).

METHODS

To evaluate the impact of new PDFs in childcare, we performed a comparative crossover study with Dianeal and Physioneal. We examined both intraperitoneal pressure (IPP), which partly reflects pain induction, and the total pore area available for exchange, which indicates the number of capillaries perfused in the peritoneal membrane at any given moment and therefore partly reflects peritoneal dialysis capacity. The IPP was determined after inflow of 1000 ml/m(2) body surface area (BSA) of dialysate (intraperitoneal volume; IPV). The steady-state unrestricted area over diffusion distance (A(0)/ triangle up x, in cm(2)/cm per 1.73 m(2) BSA) was calculated from the three-pore theory. Six children were enrolled in the study. On the first day, two consecutive peritoneal equilibration tests of 90 min each were performed using first Dianeal and then Physioneal. On the second study day, the procedure was repeated with the fluids given in the opposite order.

RESULTS

The mean IPP normalized to IPV (ml/m(2)) was significantly higher for Dianeal (9.5 +/- 0.9 cm/1000 ml/m(2)) than for Physioneal (7.9 +/- 1.2 cm/1000 ml/m(2), P < 0.01). The mean A(0)/ triangle up x was 17 +/- 4% larger with Dianeal (36 095 +/- 2009 cm(2)/cm per 1.73 m(2)) than with Physioneal (31 780 +/- 2185 cm(2)/cm per 1.73 m(2), P < 0.001; based on 24 data pairs).

CONCLUSIONS

These pilot study results suggest a higher biocompatibility for Physioneal than for Dianeal. Less inflow pain associated with Physioneal induced a lower IPP reflecting enhanced fill volume tolerance, and the lower A(0)/ triangle up x reflected less capillary recruitment. Taken together, these results suggest that the new more biocompatible PDFs will improve peritoneal dialysis therapy, although this conclusion will require verification in extended clinical trials.

Use of different buffers in peritoneal dialysis

A buffer is included in the peritoneal dialysis solution in order to offset the hydrogen ions normally produced during the metabolic processes. Nowadays, the buffer used is lactate, and its concentration in conventional peritoneal dialysis fluids is 35 or 40 mmol/L. Despite the general thought that peritoneal dialysis adequately corrects uremic acidosis, several studies have demonstrated that more than 50% of patients present mild to moderate acidosis with the solution containing 35 mmol/L of lactate, although with a 40 mmol/L solution this percentage decreases, a substantial number of patients still remain acidotic. This acid-base derangement is characterized by a normal pH and a below-normal plasma bicarbonate concentration, although the external body base balance is in equilibrium. There is evidence that this condition contributes to uremic osteodystrophy and has a detrimental effect on protein metabolism. Conventional solutions also affect mesothelial cell viability and local leukocyte function and have potential systemic effects such as the impairment of cellular redox state. New solutions containing pure bicarbonate or a mixture of bicarbonate and lactate have recently been investigated. A bicarbonate solution containing 34 mmol/L significantly increased plasma bicarbonate levels as compared with the lactate 35 mmol/L solution. It has been demonstrated that bicarbonate solutions have better biocompatibility than the lactate buffered solution and substantially reduce abdominal discomfort experienced by a certain percentage of patients during the solution infusion. These studies demonstrated that the bicarbonate-buffered CAPD solution is safe, well-tolerated, and does not present any, even potential, side effects. Thus, it seems reasonable to consider the bicarbonate buffered solution the standard instead of the alternative, and it might entirely replace lactate as buffer in peritoneal dialysis fluid.

Randomized long-term evaluation of bicarbonate-buffered CAPD solution

BACKGROUND

Over the past 15 years, lactate has been used successfully as a buffer in peritoneal dialysis solutions, although its effectiveness in the correction of uremic acidosis and its biocompatibility on peritoneal resident cells have been questioned. In addition, some investigators have suggested other potential adverse metabolic effects resulting from the unphysiologically high lactate flux into the body during CAPD. These potential problems associated with lactate-containing CAPD solution prompted the search for alternative buffer-containing solutions. Bicarbonate, the physiological buffer, was considered when the problem of calcium and magnesium carbonate solubility was solved by the use of a two-compartment bag system, allowing the mixing of bicarbonate and divalent cations immediately before infusion. The long-term tolerance, safety, efficacy and therapeutic value of a bicarbonate-buffered peritoneal dialysis solution were evaluated in this study.

METHODS

This open, randomized, controlled, multicenter study comparing a 34 mmol/liter bicarbonate- with a 35 mmol/liter lactate-buffered peritoneal dialysis solution was performed in two consecutive 12-week-treatment phases. Fourteen Centers participated in this trial.

RESULTS

A total of 69 out of initially 123 randomized patients completed the six-month study period (36 patients in the bicarbonate group and 33 in the lactate group). While the arterial acid base status of the total study population did not change during the study period and no significant difference was observed between the two treatment groups, the acid-base status of patients in the bicarbonate group entering the study with a metabolic acidosis significantly improved (mean +/- SD; blood pH: baseline = 7.361 +/- 0.05, week 12 = 7.380 +/- 0.04, P < 0.05; week 24 = 7.388 +/- 0.03 P < 0.05; plasma bicarbonate: baseline = 19.49 +/- 3.01 mmol/liter, week 12 = 21.16 +/- 2.63 mmol/liter, P < 0.01; week 24 = 21.51 +/- 2.42 mmol/liter, P < 0.01). No significant changes were recorded in acidotic patients treated with the conventional lactate-buffered solution. The changes in plasma bicarbonate from baseline during the study was significantly different between the groups (week 12: lactate = +0.11 +/- 2.21 mmol/liter, bicarbonate = +1.69 +/- 2.55 mmol/liter, P < 0.05, 95% confidence interval for the difference 0.21 to 2.94 mmol/liter; week 24: lactate = +0.03 +/- 2.48 mmol/liter, bicarbonate = +1.82 +/- 2. 96 mmol/liter, P < 0.05, 95% confidence interval for the difference 0.16 to 3.42 mmol/liter). The normalized protein catabolic rate (nPCR) slightly but significantly decreased in the lactate group (baseline -0.90 +/- 0.23 g/kg/day, week 24 -0.83 +/- 0.21 g/kg/day, P < 0.01) and increased in the bicarbonate group (baseline +0.89 +/- 0.28 g/kg/day, week 24 +0.92 +/- 0.26 g/kg/day, P < 0.05). Changes from baseline between groups were significant (week 24, lactate = -0. 099 +/- 0.15 g/kg/day, bicarbonate = 0.049 +/- 0.12 g/kg/day, P < 0. 01, 95% confidence interval for the difference 0.068 to 0.229 g/kg/day). Other evaluated parameters (biochemical profile, peritoneal function parameters, dialysate protein loss) did not differ significantly between the two groups. No adverse effects related to the study solution were recorded.

CONCLUSIONS

These results support the efficacy and safety of bicarbonate-buffered peritoneal solutions in a controlled randomized comparison for up to six months. Peritoneal dialysis solutions containing the physiological buffer bicarbonate might effectively replace conventional lactate-buffered CAPD solutions.

Bicarbonate and bicarbonate/lactate peritoneal dialysis solutions for the treatment of infusion pain

A randomized, double-blind, cross-over study was undertaken to determine the effects of novel bicarbonate (38 mM) and bicarbonate (25 mM)/lactate (15 mM) containing peritoneal dialysis (PD) solutions on infusion pain in patients who experienced inflow pain with conventional lactate (40 mM) solution. Pain was assessed using a verbal rating scale and the validated McGill Pain Questionnaire (MPQ). Eighteen patients were recruited to the study. Both novel solutions resulted in highly statistically significant reductions in inflow pain compared to the control lactate solution, as assessed with both the verbal rating scale and the MPQ. For all pain variables assessed, the bicarbonate/lactate solution was more effective than the bicarbonate solution in alleviating pain. In conclusion, both solutions reduced the infusion pain experienced with control solution, but the bicarbonate/lactate solution appears to be the most effective. In contrast to the most widespread current treatment, which is the manual injection of sodium bicarbonate, the bicarbonate/lactate solution does not have the associated increased risk of peritonitis.

Continuous arterial-venous diahemofiltration and continuous veno-venous diahemofiltration in infants and children

Continuous arterial-venous diahemofiltration and continuous veno-venous diahemofiltration [CAVH(D)/CVVH(D)] in the infant and pediatric population is increasingly being utilized in the child needing renal replacement therapy (RRT). Difficulties with infant- and pediatric-specific equipment remains a limitation. The availability of techniques and equipment in this unique population is addressed. Use of this form of RRT as opposed to hemodialysis or peritoneal dialysis is discussed. The decision for CAVH(D) or CVVH(D) remains an individual choice.