Factors influencing peritoneal transport parameters during the first year on peritoneal dialysis: peritonitis is the main factor.

BACKGROUND: Studies on the evolution of peritoneal transport during the first year of peritoneal dialysis (PD) are scarce and their results are contradictory. The aim of the present study was to analyse the evolution of peritoneal transport and residual renal function during the first year on PD, and to determine the factors that may influence them. METHODS: We studied 249 patients on continuous ambulatory PD with glucose exchange solutions (117 men, 132 women, mean age 51.9+/-16 years) 59 of whom had diabetes (25 type I). At baseline and after 1 year, we determined the mass transfer coefficients of urea (U-MTAC) and creatinine (Cr-MTAC), net ultrafiltration and residual renal function. RESULTS: Residual renal function decreased significantly during the first year (from 3.9+/-2.8 to 2.4+/-2.2 ml/min, P<0.001). Both U-MTAC and Cr-MTAC decreased after 1 year [U-MTAC from 22.7+/-7.8 to 20.7+/-6.6 ml/min (P<0.001), Cr-MTAC from 10.5+/-5.3 to 10.1+/-4.6 ml/min (NS)]. The ultrafiltration capacity increased significantly (from 923+/-359 to 987 U 341 ml/4 h, P<0.001). The evolution of MTAC values was independent of age, sex, diabetes and amount of hypertonic glucose used. When patients were grouped according to their initial Cr-MTAC, we observed a tendency toward normalization of the parameters of peritoneal function. Patients with peritonitis (n = 88) showed a first year increase in Cr-MTAC, which was significantly higher than in patients without peritonitis (11.1+/-5 vs 9.5+/-4.2, P<0.01). Ultrafiltration decreased in patients with more than four accumulated days of peritonitis (from 1062+/-447 to 1024+/-340 ml/4 h, NS); it increased in patients without peritonitis. CONCLUSIONS: The peritoneal transport parameters tended toward normalization during the first year on PD, mainly with a decrease of small solute transport and an increase of ultrafiltration capacity. This evolution is independent of age, gender, diabetes and higher exposure to glucose in PD solutions. Peritonitis was the only independent factor that affected peritoneal function during the first year on peritoneal dialysis.     

The importance of ultrasonographic measurement of peritoneal wall thickness in pediatric chronic peritoneal dialysis patients

Abstract

Loss of peritoneal function due to peritoneal fibrosing syndrome (PFS) is a major factor leading to treatment failure in chronic peritoneal dialysis (PD) patients. Although the precise biologic mechanisms responsible for these changes have not been defined, the general assumption is that alterations in peritoneal function are related to structural changes in the peritoneal membrane. Studies of the peritoneal membrane by non-invasive ultrasonography (US) in chronic PD patients are limited. The aim of the present study is to assess the relationship between functional parameters of peritoneum and peritoneal thickness measured by US in children treated by chronic PD. We recruited two groups of patients: 23 subjects (13 females, 10 males) on chronic PD (patient group) and 26 (7 females, 19 males) on predialysis out-patient follow-up (creatinine clearance: 20–60?mL/min/1.73?m²) (control group). Age, sex, weight, height, body mass index (BMI), chronic PD duration, episodes of peritonitis and the results of peritoneal equilibration test (PET) were recorded. Hemoglobin (Hb), blood pressure (BP), left ventricular mass index (LVMI) and renal osteodystrophy (ROD) parameters were also obtained. The thickness of the parietal peritoneum was measured by trans-abdominal US in all children. Statistical analyses were performed by using Student's t and Pearson's correlation tests. Mean peritoneal thickness in chronic PD patients (1028.26?±?157.26?μm) was significantly higher than control patients (786.52?±?132.33). Mean peritoneal thickness was significantly correlated with mean body height (R²?=?0.93, p?<?0.05), BMI (R²?=?0.25, p?<?0.05), chronic PD duration (R²?=?0.64, p?<?0.05), episodes of peritonitis (R²?=?0.93, p?<?0.05), D/P_creatinine (R²?=?0.76, p?<?0.05) and D4/D0_glucose (R²?=?0.81, p?<?0.05). No correlation was found between peritoneal thickness and Hb, BP, LVMI and ROD parameters. In conclusion, ultrasonographic measurement of peritoneal membrane thickness is a simple and non-invasive method in chronic PD children. This diagnostic tool likely enables to assess peritoneal structure and function in these patients.     

Activation of matrix metalloproteinase-2 causes peritoneal injury during peritoneal dialysis in rats.

BACKGROUND: Sclerosing peritonitis (SP) and encapsulating peritoneal sclerosis (EPS) are serious complications of continuous ambulatory peritoneal dialysis. Although we have shown previously that matrix metalloproteinase-2 (MMP-2) is increased in peritoneal injury leading to SP/EPS, most of the MMP-2 in the dialysate drained from the peritoneal cavity was the latent form that was lacking activity. In the present study, we investigated whether MMP-2 causes peritoneal injury. METHODS: To create an animal model of peritoneal injury, we administered intraperitoneally chlorhexidine gluconate to rats. Dialysate drained from these rats was analysed by gelatin zymography and MMP-2 activity was analysed by an in situ film zymography method. In vitro myofibroblasts were cultured in collagen three-dimensional culture and then MMP-2 in conditioned medium from the culture was analysed by gelatin zymography. RESULTS: Zymographic analysis revealed that latent form MMP-2 levels were high in the dialysate from peritoneal injury rats, whereas the active form was barely detectable. MMP-2 activity in the peritoneal tissue of the peritoneal injury rats was strongly detected by in situ film zymography. In vitro myofibroblasts were promoted to produce MMP-2 and to activate MMP-2 in collagen three-dimensional culture. CONCLUSIONS: In the present model, most of the MMP-2 was in the latent form, but activation of MMP-2 was promoted in the peritoneum during peritoneal injury. Activated MMP-2 may be associated with the progression of peritoneal injury.     

Comparison of infectious complications in peritoneal dialysis patients using either a twin-bag system or automated peritoneal dialysis.

BACKGROUND: Automated peritoneal dialysis (APD) and twin-bag (TB) systems are two major peritoneal dialysis (PD) modalities. Published data comparing the infectious complications of these modalities is limited. Subjects and methods. Ninety-five patients using APD (the APD group) and 117 patients using TB system (the TB group) were recruited. Among them, 35 patients used both modalities. The two groups' clinical characteristics, incidences of infectious complications, and the time intervals to first PD-related infection were compared. RESULTS: Clinical characteristics, incidence of exit-site infection (ESI), and time intervals to first ESI were similar in the TB and APD groups. The incidence of peritonitis in the APD group (1.22 episodes/100 patient-months) was significantly (P < 0.001) lower than that of the TB group (2.28 episodes/100 patient-months). Using the Cox proportional hazard model, APD was found to have a lower risk of peritonitis relative to TB systems, with marginal significance (RR 0.58, P = 0.051). CONCLUSION: APD was found to have a lower peritonitis rate than the TB system. Since reducing the peritonitis rate helps to maintain technical survival during PD, from this viewpoint, APD may be preferred for patients undergoing PD, unless contraindicated.     

Longitudinal changes in peritoneal kinetics: the effects of peritoneal dialysis and peritonitis

BACKGROUND.: Peritoneal infection and poor ultrafiltration continue to bethe major causes of treatment failure in CAPD. The combinedeffects of peritonitis and the continuous exposure to dialysisfluid remain the most likely candidates affecting the peritoneumin the long term. The purpose of this study was to observe theeffects of peritonitis and dialysis on longitudinal peritonealfunction. METHODS.: The peritoneal equilibration test (PET) was utilized to quantifylongitudinal changes in low-molecular-weight solute transfer(D/P_creat) and ultrafiltration (UF) in 233 patients treatedwith CAPD. Of these, 166 represented an unselected cohort (Group1) studied prospectively from commencing treatment for up to54 months, and 67 were selected patients (Group 2) with PETdata available at commencement of the study, having been ondialysis for a minimum of 18 months. PETs were performed either6-monthly or following peritonitis episodes. RESULTS.: Data on the short-term effect of peritonitis kinetics were pooledfor groups 1 and 2. Single, isolated episodes (n = 86) had nosignificant effect on D/P_creat or UF, whereas recurrences orclusters of infection (n = 70) caused increases in D/Pcreatand reductions in UF, the significance of which increased withthe number of episodes. There were significant correlationsbetween both changes in D/P_creat and UF with the cumulativedialysate leukocyte count, regardless of infecting organism,suggesting that intensity of peritoneal inflammation is alsoimportant. Those organisms associated with greater change inperitoneal kinetics, e.g. S. aureus, Pseudomonas, also had thehighest neutrophil counts. The longitudinal changes in peritoneal kinetics were analysedfor patients in group 1 only. There was a highly significantincrease in D/P_creat after 6 months treatment; this increasedfurther with time on treatment, reaching further significanceat 42 and 48 months. There was an associated reduction in UF.In view of the short-term effects of peritonitis on kineticsgroup 1 was further subdivided into patients who were eitherperitonitis free or only experienced isolated infections, group1a, and those that had multiple infection episodes, group 1b.Treatment drop-out, due to death or technical failure occurredat double the rate in group 1b, who also had significantly higherD/P_creat and lower UF at 1, 6, 12, 18 and 24 months of treatment.Group 1a subsequently caught up, however, indicating that peritonitisis not the only factor influencing long-term changes in peritonealkinetics. CONCLUSIONS.: These data suggest that solute transfer increases and UF declineswith time on peritoneal dialysis. This process is exacerbatedand accelerated by peritonitis, and appears to be proportionalto the degree of associated inflammation and number of infectionsin close proximity.     

Disposition of fusidic acid during peritoneal dialysis

Summary: Fusidic acid has characteristics that suggest it might be a useful agent in the management of staphylococcal peritonitis in patients undergoing peritoneal dialysis. the present investigation was undertaken to establish the relationship between serum and peritoneal dialysis effluent concentrations of fusidic acid and to determine whether therapeutic levels of fusidic acid could be achieved in the dialysate following oral administration of the agent. Concentrations of fusidic acid up to 80 times the MIC for staphylococci were found after repeated oral doses. the results have provided basic data needed to initiate clinical studies of the role of fusidic acid as an adjunctive agent in the management of staphylococcal peritonitis.     

Transfer of autologous haemoglobin from the peritoneal cavity during peritoneal dialysis.

Transfer of autologous haemoglobin from the peritoneal cavity was evaluated retrospectively in 14 patients who received this marker intraperitoneally (group 1) during routine continuous ambulatory peritoneal dialysis (CAPD). Five additional patients were studied during acute peritonitis (group 2). A model for balance of both dialysate volume and amount of haemoglobin is developed to assess movement of the compound into lymph or adjacent tissues. Under the conditions of the study the transfer was slow (8 +/- 10 ml/h) in patients without peritonitis (group 1), and significantly faster (25 +/- 22 ml/h) in those with peritonitis (group 2). These clearance values are the upper limits for lymph flow.     

Antibacterial peritoneal defence in automated peritoneal dialysis: Advantages of tidal over continuous cyclic peritoneal dialysis?

In tidal peritoneal dialysis (TPD) only a part of the infuseddialysate is drained with each exchange, leaving a residualvolume on top of which fresh fluid is cycled. As the persistentpresence of a buffered intraperitoneal reserve volume mightfavour peritoneal macrophage (PMO) function, PMO obtained fromeight patients during a 3-h continuous cyclic peritoneal dialysis(CCPD) or TPD session were studied in a randomized cross-overtrial. PMO were studied for uptake of E. coli (complement-dependent)and S. epidermidis (antibody-dependent), as well as for theirkilling capacity and peak chemiluminescence response. In addition,dialysate was sampled during both treatment sessions and studiedfor pH, osmolality, and effect on the viability of donor phagocytesand mesothelial cells. TPD-derived PMO were significantly better able to phagocytoseE. coli than CCPD-PMO (48 ±8 versus 33±6% uptake,P<0.05), whereas the other tested functional capacities revealedno significant difference between TPD- and CCPD-PMO. DuringTPD dialysate pH ranged from 6 to 7 as compared to a pH rangefrom 5 to 7 in CCPD. The presence of a residual dialysate volumeresulted in less wash-out of cells and opsonins early in thetreatment, and to some extent blunted the noxious effects offresh dialysis solutions. Overall, however, tidal PD appearedto have no advantage over CCPD regarding preservation of peritonealdefences.     

Polydipsia: a feature of peritoneal dialysis.

BACKGROUND: Some dialysis patients fail to comply with their fluid restriction causing problems due to volume overload. These patients sometimes blame excessive thirst. There has been little work in this area and no work documenting polydipsia among peritoneal dialysis (PD) patients. METHODS: We measured motivation to drink and fluid consumption in 46 haemodialysis patients (HD), 39 PD patients and 42 healthy controls (HC) using a modified palmtop computer to collect visual analogue scores at hourly intervals. RESULTS: Mean thirst scores were markedly depressed on the dialysis day (day 1) for HD (P<0.0001). The profile for day 2 was similar to that of HC. PD generated consistently higher scores than HD day 1 and HC (P = 0.01 vs. HC and P<0.0001 vs HD day 1). Reported mean daily water consumption was similar for HD and PD with both significantly less than HC (P<0.001 for both). However, measured fluid losses were similar for PD and HC whilst HD were lower (P<0.001 for both) suggesting that the PD group may have underestimated their fluid intake. CONCLUSION: Our results indicate that HD causes a protracted period of reduced thirst but that the population's thirst perception is similar to HC on the interdialytic day despite a reduced fluid intake. In contrast, the PD group recorded high thirst scores throughout the day and were apparently less compliant with their fluid restriction. This is potentially important because the volume status of PD patients influences their survival.     

Intraperitoneal heparin reduces peritoneal permeability and increases ultrafiltration in peritoneal dialysis patients.

BACKGROUND: Patients on long-term treatment with peritoneal dialysis (PD) suffer from increasing peritoneal permeability and loss of ultrafiltration as a result of persistent inflammation, which may be triggered by bioincompatible dialysis fluids. Heparins have anti-inflammatory and anticoagulant properties. We have examined the effect of intraperitoneal (IP) low-molecular weight heparin (tinzaparin) on peritoneal permeability and ultrafiltration in PD patients. METHODS: By means of a double-blinded cross-over design, 21 PD patients were randomized to receive either placebo or tinzaparin intraperitoneally once a day for two treatment periods of 3 months, separated by a wash-out period. The effect of heparin on peritoneal permeability and ultrafiltration was assessed using the 4 h standard peritoneal equilibration test. RESULTS: IP tinzaparin reduced significantly the dialysate-to-plasma ratios (D/P) of creatinine (P < 0.01), urea (P < 0.01) and albumin (P<0.05). In addition, the ratio of glucose concentration in dialysate at 4 h dwell to that of 0 h dwell (D(4)/D(0)) was increased (P<0.05) along with an increase in ultrafiltration volume (P<0.05). CONCLUSIONS: IP tinzaparin reduces peritoneal permeability to small solutes and increases ultrafiltration in PD patients.     

Laparoscopic placement of peritoneal dialysis catheters: 7 years experience

Background: Since 1994 we have placed all peritoneal dialysis (Tenckhoff) catheters at our hospital laparoscopically using a technique that incorporates suture fixation into the pelvis. The purpose of this study was to determine the long‐term outcome of this approach. Method: Perioperative and follow‐up data for all patients undergoing placement of a peritoneal dialysis catheter at the Royal Adelaide Hospital were collected prospectively and managed on unit specific and hospital wide computerized databases. A total of 148 procedures were carried out in 123 patients from March 1994 to November 2001. Follow‐up ranged from 3 to 68 months (median, 42 months). All procedures were undertaken or supervised by one surgeon, and catheters were routinely sutured into the pelvis at laparoscopy. Results: There was no perioperative mortality in this series, and only one catheter could not be placed laparoscopically. This was in a patient with extensive intra‐abdominal adhesions. Mean operative time was 27 min (range, 10?100 min), and mean postoperative stay was 2.8 days (range, 1?12 days). Seven (5%) patients experienced peri/postoperative haemorrhage, and four of these underwent surgical re‐exploration. Twenty‐five (17%) catheters are still used for dialysis. Thirty‐four (23%) catheters were removed when the recipient received a subsequent renal transplant, and 42 (28%) patients died during follow‐up. Forty‐six (31%) patients required catheter revision or removal because of technical problems; 26 (18%) recurrent peritonitis or exit site infection; and 20 (14%) catheter blockage. Twenty‐eight reinsertion procedures were carried out in 25 patients. Ten (7%) patients developed port site hernias at late follow‐up, and required hernioplasty. Catheter migration leading to malfunction (poor drainage) occurred in eight (5%) patients only. Conclusions: Laparoscopic placement of peritoneal dialysis catheters is a safe and effective procedure. The majority of patients will dialyse successfully using this technique. Suturing the catheter tip into the pelvis is associated with a low rate of catheter migration.     

A high peritoneal large pore fluid flux causes hypoalbuminaemia and is a risk factor for death in peritoneal dialysis patients.

BACKGROUND: Hypoalbuminaemia is common in peritoneal dialysis (PD) patients and has an associated high mortality. An excess morbidity and mortality has previously been found in patients with high peritoneal transport. A high peritoneal large pore fluid flux (Jv(L)) results in increased peritoneal loss of protein that possibly contributes to patient morbidity. Alternatively, hypoalbuminaemia and high transport status could be just a marker of capillary pathology associated with atherosclerotic comorbidity. METHODS: Peritoneal dialysis capacity computer modelling of peritoneal transport, based on Rippe's three-pore model, was performed to measure Jv(L) in 155 incident PD patients 2-4 weeks after PD initiation. Patient clinical and biochemical status was determined -6, -3, -1, 1 and 6 months after PD initiation, and every 6 months thereafter. Jv(L) was redetermined in prevalent patients 2 and 4 years after PD initiation. RESULTS: Jv(L) was 0.106+/-0.056 ml/min/1.73 m(2) (median 0.094, interquartile range 0.068-0.128). It was correlated to age*** (*P<0.05; **P<0.01; ***P<0.001) (20-30 years 0.079+/-0.04; 70 years 0.121+/-0.071), but not to gender. No correlation to diabetic or preexisting renal replacement therapy was seen, but patients with atherosclerosis had higher Jv(L) (0.123+/-0.06 vs 0.100+/-0.056*) as had patients with other systemic disease (0.121+/-0.68 vs 0.100+/-0.051*). Jv(L) was positively correlated to area parameter (r = 0.41***), and negatively correlated to plasma albumin (-0.36***). Patients were divided into three equal groups: group 1, Jv(L) <0.075 ml/min/1.73 m(2); group 2, 0.075-0.11; group 3: >0.11. There was no difference between the groups in p-albumin prior to PD. Immediately after PD start, differences between the three groups appeared (1 month p-albumin: (micromol/l) group 1, 548+/-83; group 2, 533+/-86; group 3, 497+/-78**), and persisted for up to 6 years. No significant change in Jv(L) was seen at 2 and 4 years. Patients with significant albuminuria also had hypoalbuminaemia (<1 g/day: 546+/-81 mumol/l; >2 g/day: 503+/-54 micromol/l). Intermittent PD ameliorated the effect of Jv(L) on albumin losses and clearance. Mortality was increased significantly with raised Jv(L), independently of age (2 year mortality: group 1, 10%, group 3, 32%*). There was no overall effect on technique survival, but hypoalbuminaemic group 3 patients had a higher failure rate. CONCLUSION: Jv(L) is related to hypoalbuminaemia and mortality after PD initiation. A high Jv(L) seems to be a marker of preexisting vascular pathology, and to cause hypoalbuminaemia after PD initiation. It is suggested that peritoneal albumin loss can have an identical pathogenic effect as urinary albumin loss, by causing an iatrogenic "nephrotic" syndrome.     

Quality of life on chronic dialysis: comparison between haemodialysis and peritoneal dialysis.

BACKGROUND: Quality of life (QOL) assessment in patients on chronic haemodialysis (HD) or peritoneal dialysis (PD) has only rarely been carried out with the generic Euroqol-5D questionnaire. METHODS: All chronic HD and PD patients in the 19 centres of western Switzerland were requested to fill in the validated Euroqol-5D generic QOL questionnaire, assessing health status in five dimensions and on a visual analogue scale, allowing computation of a predicted QOL value, to be compared with the value measured on the visual analogue scale. RESULTS: Of the 558 questionnaires distributed to chronic HD patients, 455 were returned (response rate 82%). Fifty of 64 PD patients (78%) returned the questionnaire. The two groups were similar in age, gender and duration of dialysis treatment. Mean QOL was rated at 60+/-18% for HD and 61+/-19% for PD, for a mean predicted QOL value of 62+/-30 and 58+/-32% respectively. Results of the five dimensions were similar in both groups, except for a greater restriction in usual activities for PD patients (P = 0.007). The highest scores were recorded for self-care, with 71% HD and 74% PD patients reporting no limitation, and the lowest scores for usual activities, with 14% HD and 23% PD patients reporting severe limitation. Experiencing pain/discomfort (for HD and PD) or anxiety/depression (for PD) had the highest impact on QOL. CONCLUSIONS: QOL was equally diminished in HD and PD patients. The questionnaire was well accepted and performed well. Improvement could be achievable in both groups if pain/discomfort and anxiety/depression could be more effectively treated.     

Growth of children following the initiation of dialysis: a comparison of three dialysis modalities

Maintenance dialysis usually serves as an interim treatment for children with end-stage renal disease (ESRD) until transplantation can take place. Some children, however, may require dialytic support for an extended period of time. Although dialysis improves some of the problems associated with growth failure in ESRD (acidosis, uremia, calcium, and phosphorus imbalance), many children continue to grow poorly. Therefore, three different dialysis modalities, continuous ambulatory peritoneal dialysis (CAPD), cycler/intermittent peritoneal dialysis (CPD), and hemodialysis (HD), were evaluated with regard to their effects on the growth of children initiating dialysis and remaining on that modality for 6–12 months. Growth was best for children undergoing CAPD when compared with the other two modalities with regard to the following growth parameters: incremental height standard deviation score for chronological age [–0.55±2.06 vs. –1.69±1.22 for CPD (P<0.05) and –1.80±1.13 for HD (P<0.05)]; incremental height standard deviation score for bone age [–1.68±1.71 vs. –2.45±1.43 for CPD (P=NS) and –2.03±1.28 for HD (P=NS)]; change in height standard deviation score during the dialysis period [0.00±0.67 vs. –0.15±.29 for CPD (P=NS) and –0.23±.23 for HD (P=NS)]. The reasons why growth appears to be best in children receiving CAPD may be related to its metabolic benefits: lower levels of uremia, as reflected by the blood urea nitrogen [50±12 vs. 69±16 mg/dl for CPD (P<0.5) and 89±17 for HD (P<0.05)], improved metabolic acidosis, as indicated by a higher serum bicarbonate concentration [24±2 mEq/l vs. 22±2 for CPD (P<0.05) and 21±2 for HD (P<0.05)]. In addition, children undergoing CAPD receive significant supplemental calories from the glucose absorbed during dialysis. CAPD, and possibly, other types of prolonged-dwell daily peritoneal dialysis appear to be most beneficial for growth, which may be of particular importance for the smaller child undergoing dialysis while awaiting transplantation.