Peritoneal Transport Characteristics Research Articles

High Peritoneal Permeability is Not Associated with Higher Mortality or Technique Failure in Patients on Automated Peritoneal Dialysis

Patients on continuous ambulatory peritoneal dialysis (CAPD) who have high small-molecule peritoneal transport have increased mortality. To investigate the impact of baseline peritoneal transport characteristics on patient and technique survival in incident peritoneal dialysis (PD) patients, most of whom are on automated PD (APD), with the use of icodextrin. Retrospective observational cohort study. A single PD unit. 193 new patients that began PD between January 2000 and September 2004, and had an initial peritoneal equilibration test within 6 months of commencement of PD. Patients were divided into low (L), low average (LA), high average (HA), and high (H) peritoneal transport groups. Death-censored technique failure and patient survival were examined. Of the 193 patients, 151 (78.1%) were on APD or on APD with icodextrin or on CAPD with icodextrin. At the end of 1, 3, and 5 years, patient survival was 91%, 82%, and 67% in LA group; 95%, 77%, and 69% in HA group; and 96%, 71%, and 71% in H group. Technique survival was 100%, 90%, and 77% in LA group; 96%, 84%, and 72% in HA group; and 92%, 87%, and 77% in H group. High peritoneal permeability did not predict worse patient survival or technique failure, while age, diabetes, a lower glomerular filtration rate, and high body mass index (> or =30 kg/m(2)) were independent predictors of death. This study suggests that higher peritoneal transport is not a significant independent risk factor for either mortality or death-censored technique failure. The favorable outcome for high transporters in this study may be due to improved management of volume status by the increased use of APD and the use of icodextrin-based dialysis fluid.

Evaluating Peritoneal Fluid Transport in Continuous Peritoneal Dialysis Patients: A Practical Approach

Background/Aims: Evaluating the peritoneal fluid kinetics is of clinical importance in peritoneal dialysis treatment. We have previously developed a simple way to evaluate the peritoneal fluid transport characteristics in continuous ambulatory peritoneal dialysis patients which, however, cannot be applied to those patients on a fixed dialysis schedule. Therefore, in the present study, we tested the possibility to vary the peritoneal dwell time and tried to develop a more patient-friendly ultrafiltration (UF) collection protocol. Methods: The patients’ UF volume was recorded for 10 days. All patients recruited were asked to perform their usual dialysis exchanges with, however, a special UF data collection protocol to improve the accuracy of computer simulation: at least one dwell of 2–4 h, one of 4–7 h, and one of more than 7 h. The fluid transport model was applied to the pooled UF volume for fluid kinetics simulation, and the data from the following day’s UF records using the same glucose concentration and dwell time were used to evaluate reliability and accuracy of the simulated UF value. Results: Fifty-two chronic peritoneal dialysis patients were included in the present study. All of the UF data could be used in the computer simulation, and there was a significant negative correlation between fluid absorption rate (K_e; see text) and actual UF volume on the following day using a glucose concentration of 1.5% and a dwell time of 4 h (r = –0.336, p < 0.05). The estimated UF values correlated significantly with the actually measured UF values. The variability of the results, expressed by the width between the 95% limits of agreement, fell within –139.2 to 131.9 ml, while the mean difference was –3.7 ml. Conclusions: Our present study showed that varying the peritoneal dwell time was a patient-friendly UF data collection protocol for continuous ambulatory peritoneal dialysis patients on a fixed dialysis schedule. Applying the fluid transport model and nonlinear least squares regression analysis to pooled UF values might be a good and simple way to predict the peritoneal UF capacity.

Peritoneal thickening is not inevitable in long-term peritoneal dialysis and is associated with peritoneal transport characteristics: a two-centre sonographic study

The peritoneum is subject to alterations in the life-long course of peritoneal dialysis (PD). Studies of the parietal peritoneum by non-invasive ultrasonography in PD patients are limited. We hypothesize that a prolonged PD duration is associated with a thicker peritoneum on ultrasonography and alterations in Doppler indexes of mesenteric vessels. We recruited two groups of patients, 18 who had >7 years of PD and 18 who had <12 months of PD. We excluded patients with active peritonitis, history of major abdominal surgery, cirrhosis or malignancy. We measured the sonographic thickness of the parietal peritoneum and Doppler indexes of mesenteric vessels by trans-abdominal ultrasonography at two PD units in Taiwan. We found no significant difference between two groups of PD patients in peritoneal thickness and in Doppler indexes. However, our univariate and multivariate analysis indicated that peritoneal thickness is associated with peritoneal transport characteristics (dialysate/plasma creatinine) but not with age, duration of dialysis, body height, body weight or Doppler index. The peritoneum is significantly thicker in rapid transporters than in slow transporters (RUQ: 0.59 +/- 0.40 mm versus 0.27 +/- 0.29 mm, P = 0.01; LUQ: 0.60 +/- 0.40 mm versus 0.27 +/- 0.32 mm, P = 0.016; LQ: 1.07 +/- 0.85 mm versus 0.48 +/- 0.53 mm, P = 0.026). In addition, rapid transporters have a marginally lower Doppler resistive index of the superior mesenteric artery (0.87 +/- 0.08 versus 0.90 +/- 0.10, P = 0.028). Our data showed that peritoneal thickening is not inevitable in long-term PD patients. Sonographic thickness in the parietal peritoneum is associated with transport characteristics. Rapid transporters have a significantly thicker peritoneum. The Doppler index of mesenteric vessels had no association with PD duration or transport characteristics. Trans-abdominal ultrasonography is non-invasive and useful in evaluating peritoneal characteristics of PD patients.

Effects of Peritoneal Resting on Peritoneal Fluid Transport Kinetics

Peritoneal resting has been used to restore peritoneal ultrafiltration capacity in peritoneal dialysis patients. Therefore, in the present study, we made a detailed investigation on the effects of peritoneal resting on peritoneal fluid transport characteristics in patients on continuous ambulatory peritoneal dialysis (CAPD). A temporary transfer to daytime ambulatory peritoneal dialysis with a nocturnal "empty belly" was applied to let the peritoneal membrane rest overnight in patients with poor ultrafiltration capacity. All included patients were asked to record appropriately their dialysis exchanges for the assessment of peritoneal fluid transport characteristics, which were evaluated before and after peritoneal resting. Seven CAPD patients were included in the present study. There was a significant improvement in peritoneal ultrafiltration capacity as assessed by ultrafiltration volume per gram of glucose load. Patients' daily glucose exposure and dialysate-to-plasma ratio of creatinine were significantly decreased after peritoneal resting. The peritoneal fluid absorption rate was also significantly decreased after peritoneal resting: 1.011 +/- 0.4484 versus 0.625 +/- 0.3833 mL/minute. The present study suggests that peritoneal resting can improve CAPD patients' ultrafiltration capacity and decrease the use of hypertonic dialysis solution. The improved ultrafiltration capacity by peritoneal resting was due to decreased membrane solute transport rate and decreased peritoneal fluid absorption rate.

Ultrafiltration Capacity and Peritoneal Fluid Kinetics in Continuous Ambulatory Peritoneal Dialysis Patients

Volume control is critical for peritoneal dialysis. Although peritoneal equilibration test (PET) has been used to clarify the peritoneal membrane characteristics, it is not able to adequately predict peritoneal fluid removal and optimize appropriately the dwell time. In the present study, we applied computer simulation and performed a more detailed evaluation of the fluid kinetics in patients with different ultrafiltration (UF) capacity. Patients who used three to four exchanges of 2.27% glucose dialysate per day (poor UF capacity group), and patients who used three to four exchanges of 1.36% glucose dialysate per day (good UF capacity group) to achieve adequate amount of peritoneal fluid removal were included in the present analysis. All included patients were asked to record appropriately their dialysis exchanges for the assessment of their peritoneal fluid transport characteristics. Seventeen continuous ambulatory peritoneal dialysis patients were selected in the present study, nine in poor UF capacity group and eight in good UF capacity group. Patients in poor UF capacity group had significantly higher daily glucose exposure, higher dialysate-to-plasma ratio of creatinine (D/P creatinine) values, and higher peritoneal fluid absorption rate, K(e), as compared to patients with good UF capacity. Our results suggest that patients with poor UF capacity have significant higher peritoneal small solute transport rate, and more importantly, higher peritoneal fluid absorption rate as compared to patients with good UF capacity.

Impact of ACE Inhibitors and AII Receptor Blockers on Peritoneal Membrane Transport Characteristics in Long-Term Peritoneal Dialysis Patients

Long-term peritoneal dialysis (PD) may lead to peritoneal fibrosis and ultrafiltration failure. The latter occurs due to high solute transport rates and diabetiform peritoneal sclerosis. Angiotensin-II (AII) is known to be a growth factor in the development of fibrosis and a number of animal studies have shown it likely that inhibiting the effects of AII by angiotensin-converting enzyme (ACE) or angiotensin receptor blocker (ARB) will attenuate these complications. To investigate the effects of ACE/AII inhibitors in long-term PD patients. We analyzed data from 66 patients treated with PD therapy at our center for at least 2 years, during which time at least 2 standard peritoneal permeability analyses (SPAs) were performed. 36 patients were treated with ACE/AII inhibitors (ACE/ARB group); the other 30 received none of the above drugs during the entire follow-up (control group). The two groups were compared with respect to changes in peritoneal transport over the follow-up time. A significant difference in time course of peritoneal transport was found between the 2 groups: in the ACE/ARB group, small solute transport had decreased, while it had increased in the control group. This finding was confirmed by analysis using mixed model for repeated measures. The value of mass transfer area coefficient of creatinine was influenced by the duration of PD therapy (p = 0.017) and this interaction was different with respect to use of ACE/AII inhibitors (p = 0.037). The trend was not found in protein clearances or fluid kinetics. Our findings suggest that ACE/AII inhibition is likely to prevent the increase in mass transfer area coefficients that occurs in long-term PD, which is in line with results of experimental animal studies.

Peritoneal transport characteristics and dwelling time significantly impact ghrelin clearance in peritoneal dialysis patients

Plasma ghrelin exerts widespread bioactivities. Although it is effectively removed from the blood by a single course of haemodialysis, peritoneal clearance of ghrelin is uncertain. Our study aimed to determine (i) whether there is a correlation between plasma ghrelin levels and characteristics of peritoneal ghrelin clearance, and (ii) whether plasma ghrelin levels significantly impact markers of mortality or morbidity in continuous ambulatory peritoneal dialysis (CAPD) patients. We enrolled 50 qualified CAPD patients. Blood was drawn during the fasting state and 2 h post-prandially. Also during these periods, peritoneal effluents were collected for radioimmunoassay of total plasma ghrelin level and measurement of other parameters. Twenty-four hour ascites were collected for determination of ghrelin daily mass transfer. Peritoneal ghrelin clearance was positively correlated with the dialysate-peritoneal creatinine (D/P(Cr)) ratio. Fasting plasma ghrelin levels were inversely correlated with the peritoneal/plasma (D/P(ghrelin)) ratio (P = 0.045). Plasma ghrelin levels were negatively correlated with body mass index, waist-hip ratio, fasting insulin and triglyceride level, and positively correlated with lean body mass. Plasma ghrelin levels were positively correlated with left ventricular mass (LVM), left ventricular mass index and blood pressure. Peritoneal transporter characteristics may modulate plasma ghrelin levels in CAPD subjects. By contributing to the level of plasma ghrelin, dwelling time may have an impact on LVM and associated morbidity in CAPD patients.

Comparison of Kinetic Characteristics of Amino Acid-Based and Dipeptide-Based Peritoneal Dialysis Solutions

A mixture of dipeptides (DP) has been proposed as alternatives (to glucose and amino acids, (AA)) osmotic agent in peritoneal dialysis (PD) solutions. DP based solutions may have metabolic and nutritional advantages compared to AA based solutions, as some sources of AA (such as tyrosine) are poorly soluble in water. In a previous study, we compared the kinetic characteristics of DP and AA based solutions; however, the amount of AA differed substantially. The aim of the present study was to compare solutions with almost equal amounts of AA. The following solutions were used: (1) amino acid (AA) solution containing leucine, valine, lysine, isoleucine, threonine, phenylalanine and histidine (tyrosine was omitted because of its poor solubility), (2) dipeptide (DP) solution containing leucyl-valine, lysyl-isoleucine, threonyl-phenylalanine and histidyl-tyrosine. Sixteen Sprague-Dawley rats were divided in two groups and were subjected to intraperitoneal injection of either 25 mL of AA (n=8) or DP solution. Dialysate and blood samples were taken frequently postinfusion for measurement of AA and DP concentrations as well as AA from DP. Kinetic models were developed for estimation of diffusive mass transport coefficient between peritoneal cavity and blood (K BD), DP hydrolysis rate coefficient (K H) and AA clearance in the body (K C). Calculations showed that K H is about ten times lower than K BD. Thus, hydrolysis rate in peritoneal cavity is much lower than the diffusive transport rate of DP. K BD for AA appeared to be similar to K BD for dipeptides. K C was much higher than K BD for AA. This finding explains the rapid clearance of amino acids from blood. Nevertheless, the AA-based solution resulted in much higher peak concentrations of AA in blood after 120 min of the dwell than AA concentrations achieved following the use of the DP-based solution. Peritoneal transport characteristics of AA and DP were similar; however their kinetics in blood differs substantially. The DP solution resulted in a less pronounced increase in AA concentrations in blood, suggesting that DP solution could provide AA in a more physiological way.

Peritoneal Inflammation and High Transport Status

Current US average annual growth of peritoneal dialysis (PD) is reported to be around 6 to 11% (1). There are wide variations in the utilization of PD in different countries. Similarly, there are wide variations in technique survival among various centers. If death and transplantation are excluded, infectious complications have been the most common reason for transfer out of PD. Over the past two decades, with improved technology and connectology systems, there has been a significant reduction in the rate of infectious complications. Centers with longer PD experience report PD-associated peritonitis rates on an average close to one episode for every six to seven patient years. In parallel, there has been increasing recognition of the importance of adequacy and ultrafiltration capacity. New adequacy guidelines now include, in addition to targets for solute clearances, ultrafiltration capacity recognition and BP control recommendations. There is now an acute awareness of the importance of peritoneal membrane transport characteristics in achieving favorable long-term morbidity and mortality. Factors that determine peritoneal membrane function in an individual are confounded by the coexistence of chronic inflammation due to uremia or other diseases, malnutrition, obesity, advanced cardiovascular diseases with hyperlipidemic state, diabetes, old age, ethnicity, and duration of PD. Recently, high peritoneal transport status in incident PD patients in particular has received increased attention due to poor outcome in some of them. It is as yet unclear what determines such a status in new patients starting PD. Interestingly, some of these high transporters have poor outcome and others do as well as other PD patients. Those with poor outcomes are recognized by the higher prevalence of markers of inflammation, malnourishment, and/or hypoalbuminemia. Studies to address these issues have been inconclusive and often are anecdotal experiences and based on small population studies. Peritoneal membrane permeability varies widely among individuals and …

Higher Peritoneal Transport Status Is Associated with Higher Mortality and Technique Failure in the Australian and New Zealand Peritoneal Dialysis Patient Populations

Although early studies observed that peritoneal membrane transport characteristics were determinants of morbidity and mortality in peritoneal dialysis (PD) patients, more recent investigations, such as the Ademex trial, have refuted these findings. The aim of this study was to determine whether baseline peritoneal transport status predicted subsequent survival in Australian and New Zealand PD patients. The study included all adult patients in Australia and New Zealand who commenced PD between April 1, 1999, and March 31, 2004, and had a peritoneal equilibration test (PET) performed within 6 mo of PD commencement. Times to death and death-censored technique failure were examined by Kaplan-Meier analyses and multivariate Cox proportional hazards models. PET measurements were available in 3702 (72%) of the 5170 individuals who began PD treatment in Australia or New Zealand during the study period. In these patients, high transporter status was found to be a significant, independent predictor of death-censored technique failure (adjusted hazard ratio [AHR] 1.23; 95% confidence interval [CI] 1.02 to 1.49; P = 0.03) and mortality (AHR 1.34; 95% CI 1.05 to 1.79, P = 0.02) compared with low-average transport status. High-average transport class was also associated with mortality (AHR 1.21; 95% CI 1.00 to 1.48; P = 0.047) but not death-censored technique failure (AHR 1.04; 95% CI 0.90 to 1.21) compared with low-average transport status. When transport status was alternatively analyzed as a continuous variable, dialysate:plasma creatinine ratio at 4 h was independently predictive of both death-censored technique failure (AHR 1.07; 95% CI 1.01 to 1.295; P = 0.031) and death (AHR 1.09; 95% CI 1.01 to 1.373; P = 0.036 per 0.1 change in dialysate:plasma creatinine). Peritoneal transport rate is a highly significant risk factor for both mortality and death-censored technique failure in the Australian and New Zealand incident PD patient populations.

Peritoneal Transport Status Influence on Atherosclerosis/Inflammation in CAPD Patients

Peritoneal transport status is one of the main determinants of dialysis adequacy and dialysis-related complications in end-stage renal disease patients receiving continuous ambulatory peritoneal dialysis (CAPD). In this study we aimed to investigate the relationship between peritoneal transport characteristics and known promoters of atherosclerosis in a group of patients receiving CAPD for a minimum of 36 months. We performed a cross-sectional study of a cohort of 84 patients with end-stage renal disease (37 men, 47 women; age, 44.0 +/- 15.7 years; dialysis duration, 40.3 +/- 8.1 months) who were receiving CAPD for minimum 36 months. Peritoneal transport characteristics were identified after a peritoneal equilibration test (PET) determined at the third month of CAPD using Dialysate/Plasma (D/P) reference values. Patients were classified according to one of four peritoneal transport types: high (H), high-average (HA), low-average (LA), and low (L). After PET, patients were grouped as high (H/HA group, n = 51) or low (L/LA group, n = 33) transporters. The patient groups' clinical and laboratory data before dialysis and after initiation of the CAPD were collected retrospectively. The patients' follow-up data were retrieved for the diagnosis of any atherosclerosis-related event after the initiation of CAPD. The following events were collected, including myocardial infarction, having been diagnosed as having coronary artery disease by angiography or myocardium scintigraphy, cerebrovascular accident, and development of clinically evident peripheral arterial disease. A comparison of follow-up data revealed that the H/HA transport characteristic was associated with lower albumin (P < .01), higher C-reactive protein (CRP) (P < .0001) levels, and higher recombinant human erythropoietin (rHuEPO) needs (P < .001) when compared with the L/LA type. During follow-up, 28 patients showed an atherosclerosis-related event. Twenty-two of these were in the H/HA group (43.1%), whereas only six were in the L/LA group (18.1%, P < .01). Reanalysis of 18 patients with atherosclerosis-related events and high CRP levels (> 10 mg/L) showed that 15 were in the H/HA and 3 were in the L/LA group. Sixty-eight percent of the H/HA patients with atherosclerosis and 50% of the L/LA patients with an atherosclerotic event also had chronic inflammation (P < .001). A Pearson correlation analysis showed that there was a positive correlation between D/P creatinine levels and 36-month mean CRP levels (r = 0.608, P < .0001), and a negative correlation between D/P creatinine levels and 36-month mean albumin levels (r = -0.299, P < .005). This study shows that the high transporter peritoneal membrane characteristic is a risk factor for inflammatory state in patients with end-stage renal disease. High-transporter patients are at an increased risk of atherosclerosis when compared with their low-transporter counterparts through chronic inflammation.

Fluid and Solute Transport in CAPD Patients before and after Permanent Loss of Ultrafiltration Capacity

Two major types of permanent loss of ultrafiltration capacity (UFC) were previously distinguished among patients treated with CAPD: 1) type HDR with high diffusive peritoneal transport rate of small solutes and low osmotic conductance,but with normal fluid absorption rate, and 2) type HAR with high fluid absorption rate, but with normal diffusive peritoneal transport rate of small solutes and normal osmotic conductance. However, the detailed pattern of changes in peritoneal transport parameters in patients developing loss of ultrafiltration capacity is not known. Analysis of solute and fluid transport parameters in the same patient before and after UFC loss. Seven CAPD patients who had undergone repeated dwell studies,which were carried out before and/or after the onset of UFC loss. Dialysis fluids (2 L) with glucose or a mixture of amino acids as osmotic agent at three basic tonicities were applied during 6 hour dwell studies. Fluid and solute transport parameters were previously shown not to be affected by these dialysis solutions (except by hypertonic amino acid-based solution). Intraperitoneal dialysate volume and fluid absorption rate were assessed using radiolabeled human serum albumin (RISA). Osmotic conductance (a(OS))was estimated by a mathematical model as ultrafiltration rate induced by unit osmolality gradient. Diffusive mass transport coefficients, K(BD), for glucose,urea,and creatinine were estimated using the modified Babb-Randerson-Farrell model. Five patients had increased K(BD) for small solutes after the onset of UFC loss,and three of them had decreased a(OS),whereas two patients had normal a(OS). In one of them, a(OS) decreased with time after the onset of UFC loss with concomitant normalization of glucose absorption. In all studies of these five patients the fluid absorption rate was within the normal range. Two other patients had increased fluid absorption rate (about 5 ml/min),and one of them also had increased K(BD) for small solutes,in two consecutive dwell studies in each patient with the second study being carried out at 1 and 7 months respectively after the first one. In all four studies in these two patients, the a(OS) was within the normal range. The sodium dip during dialysis with 3.86% glucose-based solution was lost, not only among most patients with UFC loss related to reduced osmotic conductance, but also in patients with increased K(BD). The occurrence of two major types of UFC loss was confirmed. However, a case of a mixed type of UFC loss with high fluid absorption rate and high K(BD) for small solutes, but normal osmotic conductance, and with normalization of initially high K(BD) for small solutes, linked with decreasing initially normal osmotic conductance,was also found. As a reduced sodium dip with hypertonic glucose solution is not only seen in patients with reduced osmotic conductance, it cannot reliably be used as a single measure of decreased aquaporin function. Permanent ultrafiltration capacity loss may be a dynamic phenomenon with a variety of alterations in peritoneal transport characteristics.

Peritoneal dialysis patient survival: a comparison between a Swedish and a Korean centre

Dialysis patient mortality remains high, and this high mortality may be due to many factors. In peritoneal dialysis (PD) patients, old age, co-morbid diseases, malnutrition, low residual renal function (RRF) and a high peritoneal transport rate have been shown to influence survival, but the relative importance of these factors may differ between different patient populations. Besides, centre practice patterns may differ between centres and may influence patient survival. In addition, the literature suggests that dialysis patient survival may be better in Asian than in Caucasian patients. The influence of centre and patient characteristics on patient survival was investigated in 132 Korean and 106 Swedish incident PD patients, who underwent initial biochemical measurements and assessment of adequacy of dialysis, nutritional status, RRF and peritoneal transport characteristics. At the start of PD, Korean patients had a higher prevalence of diabetes, peritoneal Kt/V(urea), peritoneal creatinine clearance and peritoneal fluid removal, and lower body mass index, RRF and dialysate to plasma creatinine concentration ratio (D/P Cr) compared with Swedish patients. Significantly more patients from Korea were placed on temporary haemodialysis before PD (100 out of 132) when compared with Swedish patients (21 out of 106). During the follow-up, there was a significantly higher rate of transfer to other units in Korea and a significantly higher rate of kidney transplantation in Sweden. On Kaplan-Meier analysis, overall patient survival did not differ and relative risk for death was also not different between the two centres even after adjustment for age, diabetes, cardiovascular disease, RRF and D/P Cr. On Cox proportional hazards multivariate analysis, age, diabetes, RRF and D/P Cr were found to be independent predictors of mortality in the combined cohort of patients. While age, diabetes and D/P Cr were independent predictors of mortality in Korean patients, age and RRF independently predicted mortality in Swedish patients. Although there were significant differences in centre and patient characteristics, we were unable to confirm a survival advantage for Korean over Swedish PD patients. The results of this study suggest that the reported difference in survival between Asian and Caucasian dialysis patients may have been due, in part, to differences in centre and patient characteristics rather than to race as such. The genetic influence on patient characteristics remains, however, to be elucidated.

Diálisis peritoneal: Correlación entre volumen, transporte peritoneal e hipertensión arterial

Objetivo: determinar si existe relación entre el volumen medido por bioimpedanciometría, el tipo de transporte peritoneal y la incidencia de hipertensión arterial (HA) en pacientes en diálisis peritoneal (DP).Materiales y métodos: se realizó un estudio de corte transversal. Se incluyeron 72 pacientes en DP del Hospital de San José a quienes se les midió el volumen de líquido corporal mediante bioimpedanciometría. Los pacientes fueron clasificados según las características del transporte peritoneal, establecido a través de la prueba de equilibrio peritoneal (PEP), en transportadores altos (TA), promedio (TP) y bajos (TB). Se evaluaron las cifras de tensión arterial, clasificando a los pacientes en normotensos, hipertensos controlados con hipotensores e hipertensos no controlados.Resultados: el exceso de agua fue de 2,98 +/- 2,36 L en TP y de 3,631L +/- 1,81 L en TA. En los pacientes normotensos, hipertensos controlados con medicación e hipertensos no controlados, se encontraron valores promedio de exceso de agua 3,16 L +/- 2,56, 2,79 L +/- 2,11 y 3,79 L +/- 2,39 L respectivamente. Se halló una frecuencia de normotensión de 28,1 %, hipertensión controlada de 56,1% y de hipertensión no controlada de 15,8 %. en los TP. En los TA estos valores fueron 10 %, 50% y 40% respectivamente. Conclusión: los TA tienden hacia un mayor exceso de líquido que los TP y tienen mayor frecuencia de HA no controlada. Esto podría explicar el exceso de mortalidad reportado en este grupo. El exceso de volumen independientemente del estado transportador, se relaciona con la presencia de HA.

Peritoneal Transport Characteristics with Glucose Polymer–Based Dialysis Fluid in Children

Scarce data are available on the use of glucose polymer-based dialysate in children. The effects of glucose polymer-based dialysate on peritoneal fluid kinetics and solute transport were studied in pediatric patients who were on chronic peritoneal dialysis, and a comparison was made with previously published results in adult patients. In nine children, two peritoneal equilibration tests were performed using 3.86% glucose and 7.5% icodextrin as a test solution. Dextran 70 was added as a volume marker to calculate fluid kinetics. Serum and dialysate samples were taken for determination of urea, creatinine, and sodium. After calculation of the initial transcapillary ultrafiltration (TCUF) rate, it was possible to calculate the contribution of aquaporin-mediated (AQP-mediated) water transport to ultrafiltration for icodextrin and 3.86% glucose and the part of L(p)S (the product of the peritoneal surface area and the hydraulic permeability) caused by AQP. In children, the transport parameters were similar for the two solutions, except for TCUF, which was lower for icodextrin (0.9 ml/min per 1.73 m(2)) as compared with 3.86% glucose (4 ml/min per 1.73 m(2)). Transport parameters were similar in children and adults for glucose, but with icodextrin, TCUF and marker clearance were significantly lower in children. AQP-mediated water flow was 83 versus 50% with glucose (child versus adult; P < 0.01) and 18 versus 7% with icodextrin (P < 0.01). Data indicate that transport parameters in children using icodextrin are similar to glucose except for TCUF. Differences are explained by the absence of crystalloid osmosis and that TCUF was determined after a 4-h dwell. Comparison of transport parameters and peritoneal membrane characteristics between children and adults reveal that there seem to be differences in the amount and functionality of AQP. However, there are no differences in clinical efficacy of this transport pathway because the absolute flow through the AQP is identical in both groups using 3.86% glucose.

POOR NUTRITIONAL STATUS AND INFLAMMATION: Metabolic Consequences of Peritoneal Dialysis

ABSTRACTOptimization of the peritoneal dialysis (PD) prescription includes attempts to normalize the patient's blood pressure and extracellular volume. To do so, one must utilize crystalloid or colloid osmotic agents to achieve ultrafiltration. These osmotic agents are systemically absorbed and thus have both potential benefits and adverse effects. With glucose‐based dialysate solutions, the average patient absorbs 300–450 kcal of glucose per day on either continuous ambulatory peritoneal dialysis (CAPD) or the cycler. The amount of glucose absorbed varies based on peritoneal transport characteristics, prescription, and tonicity of fluids used. Alternative osmotic agents such as amino acids and macromolecular solutions, including polypeptides and polyglucose (icodextrin) solutions, have a different rate of systemic absorption and thus a different caloric load profile. In addition, there are protein losses that average about 10 g/day with glucose‐based solutions and glucose losses with either amino acid or icodextrin dialysate solutions. There are also potential advantages of these alternative solutions with regard to ultrafiltration. Glucose‐based solutions require the development of significant crystalloid osmotic forces, which are dissipated as glucose is absorbed systemically. In contrast, macromolecular solutions achieve ultrafiltration via differences in colloid osmotic pressure, and the absorption of these agents is of a lesser magnitude than glucose‐based solutions. Further research is needed to determine other potential risks and benefits of these alternative dialysate solutions.

Neurotoxicity Secondary to Intraperitoneally Administered Cefepime: Report of Two Cases

Cefepime is a broad-spectrum antibiotic used successfully as empirical monotherapy in patients with continuous ambulatory peritoneal dialysis (CAPD) peritonitis. Unfortunately, current intraperitoneal dosage recommendations are based on clinical experience rather than solid pharmacokinetic knowledge. We report two cases of cefepime-related confusion in CAPD peritonitis treated with intraperitoneal cefepime at a commonly used dosage. High peritoneal membrane transport characteristics and deteriorating residual renal function may alert clinicians to the risk of cefepime-induced neurotoxicity. Pharmacokinetic data are essential for rational prescription when the drug is to be administered intraperitoneally.

A Comparison of Peritoneal Equilibration Tests Performed 1 and 4 Weeks after PD Commencement

The aim of this study was to prospectively evaluate the ability of a peritoneal equilibration test (PET) performed in the first week of peritoneal dialysis (PD) to predict subsequent transport status, as determined by a PET at 4 weeks and >1 year after PD commencement. Prospective observational study of an incident PD cohort at a single center. Tertiary-care institutional dialysis center. The study included 50 consecutive patients commencing PD at the Princess Alexandra Hospital between 25/2/2001 and 14/5/2003 (mean age 60.9 +/- 12.2 years, 54% male, 92% Caucasian, 38% diabetic). All patients were initially prescribed continuous ambulatory PD. Measurements performed during paired PETs included dialysate-to-plasma ratios of urea (D/P urea) and creatinine (D/P creatinine) at 4 hours, the ratio of dialysate glucose concentrations at 0 and 4 hours (D/D0 glucose), and drain volumes at 4 hours. When paired 1-week and 1-month PET data were analyzed, significant changes were observed in measured D/P urea (0.91 +/- 0.07 vs 0.94 +/- 0.07 respectively; p < 0.05), D/P creatinine (0.55 +/- 0.12 vs 0.66 +/- 0.11, p < 0.001), and D/D0 glucose (0.38 +/- 0.08 vs 0.36 +/- 0.10, p < 0.05). Using Bland-Altman analysis, the repeatability coefficients were 0.17, 0.20, and 0.13, respectively. Agreement between 1-week and 1-month PET measurements with respect to peritoneal transport category was moderate for D/D0 glucose (weighted kappa 0.52), but poor for D/P urea (0.30), D/P creatinine (0.35), and drain volumes (0.20). The PET measurements performed more than 1 year following PD commencement (n = 28) generally agreed closely with 1-month measurements, and poorly with 1-week measurements. Peritoneal transport characteristics change significantly within the first month of PD. PETs carried out during this time should be considered preliminary and should be confirmed by a PET 4 weeks later. Nevertheless, performing an early D/D0 glucose measurement at 1 week predicted ultimate transport status sufficiently well to facilitate early clinical decision-making about optimal PD modality while patients were still receiving PD training. On the other hand, the widespread practice of using measured drain volumes in the first week to predict ultimate transport category is highly inaccurate and not recommended.

The Euro-Balance Trial: The effect of a new biocompatible peritoneal dialysis fluid (balance) on the peritoneal membrane

Although peritoneal dialysis (PD) is a widely accepted form of renal replacement therapy (RRT), concerns remain regarding the bioincompatible nature of standard PD fluid. In order to evaluate whether a newly formulated fluid of neutral pH, and containing low levels of glucose degradation products (GDP), resulted in improved in vivo biocompatibility, it was compared in a clinical study to a standard PD fluid. In a multicenter, open, randomized, prospective study with a crossover design and parallel arms, a conventional, acidic, lactate-buffered fluid (SPDF) was compared with a pH neutral, lactate-buffered, low GDP fluid (balance). Overnight effluent was collected and assayed for cancer antigen 125 (CA125), hyaluronic acid (HA), procollagen peptide (PICP), vascular endothelial growth factor (VEGF), and tumor necrosis factor alpha (TNFalpha). Serum samples were assayed for circulating advanced glycosylation end products (AGE), N(epsilon)-(carboxymethyl)lysine (CML), and imidazolone. Clinical end points were residual renal function (RRF), adequacy of dialysis, ultrafiltration, and peritoneal membrane function. Eighty-six patients were randomized to either group I starting with SPDF for 12 weeks (Phase I), then switching to "balance" for 12 weeks (Phase II), or group II, which was treated vice versa. Seventy-one patients completed the study with data suitable for entry into the per protocol analysis. Effluent and serum samples, together with peritoneal function tests and adequacy measurements, were undertaken at study centers on three occasions during the study: after the four-week run-in period, after Phase I, and again after Phase II. In patients treated with balance there were significantly higher effluent levels of CA125 and PICP in both arms of the study. Conversely, levels of HA were lower in patients exposed to balance, while there was no change in the levels of either VEGF or TNFalpha. Serum CML and imidazolone levels fell significantly in balance-treated patients. Renal urea and creatinine clearances were higher in both treatment arms after patients were exposed to balance. Urine volume was higher in patients exposed to balance. In contrast, peritoneal ultrafiltration was higher in patients on SPDF. When anuric patients were analyzed as a subgroup, there was no significant difference in peritoneal transport characteristics or in ultrafiltration on either fluid. There were no changes in peritonitis incidence on either solution. This study indicates that the use of balance, a neutral pH, low GDP fluid, is accompanied by a significant improvement in effluent markers of peritoneal membrane integrity and significantly decreased circulating AGE levels. Clinical parameters suggest an improvement in residual renal function on balance, with an accompanying decrease in peritoneal ultrafiltration. It would appear that balance solution results in an improvement in local peritoneal homeostasis, as well as having a positive impact on systemic parameters, including circulating AGE and residual renal function.

Predictors of baseline peritoneal transport status in Australian and New Zealand peritoneal dialysis patients

Background: Factors that predict peritoneal transport status in peritoneal dialysis (PD) patients are poorly understood. The aim of the present study is to determine these factors in Australian and New Zealand incident PD patients. Methods: The study included all patients on the Australian and New Zealand Dialysis and Transplant Registry who started PD therapy between April 1, 1991, and March 31, 2002, and underwent a peritoneal equilibration test (PET) within the first 6 months. Predictors of peritoneal transport category and dialysate-plasma creatinine ratio at 4 hours (D-P Cr 4h) were assessed by multivariate ordinal logistic regression and multiple linear regression, respectively. Results: A total of 3,188 patients were studied. Mean D-P Cr 4h was 0.69 ± 0.13. High transport status was associated with older age (adjusted odds ratio [OR], 1.08 for each 10 years; 95% confidence interval [CI], 1.03 to 1.13), Maori and Pacific Islander racial origin (OR, 1.48; 95% CI, 1.13 to 1.94), and normal body mass index (BMI; < 18.5 kg/m2: OR, 0.90; 95% CI, 0.65 to 1.24; BMI of 18.5 to 25 kg/m2: OR, 1 [reference]; BMI of 25 to 30 kg/m2: OR, 0.81; 95% CI, 0.70 to 0.95; BMI > 30 kg/m2: OR, 0.71; 95% CI, 0.58 to 0.86), but was not independently predicted by sex, diabetes, other comorbid diseases, smoking, previous hemodialysis therapy or transplantation, or residual renal function. Similar results were found when peritoneal permeability was modeled as a continuous variable (D-P Cr 4h). Conclusion: In Australian and New Zealand PD patients, higher peritoneal transport status is independently associated with racial origin, older age, and lower BMI. The diversity of peritoneal transport characteristics in different ethnic populations suggests that additional validation of PET measurements in various racial groups and study of their relationship to patient outcomes are warranted.