1
|
Öberg CM. Optimization of bimodal automated peritoneal dialysis prescription using the three-pore model. Perit Dial Int 2021; 41:381-393. [PMID: 33910417 DOI: 10.1177/08968608211010055] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Previous studies suggested that automated peritoneal dialysis (APD) could be improved in terms of shorter treatment times and lower glucose absorption using bimodal treatment regimens, having 'ultrafiltration (UF) cycles' using a high glucose concentration and 'clearance cycles' using low or no glucose. The purpose of this study is to explore such regimes further using mathematical optimization techniques based on the three-pore model. METHODS A linear model with constraints is applied to find the shortest possible treatment time given a set of clinical treatment goals. For bimodal regimes, an exact analytical solution often exists which is herein used to construct optimal regimes giving the same Kt/V urea and/or weekly creatinine clearance and UF as a 6 × 2 L 1.36% glucose regime and an 'adapted' (2 × 1.5 L 1.36% + 3 × 3 L 1.36%) regime. RESULTS Compared to the non-optimized (standard and adapted regimes), the optimized regimens demonstrated marked reductions (>40%) in glucose absorption while having an identical weekly creatinine clearance (35 L) and UF (0.5 L). Larger fill volumes of 1200 mL/m2 (UF cycles) and 1400 mL/m2 (clearance cycles) can be used to shorten the total treatment time. CONCLUSION These theoretical results imply substantial improvements in glucose absorption using optimized APD regimens while achieving similar water and solute removal as non-optimized APD regimens. While the current results are based on a well-established theoretical model for peritoneal dialysis, experimental and clinical studies need to be performed to validate the current findings.
Collapse
Affiliation(s)
- Carl M Öberg
- Department of Nephrology, 5193Lund University, Skåne University Hospital, Clinical Sciences Lund, Sweden
| |
Collapse
|
2
|
Physiological Properties of the Peritoneum in an Adult Peritoneal Dialysis Population over a Three-Year Period. Perit Dial Int 2020. [DOI: 10.1177/089686080602600413] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Objectives To describe the physiological properties of the peritoneal membrane in adult patients treated with peritoneal dialysis (PD) and to analyze the effects of patient characteristics and time. Design Observational study. Setting Department of Nephrology at the Sahlgrenska University Hospital. Method Peritoneal function was analyzed by the Personal Dialysis Capacity (PDC) test, based on the three-pore theory of capillary transport. The functional PDC variables are absorption, large-pore flow, and the area parameter (A0/Δx), which determines the diffusion of small solutes. The ultra-filtration (UF) coefficient is determined mainly by A0/Δx. Patients All patients ( n = 280) who had at least one PDC test done between September 1990 and August 1999. Results In 249 patients examined soon after start of PD, area was 19000 (SD 7100) cm2/cm/1.73 m2, large-pore flow 0.112 (SD 0.052) mL/min/1.73 m2, and the UF coefficient 0.071 (SD 0.032) mL/minute/mmHg/1.73 m2. Absorption was 1.54 (SD +2.64, –0.97) mL/min/1.73 m2. Large-pore flow was greater in patients with severe comorbidity than in patients with fewer comorbid conditions. Elderly patients had a lower UF coefficient than did younger patients ( p < 0.05). Repeated PDC tests were performed in 208 patients during a mean observation time of 18.4 months. There was a slight increase in the slope of the area-versus-time curve of 54 cm2/cm/1.73 m2 per month (approximately 10% after 3 years, p < 0.01); all other parameters remained constant. Conclusion Patient characteristics have an impact on peritoneal performance already at the start of dialysis. Peritoneal function can remain essentially stable during medium long-term PD.
Collapse
|
3
|
Changes of peritoneal transport parameters with time on dialysis: assessment with sequential peritoneal equilibration test. Int J Artif Organs 2017; 40:595-601. [PMID: 28708209 DOI: 10.5301/ijao.5000622] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2017] [Indexed: 11/20/2022]
Abstract
BACKGROUND Sequential peritoneal equilibration test (sPET) is based on the consecutive performance of the peritoneal equilibration test (PET, 4-hour, glucose 2.27%) and the mini-PET (1-hour, glucose 3.86%), and the estimation of peritoneal transport parameters with the 2-pore model. It enables the assessment of the functional transport barrier for fluid and small solutes. The objective of this study was to check whether the estimated model parameters can serve as better and earlier indicators of the changes in the peritoneal transport characteristics than directly measured transport indices that depend on several transport processes. METHODS 17 patients were examined using sPET twice with the interval of about 8 months (230 ± 60 days). RESULTS There was no difference between the observational parameters measured in the 2 examinations. The indices for solute transport, but not net UF, were well correlated between the examinations. Among the estimated parameters, a significant decrease between the 2 examinations was found only for hydraulic permeability LpS, and osmotic conductance for glucose, whereas the other parameters remained unchanged. These fluid transport parameters did not correlate with D/P for creatinine, although the decrease in LpS values between the examinations was observed mostly for patients with low D/P for creatinine. CONCLUSIONS We conclude that changes in fluid transport parameters, hydraulic permeability and osmotic conductance for glucose, as assessed by the pore model, may precede the changes in small solute transport. The systematic assessment of fluid transport status needs specific clinical and mathematical tools beside the standard PET tests.
Collapse
|
4
|
Peritoneal Fluid Transport rather than Peritoneal Solute Transport Associates with Dialysis Vintage and Age of Peritoneal Dialysis Patients. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:8204294. [PMID: 26989432 PMCID: PMC4771885 DOI: 10.1155/2016/8204294] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 01/13/2016] [Indexed: 11/18/2022]
Abstract
During peritoneal dialysis (PD), the peritoneal membrane undergoes ageing processes that affect its function. Here we analyzed associations of patient age and dialysis vintage with parameters of peritoneal transport of fluid and solutes, directly measured and estimated based on the pore model, for individual patients. Thirty-three patients (15 females; age 60 (21–87) years; median time on PD 19 (3–100) months) underwent sequential peritoneal equilibration test. Dialysis vintage and patient age did not correlate. Estimation of parameters of the two-pore model of peritoneal transport was performed. The estimated fluid transport parameters, including hydraulic permeability (LpS), fraction of ultrasmall pores (αu), osmotic conductance for glucose (OCG), and peritoneal absorption, were generally independent of solute transport parameters (diffusive mass transport parameters). Fluid transport parameters correlated whereas transport parameters for small solutes and proteins did not correlate with dialysis vintage and patient age. Although LpS and OCG were lower for older patients and those with long dialysis vintage, αu was higher. Thus, fluid transport parameters—rather than solute transport parameters—are linked to dialysis vintage and patient age and should therefore be included when monitoring processes linked to ageing of the peritoneal membrane.
Collapse
|
5
|
Teixidó-Planas J, Troya-Saborido MI, Pedreira-Robles G, Del-Rio-Lafuente M, Romero-Gonzalez R, Bonet-Sol J. Measuring peritoneal absorption with the prolonged peritoneal equilibration test from 4 to 8 hours using various glucose concentrations. Perit Dial Int 2015; 34:605-11. [PMID: 25228213 DOI: 10.3747/pdi.2013.00235] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Peritoneal fluid flows such as small-pore ultrafiltration and free water transport can now be calculated by means of the modified peritoneal equilibration test (PET). To calculate peritoneal fluid absorption, volume markers have been used, but that method is not easily applicable in clinical practice. Alternatively, absorption can be estimated using the personal dialysis capacity test. However, a method of measuring overall peritoneal absorption together with the PET is lacking. The aim of the present study was to assess whether overall peritoneal absorption was different when measured from the 4th to 8th hour in a prolonged PET using three different glucose solutions. METHODS The study enrolled 32 stable peritoneal dialysis (PD) patients from a tertiary university hospital, who underwent three 8-hour prolonged PETs with 1.36%, 2.27%, and 3.86% glucose solution. The PETs were performed in random order over a period of less than 1 month. During the prolonged PET, the peritoneal volume was emptied and reinfused at 60 and 240 minutes and drained at 480 minutes. Peritoneal absorption was calculated as the volume difference between the 4th and the 8th hour. RESULTS The dialysate-to-plasma ratio (D/P) of urea, the D/P creatinine, and the mass transfer area coefficient (MTC) of creatinine at 240 minutes were not significantly different with the three glucose solutions. The end-to-initial (D/D0) glucose, MTC urea, and MTC glucose were significantly different. All water transport parameters were significantly different, except for the 4- to 8-hour absorption volumes and rates. The peritoneal absorption rates were, for 1.36% solution, 1.03 ± 0.58 mL/min [95% confidence interval (CI): 0.83 to 1.24 mL/min]; for 2.27% solution, 0.86 ± 0.71 mL/min (95% CI: 0.61 to 1.11 mL/min); and for 3.86% solution, 1.05 ± 0.78 mL/min (95% CI: 0.77 to 1.33 mL/min). Peritoneal absorption volumes and rates from the 4th to the 8th hour showed good correlations for the various solutions. CONCLUSIONS Using any glucose solution, the prolonged PET with voiding and reinfusion at the 4th hour could be a practical method for calculating overall peritoneal absorption from the 4th to the 8th hour in PD patients.
Collapse
Affiliation(s)
- Josep Teixidó-Planas
- Nephrology Department, Hospital Universitari, and Fundació Institut d'Investigació en Ciències de la Salut, Germans Trias i Pujol, Barcelona, Spain Nephrology Department, Hospital Universitari, and Fundació Institut d'Investigació en Ciències de la Salut, Germans Trias i Pujol, Barcelona, Spain
| | - Maria Isabel Troya-Saborido
- Nephrology Department, Hospital Universitari, and Fundació Institut d'Investigació en Ciències de la Salut, Germans Trias i Pujol, Barcelona, Spain
| | - Guillermo Pedreira-Robles
- Nephrology Department, Hospital Universitari, and Fundació Institut d'Investigació en Ciències de la Salut, Germans Trias i Pujol, Barcelona, Spain
| | - Milagros Del-Rio-Lafuente
- Nephrology Department, Hospital Universitari, and Fundació Institut d'Investigació en Ciències de la Salut, Germans Trias i Pujol, Barcelona, Spain
| | - Ramon Romero-Gonzalez
- Nephrology Department, Hospital Universitari, and Fundació Institut d'Investigació en Ciències de la Salut, Germans Trias i Pujol, Barcelona, Spain
| | - Josep Bonet-Sol
- Nephrology Department, Hospital Universitari, and Fundació Institut d'Investigació en Ciències de la Salut, Germans Trias i Pujol, Barcelona, Spain
| |
Collapse
|
6
|
Galach M, Antosiewicz S, Baczynski D, Wankowicz Z, Waniewski J. Sequential peritoneal equilibration test: a new method for assessment and modelling of peritoneal transport. Nephrol Dial Transplant 2013; 28:447-54. [PMID: 23413278 DOI: 10.1093/ndt/gfs592] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND In spite of many peritoneal tests proposed, there is still a need for a simple and reliable new approach for deriving detailed information about peritoneal membrane characteristics, especially those related to fluid transport. METHODS The sequential peritoneal equilibration test (sPET) that includes PET (glucose 2.27%, 4 h) followed by miniPET (glucose 3.86%, 1 h) was performed in 27 stable continuous ambulatory peritoneal dialysis patients. Ultrafiltration volumes, glucose absorption, ratio of concentration in dialysis fluid to concentration in plasma (D/P), sodium dip (Dip D/P Sodium), free water fraction (FWF60) and the ultrafiltration passing through small pores at 60 min (UFSP60), were calculated using clinical data. Peritoneal transport parameters were estimated using the three-pore model (3p model) and clinical data. Osmotic conductance for glucose was calculated from the parameters of the model. RESULTS D/P creatinine correlated with diffusive mass transport parameters for all considered solutes, but not with fluid transport characteristics. Hydraulic permeability (L(p)S) correlated with net ultrafiltration from miniPET, UFSP60, FWF60 and sodium dip. The fraction of ultrasmall pores correlated with FWF60 and sodium dip. CONCLUSIONS The sequential PET described and interpreted mechanisms of ultrafiltration and solute transport. Fluid transport parameters from the 3p model were independent of the PET D/P creatinine, but correlated with fluid transport characteristics from PET and miniPET.
Collapse
Affiliation(s)
- Magda Galach
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, 02-109 Warsaw, Poland
| | | | | | | | | |
Collapse
|
7
|
van Biesen W, Heimburger O, Krediet R, Rippe B, La Milia V, Covic A, Vanholder R. Evaluation of peritoneal membrane characteristics: clinical advice for prescription management by the ERBP working group. Nephrol Dial Transplant 2010; 25:2052-62. [PMID: 20203287 DOI: 10.1093/ndt/gfq100] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Wim van Biesen
- Renal Division, University Hospital Ghent, Ghent, Belgium.
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Haag-Weber M, Krämer R, Haake R, Islam MS, Prischl F, Haug U, Nabut JL, Deppisch R. Low-GDP fluid (Gambrosol trio) attenuates decline of residual renal function in PD patients: a prospective randomized study. Nephrol Dial Transplant 2010; 25:2288-96. [PMID: 20197284 DOI: 10.1093/ndt/gfq087] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Residual renal function (RRF) impacts outcome of peritoneal dialysis (PD) patients. Some PD fluids contain glucose degradation products (GDPs) which have been shown to affect cell systems and tissues. They may also act as precursors of advanced glycosylation endproducts (AGEs) both locally and systemically, potentially inflicting damage to the kidney as the major organ for AGE elimination. We conducted a clinical study in PD patients to see if the content of GDP in the PD fluid has any influence on the decline of the residual renal function. METHODS In a multicentre approach, 80 patients (GFF > or = 3 mL/min/1.732 or creatinine clearance > or =3 mL/min/1.73 m(2)) were randomized to treatment with a PD fluid containing low levels of GDP or standard PD fluid for 18 months. RRF was assessed every 4-6 weeks. Fluid balance, mesothelial cell mass marker CA125, peritoneal membrane characteristics, C-reactive protein (CRP), total protein, albumin, electrolytes and phosphate were measured repeatedly. RESULTS Data from 69 patients revealed a significant difference in monthly RRF change: -1.5% (95% CI = -3.07% to +0.03%) with low GDP (43 patients) vs -4.3% (95% CI = -6.8% to -2.06%) with standard fluids (26 patients) (P = 0.0437), independent of angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker medication. Twenty-four-hour urine volume declined more slowly with low-GDP fluid compared to standard fluids (12 vs 38 mL/month, P = 0.0241), and monthly change of phosphate level was smaller (+0.013 vs +0.061 mg/dL, P = 0.0381). CONCLUSIONS Our prospective study demonstrates for the first time a significant benefit concerning preservation of RRF and urine volume of using a PD fluid with low GDP levels. These findings suggest that GDPs might affect patient outcome related to RRF.
Collapse
|
9
|
Pletinck A, Consoli C, Van Landschoot M, Steppan S, Topley N, Passlick-Deetjen J, Vanholder R, Van Biesen W. Salt intake induces epithelial-to-mesenchymal transition of the peritoneal membrane in rats. Nephrol Dial Transplant 2010; 25:1688-96. [PMID: 20150166 DOI: 10.1093/ndt/gfq036] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Dietary salt intake has been linked to hypertension and cardiovascular disease through volume-mediated effects. Accumulating evidence points to direct negative influence of salt intake independent of volume overload, such as cardiac and renal fibrosis, mediated through transforming growth factor beta (TGF-beta). Epithelial-to-mesenchymal transition (EMT) has been implicated as a key process in chronic fibrotic diseases, such as chronic kidney disease or heart failure. The potential role of dietary salt intake on cell transdifferentiation has never been investigated. This study analysed the effect of dietary salt intake on EMT and fibrosis in the peritoneal membrane (PM) in a rat model. METHODS Twenty-eight Wistar rats were randomized to a normal salt (NS) or a high salt (HS) intake. NS and HS rats had free access to tap water or NaCl 2% as drinking water, respectively. After 2 weeks, samples of peritoneum were taken, and TGF-beta(1), Interleukin 6 (IL-6) and vascular endothelial growth factor (VEGF) mRNA expression were quantified with qRT-PCR. Fibrosis and submesothelial PM thickness were scored. EMT was evaluated using fluorescence staining with cytokeratin and alpha smooth muscle actin (alpha-SMA). RESULTS Dietary salt intake caused peritoneal fibrosis and thickening of the submesothelial layer and induced EMT as identified by colocalization of cytokeratin and alpha-SMA in cells present in the submesothelial layer. Peritoneal TGF-beta(1) and IL-6 mRNA expression were upregulated in the HS group. CONCLUSION High dietary salt intake induces EMT and peritoneal fibrosis, a process coinciding with upregulation of TGF-beta1.
Collapse
Affiliation(s)
- Anneleen Pletinck
- Renal Division, Department of Internal Medicine, Gent University Hospital, Gent, Belgium
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Abstract
Peritoneal dialysis is now utilized as a renal replacement therapy modality in a substantial percentage of patients with end-stage renal disease, with excellent short-term patient and technique survival rates. However, the potential complications associated with longer-term therapy, such as ultrafiltration failure or encapsulating peritoneal sclerosis, have led to raise some concern about peritoneal dialysis as an adequate mode of treatment of end-stage renal disease in the long term. In the last decade, a substantial amount of information has been gathered on the characteristics of the peritoneal membrane at the onset of peritoneal dialysis, and on the anatomical and pathophysiologic changes that occur with long-term peritoneal dialysis. I will review this subject with a special focus on the various strategies that can help protect the peritoneal membrane during peritoneal dialysis so as to allow peritoneal dialysis to succeed as a long-term dialysis modality.
Collapse
Affiliation(s)
- Eric Goffin
- Department of Nephrology, Université Catholique de Louvain, Brussels, Belgium.
| |
Collapse
|
11
|
Abstract
Membrane function at the start of peritoneal dialysis (PD) treatment, measured as solute transport rate and ultrafiltration capacity, varies considerably between individuals. Although this can be correlated to clinical factors such as age and body habitus, this accounts for little of the variance seen. It is increasingly clear, however, that this variability in membrane function does impact on clinical outcomes. Specifically, high solute transport increases mortality risk, independent of other known factors such as age, comorbidity, and residual renal function. High solute transport causes earlier loss of the osmotic gradient when a low molecular weight osmolyte such as glucose is used. This will result in an earlier and lower peak in the ultrafiltration achieved combined with a higher fluid absorption rate once the osmotic gradient is lost. It is therefore quite plausible that the worse clinical outcomes associated with high transport reflect less good ultrafiltration, although other explanations must be considered, including higher peritoneal protein losses and a possible association with systemic inflammation. Strategies now exist to mitigate the effects of high transport on fluid removal. These include optimization of the short dwell lengths using automated PD (APD) combined with icodextrin which will result in sustained ultrafiltration and thus prevention of reabsorption in the long dwell. Survival analysis of APD patients, especially in cohorts in which icodextrin has been used, would suggest that high transport status is not a risk factor, although some of these data are only preliminary. In contrast, low ultrafiltration capacity of the membrane seems to be more important in these patients, especially if anuric. Here the best strategy would seem to be prevention as patients who develop low ultrafiltration capacity are not easily treated on PD. Avoiding excessive hypertonic glucose exposure and preserving residual renal function offers the best available approach.
Collapse
Affiliation(s)
- S J Davies
- Institute for Science and Technology in Medicine, Keele University, Keele, UK.
| |
Collapse
|
12
|
Martikainen T, Ekstrand A, Honkanen E, Teppo AM, Grönhagen-Riska C. Do interleukin-6, hyaluronan, soluble intercellular adhesion molecule-1 and cancer antigen 125 in dialysate predict changes in peritoneal function? A 1-year follow-up study. ACTA ACUST UNITED AC 2006; 39:410-6. [PMID: 16257844 DOI: 10.1080/00365590500386809] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE Diminishing ultrafiltration and dialysis adequacy may limit the long-term use of peritoneal dialysis (PD). Inflammation may play a role in changes in peritoneal function. This study was designed to evaluate alterations in peritoneal function and soluble factors in dialysate during a 1-year follow-up period. MATERIAL AND METHODS A personal dialysis capacity test was performed at the start of the study and after 6 and 12 months in 20 patients in order to determine dialysis adequacy and membrane characteristics. Dialysate was collected during the test days for analyses of interleukin-6 (IL-6), soluble intercellular adhesion molecule-1, hyaluronan and cancer antigen 125 (CA125). RESULTS There were no significant changes in dialysis adequacy or membrane characteristics during the 1-year follow-up period. The appearance rate of IL-6 in dialysate increased significantly (419.8+/-63.3 at the start, 784.1+/-136.4 after 6 months and 1149.3+/-252.2 ng/24 h after 12 months; p=0.006) during follow-up. Furthermore, the appearance rate of CA125 increased throughout the study in patients using icodextrin, but decreased slightly in patients using only conventional dialysis solutions. CONCLUSIONS There were no major changes in dialysis adequacy or membrane characteristics during the follow-up period, but increased IL-6 in dialysate may reflect peritoneal inflammation, which may lead to long-term alterations in the peritoneal membrane. Icodextrin may have a preventive effect on the longevity of the peritoneal membrane.
Collapse
Affiliation(s)
- Terhi Martikainen
- Department of Medicine, Division of Nephrology, Helsinki University Central Hospital, Helsinki, Finland
| | | | | | | | | |
Collapse
|
13
|
Van Biesen W, Van der Tol A, Veys N, Dequidt C, Vijt D, Lameire N, Vanholder R. The personal dialysis capacity test is superior to the peritoneal equilibration test to discriminate inflammation as the cause of fast transport status in peritoneal dialysis patients. Clin J Am Soc Nephrol 2005; 1:269-74. [PMID: 17699216 DOI: 10.2215/cjn.00820805] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This study evaluated the potential of the Personal Dialysis Capacity (PDC) test to discriminate fast transport status (FTS) as a consequence of inflammation versus FTS because of other causes. This distinction is important because new therapeutic options such as icodextrin and automated peritoneal dialysis can abolish the negative impact on outcome of FTS if fast transport is not caused by inflammation. A PDC test and a Peritoneal Equilibration Test (PET) were performed in 135 incident PD patients. Membrane characteristics were related with baseline biochemical parameters and C-reactive protein. After correction for other covariates, only large pore flux (J(v)L) but not surface area over diffusion distance (A0/dX) or dialysate over plasma concentration was related to C-reactive protein. Using the PDC test for detection of inflammation, positive and negative predictive values were 16/36 and 80/99, respectively, whereas with PET, positive predictive value was 5/20 and negative predictive value 92/115 (chi2 = 0.009). In a Cox regression for patient survival with correction for age, a J(v)L higher than expected by the surface area over diffusion distance, predicted outcome (P = 0.04). Patients with inflammation had a higher J(v)L (0.21 +/- 0.12 versus 0.17 +/- 0.09; P = 0.06) and a lower ultrafiltration (89 +/- 631 versus 386 +/- 601 ml/d; P = 0.06) and urine output (878.45 +/- 533.55 versus 1322 +/- 822 ml/d; P = 0.023) than patients without inflammation. There was no difference for surface area over diffusion distance (A0/dX) or dialysate over plasma concentration. A PDC test yields far more information about the peritoneal membrane characteristics than a PET. A J(v)L higher than expected by the A0/dX is an indicator of inflammation and is related to an increased mortality. The PET is not able to discriminate between FTS because of inflammation versus because of anatomic reasons, whereas the PDC test does.
Collapse
Affiliation(s)
- Wim Van Biesen
- Department of Nephrology, University Hospital Ghent, De Pintelaan 185, Ghent 9000, Belgium.
| | | | | | | | | | | | | |
Collapse
|
14
|
Aanen MC, Venturoli D, Davies SJ. A detailed analysis of sodium removal by peritoneal dialysis: comparison with predictions from the three-pore model of membrane function. Nephrol Dial Transplant 2005; 20:1192-200. [PMID: 15827048 DOI: 10.1093/ndt/gfh806] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND The development of fluid and salt retention is a potential problem for all peritoneal dialysis (PD) patients. Sodium removal by the peritoneum is predominantly determined by convective fluid loss but influenced by diffusion and sieving due to free water transport as predicted by the three-pore model (TPM). The aim of the study was to establish the effect of transport status, dwell length and glucose concentration on observed ultrafiltration (UF), dialysate sodium concentration ([Na(+)](D)) and removal, and compare this with that predicted by a computer program based on the principles of the TPM. METHODS This was a cross-sectional study of UF and [Na(+)](D) collected prospectively from dwells classified by length, glucose concentration and membrane transport characteristics. Solute transport, converted to area parameter and UF capacity, was measured on each occasion by the peritoneal equilibration test. These parameters, along with plasma [Na(+)], were entered into the computer model. Fixed values for other parameters, e.g. hydraulic conductance and lymphatic absorption and sump volume, were used. RESULTS A total of 1853 dwells from 182 patients [10% were on automated PD (APD)] were analysed. There was a high degree of correlation (r = 0.83-95, P<0.001) between the observed and predicted values for UF, [Na(+)](D) and sodium removal across the full range of dwell categories. The model overpredicted UF as the net volume increased with increasing glucose concentration, independently of solute transport. This bias was not fully explained by the preferential use of hypertonic dialysate by patients with reduced UF capacity. The prediction of [Na(+)](D) described sodium sieving, which was overestimated in a small number of patients with UF failure. There were no discrepancies between continous ambulatory PD (CAPD) and APD patients. CONCLUSION This analysis endorses the TPM as a description of membrane function, particularly in relation to sodium sieving and removal. The relationship between dialysate glucose concentration and achieved UF appears to be more complex; even accounting for extended time on treatment and reduction in the osmotic conductance in patients preferentially using hypertonic exchanges, further adjustments may be needed to account for the tendency to overestimate UF.
Collapse
Affiliation(s)
- Marissa C Aanen
- Department of Nephrology, Academic Medical Center, University of Amsterdam, The Netherlands
| | | | | |
Collapse
|