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Dirk G Struijk

Publications and source records attributed to Dirk G Struijk.

16 recordsLinked to original sources
PubMed2005

The contribution of free water transport and small pore transport to the total fluid removal in peritoneal dialysis.

BACKGROUND: Water transport in peritoneal dialysis (PD) patients is across the small pores and water channels, the latter allowing free water transport. The objective of the study was to investigate the contribution of each transport route on transcapillary ultrafiltration (TCUF). METHODS: Standard peritoneal permeability analyses of 80 stable PD patients were analyzed. Twenty-nine patients were followed longitudinally. Fluid transport through small pores (SPT) was assessed by the amount of transported sodium. Free water transport (FWT) was calculated by subtracting SPT from TCUF. The contribution of FWT and SPT to the TCUF and water transport rates at any time point was computed. RESULTS: The ultrafiltered volume due to SPT increased gradually during the dwell, while FWT reached its maximum around 3 hours. The rate of FWT decreased continuously during the dwell. SPT decreased during the initial 2 hours and remained stable thereafter. At 60 minutes, the SPT (P < 0.05) and its contribution (P < 0.05) were positively related to the MTAC(creat). The contribution of FWT after 1 hour, but not the absolute amount, showed an inverse relationship. Peritoneal solute transport parameters (P < 0.01) and the contribution of SPT (P= 0.08), but none of the other fluid parameters showed a U-shape with the lowest values in the second year of PD (P < 0.01). CONCLUSION: The dwell courses of water transport suggest that the activity of water channels is dependent and limited by the crystalloid osmotic pressure gradient, while other determinants are important in SPT. The time-course of SPT paralleled that of peritoneal solute transport parameters.

Adult↗
PubMed2005

The difference in causes of early and late ultrafiltration failure in peritoneal dialysis.

OBJECTIVE: Ultrafiltration failure (UFF) is a major complication of peritoneal dialysis. Although it seems associated with long-term treatment, it can also occur in recently started patients. To identify the causes of this complication in patients with early and late UFF we studied a group of 48 patients. Patients were classified as early if they had been treated for less than 2 years and as late if they had been treated for more than 4 years. METHOD: The patients were studied using a standard peritoneal permeability analysis. They all had a net ultrafiltration of less than 400 mL after a 4-hour dwell with 3.86% glucose. As possible causes for UFF, the solute transport parameters dialysate-to-plasma ratio (D/P) and mass transfer area coefficient of creatinine were compared, as well as the effective lymphatic absorption rate (ELAR) and the maximum dip in D/P sodium as an assessment of osmotic conductance to glucose. RESULTS: 25 short-term patients were compared with 23 long-term patients. Both groups showed an equal distribution of high small solute transport rates as a cause of UFF. The chi-square test showed that a high ELAR was a more frequent cause in early UFF compared to late UFF. However, a decreased osmotic conductance to glucose was significantly more often observed in late UFF. Some patients showed more than one cause of the complication. CONCLUSION: This study has shown that UFF in long-term patients is often caused by a decreased osmotic conductance to glucose, most likely caused by a dysfunction of peritoneal water channels in combination with increased peritoneal surface area. In short-term patients, aquaporin dysfunction is rare, but a high ELAR was a very important factor in the occurrence of UFF.

Adult↗
PubMed2004

Free-water transport in fast transport status: a comparison between CAPD peritonitis and long-term PD.

BACKGROUND: Ultrafiltration failure (UFF) in continuous ambulatory peritoneal dialysis (CAPD) is a transient phenomenon during acute peritonitis and a permanent complication in long-term peritoneal dialysis (PD). The high solute transport rates during acute peritonitis are probably caused by an increased number of perfused peritoneal capillaries. Long-term PD is associated with an increased number of peritoneal microvessels, leading to an enlargement of the anatomic vascular surface area. This leads to high mass transfer area coefficients (MTAC) and to UFF. Impaired conductance to glucose, leading to a reduction in free-water transport, may be a contributing factor to UFF in long-term PD. We hypothesized that UFF during acute peritonitis is, in the absence of permanent structural changes, only caused by an increased vascular surface area, while in long-term patients it is often the result of an increased surface area in combination with an impaired conductance to glucose. Therefore, the peritoneal transport parameters of patients with acute peritonitis were compared to those in long-term PD patients. METHODS: A standard peritoneal permeability analysis (SPA) was done in 10 PD patients during the first 48 hours after the diagnosis of peritonitis. The results were compared to those obtained in 10 long-term PD patients matched for the MTAC creatinine. In addition, the results of 8 peritonitis patients were compared with SPA results of 8 recently started PD patients, matched for MTAC creatinine. RESULTS: Peritonitis patients had a deeper maximal dip in D/P sodium, corrected for diffusion, than long-term patients (0.058 vs. 0.039, P < 0.05). Most parameters of peritoneal fluid transport were not different, except that t50 (i.e., the time to reach 50% of the maximum transcapillary ultrafiltration) was reached earlier during the dwell in peritonitis than in long-term PD-128 versus 175 minutes, P < 0.05. This confirmed the difference in the shape of the intraperitoneal volume versus time curve, which was blunted in the long-term patients. No differences were found for the parameters of solute transport between peritonitis patients and recently started patients. CONCLUSION: In contrast to patients with long-term PD, the osmotic conductance to glucose is unaffected in peritonitis, despite the lower net ultrafiltration caused by high solute transport. This implies that impaired free- water transport in chronic PD must be regarded as a contributing factor to UFF.

Acute Disease↗
PubMed2004

Quantification of free water transport in peritoneal dialysis.

BACKGROUND: In peritoneal dialysis (PD) total net ultrafiltration (NUF) is dependent on transport through small pores and through water channels in the peritoneum. These channels are impermeable to solutes, and therefore, crystalloid osmotic-induced free water transport occurs through them. Several indirect methods to assess free water transport have been suggested. The difference in NUF between a 3.86% and a 1.36% solution gives a rough indication, but is very time consuming. The magnitude of the dip in dialysate/plasma (D/P) sodium in the initial phase of a 3.86% exchange is another way to estimate free water transport. In the present study, a method was applied to calculate free water transport by calculating sodium-associated water transport in one single 3.86% glucose dwell. METHODS: Forty PD patients underwent one standard peritoneal permeability analysis (SPA) with a 1.36% glucose solution, and another with a 3.86% glucose solution. At different time points intraperitoneal volume and sodium concentration were assessed. This made it possible to calculate total sodium transport. By subtracting this transport (which must have occurred through the small pores) from the total fluid transport, free water transport remained. These results were compared with the other methods to estimate free water transport. RESULTS: For the 1.36% glucose dwell, total transcapillary ultrafiltration in the first hour (TCUF(0-60)) was 164 mL, transport through the small pores was 129 mL, and free water transport was 35 mL (21%). For the 3.86% glucose solution, total TCUF(0-60) was 404 mL, transport through the small pores was 269 mL, and free water transport was 135 mL (34%). The contribution of free water transport in the first minute (TCUF(0-1)) was 39% of the total fluid transport. From the 40 patients, 11 patients had ultrafiltration failure (NUF <400 mL after 4 hours). For these patients the contribution of free water to TCUF(0-1) was significantly lower than for those with normal ultrafiltration (20% vs. 48%, P < 0.05). A strong correlation was present between free water transport as a percentage of total fluid transport and the maximum dip in D/P sodium (r= 0.84). The correlation was not significant with the difference in net ultrafiltration of 3.86% and 1.36% solutions (r= 0.24, P= 0.3). CONCLUSION: The method applied here is the first direct quantification of free water transport, calculated from a single standard peritoneal function test. It offers a quick possibility to evaluate patients suffering from ultrafiltration failure. In these patients free water transport was impaired, but the origin of this impairment is still to be determined.

Adult↗
PubMed2004

Free water transport in patients starting with peritoneal dialysis: a comparison between diabetic and non diabetic patients.

Peritoneal transport rates and net drained volume are reported to be different for peritoneal dialysis (PD) patients with diabetes mellitus (DM) as compared with patients without DM. The difference has been considered to be caused by exposure to high plasma glucose levels before PD initiation. However, the results of previous studies conflict. Transport of small solutes has been reported to be either higher than or similar to that seen in patients without DM, and ultrafiltration to be either similar or lower. No information on free water transport is available. The main problem in earlier reports is the wide variation in duration of PD, which may have influenced the outcomes. In the present study, we compared the results of peritoneal function tests in 10 patients with DM to results in 10 patients without DM. All patients were investigated within the first 4 months of PD treatment. No differences were observed in transcapillary ultrafiltration rate, net ultrafiltration, or lymphatic absorption. Free water transport, estimated using the maximum dip in the dialysate-to-plasma ratio of sodium and quantified by calculating the transport through the ultrasmall pores, showed no differences. Small-solute transport was also similar. These findings imply that a mild chronic hyperglycemic state in the peritoneal vessels does not contribute to important peritoneal changes or to changes in aquaporin-1 function. The influence of continuous treatment with hyperosmolar glucose solutions on the latter is worth investigating.

Absorption↗
PubMed2003

Diffusion correction of sodium sieving applicable in a peritoneal equilibration test.

Sodium sieving is a measure of free water transport. However its assessment is disturbed when a large difference exists between sodium concentrations in plasma and in dialysate--that is, when the diffusion rate is high. Based on previous findings concerning similarity in the mass transfer area coefficients (MTACs) of sodium and urate, we developed a model that corrects for high diffusion. The model enabled us to predict the dialysate sodium concentration resulting from diffusion alone at any time point during a dwell. The correction was based on knowledge of the intraperitoneal volume at any time point during the dwell, which can be calculated by using a volume marker (reference method). However, in a peritoneal equilibration test (PET), only the drained volume after 4 hours is available, and urate concentration is not routinely measured. Therefore, our objective in the present study was to investigate whether a diffusion correction using the MTAC of creatinine and the drained volume at the end of the dwell would be as accurate in estimating maximum sodium sieving as the reference method is. We analyzed standardized 4-hour dwells in 28 patients, 19 with stable PD and 9 with ultrafiltration failure. The dialysate consisted of a 3.86% glucose-containing solution to which dextran 70 was added as a volume marker. The correlation coefficient between the PET correction method and the reference method was 0.92 in all patients [0.90 in stable patients and 0.95 in the patients with ultrafiltration failure (p < 0.01 for all)]. We conclude that a diffusion correction for sodium can be made using PET data. A diffusion correction yields a better estimate of sodium sieving than does the sole use of the lowest dialysate-to-plasma (D/P) sodium irrespective of diffusion rate.

Adult↗
PubMed2003

Peritoneal effluent markers of inflammation in patients treated with icodextrin-based and glucose-based dialysis solutions.

Chronic exposure to peritoneal dialysis (PD) solutions is associated with a low-grade local inflammatory state of the peritoneum. The occurrence of culture-negative peritonitis in some PD patients treated with icodextrin focused our interest on subclinical inflammation in icodextrin-treated patients without peritonitis. The aim of the present study was to compare signs of inflammation in icodextrin-treated patients with the same signs in patients using glucose/lactate-based (GL) dialysis solutions only. Overnight PD effluents from 19 patients treated with icodextrin and 19 patients treated with GL were investigated for leukocyte count (LC) and differentiation (LD), and for dialysate concentrations of cancer antigen 125 (CA125, the marker of mesothelial cell mass) and hyaluronan (marker of inflammation and tissue remodeling in the peritoneal cavity). Blood cell counts and serum dextran antibodies (DA) were also determined. Total LC in the GL group was significantly lower than that in the icodextrin group. The LD was not different between the two groups, except for the percentage of eosinophils. The blood cell count did not differ between the groups. The median value of DA was similar in both groups. The hyaluronan concentration was markedly higher in the icodextrin group. No significant difference was found for dialysate CA125. In conclusion, the higher effluent cell count, higher percentage of eosinophils, and higher effluent hyaluronan levels in icodextrin-treated patients are consistent with a greater degree of subclinical inflammation during icodextrin treatment than during GL treatment.

Adult↗
PubMed2002

Clinical advantages of new peritoneal dialysis solutions.

A review is given of the various mechanisms by which conventional glucose/lactate-based peritoneal dialysis solutions can induce damage to the peritoneal membrane. The potential advantages of newly developed dialysis solutions and the results of recent studies on their use in patients are discussed.

Amino Acids↗
PubMed2002

Peritoneal membrane failure in peritoneal dialysis patients.

A review is given of the conditions associated with peritoneal membrane failure, and the possible causes. Ultrafiltration failure is the most important manifestation. It is mostly associated with high transport rates of low molecular weight solutes suggesting the presence of a large vascular surface area. Enlargement of the peritoneal surface area can be functional (effective surface area: more perfused microvessels) or anatomic (more microvessels). The former is likely to be present in some patients in the beginning of peritoneal dialysis, and also during peritonitis. The latter can develop in long-term peritoneal dialysis.

Humans↗
PubMedDate not supplied

Influence of dialysate on gastric emptying time in peritoneal dialysis patients.

OBJECTIVE: Peritoneal dialysis (PD) patients frequently suffer from dyspeptic complaints such as nausea, vomiting, abdominal distension, early satiety, and anorexia. Gastroparesis might be, at least partially, a source of dyspeptic complaints in PD patients. The aim of the present study was to determine the influence of the presence and composition of dialysate on gastric emptying in PD patients. DESIGN: Prospective study. SETTING: Renal Division, Department of Internal Medicine, Ghent University Hospital, Belgium. PATIENTS: Sixty-one PD patients using different dialysate solutions, and 27 healthy volunteers. MAIN OUTCOME MEASURE: Gastric emptying of solids was assessed by the 13C-octanoic acid breath test. RESULTS: Gastric emptying was impaired in PD patients, regardless of the composition of dialysate and even if tested with an empty peritoneal cavity. Gastric emptying was significantly slower when glucose-containing dialysate was compared to an empty peritoneal cavity, or when glucose-containing dialysate was compared to icodextrin dialysate. No difference in gastric emptying could be demonstrated between glucose-containing dialysate and dialysate containing a mixture of glycerol and amino acids as osmotic agent. CONCLUSIONS: These findings suggest that the delay in gastric emptying demonstrated in the presence of peritoneal dialysate is not the consequence of a mere volume or pressure effect, but of the absorption of substrate substances with caloric and/or metabolic activity, such as glucose or glycerol and amino acids.

Adult↗
PubMedDate not supplied

Acute effects of high-dose furosemide on residual renal function in CAPD patients.

BACKGROUND: High doses of furosemide can increase urine volume in chronic peritoneal dialysis (CAPD) patients. However, no information is available about effects on urinary solute excretion in relation to residual glomerular filtration rate (GFR), urinary furosemide excretion, and peritoneal solute kinetics. METHODS: Diuretic response and the effect on peritoneal fluid and solute transport parameters were investigated in 7 stable CAPD patients with residual renal function (median urine volume 350 mL/24 hours, range 140- 1900 mL/24 hours). Comparisons were made during two clearance periods of 24 hours: one without (P1) and one during 2 g furosemide (P2). RESULTS: The median increase in urine volume was 400 mL (range 270 - 910 mL, p < 0.02) and the increase in sodium excretion was 54 mmol (range 25 - 118 mmol, p < 0.02). No change in GFR was found between P1 (2.4 mL/ minute, range 0.6 - 5.7 mL/min) and P2 (2.0 mL/min, range 1.0 - 4.8 mL/min). An increase in fractional clearance was found for volume, sodium, potassium, and osmolality (p < 0.02). No change was found in the fractional clearance of urea and electrolyte-free water. Furosemide excretion in urine was 8.7 mg/24 hours (range 2.1 - 38 mg/24 hours) and in dialysate 4.9 mg/24 hours (range 1.9 - 7.8 mg/ 24 hours). Plasma furosemide concentration was 29.5 mg/L (range 6.2 - 43.9 mg/L). A positive correlation was found between residual GFR and total urine furosemide excretion (r = 0.93, p < 0.005). Efficiency, expressed as the increase in fractional sodium clearance (percent) per milligram of furosemide excreted per 24 hours, was 1.2%/mg (range 0.3% - 11.3%/mg). CONCLUSION: High-dose furosemide is effective in CAPD patients in increasing urine volume and electrolyte excretion without affecting urea and creatinine clearance. In CAPD patients, the individual response to an identical high dose of furosemide is dependent on the magnitude of residual GFR.

Adult↗
PubMedDate not supplied

Peritoneal function and assessment of reference values using a 3.86% glucose solution.

BACKGROUND: The most widely used peritoneal function test, the peritoneal equilibration test (PET), is performed with a 2.27% glucose solution. Recently, the International Society for Peritoneal Dialysis committee on ultrafiltration failure (UFF) advised performing the test with 3.86% glucose solution because it is more sensitive for detecting clinically significant UFF. Because no reference values for this test were available, we analyzed the results of standard peritoneal permeability analyses (SPAs) using 3.86% glucose. METHODS: The tests were performed in our center on 154 clinically stable peritoneal dialysis (PD) patients that were free of peritonitis for at least 4 weeks. For the assessment of reference values, we used two approaches. In approach A, patients with UFF, defined as net ultrafiltration (UF) < 400 mL/4 hours, were excluded. In approach B, only patients within their first 2 years of PD treatment were included, regardless of net UF. Means and 95% confidence intervals (95% CI) were calculated for the transport parameters of the PET and SPA. RESULTS: Means of normal distribution with 95% CI in approach A were as follows: for 2.0-L exchanges, mass transfer area coefficient (MTAC) for creatinine 8.8 mL/minute (4.7 - 12.7 mL/min), dialysate/plasma ratio (D/P) creatinine 0.70 (0.52 - 0.88), glucose absorption 58% (44% - 72%), dialysate240/initial dialysate ratio of glucose (Dt/D0) 0.28 (0.18- 0.38), net UF 675 mL (375 - 975 mL), and maximal dip in D/P sodium after correction for diffusion from the circulation 0.110 (0.050 - 0.164); for 1.5-L exchanges, MTAC creatinine 7.4 mL/min (3.8 - 11.0 mL/min), D/P creatinine 0.69 (0.52 - 0.86), glucose absorption 62% (52% - 72%), Dt/D0 glucose 0.25 (0.17- 0.32), net UF 551 mL (430 - 670 mL), and maximal dip D/P sodium 0.120 (0.048 - 0.166). In approach B, most of the transport values were similar; however, values for lymphatic absorption were significantly higher [1.52 mL/min (2-L) and 1.40 mL/min (1.5-L), p < 0.01] and values for the maximum dip in D/P sodium were lower [0.101 (2-L) and 0.112 (1.5-L), p > 0.05]. This was probably the result of including patients with UFF in approach B, since these parameters can be causative factors of UFF. CONCLUSIONS: A peritoneal transport function test using 3.86% glucose provides data on various aspects of transport. This study gives normal reference values that can be used for analysis of causes of UFF.

Adolescent↗
PubMedDate not supplied

Does lymphatic absorption change with the duration of peritoneal dialysis?

BACKGROUND: Ultrafiltration failure is an important complication of long-term peritoneal dialysis (PD). A high effective lymphatic absorption rate (ELAR) can contribute to impaired ultrafiltration. It is unknown whether the ELAR increases with time on PD. OBJECTIVE: The relationship between the ELAR and duration of PD was analyzed, as well as the correlation between the ELAR and other transport parameters. We also studied the relation between the ELAR and cancer antigen 125 (CA125) a marker for mesothelial cell mass. SETTING: Peritoneal dialysis unit in the Academic Medical Center, Amsterdam. DESIGN: Cross-sectional and longitudinal studies of standard peritoneal permeability analyses (SPAs; 4-hour dwells, dextran 70 as a volume marker) with glucose 3.86% in 130 PD patients. METHODS: SPAs were analyzed in 130 stable PD patients (77 males). Median duration of PD was 25 months (range 1-214) in a cross-sectional study. The last SPA from each patient was analyzed. The longitudinal analysis included 24 patients (12 males) from whom at least 3 SPAs were available with a minimum interval of 8 months. Dextran 70, 1 g/L, was administered intraperitoneally at the initiation of the test. Lymphatic absorption was calculated from the disappearance rate of dextran 70 during the 4-hour dwell. Therefore, the ELAR included both transmesothelial and subdiaphragmatic uptake of dextran 70. RESULTS: Median ELAR was 1.43 mL/minute (range 0.17- 6.59 mL/minute). No relationship was found between the ELAR and duration of PD in the cross-sectional analysis, nor was there a trend in time for 20 of the 24 patients studied longitudinally. In 4 patients, a negative trend was found. None of these had ultrafiltration failure and all 4 patients had a different cause for end-stage renal failure. The ELAR was correlated with parameters of peritoneal solute transport, but not with CA125 when investigated in a cross-sectional analysis. Only after 48 months of PD treatment was a significant relationship between the ELAR and CA125 seen (r = 0.46, p < 0.05). CONCLUSIONS: No time trend is present for the effective peritoneal lymphatic absorption rate, and it is not associated with patient or technique survival. Although increased lymphatic absorption is one of the causes of ultrafiltration failure, it is unlikely to contribute to the development of ultrafiltration failure in long-term PD patients with well-maintained transcapillary ultrafiltration.

Adolescent↗
PubMedDate not supplied

Analysis of the prevalence and causes of ultrafiltration failure during long-term peritoneal dialysis: a cross-sectional study.

BACKGROUND: Ultrafiltration failure (UFF) is a major complication of peritoneal dialysis (PD). It can occur at any stage of PD, but develops in time and is, therefore, especially important in long-term treatment. To investigate its prevalence and to identify possible causes, we performed a multicenter study in The Netherlands, where patients treated with PD for more than 4 years were studied using a peritoneal function test (standard peritoneal permeability analysis) with 3.86% glucose. UFF was defined as net UF < 400 mL after a 4-hour dwell. RESULTS: 55 patients unselected for the presence or absence of UFF were analyzed. Mean age was 48 years (range 18 - 74 years); duration of PD ranged from 48 to 144 months (median 61 months); UFF was present in 20 patients (36%). Patients with and without UFF did not differ in age or duration of PD. Median values for patients with normal UF compared to patients with UFF were, for net UF 659 mL versus 120 mL (p < 0.01), transcapillary UF rate 3.8 versus 2.1 mL/ minute (p < 0.01), effective lymphatic absorption 1.0 versus 1.6 mL/min (p < 0.05), mass transfer area coefficient (MTAC) for creatinine 9.0 versus 12.9 mL/min (p< 0.01), dialysate-to-plasma ratio (D/P) for creatinine 0.71 versus 0.86 (p < 0.01), glucose absorption 60% versus 73% (p < 0.01), maximum dip in D/P sodium (as a measure of free water transport) 0.109 versus 0.032 (p < 0.01), and osmotic conductance to glucose 3.0 versus 2.1 microL/min/mmHg (p < 0.05). As causes for UFF, high MTAC creatinine, defined as > 12.5 mL/min, or a glucose absorption > 72%, both reflecting a large vascular surface, a lymphatic absorption rate (LAR) of > 2.14 mL/min, and a decreased dip in D/P sodium of < 0.046 were identified. Most patients had a combination of causes (12 patients), whereas there was only a decreased dip in D/P sodium in 3 patients, only high MTAC creatinine in 1 patient, and only high LAR in 2 patients. We could not identify a cause in 2 patients. Both groups had similar clearances of serum proteins and peritoneal restriction coefficients. However, dialysate cancer antigen 125 concentrations, reflecting mesothelial cell mass, were lower in the UFF patients (2.79 vs 5.38 U/L). CONCLUSION: The prevalence of UFF is high in long-term PD. It is caused mainly by a large vascular surface area and by impaired channel-mediated water transport. In addition, these patients also had signs of a reduced mesothelial cell mass, indicating damage of the peritoneum on both vascular and mesothelial sites.

Biological Transport↗