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D G Struijk

Publications and source records attributed to D G Struijk.

At least 19 recordsLinked to original sources
PubMed1998

Are phospholipase A2 and nitric oxide involved in the alterations in peritoneal transport during CAPD peritonitis?

The alterations in peritoneal permeability characteristics during peritonitis can only partly be explained by the increased concentrations of prostaglandins and cytokines in the dialysate. Fifteen patients undergoing continuous ambulatory peritoneal dialysis (CAPD) with 16 peritonitis episodes were examined in the acute phase of the infection by using standard peritoneal permeability analyses (SPAs). In 9 of these patients, a control SPA could be performed. The contribution of nitric oxide (NO), prostaglandins, and the acute phase reactants C-reactive protein (CRP) and secretory phospholipase A2 (sPLA2) were analyzed. The mass transfer area coefficients (MTACs) of low-molecular-weight solutes increased during peritonitis: urea 26%, creatinine 45%, and urate 45%. The MTAC of CO2, calculated to estimate peritoneal blood flow, was 71 mL/min (34 to 254 mL/min) during peritonitis and 55 mL/min (42 to 63 mL/min) after recovery, P < or = .05. The peritoneal protein clearances were also greater during peritonitis, but this increase was not related to the molecular weight of the protein. Therefore the restriction coefficients to macromolecules were not different. The net ultrafiltration in all peritonitis episodes was lower as compared with the control dwells: -97 mL (-196 to 19 mL) versus 25 mL (-132 to 216 mL), P = .03. The prostaglandin concentrations in dialysate were greater during peritonitis than after recovery. The median increase was 199% for prostaglandin E2 (PGE2), 68% for 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha), and 44% for thromboxane B2 (TxB2). Plasma sPLA2 values were 22.7 microg/L (7.3 to 407.6) during peritonitis and 8.9 microg/L (5.5 to 11.5) after recovery, P < .01. The increased plasma sPLA2 during peritonitis correlated with plasma CRP (r = .6; P = .02). The peritoneal clearances of sPLA2 were greater during peritonitis, but this could be attributed completely to the increased peritoneal transport. Both during peritonitis and after recovery, the sPLA2 clearances did not exceed the predicted values based on transport from the circulation to the dialysate. No evidence was found for local production of nitrite or nitrate. However, the MTAC of cyclic guanosine monophosphate (cGMP) was greater during the experiments performed 48 to 72 hours after the onset of peritonitis, which suggests the synthesis of NO. It can be concluded that peritonitis does not induce detectable local release of sPLA2 and that the inflammation-induced increase in the vascular surface area could not be attributed to NO in the acute phase. The activation of inducible NO synthase may occur after 48 hours.

Adult↗
PubMed1998

Augmenting solute clearance in peritoneal dialysis.

BACKGROUND: The removal of low molecular weight solutes by peritoneal dialysis is less than by hemodialysis. The targets for Kt/Vurea and creatinine clearance formulated in the Dialysis Outcome Quality Initiative are unlikely to be achieved in a substantial portion of peritoneal dialysis patients. Possibilities to increase small solute clearances have therefore been subject to many investigations. METHODS: A review of the literature and of recent new data on determinants of solute removal, such as residual renal function, the role of drained dialysate volume and manipulation of the diffusive capacity of the peritoneum are presented. RESULTS: The contribution of residual GFR is more important for the clearance of creatinine than for Kt/Vurea. It is even more important for the removal of organic acids that are removed from the body by tubular secretion. High dosages of furosemide increase the urinary volume and the fractional Na+ excretion, but have no effect on the magnitude of residual GFR, renal creatinine clearance, renal urea clearance, and peritoneal transport characteristics. The drained dialysate volume per day is the main determinant of the peritoneal removal of urea. Its effect decreases the higher the molecular weight of a solute. It can be augmented by using large instillation volumes, by the application of more exchanges, and by increasing peritoneal ultrafiltration. A large exchange volume is especially effective in patients with an average transport state, but in those with high solute transport rates, Kt/Vurea is especially influenced by the number of exchanges. Possibilities to increase ultrafiltration are discussed. The diffusive capacity of the peritoneum can be augmented by using low dosages of intraperitoneally administered nitroprusside. This increases solute transport most markedly when it is applied in combination with icodextrin as osmotic agent. CONCLUSIONS: Small solutes clearances cannot be increased by furosemide. Increasing the instilled volume of dialysis fluid and the number of exchanges both affect solute clearance. Studies are necessary on long-term effects of manipulation of the peritoneal membrane with nitroprusside.

Diffusion↗
PubMed1998

Day-to-day variability of fluid and solute transport in upright and recumbent positions during CAPD.

BACKGROUND: The effect of posture on peritoneal transport characteristics during CAPD is unpredictable because (1) although the capillary pressure is higher in the upright position, the intraperitoneal pressure is also elevated, and (2) the contact of dialysate with the subdiaphragmatic lymphatics is probably more extensive during recumbency. METHODS: In eight CAPD patients, six peritoneal permeability tests (4 h, glucose 2.27%, dextran 70 as volume marker) were performed within 2 weeks, while the body posture was either recumbent (3 tests) or upright (3 tests). In addition, intraperitoneal pressure measurements were done in the recumbent and upright positions. RESULTS: The intraperitoneal pressure, not corrected for the contribution of the hydrostatic column, was higher in upright position (12.6 +/- 0.8 mmHg, mean +/- SEM) than during recumbency (6.7 +/- 0.8; P < 0.0005). Net ultrafiltration rate was lower when upright: 0.96 +/- 0.09 ml/min/1.73 m2, compared to 1.14 +/- 0.12 in the supine position (P < 0.05). This was achieved because the effective lymphatic absorption rate was marginally higher and the transcapillary ultrafiltration rate was slightly lower in the upright position. The mass transfer area coefficient of creatinine, representing effective peritoneal surface area, decreased from 10.7 +/- 1.3 ml/min/1.73 m2 (recumbent) to 9.9 +/- 1.4 (upright; P = 0.08). The clearances of five serum proteins decreased more the higher the molecular weight. As a consequence the restriction coefficient was 2.07 +/- 0.09 (recumbent) vs 2.23 +/- 0.08 (upright; P = 0.06). Hence the intrinsic permeability to macro-molecules was higher during recumbency. The intraperitoneal pressure was correlated with the net ultrafiltration rate (r = -0.71, P = 0.05) only during recumbency. In upright position relations were found between the effective lymphatic absorption rate and the mass transfer area coefficients of low molecular solutes. The coefficients of variation of fluid and solute parameters were not different between both positions. CONCLUSIONS: It is concluded that the decrease in net ultrafiltration rate in the upright position is only small and probably caused by counteracting effects of a higher intra-abdominal pressure and the effect of gravity. The upright position also led to only small decreases in solute transport parameters.

Adult↗
PubMed1998

Peritonitis in peritoneal dialysis patients after renal transplantation.

BACKGROUND: The occurrence of peritonitis in peritoneal dialysis patients after renal transplantation during immunosuppression might increase morbidity and mortality. Hence the timing of catheter removal is still controversial. The associated risk factors of this complication have not been analyzed. METHODS: We analyzed, retrospectively, the incidence of peritonitis within 90 days after transplantation, its associated morbidity and mortality, as well as risk factors. From 1980 until March 1995, 238 consecutive kidney transplants in peritoneal dialysis patients were performed. Univariate and multivariated logistic regression analysis were used to identify risk factors for the development of peritonitis. RESULTS: 232 cases (141 men, 91 women) were available for analysis. In 191 patients, the catheter was removed with a mean interval after transplantation of 122 days (range 0-573). Thirty peritonitis episodes with predominantly Staphylococcus aureus (10/30) or gram-negative bacteria (12/30) were observed. Independent risk factors before transplantation were the total number of peritonitis episodes (P<10(-5)), previous peritonitis with S. aureus bacteria (P<10(-5)), and male sex (P<0.004). Risk factors after transplantation were technical surgical problems (P<10(-5)), more than two rejection episodes (P<0.02), permanent graft nonfunction (P<0.026), and urinary leakage (P<0.035). CONCLUSIONS: Transplantation without simultaneous peritoneal catheter removal is feasible. However, this increases the risk of peritonitis after transplantation. Early catheter removal should be considered seriously in those patients at risk. When peritonitis develops, antibiotic treatment should be directed against gram-positive as well as gram-negative bacteria until culture results are available.

Adult↗
PubMed1998

Icodextrin with nitroprusside increases ultrafiltration and peritoneal transport during long CAPD dwells.

Addition of the nitric oxide (NO) donor nitroprusside to 1.36% glucose dialysate enlarges the effective peritoneal surface area during four-hour dwells. The theoretical positive effect on ultrafiltration is, however, counteracted by an increase in glucose absorption. The absorption of the glucose polymer icodextrin is much lower in comparison with glucose-based dialysis solutions, due to its high molecular weight. In the present study 7.5% icodextrin dialysis solution with and without the addition of 4.5 mg/liter nitroprusside was studied during eight-hour CAPD dwells. Two Standard Peritoneal permeability Analyses, adapted for eight-hour dwells, were performed in 10 stable CAPD patients. Nitrate and cGMP were measured as parameters of NO synthesis. The transcapillary ultrafiltration increased in a linear way with icodextrin (ICO) and was even higher after the addition of nitroprusside (NP): 666 (ICO) versus 834 (NP) ml/8 hr, P = 0.03. The effective lymphatic absorption rate was not different. The resulting net ultrafiltration increased with nitroprusside: 344 (ICO) versus 540 (NP) ml/8 hr, P < 0.01. The mass transfer area coefficient of urea increased 15% and that of creatinine 26% with nitroprusside, consistent with the expected enlargement of the vascular peritoneal surface area. The increase in protein clearances was more pronounced the larger the protein: beta 2-microglobulin 19%, albumin 47%, IgG 63% and alpha 2-macroglobulin 95%. Dialysate/plasma (D/P) ratios of nitrate were not higher than the expected values on the basis of its molecular weight (P < 0.001). They increased 19% with nitroprusside. Also, the D/P ratio cyclic guanosine monophosphate (cGMP) after four hours increased with nitroprusside (0.39, range 0.13 to 0.55 ICO, and 0.82, range 0.36 to 1.39 NP, P = 0.01). With nitroprusside the D/P ratio cGMP was higher than expected after four and eight hours (P < 0.001). This points to local generation of NO after addition of nitroprusside. The nitroprusside induced increase in the mass transfer area coefficients (MTAC) of creatinine and in the ultrafiltration caused an increase in the creatinine clearance from 4.2 ml/min to 5.0 ml/min during the eight-hour dwell. This means that nitroprusside adds 3 liters/week to the peritoneal clearance of creatinine. The adequacy of peritoneal dialysis can therefore be improved by the addition of nitroprusside to 7.5% icodextrin, used for the long exchange.

Adult↗
PubMed1998

Similarities and differences between the effects of amino acids and nitroprusside on peritoneal permeability during CAPD.

OBJECTIVE: Intraperitoneal administration of amino acid based dialysis solutions affects the surface area available for diffusion, with almost no effect on the intrinsic permeability to macromolecules. Intraperitoneally administered nitroprusside affects the vascular surface area and the intrinsic permeability without effect on the peritoneal blood flow. In the present study, these differences were translated into different effects on the radii of the pores in the peritoneal membrane. METHODS: Effects of amino acid based dialysate and nitroprusside on peritoneal permeability characteristics were evaluated in standard peritoneal permeability analyses with L-arginine-containing amino acid dialysate (10 patients) or with 1.36% glucose dialysate with nitroprusside (10 patients). In each patient a control experiment with 1.36% glucose was performed. Kinetic modeling was done to analyze the effects in terms of the pore theory. RESULTS: Both interventions increased the mass transfer area coefficients of low molecular weight solutes. This is in accordance with an increase in the unrestricted area over diffusion distance found with modeling. With amino acids almost no effect was found on the protein clearances; the increase in the large-pore radius was only small. Nitroprusside induced a marked increase in protein clearances. This was in accordance with an evident increase in the average large-pore radius. CONCLUSIONS: Amino acids affect the radii of the small pores and the large pores to the same extent. Nitroprusside influences especially the large pores. Both amino acids and nitroprusside are vasoactive, although the effects on the peritoneal microcirculation are different.

Adult↗
PubMed1997

Longitudinal follow-up of CA125 in peritoneal effluent.

Mesothelial changes occur during peritoneal dialysis. CA125 provides a way to study the mesothelial cells in the in vivo situation. In the present study longitudinal changes of CA125 were analyzed. In addition, the appearance of CA125 in peritoneal effluent and day-to-day variability were studied. CA125 was measured in the effluent of five stable CAPD patients during four hour dwells with 1.36% glucose, with 3.86% glucose and with 7.5% icodextrin. In addition, CA125 was determined on six consecutive days in four hour effluents of three patients and appearance rates (AR) were calculated. Longitudinal follow-up was performed in 31 patients in whom three to seven yearly observations had been made. Linear appearance of CA125 was present in all dwells. No difference was found between the appearance rates of CA125 with 3.86% glucose, compared to either 1.36% glucose or icodextrin. Mean day-to-day coefficient of variation was 6.4% for CA125 AR, but a wide variation existed in stable CA125 values among patients (mean 22.1, range 2 to 48 U/ml). A negative trend with duration of CAPD was present in the longitudinal study. A mean decrease of 2.2% per year could be calculated, but substantial interindividual differences existed. Sudden decreases of CA125 AR were found in five patients. Possible causes were found in all of them and included a severe or recurrent peritonitis, and temporary cessation of peritoneal dialysis. In one patient a sudden decrease preceded the manifestation of peritoneal sclerosis. It can be concluded that CA125 can be used for the in vivo follow-up of the mesothelium in peritoneal dialysis patients. The appearance of CA125 in effluent is linear in time and not influenced by the initial lysis of mesothelial cells. A gradual loss of mesothelial cells is likely to occur, although interindividual variability is substantial. An acceleration of the process may be caused by severe peritonitis and perhaps by temporary cessation of peritoneal dialysis. A sudden decrease in CA125 may be an alarming sign for the development or manifestation of peritoneal sclerosis.

CA-125 Antigen↗
PubMed1997

The nitric oxide donor nitroprusside intraperitoneally affects peritoneal permeability in CAPD.

Nitroprusside is a nitric oxide (NO) donor. To investigate effects of nitroprusside i.p. on peritoneal permeability and perfusion, standard peritoneal permeability analyses were performed. Ten stable CAPD patients were studied twice within one week with glucose based dialysate (1.36% Dianeal) with and without addition of nitroprusside 4.5 mg/liter. Mass transfer area coefficients (MTAC) of CO2 were calculated to estimate peritoneal blood flow. Nitrate, a stable metabolite of NO, and cGMP, a second messenger of NO synthesis, were measured in plasma and dialysate. The MTACs of low molecular weight solutes were greater with nitroprusside (NP) compared to the control dwell (C): creatinine median 14.1 (NP) versus 9.9 ml/min (C), urea 21.7 (NP) versus 18.5 ml/min (C) and urate 10.5 (NP) versus 8.6 ml/min (C) (P < 0.05 for all). This points to an increased effective peritoneal surface area with nitroprusside. Furthermore, the restriction coefficient for the low molecular weight solutes decreased from 1.28 (C) to 1.23 (NP) (P = 0.02), suggesting some effect also on the size selectivity to these solutes. The effect of nitroprusside on the clearances of serum proteins was more pronounced. The increase with nitroprusside was 34% for beta 2-microglobulin, 70% for albumin, 77% for IgG and 143% for alpha 2-macroglobulin. This reduction in size selectivity was reflected in a decrease in the restriction coefficient for macromolecules from 2.29 (C) to 1.86 (NP), P < 0.01. This implies an increase in the intrinsic permeability of the peritoneal membrane. Kinetic modeling, using computer simulations, was done to analyze these effects in terms of the pore theory, using a convection model and a diffusion model for the transport of macromolecules. Nitroprusside led to an increase of both the large pore radius and the small pore radius and of the unrestricted area over diffusion distance. These effects were more pronounced with the diffusion model. The MTAC CO2 was not different: NP 76.9 and C 84.1 ml/min. MTACs of nitrate were not greater than expected on the basis of the molecular weight during both dwells. The dialysate/plasma (D/P) ratio of cGMP was greater after addition of nitroprusside: 0.36, range 0.21 to 0.77 (C) and 0.74, 0.23 to 2.50 (NP), P = 0.02. With nitroprusside the D/P ratio of cGMP was greater than expected on the basis of its molecular weight (P < 0.001). This points to local generation of cGMP after the addition of nitroprusside, induced by NO. No differences were found in the dialysate concentrations of the prostaglandins (PG) PGE2 and 6-keto-PGF1 alpha and thromboxane B2 after addition of nitroprusside. The transcapillary ultrafiltration rate and the net ultrafiltration rate during four hours were not different with nitroprusside. In conclusion, nitroprusside i.p. increased the effective peritoneal surface area and the intrinsic permeability, but the peritoneal blood flow did not change. The greater than expected D/P ratios of cGMP point to local generation of cGMP with nitroprusside, induced by NO.

Adult↗
PubMed1997

Predicting mortality in intensive care patients with acute renal failure treated with dialysis.

Existing prognostic methods were compared in their ability to predict mortality in intensive care unit (ICU) patients on dialysis for acute renal failure (ARF). The clinical goal of this study was to determine whether these models could identify a group of patients where dialysis would provide no benefit because of a near 100% certainty of death even with dialysis treatment. This retrospective cohort study included 238 adult patients who received a first dialysis treatment for ARF in the ICU. This study examined the performance of seven general ICU mortality prediction models and four mortality prediction models developed for patients with ARF. These models were assessed for their ability to discriminate mortality form survival and for their ability to calibrate the observed mortality rate with the expected mortality rate. The observed in hospital mortality was 76% for our patient group. Areas under the receiver operating characteristic curve ranged from 0.50 to 0.78. With the Acute Physiology and Chronic Health Evaluation (APACHE) III and the Liano models, the observed mortality in the highest quintiles of risk were 97% and 98%. In conclusion, although none of the models examined in this study showed excellent discrimination between those patients who died in hospital and those who did not, some models (APACHE III, Liano) were able to identify a group of patients with a near 100% chance of mortality. This indicates that these models may have some use in supporting the decision not to initiate dialysis in a subgroup of patients.

Acute Kidney Injury↗
PubMed1997

Markers of peritoneal mesothelial cells during treatment with peritoneal dialysis.

Loss of peritoneal mesothelial cells and decrease of mesothelial cell mass have been described in peritoneal dialysis (PD) patients. Longitudinal follow-up in individual PD patients cannot be performed by serial peritoneal biopsies. Markers of mesothelial integrity, measured in the effluent, may therefore be a valuable approach to detect changes in the mesothelium in vivo. In the present study, markers that are known to be produced by mesothelial cells were followed in individual patients: cancer antigen 125 (CA125), phospholipids (PHL), and hyaluronan (HA). CA125 is considered to be a reflection of mesothelial cell mass or stable mesothelial cell turnover. Appearance rates (AR) were determined in the effluents of 30 PD patients on a yearly basis. Median AR (range) were: CA125: 111 U/min (10-610), PHL: 15 mg/min (3-46), HA: 666 mg/min (135-6200). Cross sectionally, the AR for CA125 was negatively related to duration of PD (r = -0.47, p < 0.0001) and weakly related to peritonitis incidence (r = -0.20, p < 0.05). Patients treated with PD for more than 4 years had lower CA125 appearance than patients treated less than 4 years (p < 0.0004). HA was also related to the incidence of peritonitis, but positively (r = 0.32, p < 0.004). PHL were not related to either parameter. A significant negative trend with time of PD treatment was observed for CA125 only [mean regression coefficient (t) -3.75, SD 1.2]. No trend in time of PD treatment could be detected for HA and PHL. These data indicate a gradual loss of mesothelial cell mass during PD by the decrease of CA125 with time. The lack of a decrease in HA and its positive relation to incidence of peritonitis suggest an additional release of HA by cells other than the mesothelial cells, such as fibroblasts and leukocytes. Alternatively, an activation of (mesothelial) cells with duration of PD and possibly with increased peritonitis incidence cannot be excluded. The relation between PHL and duration of PD suggested by others was not confirmed in this study. PHL are probably released by a number of different cells, and therefore changes in PHL cannot be used as a reflection of changes in mesothelial cell mass. It is concluded that CA125 is the most specific marker for the follow-up of mesothelial cell mass in vivo.

Biomarkers↗
PubMed1997

Differences in fluid and solute transport between diabetic and nondiabetic patients at the onset of CAPD.

Loss of transcapillary ultrafiltration (TCUF) can occur during continuous ambulatory peritoneal dialysis (CAPD) and may be caused by exposure to the high glucose concentrations in the dialysate, leading to glycation of water channels in the endothelial cells of the peritoneal microvessels. If this hypothesis is correct, diabetic patients should have lower TCUF rates at the onset of CAPD than nondiabetic controls. Such a difference should disappear during longer-duration CAPD because of the continuous glucose exposure in both groups, induced by the high glucose concentrations in the dialysate. Therefore, the standard peritoneal permeability analysis of 11 diabetic (mean age 48 years, range 33-70 years) and 11 nondiabetic patients (mean age 49 years, range 36-69 years) matched for sex, age, and duration of CAPD were studied shortly after the onset of CAPD treatment (mean duration 162 vs 131 days) and one year later. No differences were found in solute transport or protein clearances between the two groups at the onset of CAPD. The TCUF rate was lower in the diabetic patients: 0.9 mL/min (0.09-2.25) versus 1.51 mL/min (0.97-2.44), p = 0.01. The other parameters of fluid transport were not different. The mean osmotic pressure gradient, exerted by albumin and glucose, was 1.72 mmHg in the diabetic patients and 5.44 mmHg in the controls (p = 0.0004). No differences were found in peritoneal permeability, including TCUF, after one year between the two groups. In conclusion, the TCUF rate was lower in diabetic patients compared to nondiabetics only shortly after the onset of CAPD. These results suggest that long-term exposure to high glucose concentrations in diabetics prior to CAPD may cause changes in capillary wall aquaporins, similar to long-term exposure to high glucose concentrations in the dialysate in CAPD.

Adult↗
PubMed1997

Restriction coefficients of low molecular weight solutes and macromolecules during peritoneal dialysis.

The intrinsic permeability of the peritoneal membrane can be functionally represented by the restriction coefficient (RC). The RC can be calculated as the exponent of the power relation between the mass transfer area coefficients (MTACs) of various solutes and their free diffusion coefficients in water. When the RC = 1.0, transport is determined by free diffusion only, as is expected for low molecular weight (LMW) solutes. A RC > 1.0 suggests that transport is restricted by the peritoneal membrane in a size-selective way, as has been found previously for macromolecules (MM). RCLMW can be calculated using the MTACs of urea, creatinine, urate, and beta 2-microglobulin, whereas RCMM can be calculated from clearances of beta 2-microglobulin, albumin, IgG, and alpha 2-macroglobulin. RCLMW and RCMM were determined in 108 peritoneal dialysis (PD) patients. In 36 patients, 3 or more (range 3-13) observations for RCLMW during a period of at least 2 years were available. RCMM were analyzed when present in the same patients. The median cross sectional values (n = 108) were: RCLMW: 1.22 (range 0.75-2.18) and RCMM: 2.30 (range 1.86-3.27). RCLMW was not correlated with time on PD, neither cross sectionally (r = -0.07, NS) nor after analysis of trend (mean regression coefficient t = 0.26, SD = 0.07). For RCMM a positive correlation with duration of PD was demonstrated (cross sectionally r = -0.18, p = 0.02, analysis of trend: t = 2.27, SD = 0.11, n = 27). Both RCs were not interrelated (r = -0.18, NS). The absence of a relation between both RCs suggests that LMW solutes and MM are transported by different pathways. The mean value of 1.22 for the RCLMW illustrates that the transport of LMW solutes is mainly by free diffusion, through the small-pore system. MM, which have to pass through the large-pore system, are restricted by the peritoneal membrane in a size-selective way, as shown by the high value of the RCMM. The lack of a correlation between the RCLMW and duration of PD indicates that no systematic changes occur in the small pores of the peritoneal vessels. In contrast, the increase of RCMM with duration of PD suggests restrictive changes at the level of the large-pore system.

Biological Transport↗
PubMed1996

Peritoneal transport characteristics with glucose polymer based dialysate.

Dialysate fluids containing glucose polymers as osmotic agent are different from the conventional solutions, because they are iso-osmotic to plasma and produce transcapillary ultrafiltration (TCUF) by colloid osmosis. To investigate the effects on fluid and solute kinetics, a comparison was made between a 7.5% glucose polymer based dialysate (icodextrin) and 1.36% and 3.86% glucose based dialysate in 10 stable CAPD patients. In each patient three standard peritoneal permeability analyses (SPA) were done with the osmotic agents and concentrations mentioned above. Dextran 70 was added to the glucose solutions to calculate fluid kinetics. In the glucose polymer SPAs fluid kinetics were calculated from the dilution and disappearance of dextrin. The TCUF rate with icodextrin was closer to that obtained with 3.86% glucose than to 1.36% glucose. Extrapolation of the fluid profiles revealed sustained ultrafiltration with icodextrin. TCUF increased linearly in time in the icodextrin tests, whereas a hyperbola best described the glucose profiles. The effective lymphatic absorption rate with icodextrin was similar to the glucose based solutions. Mass transfer area coefficients of low molecular weight solutes with icodextrin were also similar to the values obtained with glucose, as was D/P creatinine. A positive correlation was present between the MTAC creatinine and the TCUF rate with icodextrin (r = 0.66, P = 0.05), which was absent in the glucose SPAs. This suggests that in patients with a larger effective peritoneal surface area, more ultrafiltration can be achieved by glucose polymer solutions. Clearances of beta 2-microglobulin (beta 2m) were higher with icodextrin than with 3.86% glucose and 1.36% glucose dialysate (P < 0.05). No differences were found for the larger serum proteins albumin, IgG and alpha 2-macroglobulin. Initial D/PNa-->was higher (0.96) with icodextrin than with the glucose based solutions (0.92), due to the higher Na+ concentration of icodextrin, and it remained unchanged during the dwell. In contrast, D/PNa+ of 1.36% glucose increased during the dwell, whereas D/PNa+ decreased with 3.86% glucose until 60 minutes, followed by a subsequent increase. The ultrafiltration coefficient (UFC) of the total peritoneal membrane was assessed using 3.86% glucose (0.18 +/- 0.04 ml/min/mm Hg), and the UFC of the small pores was assessed using icodextrin (0.06 +/- 0.008 ml/min/mm Hg). The difference between these represented the UFC through the transcellular pores, which averaged 50.5% of the total UFC, but with a very wide range (0 to 85%). An inverse relation existed between the duration of CAPD treatment and the total ultrafiltration coefficient (r = -0.68, P < 0.04), which could be attributed to a lower UFC of the transcellular pores in long-term patients (r = -0.66, P < 0.05), but not to the UFC of the small pores (r = -0.48, NS). The TCUFRo-60 min through the transcellular pores correlated with the sodium gradient, corrected for diffusion, in the first hour of the dwell (r = 0.69, P < 0.04), indicating that both parameters indeed measure transcellular water transport. It can be concluded that the glucose polymer solution induced sustained ultrafiltration and had no effect on peritoneal membrane characteristics. In addition, the results of the present study support the hypothesis that the glucose polymer solutions exerts its osmotic pressure across intercellular pores with radii of about 40 A. This leads to increased clearances of low molecular weight proteins such as beta 2m that are transported through these pores without sieving of Na+. The latter, as found during 3.86% glucose dialysate, is probably caused by transcellular water transport. The transcellular water transport accounted for 50% of the total ultrafiltration with glucose based dialysis solutions. It was lower in long-term CAPD patients.

Adult↗
PubMed1996

Fluid kinetics in CAPD patients during dialysis with a bicarbonate-based hypoosmolar solution.

The magnitude of transcapillary backfiltration by the colloidosmotic pressure within the peritoneal capillaries compared to the effective lymphatic absorption was investigated in continuous ambulatory peritoneal dialysis patients. This was done during a 4-hour dwell period, using a hypoosmolar dialysis fluid (280 mosm/kg H2O) in 8 patients and compared to 5 of these patients using a 1.36% glucose (GS; 324 mosm/kg H2O). The low molecular weight solute transport did not differ between the two solutions. The intraperitoneal dextran 70 concentration increased during the dwell with the hypoosmolar dialysis fluid (from 770 to 945 mg/l; p = 0.000002) and decreased with the GS (from 859 to 719 mg/l; p = 0.007). With the GS the transcapillary ultrafiltration was directed towards the abdominal cavity during the dwell period. With the hypoosmolar fluid, the transcapillary ultrafiltration was continuously directed towards the circulation. In this solution, the magnitude of transcapillary backfiltration due to colloidosmotic pressure within the peritoneal capillaries was 0.4 +/- 0.1 ml/min. In conclusion, intraperitoneal markers can be used in continuous ambulatory peritoneal dialysis patients for determination of effective lymphatic absorption and transcapillary fluid passage in both transport directions.

Adult↗
PubMed1996

Measurement of residual renal function in patients treated with continuous ambulatory peritoneal dialysis.

Renal function contributes markedly to the adequacy of continuous ambulatory peritoneal dialysis (CAPD). The best way to measure it in clinical practice has not been established. Ten stable CAPD patients with residual renal function were investigated to compare the GFR measured as inulin clearance (Cli) with the creatinine clearance (Clc), the urea clearance (Clu), and with 0.5(Clc + Clu). Thereafter, an analysis of whether the administration of cimetidine could improve the accuracy of these clearances was performed. Two clearance periods (CP) of 24 h were investigated. During CP-2, patients received 400 mg cimetidine twice daily, for a total dose of 1200 mg. Two h before the urine and dialysate collection period, inulin was administered iv. Calculations were done for each CP for Cli, Clc, Clu, Clc-Cli, the Clc/Cli ratio, and the tubular secretion of creatinine (TSc). No differences between CP-1 and CP-2 were present for urinary excretion of volume and solutes, and clearance rates of inulin and urea. The median TSc decreased from 0.71 mumol/min (range, -0.24 to 5.90) in CP-1 to 0.30 mumol/min (range, -0.18 to 0.64) in CP-2 (P < 0.05). Therefore, the median ratio of Clc/Cli decreased from 1.23 (range, 0.87 to 2.20) in CP-1 to 1.11 (range, 0.95 to 1.51) in CP-2 (P < 0.05). The median overestimation of the Cli in CP-1 by the Clc was 0.90 mL/min (range, -0.28 to 3.80) and by the 0.5(Clc + Clu) was 0.30 (range, -0.67 to 1.52). The median overestimation of Cli during cimetidine treatment in CP-2 was 0.43 mL/min (range, -0.21 to 1.20). The range, in differences between Cli and Clc, in CP-2 was smaller than that between Cli and 0.5(Clc + Clu) in CP-1. The difference between the clearance rate of inulin and creatinine or the combined clearance rate of urea and creatinine was not influenced by the magnitude of the average GFR. It can be concluded that the administration of cimetidine improved the accuracy of measuring the GFR with the Clc in CAPD patients.

Adult↗
PubMed1996

Effect of electric charge on the transperitoneal transport of plasma proteins during CAPD.

BACKGROUND: Controversy exists as to whether electric charges of plasma proteins influence their transport across the peritoneal membrane during CAPD. Fixed negative charges in the peritoneal membrane are diminished during peritonitis in rats. METHODS: Peritoneal clearances of 10 proteins and their isoforms were used to establish the relationship between peritoneal clearance and molecular weight. The observed protein clearances were compared with the predicted clearances based on molecular weight. Clearances of proteins with different charge but identical size were compared. Stable patients and peritonitis patients were compared. Results. Only the peritoneal clearance of lipase, LDH 4/5 and IgG3 were significantly different from the predicted values (P<=0.05). The peritoneal clearance of slightly anionic beta2 microglobulin (1072 microl/min) and cationic lysozyme (572 microl/min) showed no evidence for charge selectivity; neither did the peritoneal clearance of slightly anionic transferrin (86 microl/min) and highly anionic albumin (99 microl/min). The peritoneal clearance of IgG1, IgG2 and IgG4 were identical (32, 31 and 31 microl/min), despite their different charge. The peritoneal clearance of cationic LDH 4/5 was 137 microl/min and higher than the peritoneal clearance of neutral LDH 3 (97 microl/min, P=0.01) and LDH 1 (59 microl/min, P=0. 02). These results suggested charge selectivity; however in five additional patients during peritonitis the peritoneal clearance of LDH 4/5 increased to 10 times the peritoneal clearance of LDH 1. Local LDH isoenzyme release from the cells present in the dialysate was shown to be responsible in stable and peritonitis patients. Likewise, the higher peritoneal clearance of neutral pancreatic amylase (234 microl/min) compared to anionic salivary amylase (142 microl/min, P=0.03) could probably be attributed to local release of the former from the pancreas, as the peritoneal clearance of lipase (highly anionic) was higher than predicted and the difference remained during peritonitis. CONCLUSIONS: The peritoneal membrane constitutes a size- but probably not a charge-selective barrier for the transport of macromolecules between blood and dialysate during stable CAPD.

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