Oral neostigmine and lymphatic absorption in a myasthenia gravis patient on continuous ambulatory peritoneal dialysis (CAPD)

The effects of oral neostigmine on peritoneal lymph absorption and transcapillary and net ultrafiltration were studied in a myasthenia gravis patient on continuous ambulatory peritoneal dialysis (CAPD). Oral neostigmine decreased lymphatic absorption, but only up to a threshold dose. The effect on net ultrafiltration however was nullified to some extent by a concurrent decrease in cumulative transcapillary ultrafiltration.     

Loss of ultrafiltration in continuous ambulatory peritoneal dialysis (CAPD)

Fifteen patients on long-term continuous ambulatory peritoneal dialysis (CAPD) were assessed with respect to net ultrafiltration capacity. Eight patients were defined as having good and seven as having poor ultrafiltration on the basis of net ultrafiltrate obtained/mmol glucose infused. Subsequently, dialysate was sampled at times 0, 1, 15, 30, 60, 90, 120, 180, and 240 min. No difference in residual volume was observed between the groups. A significantly greater decrease in dialysate sodium during the initial dialysis period in those patients with good as compared to those with poor ultrafiltration occurred, reflecting a greater transcapillary movement of electrolyte poor ultrafiltrate. In those with good ultrafiltration, glucose transfer was normal in five and rapid in three, suggesting the latter had low rates of lymphatic reabsorption. Five of seven patients with poor ultrafiltration had no fall in dialysate sodium in association with a high rate of glucose transfer, suggesting a low rate of transcapillary water movement and normal to high lymphatic absorption. Two patients with low ultrafiltration had an initial fall in dialysate sodium with a normal glucose transfer and thus net ultrafiltration is low due to elevated lymphatic reabsorption. We thus propose that the relative contribution of transcapillary water movement and lymphatic reabsorption can be determined by assessing net ultrafiltration and dialysate sodium concentration in conjunction with solute transfer.     

Effects of peritoneal resting on peritoneal fluid transport kinetics.

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

Dialysis efficiency in continuous ambulatory peritoneal dialysis patients treated with erythropoietin.

OBJECTIVE: To determine the effect of subcutaneous erythropoietin treatment on dialysis efficiency in continuous ambulatory peritoneal dialysis (CAPD) patients. DESIGN: Dialysis efficiency, platelet and white cell aggregation, and red cell deformability were measured monthly for six months in nine anaemic CAPD patients treated with erythropoietin, and on a single occasion in seven control CAPD patients with intrinsically high haemoglobin concentrations. SETTING: Renal dialysis unit. PATIENTS: Nine patients stable on CAPD for a minimum of six months and with haemoglobin concentrations less than 8.5 g/dl were treated with erythropoietin. Seven CAPD patients matched for age and renal function, with haemoglobins greater than 9.0 g/dl served as controls. RESULTS: Daily peritoneal clearances and net ultrafiltration volumes were unchanged when haematocrit increased from 25.0 +/- 2.2% to 36.5 +/- 3.5%. Spontaneous whole blood platelet aggregation was significantly increased from week twelve (pre-treatment aggregation 46 +/- 23%; 12 weeks: 67 +/- 19%, p less than 0.05; 16 weeks: 64 +/- 19%, p less than 0.01; 20 weeks: 71 +/- 16%, p less than 0.01; 24 weeks: 73 +/- 10%, p less than 0.01). CONCLUSIONS: The increase in haematocrit and platelet aggregation associated with erythropoietin treatment did not affect peritoneal clearances or ultrafiltration capacity.     

Peritoneal fluid transport in CAPD patients with different transport rates of small solutes.

BACKGROUND: Continuous ambulatory peritoneal dialysis (CAPD) patients with high peritoneal solute transport rate often have inadequate peritoneal fluid transport. It is not known whether this inadequate fluid transport is due solely to a too rapid fall of osmotic pressure, or if the decreased effectiveness of fluid transport is also a contributing factor. OBJECTIVE: To analyze fluid transport parameters and the effectiveness of dialysis fluid osmotic pressure in the induction of fluid flow in CAPD patients with different small solute transport rates. PATIENTS: 44 CAPD patients were placed in low (n = 6), low-average (n = 13), high-average (n = 19), and high (n = 6) transport groups according to a modified peritoneal equilibration test (PET). METHODS: The study involved a 6-hour peritoneal dialysis dwell with 2 L 3.86% glucose dialysis fluid for each patient. Radioisotopically labeled serum albumin was added as a volume marker.The fluid transport parameters (osmotic conductance and fluid absorption rate) were estimated using three mathematical models of fluid transport: (1) Pyle model (model P), which describes ultrafiltration rate as an exponential function of time; (2) model OS, which is based on the linear relationship of ultrafiltration rate and overall osmolality gradient between dialysis fluid and blood; and (3) model G, which is based on the linear relationship between ultrafiltration rate and glucose concentration gradient between dialysis fluid and blood. Diffusive mass transport coefficients (K(BD)) for glucose, urea, creatinine, potassium, and sodium were estimated using the modified Babb-Randerson-Farrell model. RESULTS: The high transport group had significantly lower dialysate volume and glucose and osmolality gradients between dialysate and blood, but significantly higher K(BD) for small solutes compared with the other transport groups. Osmotic conductance, fluid absorption rate, and initial ultrafiltration rate did not differ among the transport groups for model OS and model P. Model G yielded unrealistic values of fluid transport parameters that differed from those estimated by models OS and P. The K(BD) values for small solutes were significantly different among the groups, and did not correlate with fluid transport parameters for model OS. CONCLUSION: The difference in fluid transport between the different transport groups was due only to the differences in the rate of disappearance of the overall osmotic pressure of the dialysate, which was a combined result of the transport rate of glucose and other small solutes. Although the glucose gradient is the major factor influencing ultrafiltration rate, other solutes, such as urea, are also of importance. The counteractive effect of plasma small solutes on transcapillary ultrafiltration was found to be especially notable in low transport patients. Thus, glucose gradient alone should not be considered the only force that shapes the ultrafiltration profile during peritoneal dialysis. We did not find any correlations between diffusive mass transport coefficients for small solutes and fluid transport parameters such as osmotic conductance or fluid and volume marker absorption. We may thus conclude that the pathway(s) for fluid transport appears to be partly independent from the pathway(s) for small solute transport, which supports the hypothesis of different pore types for fluid and solute transport.     

Impact of fill volume on peritoneal clearances and cytokine appearance in peritoneal dialysis.

BACKGROUND: Current adequacy guidelines for peritoneal dialysis encourage the use of large fill volumes for the attainment of small solute clearance targets. These guidelines have influenced clinical practice in a significant way, and adoption of higher fill volumes has become common in North America. Several studies, however, have challenged the relevance of increasing small solute clearance; this practice may result in untoward consequences in patients. OBJECTIVE: The present study was designed to explore the relationship between dialysate volume and the clearance of different sized molecules, fluid dynamics, and appearance of peritoneal cytokines. METHODS: Thirteen adult prevalent patients on continuous ambulatory peritoneal dialysis were studied. Three different dialysate volumes (2.0, 2.5, and 3.0 L) were infused on consecutive days in a random order. Several measurements of peritoneal fluid dynamics (intraperitoneal pressure, net ultrafiltration, fluid absorption), solute clearances (urea, creatinine, beta2-microglobulin, albumin, IgG, and transferrin), and appearance of interleukin-6 and tumor necrosis factor alpha (TNFalpha) were assessed. RESULTS: Increase in dialysate fill volume (from 2 to 2.5 to 3 L) was examined in relationship to body surface area (BSA). The dialysate volume/BSA (DV/BSA) ratio increased from 1262 to 1566 to 1871 mL/m2 on 2.0, 2.5, and 3.0 L dialysate volumes, respectively. In parallel, diastolic blood pressure increased from 82.7 +/- 8.8 to 87.0 +/- 9.5 to 92 +/- 8.3 mmHg (p < 0.05). Net ultrafiltration rate also increased, from 0.46 +/- 0.48 to 0.72 +/- 0.42 to 0.97 +/- 0.49 mL/minute (p < 0.01), despite a concomitant increase in fluid absorption, from 1.05 +/- 0.34 to 1.21 +/- 0.40 to 1.56 +/- 0.22 mL/min (p < 0.01). Urea peritoneal clearance increased from 8.27 +/- 0.68 to 9.92 +/- 1.6 to 12.98 +/- 4.03 mL/min (p < 0.01); creatinine peritoneal clearance increased from 6.69 +/- 1.01 to 7.64 +/- 1.12 to 8.69 +/- 1.76 mL/min (p < 0.01). Clearance of the other measured molecules did not change. Appearance of interleukin-6 increased 17% and 43% (p < 0.01), and TNFalpha appearance increased 14% and 50% (p < 0.01) when dialysate volumes of 2.5 and 3.0 L were used, compared with 2.0 L. CONCLUSIONS: These results show that, with higher values of DV/BSA ratio, small solute peritoneal clearance is increased, but clearances of large molecules remain unchanged. With the use of higher volumes, fluid absorption rate and the appearance of proinflammatory cytokines in the dialysate are increased.     

不同超滤功能的持续不卧床腹膜透析患者腹膜液体转运功能评估

目的 容量控制对于腹膜透析至关重要.腹膜平衡实验(peritoneal equilibration test,PET)可以评估腹膜小分子溶质转动功能,对优化腹膜透析存腹时间提供依据,但是不能预测腹膜液体转运功能.所以,本研究使用计算机拟合对不同超滤功能腹膜透析患者的腹膜液体转运功能进行评估.方法 纳入研究患者包括每天使用3～4袋2.5％葡萄糖透析液者(为腹膜超滤功能差组)和使用3～4袋1.5％葡萄糖透析液者(为腹膜功能好组),两组患者在上述透析处方下都能达到足够的液体清除.所有入组的患者都要求详细记录自己每天的腹膜透析换液情况,以评估腹膜液体转运功能.结果 本研究包括了17名持续不卧床腹膜透析患者(continuous ambulatory peritoneal dialysis,CAPD),其中9名为超滤功能差组,8名为超滤功能好组.与超滤功能好组相比,超滤功能差组的患者每天更多的处于高葡萄糖(P＜0.01)环境中,透析液/血浆肌酐比值(D/Pcre)更高(P＜0.05),有更高的腹膜液体吸收率(Ke)(P＜0.01). 结论 与超滤功能好的患者相比超滤功能差的患者的腹膜小分子溶质转运率更高,更为重要的是,超滤能力差的患者腹膜液体吸收率更高.     

Fluid and solute transport using different sodium concentrations in peritoneal dialysis solutions.

BACKGROUND: Fluid and sodium balance is important for the success of long-term peritoneal dialysis. Convective transport is the major determinant for sodium removal during peritoneal dialysis using conventional dialysis solutions. However, recent studies showed that lower sodium concentration in dialysate could significantly increase sodium removal by increasing the diffusion gradient, thereby increasing diffusive transport. In the present study, we investigated the influence of the sodium concentration gradient on the diffusive transport coefficient, K(BD) for sodium. METHODS: A 4-hour dwell study was done in Sprague-Dawley rats using 25 mL 5% glucose (NS), 5% glucose + 0.3% NaCl (LS), 5% glucose + 0.6% NaCl (MS), or 5% glucose + 0.9% NaCl (HS), with frequent dialysate and blood sampling. Radiolabeled human albumin (RISA) was added to the solution as an intraperitoneal volume marker. The peritoneal fluid and sodium transport characteristics were evaluated. RESULTS: Significant ultrafiltration (both net ultrafiltration and transcapillary ultrafiltration) was observed in each group despite the osmolality of the 5% glucose solution being slightly lower than the plasma osmolality. There was no difference in peritoneal fluid absorption rate and direct lymphatic absorption among the four groups. With the sieving coefficient for sodium set to 0.55, a significantly higher K(BD) for sodium was found in the NS compared to the HS group. The K(BD) for sodium was 0.21+/-0.01, 0.20+/-0.01, 0.17+/-0.01, and 0.09+/-0.01 mL/min for the NS, LS, MS, and HS groups, respectively. The K(BD) values for glucose were significantly lower in the NS and LS groups compared to the MS and HS groups. CONCLUSIONS: Our results suggest that (1) sodium concentration may affect peritoneal sodium K(BD)--as the sodium concentration gradient increased, the K(BD) decreased; (2) 5% glucose solution could induce significant peritoneal ultrafiltration in normal rats despite its initial hypo-osmotic nature, this was due to the significantly lower glucose transport rate than sodium transport rate; and (3) a lower dialysate sodium concentration may decrease peritoneal glucose absorption.     

Moxalactam kinetics during continuous ambulatory peritoneal dialysis after intraperitoneal administration.

Moxalactam kinetics during continuous ambulatory peritoneal dialysis (CAPD) was followed in eight patients after a single intraperitoneal dose of 1 g. Approximately 60% of the dose was absorbed after a dwell time of 4 h. Dialysis solutions were exchanged at 4-h intervals with an overnight dwell of 8 h. The mean (+/- standard deviation) elimination half-life was 13.2 +/- 2.9 h, and the mean apparent volume of distribution was 0.22 +/- 0.08 liters/kg. Mean total clearance was 11.5 +/- 2.4 ml/min, with a mean dialysis clearance of 2.3 +/- 0.5 ml/min. The maximum concentration in plasma ranged from 24.5 to 54.1 micrograms/ml. Moxalactam concentrations in the peritoneal dialysis fluid were above 80 micrograms/ml during the first exchange and above 2 micrograms/ml for a further three exchanges. A suggested intraperitoneal dose regimen for patients undergoing CAPD is 1 g initially, followed by 15 to 25% of the recommended dose for normal patients given at the same time intervals, or 30 to 50% of the recommended dose at twice the usual intervals. Moxalactam is suggested for initial treatment of peritonitis in CAPD patients who do not have ready access to the antibiotic of choice.     

Combination of crystalloid (glucose) and colloid (icodextrin) osmotic agents markedly enhances peritoneal fluid and solute transport during the long PD dwell.

BACKGROUND: Fluid and sodium removal is often inadequate in peritoneal dialysis patients with high peritoneal solute transport rate, especially when residual renal function is declining. METHOD: We studied the effects of using simultaneous crystalloid (glucose) and colloid (icodextrin) osmotic agents on the peritoneal transport of fluid, sodium, and other solutes during 15-hour single-dwell exchanges using 3.86% glucose, 7.5% icodextrin, and a combination fluid with 2.61% glucose and 6.8% icodextrin in 7 prevalent peritoneal dialysis patients with fast peritoneal solute transport rate. RESULTS: The combination fluid enhanced net ultrafiltration (mean 990 mL) and sodium removal (mean 158 mmol) compared with 7.5% icodextrin (mean net ultrafiltration 462 mL, mean net sodium removal 49 mmol). In contrast, the 3.86% glucose-based solution yielded negligible ultrafiltration (mean -85 mL) and sodium removal (mean 16 mmol). The combination solution resulted in significantly improved urea (+41%) and creatinine (+26%) clearances compared with 7.5% icodextrin. CONCLUSION: A solution containing both crystalloid (glucose 2.61%) and colloid (icodextrin 6.8%) osmotic agents enhanced fluid removal by twofold and sodium removal by threefold compared with 7.5% icodextrin solution during a dwell of 15 hours, indicating that such a combination solution could represent a new treatment option for anuric peritoneal dialysis patients with high peritoneal solute transport rate.     

Peritoneal solute clearances after four years of continuous ambulatory peritoneal dialysis (CAPD)

In order to evaluate peritoneal membrane function and responsiveness of peritoneal microcirculation to vasoactive agents in long-term continuous ambulatory peritoneal dialysis (CAPD) patients, we studied peritoneal clearances of urea (Curea) and creatinine (Ccr), protein concentrations in drained dialysate (DPC), peritoneal glucose absorption (% GA), and drained dialysate volume (VD) before and after nitroprusside (NP) addition to dialysis solution in 17 long-term CAPD patients (mean duration of CAPD: 52 months) and the results were compared to those of 18 patients who were just trained for CAPD (mean duration: 0.6 month). There were no differences in the control (without NP) Curea, Ccr, DPC, %GA, and VD between the new and long-term CAPD patients. Curea, Ccr, and DPC increased significantly with NP in both new and long-term patients. Curea and Ccr with NP were not different between the new and long-term patients but DPC with NP was significantly lower in the long-term CAPD patients. The results of this study suggest that peritoneal solute clearances and the responsiveness of peritoneal microcirculation to NP remain unchanged after four years of CAPD, despite recurrent episodes of peritonitis.     

Phosphatidylcholine administration in continuous ambulatory peritoneal dialysis (CAPD) patients with reduced ultrafiltration

To evaluate the possible role of oral phosphatidylcholine administration in improving peritoneal ultrafiltration sixteen continuous ambulatory peritoneal dialysis (CAPD) patients with a reduced ultrafiltration rate (less than 500 mL/4 h after a standard 3.86% glucose exchange) were studied. Three patients spontaneously stopped phosphatidylcholine due to gastric side effects. Three out of the remaining 13 patients showed a mild increase of standard ultrafiltration, which was not followed by any increase in daily dialysate output. No differences in glucose, sodium, potassium, urea and creatinine equilibration curves were seen. In conclusion, in our series oral phosphatidylcholine is not free of side effects, and its efficacy in improving ultrafiltration is scanty, with no clinical relevance in increasing daily ultrafiltration.     

Peritoneal solute clearances in diabetics

In order to examine solute transport across the peritoneal membrane and responsiveness of the peritoneal microcirculation to a vasodilator in diabetics on continuous ambulatory peritoneal dialysis (CAPD), we obtained peritoneal clearances of urea (Curea) and creatinine (Ccr), protein concentrations in the drained dialysate (DPC), and percentage of peritoneal glucose absorption (% PGA) before and after nitroprusside (NP) addition to the dialysate in 13 diabetics (DM) and 13 nondiabetics (non-DM) matched for age, sex, body weight, and duration of CAPD. Control (before NP) Curea, Ccr, DPC, and %PGA were not different between DM and non-DM. NP significantly enhanced Curea, Ccr, and DPC in both DM and non-DM. Curea, Ccr, DPC, and %PGA after NP were again not different between DM and non-DM. The findings suggest that peritoneal solute clearances and responsiveness of the peritoneal microcirculation to NP in diabetics are not different from nondiabetics at the beginning of CAPD despite evidence for widespread vascular diseases in diabetic ESRD patients.     

Peritoneal transport characteristics with glycerol-based dialysate in peritoneal dialysis.

BACKGROUND: Glycerol is a low molecular weight solute (MW 92 D) that can be used as an osmotic agent in continuous ambulatory peritoneal dialysis (CAPD). Due to its low molecular weight, the osmotic gradient disappears rapidly. Despite the higher osmolality at the beginning of a dwell, ultrafiltration has been found to be lower for glycerol compared to glucose (MW 180 D) when equimolar concentrations are used. Previous studies have shown glycerol to be safe for long-term use, but some discrepancies have been reported in small solute transport and protein loss. OBJECTIVE: To assess permeability characteristics for a 1.4% glycerol dialysis solution compared to 1.36% glucose. DESIGN: Two standardized peritoneal permeability analyses (SPA), one using 1.4% glycerol and the other using 1.36% glucose, in random order, were performed within a span of 2 weeks in 10 stable CAPD patients. The length of the study dwell was 4 hours. Fluid kinetics and solute transport were calculated and signs of cell damage were compared for the two solutions. SETTING: Peritoneal dialysis unit in the Academic Medical Center, Amsterdam. RESULTS: Median values for the 1.4% glycerol SPA were as follows: net ultrafiltration 251 mL, which was higher than that for 1.36% glucose (12 mL, p < 0.01); transcapillary ultrafiltration rate 2.12 mL/min, which was higher than that for glucose (1.52 mL/min, p = 0.01); and effective lymphatic absorption rate 1.01 mL/min, which was not different from the glucose-based solution. Calculation of peritoneal reflection coefficients for glycerol and glucose showed lower values for glycerol compared to glucose (0.03 vs 0.04, calculated with both the convection and the diffusion models). A marked dip in dialysate-to-plasma ratio for sodium was seen in the 1.4% glycerol exchange, suggesting uncoupled water transport through water channels. Mass transfer area coefficients for urea, creatinine, and urate were similar for both solutions. Also, clearances of the macromolecules beta2-microglobulin, albumin, IgG, and alpha2-macroglobulin were not different for the two osmotic agents. The median absorption was higher for glycerol, 71% compared to 49% for glucose (p < 0.01), as could be expected from the lower molecular weight. The use of a 1.4% glycerol solution during a 4-hour dwell caused a small but significant median rise in plasma glycerol, from 0.22 mmol/L to 0.45 mmol/L (p = 0.02). Dialysate cancer antigen 125 and lactate dehydrogenase (LDH) concentrations during the dwell were not different for both solutions. CONCLUSIONS: These findings show that glycerol is an effective osmotic agent that can replace glucose in short dwells and show no acute mesothelial damage. The higher net ultrafiltration obtained with 1.4% glycerol can be explained by the higher initial net osmotic pressure gradient. This was seen especially in the first hour of the dwell. Thereafter, the osmotic gradient diminished as a result of absorption. The dip in dialysate-to-plasma ratio for sodium seen in the glycerol dwell can also be explained by this high initial osmotic pressure gradient, implying that the effect of glycerol as an osmotic agent is more dependent on intact water channels than is glucose.     

Hyaluronan preserves peritoneal membrane transport properties.

BACKGROUND: We have shown that intraperitoneal (i.p.) addition of hyaluronan (HA) in a single dwell study in rat could increase peritoneal fluid removal by decreasing the peritoneal fluid absorption rate. In this study, we investigated the impact of repeated use of HA on peritoneal membrane transport characteristics. METHODS: Twelve male Sprague-Dawley rats received a once-daily i.p. injection of 25 mL 4.25% glucose dialysis solution without (HP group, n = 6) or with 0.025% HA (HA group, n = 6) for 1 week. Forty-eight hours after the last injection, a 4-hour dwell using 25 mL 4.25% glucose dialysis solution with i.p. volume marker and frequent dialysate and blood samplings was performed in each rat as well as in rats that did not receive any injection (control group, n = 8). RESULTS: Although the i.p. volumes were significantly lower in the HP and HA groups compared to the control group, i.p. volume in the HA group was significantly higher than in the HP group. Net ultrafiltration at 4 hours was 5.6 +/- 1.3 mL, 10.2 +/- 1.8 mL, and 13.2 +/- 0.6 mL for the HP, HA, and control group, respectively. The peritoneal fluid absorption rate decreased by 45% in the HA group compared to the HP group. There was no significant difference in peritoneal fluid absorption rate between the HA and the control group. No difference was found in the direct lymphatic absorption rate between the HP and HA groups [0.010 +/- 0.003 mL/minute in the HP group and 0.011 +/- 0.004 mL/min in the HA group] although they were both higher than that of the control group (0.004 +/- 0.001 mL/min).The solute transport rates were in general significantly higher in the HP group compared to the HA and control groups, and there was no significant difference between the latter two groups, except that protein transport rate was significantly lower in the HA group compared to the control group. CONCLUSIONS: The present study suggests that (1) repeated exposure to hypertonic glucose-based dialysis solution results in increased peritoneal solute transport rates, as well as increased peritoneal fluid absorption rates; and (2) these changes, reflecting a highly permeable peritoneal membrane, were ameliorated by repeated i.p. addition of hyaluronan. The similar changes in the direct lymphatic absorption rate in rats that received daily i.p. injection of dialysis solution suggest that direct peritoneal lymphatic absorption was not influenced by hyaluronan.     

Amino-acid-based continuous ambulatory peritoneal dialysis (CAPD) fluid over twelve weeks: effects on carbohydrate and lipid metabolism

Aspects of lipid and carbohydrate metabolism were studied in 8 patients established on continuous ambulatory peritoneal dialysis (CAPD) with plasma albumin less than 35 g/L, before, during, and after substitution of 1 of the daily glucose exchanges by a commercial 1% amino acid dialysis fluid for 12 weeks. The amount of glucose absorbed from the dialysis fluid was consequently reduced by about 25%, hence total energy intake decreased by about 100 Kcal/day, but peritoneal glucose transfer kinetics were unaffected. Glucose was lost into amino acid dialysate as expected (2 g/day). Excluding 1 patient with a large rise in calorie intake, total and LDL cholesterol fell at 8 and 12 weeks (LDL cholesterol week 0, 5.26 +/- 1.13; week 8, 4.32 +/- 0.74; week 12, 4.30 +/- 1.22; mean +/- SD, p less than 0.01 for both), but returned to baseline 2 weeks after the restoration of glucose fluid (LDL 4.91 +/- 1.22, p less than 0.05 vs. week 12). Apolipoprotein B concentration also fell at 12 weeks (p less than 0.01). No changes were seen in body weight, body fat, arm muscle circumference, fasting plasma glucose, insulin, growth hormone, triglyceride, nonesterified fatty acids, or HDL cholesterol. The response of these biochemical indices to single 8-h glucose and amino acid morning exchanges at 0 and 12 weeks were studied. After 12 week's use of amino acid dialysis fluid, plasma cholesterol and apolipoprotein B were significantly lower throughout the exchange.(ABSTRACT TRUNCATED AT 250 WORDS)     

The disappearance of macromolecules from the peritoneal cavity during continuous ambulatory peritoneal dialysis (CAPD) is not dependent on molecular size.

The transport of macromolecules from the circulation to the peritoneal cavity is a size-selective restricted process, while the transport of these solutes from the peritoneal cavity is probably mainly by lymphatic absorption. If so, it should be independent of molecular size. Therefore, we studied with a clearance technique the disappearance of intraperitoneally administered inulin and polydisperse dextran 70 in nine continuous ambulatory peritoneal dialysis (CAPD) patients and compared the results with the simultaneously measured appearance clearance of serum proteins. Using gel permeation chromatography 18 dextran fractions with different molecular radii could be analyzed. Inulin clearance (2.94 mL/min) was higher than total dextran clearance (1.30 mL/min). The maximal dextran concentration in all dialysate samples was found in the 50.4 A fraction. The clearances of the dextran fractions were the same of different molecular sizes. All disappearance clearances were higher than the appearance clearances: the protein/dextran clearance ratio ranged from 0.15 for albumin/36 A to 0.04 for alpha 2-macroglobulin/91 A. This confirms that the appearance of a macromolecule, but not its disappearance is dependent on molecular size. It is concluded that the disappearance of macromolecules from the peritoneal cavity is mainly a size independent convective process, possibly by lymphatic uptake. This implies that total dextran 70 clearance can be used for measurement of lymphatic absorption in CAPD patients.     

ASPD: A prospective study of adequacy in Asian patients on long term, small volume, continuous ambulatory peritoneal dialysis.

BACKGROUND: The impact of small solute clearance on patient survival in continuous ambulatory peritoneal dialysis (CAPD) is not yet solidified. Previously, we demonstrated that CAPD using small volume (6 L) daily exchanges provides adequate dialysis for most Asian patients. METHODS: We conducted a prospective, long-term observational study to determine the optimal dialysis adequacy that may provide better patient survival for Asian patients who receive small-volume CAPD. We recruited 294 patients. The initial CAPD regime was 3 x 2-L exchanges daily. The same regime was maintained unless there was significant loss of ultrafiltration or fluid retention despite the use of hypertonic dialysate. RESULTS: Median study period was 38.9 (range 5 - 76.5) months, with 81% and 27% of patients remaining in the study at 24 and 48 months respectively. The overall survival rates at 2 and 4 years were 94.0% and 74.8% respectively. Our long-term data revealed that survival rate was related to Kt/V values. Survival rates were significantly higher for patients with total Kt/V > 2.0 than for patients with Kt/V < 1.7 (p = 0.02). The former group had lower body mass index and higher residual renal function and peritoneal Kt/V than the Latter group. On analysis using Cox proportional hazards regression models, cardiovascular disease (CVD), lower urine volume, and higher body mass index were independent predictors of mortality. Patients with higher renal Kt/V had a significantly lower risk of mortality (RR = 0.018, p = 0.01) after adjusting for the effects of CVD and diabetes mellitus. CONCLUSION: Our data recommend that 1.7 be the minimal target for total Kt/V in patients on long-term CAPD. Patients with high body mass index, low residual urine volume, and significant CVD need close monitoring.     

Pharmacologic modification of transperitoneal movement of water

Investigations concerning the influence of pharmacologic agents on transperitoneal water movement are predominantly undertaken in the hope that their results can help in a restoration of net ultrafiltration (UF) volume toward normal in cases with declining UF during long-term dialysis treatment. Net UF volume represents the difference between net transcapillary UF and lymphatic absorption. The choice of a pharmacological agent for enhancing UF depends on the mechanisms responsible for net UF loss, which include: (a) early dissipation of the transperitoneal osmotic gradient; (b) decrease in the peritoneal surface area; (c) lymphomonokine overproduction; (d) enhanced lymphatic absorption; (e) high residual volumes left in the peritoneal cavity; or (f) a combination of these factors. Leakage of dialysate to the abdominal wall sometimes occurring in peritoneally dialysed patients (1), according to a definition of net UF volume, cannot be regarded as a true UF loss.     

Indirect measurement of lymphatic absorption with inulin in continuous ambulatory peritoneal dialysis (CAPD) patients

To elucidate the importance of possible trapping of macromolecules in peritoneal tissue on the calculation of peritoneal lymphatic drainage, we compared the transport of inulin administered i.v. and i.p. in nine continuous ambulatory peritoneal dialysis (CAPD) patients on two separate days. In the intraperitoneal study inulin (5 g) was added to the dialysate and in the intravenous study inulin (5 g) was given i.v. 3 h before the test. No differences were found in the mass transfer area coefficients (MTC) of urea, creatinine, and glucose between the two tests. The MTC after inulin i.p. was 3.2 +/- 0.7 mL/min (mean +/- SD) and after inulin i.v. 1.8 +/- 0.5 (p less than 10(-5]. As the difference in transport kinetics between i.v. and i.p. administration is likely to be caused by lymphatic absorption, a mean lymphatic flow of 1.4 mL/min could be calculated. This value corresponds to the data obtained with macromolecules. Our results therefore favor the hypothesis that no local accumulation of macromolecules in the peritoneal tissues takes place and that their disappearance from the peritoneal cavity represents lymphatic absorption.