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PubMed1980

Hemodynamic changes induced by regular hemodialysis and sequential ultrafiltration hemodialysis: A comparative study.

The effects of a mean ultrafiltration of 2000 ml on hemodynamics during regular hemodialysis (RD) and during sequential ultrafiltration hemodialysis (SUH) have been compared in ten patients on maintenance dialysis. Each patient was submitted to two dialysis sessions at 2 days' interval. The hemodynamic studies were performed with a thermistor Swan-Ganz catheter. The control values of mean systemic arterial pressure, cardiac output, and heart rate were similar with either RD or SUH. During ultrafiltration without diffusion, there was an immediate prolonged and significant decrease in cardiac and stroke indexes and in pulmonary wedge pressure. The mean systemic arterial pressure remained unchanged as long as the total vascular resistance was significantly increased. During the diffusion period of SUH, total vascular resistance decreased, and seven patients became hypotensive. When ultrafiltration was associated with diffusion during RD, the total vascular resistance remained stable, despite a decrease in cardiac index. This was found to result in severe hypotensive episodes, despite a moderate ultrafiltration. These results suggest that diffusion can induce arterial vasodilation and poor hemodynamic adaptation to ultrafiltration-induced hypovolemia SUH, undertaken under careful medical control, appears to be an excellent procedure to deplete severely overhydrated dialyzed patients, but it should not be used routinely as a substitute for RD.

Adult↗
PubMed1981

An hypothesis to explain the ultrafiltration characteristics of peritoneal dialysis.

We present an hypothesis that could account for many characteristics of ultrafiltration and solute movement during peritoneal dialysis. The hypothesis describes transcapillary ultrafiltration and can account for (1) the osmotic effectiveness of rapidly absorbed glucose, (2) small solute sieving in a system permitting protein loss, (3) functional estimates of effective pore sizes as low as 11 A for urea and as high as 62 A for proteins from hydrodynamic analyses, (4) isolated loss of ultrafiltration without loss of clearance, (5) decreased ultrafiltration with decreased clearances, and (6) increased ultrafiltration with decreased clearances. Mechanisms for fluid movement from the peritoneal interstitium into the peritoneal cavity may involve both hydrostatic and osmotic pressure. Interstitial water pathway dimensions, interstitial gel surface charges, mesothelial cell surface charges, and transmesothelial-cell water movement might also account for sieving effects during peritoneal ultrafiltration.

Animals↗
PubMed2000

Use of ultrafiltration and chromatography to assess aluminum speciation in serum after deferoxamine administration.

Deferoxamine effectively chelates aluminum by forming aluminoxamine, a low-molecular-weight compound removable by dialysis. However, aluminum-bound species other than aluminoxamine might be present in serum after the administration of deferoxamine. To study aluminum speciation after the administration of deferoxamine, high-performance liquid chromatography (HPLC) and ultrafiltration techniques were used. Samples of serum were obtained from six dialysis patients 44 hours after the administration of a single dose of deferoxamine. HPLC and ultrafiltration studies were performed. In the HPLC studies, samples underwent ultrafiltration, the filtrate was injected into the chromatographic system, and detection was performed by UV light and atomic absorption spectrometry. Unknown species of aluminum other than aluminoxamine were found in the early elution fractions. In the ultrafiltration studies, the same samples of serum from the six patients underwent ultrafiltration using membranes with different molecular-weight cutoff values from 1 to 30 kd. The percentages of aluminum found by ultrafiltration using membranes with cutoff values of 5, 10, and 30 kd were greater (64.4% +/- 2.5%, 63.5% +/- 3.7%, and 65.6% +/- 4.3%, respectively) than the percentages obtained with membranes with a 1-kd cutoff value (38.7%), suggesting that the unknown species of aluminum have a molecular weight between 1 and 5 kd. The unknown species of aluminum cannot be aluminoxamine because they behaved in a different way with HPLC.

Aluminum↗
PubMed2004

Compared time profiles of ultrafiltration, sodium removal, and renal function in incident CAPD and automated peritoneal dialysis patients.

BACKGROUND: Fluid and sodium removal rates may not be equivalent in patients undergoing automated peritoneal dialysis (APD) and continuous ambulatory peritoneal dialysis (CAPD). This may influence compared cardiovascular outcomes in both groups. METHODS: The authors compared prospectively the time courses of ultrafiltration, sodium removal, and residual renal function (RRF) in a group of incident patients treated with CAPD (n = 53) or APD (n = 51) for at least 1 year (mean follow-up, 28.9 months; range, 13 to 62). The authors analyzed potential effects of these factors on blood pressure (BP) control and cardiovascular morbidity and mortality. RESULTS: Ultrafiltration and sodium removal rates were consistently lower in APD patients (mean differences, 236 mL/d; P = 0.012, and 36 mmol/d; P = 0.018, respectively, end of first year). Moreover, univariate and multivariate analysis indicated that APD therapy results in a moderate, but significantly faster decline of RRF than CAPD therapy. Analysis of clinical outcomes showed that CAPD (versus APD) therapy or higher ultrafiltration or sodium removal rates were associated with a better time course of systolic, but not diastolic, BP. We were unable to identify PD modality, ultrafiltration, or sodium removal rates as independent predictors of cardiovascular morbidity and mortality. CONCLUSION: Ultrafiltration and sodium removal rates are consistently lower in incident APD patients than in their counterparts undergoing CAPD. Moreover, RRF declines faster during APD than during CAPD therapy, although this difference may be partially counteracted by a detrimental effect of ultrafiltration on RRF. Aside from a better control of systolic BP in CAPD patients, these differences do not portend significant cardiovascular consequences during the first years of PD therapy.

Age Distribution↗
PubMed1989

An analysis of ultrafiltration during acute peritoneal dialysis in rats.

Transport into and from the peritoneal cavity is effected through separate membranes. Peritoneal function is the sum of the contributions of these membranes. The peritoneal dialysis membranes are defined as intestinal viscera and mesentery, parietal lining membrane, and liver and diaphragm. The present study was undertaken to determine which of these membranes participate in ultrafiltration during peritoneal dialysis. Studies were performed in rats using a hypertonic (1200 mOsm/L) dialysate solution containing 5.6% glucose, 2.8% amino acid, and electrolytes. Both intact and eviscerated rats were studied. The experiments were repeated in animals whose diaphragms were fibrotic and densely adherent to liver. Preparation of the diaphragm did not impact upon ultrafiltration. Ultrafiltration in controls (54 vs. 56 ml with and without a fibrotic diaphragm respectively) and in eviscerated groups (44 vs. 45 ml with and without a fibrotic diaphragm respectively) were not significantly different. However, controls had significantly more ultrafiltration than did eviscerated animals (p less than 0.01). The parietal viscera accounted for 56-59% of the ultrafiltration. This study demonstrates that both the intestinal viscera and parietal walls participate in ultrafiltration.

Animals↗
PubMed1978

Theoretical aspects of various ultrafiltration methods in artificial kidney therapy.

A mathematical model including urea, creatinine and other osmotically important solutes (such as sodium, potassium and chloride) is applied to calculate volume shifts, caused by ultrafiltration, between the fluid compartments of the body. The volume shifts between the intracellular (ICV) and the extracellular (ECV) compartments are mainly caused by alteration of extracellular sodium concentration. Various methods of achieving ultrafiltration, including conventional dialysis, initial ultrafiltration using Cuprophan (without dialysis) or hemofiltration, produce different responses. In choosing a method, one must consider that both a rapid decrease of ECV and a fast shift of water from ICV to ECV should be avoided. In pure hemofiltration, ultrafiltrate is isotonic and water is removed from ECV only. Hemofiltration with dilution produces a very slow shift of water between ICV and ECV dependent on sodium concentration of plasma and diluting fluid. In initial ultrafiltration through Cuprophan, water is shifted from ICV to ECV. With ultrafiltration throughout the entire dialysis, there are pronounced shifts between ICV and ECV dependent on the difference of the sodium concentration between plasma and dialysate.

Biological Transport, Active↗
PubMed1979

Growth of human diploid cells (strain MRC-5) in defined medium; replacement of serum by a fraction of serum ultrafiltrate.

A calf serum ultrafiltrate fraction permitted growth for at least 3.5 generations, including one subculture, of MRC-5 cells in defined medium in the absence of whole serum. The active material has a molecular weight of 10 000 Daltons or less. This suggests that there may be no requirement for a large macromolecular component of serum. The ultrafiltrate was assayed by maximum cell yield from a serum-limited inoculum in a defined medium containing non-limiting amounts of vitamins, amino acids, glucose, a 68-component supplement, iron and methylcellulose. The levels of vitamins, amino acids and glucose were based on quantitative measurements of uptake and the levels of the other components by minimum amount required for maximum yield in defined medium without ultrafiltrate or serum. With excess ultrafiltrate maximum cell yield was limited by the defined part of the medium, probably the supplement. The cell doubling time in defined medium with ultrafiltrate fractions was 70 h compared with 27 h in the medium with serum. Excess ultrafiltrate did not inhibit growth. The lowered growth rate is attributed to a nutritional deficiency in the supplement.

Blood↗
PubMed1990

[Measurement of plasma free cortisol, estradiol, testosterone and prednisolone by direct radioimmunoassay of ultrafiltrate and its clinical application].

The authors aimed at developing a simplified method for the measurement of plasma free (unbound) steroids with ultrafiltration using Grace MPS device, and its clinical application. In this method, the movement of free steroids from plasma into ultrafiltrate was monitored with [14C]glucose added to the plasma. Plasma free steroids (cortisol, testosterone, estradiol and prednisolone) were measured as follows: Plasma was incubated with [14C]glucose (1.2 X 10(4) dpm/5 microliters) for 30 min at 37 degrees C. A 0.5 ml of aliquot was transferred to MPS device containing a single YMT membrane, and centrifuged at 1100 x g, at 37 degrees C, for 30 min in a 45 degree fixed angle head with the special temperature controller. After centrifugation, [14C] in 30 microliters of plasma and ultrafiltrate were counted. For the calculation of plasma free level, steroid concentration of ultrafiltrate measured directly by radioimmunoassay (RIA) was multiplied by the ratio of [14C]glucose (dpm) in plasma to [14C]glucose (dpm) in ultrafiltrate. For RIA of cortisol, testosterone and estradiol, commercially available kits were used, and for prednisolone, anti-prednisolone antibody developed in our laboratory was utilized. Since plasma free cortisol level showed a parallel increase with rise in temperature, strict temperature control during ultracentrifugation was required. On the other hand, the duration of centrifugation and the sample volume applied to MPS did not show any significant effect on the estimated values. Intraassay and interassay variations were 4.4% and 6.1% in free cortisol, 6.3% and 8.7% in free testosterone, 8.5% and 9.2% in free estradiol, and 8.8% and 9.9% in free prednisolone, respectively. The correlations between the plasma free steroid levels obtained by ultrafiltration (y) and equilibrium dialysis (x) were as follows, respectively: free cortisol; y = 1.16x + 0.017 (r = 0.95, n = 10), free testosterone; y = 1.17x-0.027 (r = 0.92, n = 10), free estradiol; y = 1.33x + 8.55 (r = 0.98, n = 12), free prednisolone; y = 1.03x + 1.00 (r = 0.98, n = 7). The mean plasma free cortisol levels and percent free fractions (%FF) were 1.16 +/- 0.40 (+/- SD) micrograms/dl and 10.9 +/- 3.0% in 10 control patients, 4.4 +/- 1.6 micrograms/dl and 15.6 +/- 3.3% in 8 patients with Cushing's syndrome, and 1.45 +/- 0.48 micrograms/dl and 5.9 +/- 2.4% in 11 normal pregnant women (10-40 weeks of pregnancy), respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Ultrafiltrate analysis confirms the specificity of the selected method for plasma ammonia determination.

The specificity of the direct enzymatic determination of plasma ammonia has hitherto not been unequivocally confirmed, because a suitable comparison method was lacking. Therefore a method variant was elaborated, which includes ultrafiltration to eliminate the high-molecular-mass components regarded as potential sources of unspecificity in the direct measurement procedure according to Rattliff, C.R. & Hall, F. F. (Select. Meth. Clin. Chem. 9, 85-90 (1982)). As the distribution of ammonia during plasma ultrafiltration is markedly influenced by pH and protein concentration, plasma pH is adjusted to 5.5 where the distribution ratio is 1 and nearly independent of actual protein concentration. Acidification significantly diminishes the spontaneous increase of ammonia in plasma at 2-4 degrees C, and the plasma ultrafiltrate is virtually stable. Taking into consideration the slow ammonia formation during sample preparation, excellent agreement was found between ammonia concentrations measured in plasma and in plasma ultrafiltrate, using samples with an apparently normal matrix (n = 30), dysproteinaemia (n = 32) or paraproteinaemia (n = 8). Our data show that the protein matrix of the sample does not cause significant unspecificity in the direct "endpoint" procedure for ammonia determination nor does it affect imprecision. In samples with added bilirubin (up to 252 mumol/l), haemolysate (haemoglobin up to 3.87 g/l) or lipid emulsion (triacylglycerol up to 3.86 mmol/l) ammonia values determined directly in plasma differed maximally by 4% from ultrafiltrate values. A simplified procedure for the ultrafiltration of plasma may be used routinely in clinical service in cases of grossly icteric, haemolytic or turbid samples.

Ammonia↗
PubMed2002

Isolated ultrafiltration affects dynamic vectorcardiographic ischemia monitoring parameters.

AIMS: The present study was undertaken to assess the role of isolated ultrafiltration (UF phase) and hemodialysis with minimal ultrafiltration (HD phase) in changes in parameters reflecting myocardial ischemia: QRS vector difference (QRS-VD), ST change vector magnitude (STC-VM) and ST vector magnitude (ST-VM6) registered by MIDA (myocardial infarction dynamic analysis). PATIENTS AND METHODS: Twelve patients on maintenance hemodialysis were first ultrafiltrated for 2.5 h without dialysis (UF) followed by a 2.5-hour session of hemodialysis with minimal ultrafiltration (HD). Computerized vectorcardiography (VCG) was used for on-line dynamic analysis of ST segment and QRS complex changes. Blood volume (BV) changes were monitored non-invasively and continuously with the CRIT-LINE instrument. Whole-body bioelectric impedance analysis (BIA) was used for extracellular water (ECW) estimation. RESULTS: During the UF phase QRS-VD and STC-VM showed a statistically significant increasing linear trend (time effect for both QRS-VD and STC-VM p < 0.0001, while no changes were noted in ST-VM6; time effect p = 0.986). During the HD phase none of these parameters changed (time effect for QRS-VD p = 0.855, for STC-VM p = 0.275 and for ST-VM6 p = 0.976). During the UF, phase changes in QRS-VD were in close relation to those in ECW. CONCLUSION: Isolated ultrafiltration leads to an increase in the VCG ischemia monitoring parameters QRS-VD and STC-VM. The increase of QRS-VD is related to changes in ECW. Hemodialysis with minimal ultrafiltration has no effect on VCG ischemia monitoring parameters.

Adult↗
PubMed1994

[Ultrafiltration failure in a peritoneal dialysis patient due to a marked increase in lymphatic absorption a case report].

A peritoneal dialysis patient was reported who had ultrafiltration loss due to a marked increase in lymphatic absorption and peritoneal membrane permeability. A 33-year-old male was transferred from hemodialysis to peritoneal dialysis because of acute subdural hematoma. His complicated history included left testicular tumor with retroperitoneal lymph node metastasis in 1982. He was treated with CDDP, Etoposide, Bleomycin, Vinblastine sulfate and Vincristine and received operation of retroperitoneal lymph node dissection in 1982. He had been on hemodialysis since 1983 due to cisplatinum nephropaty. Ultrafiltration failure was found immediately following the insertion of Tenckhoff catheter without malfunction of peritoneal catheter. Peritoneal equilibrate test and lymphatic absorption measurement showed a high permeability peritoneum with a marked increase in lymphatic absorption rate (3.7 ml/min). These two factors were thought to result in ultrafiltration loss. CAPD with 4-6 times exchange daily did not maintain ultrafiltration, because it gave approximately 2000 ml negative water balance every day. He was well maintained on a short time exchange intermittent peritoneal dialysis (IPD) with cycler using 18 L for 8 hours. We concluded that increased lymphatic absorption is one of the important factors for ultrafiltration fafilure and IPD with frequent exchange by cycler is suitable for the patient with ultrafiltration loss.

Absorption↗
PubMed1975

Binding of 63Ni (II) to ultrafiltrable constituents of rabbit serum in vivo and in vitro.

Binding of 63Ni(ll) to ultrafiltrable constituents of rabbit serum was studied (a) after in vitro incubation (2 h, 37 degrees C) of rabbit serum with 63NiCl2 (10-100 mumol/liter), and (b) at intervals (0.25-2 h) after in vivo administration of 63NiCl2(40-160 mumol/kg body wt,i.v.). Serum ultrafiltrates were fractionated by thin-layer chromatography, and the separated compounds made visible by autoradiography and by ninhydrin staining. Severel (congruent to 5) ultrafilitrable 63Ni-complexes were demonstrable as distinct radiodense 63Ni-bands with chromatographic mobilities corresponding to those of ninhydrin-positive bands. Unbound 63Ni(ll) was not detected in serum ultraviltrates in either the in vitro or in vivo experiments. In sera (n equals 10) incubated in vitro with 63Ni(ll) (10 mumol/liter), the mean percentage of ultrafiltrable 63Ni was 36% (range equals 33-38) of total serum 63Ni. In contrast, in sera (n equals 10) obtained 2 h after i.v. injection of 63Ni(ii) (40 mumol/kg), the mean concentration of total serum 63Ni was 10.8 mumol/kg), the mean concentration of total serum 63Ni was 10.8 mumol/liter (ranger equals 6-14), and the mean percentage of ultrafiltrable 63Ni was 15% (range equals 9-21) of total serum 63Ni. The disparity between the percentages of ultrafiltrable 63Ni obtained in vitro and in vivo was obviated when the in vivo experiments were performed in rabbits bilaterally nephrectomized, with ligated common bile ducts. This investigation confirms the existence of several nickel receptors in serum ultrafilitrates and substantiates the role of ultrafiltrable complexes in the excretion of nickel.

Amino Acids↗
PubMed2002

[Effect of a dialysis solution with icodextrin on ultrafiltration and selected metabolic parameters in patients treated with peritoneal dialysis].

BACKGROUND: To date, peritoneal dialysis has been performed almost exclusively using dialysis solutions containing glucose as the osmotic agent. Use of these solutions is fraught with problems regarding adequate fluid removal from the body and is also associated with undesirable metabolic effects; hence the search for alternative osmotic agents. A dialysis solution with the glucose polymer icodextrin generates ultrafiltration on the principle of colloidal osmosis. The aim of the study was to establish the effect of icodextrin-base dialysis solution on the magnitude of ultrafiltration and evaluate selected metabolic parameters of patients treated by ambulatory peritoneal dialysis. METHODS AND RESULTS: A total of 9 patients whose glucose-based solution was replaced by an icodextrin-based solution during the night-time exchange were evaluated. A control group of 9 patients used glucose-solution during all exchanges. Night-time bag ultrafiltration, blood pressure, and the serum levels of lipids, insulin, leptin, maltose, and amylase were determined before icodextrin administration (time 0), at one-month intervals (time 1, 2, 3), and one month after study completion (time 4). In icodextrin-treated patients, ultrafiltration rose from 246.5 +/- 60.5 ml (mean +/- SEM) at time 0 to 593.1 +/- 87.4 ml; p < 0.01, at time 1, to 547 +/- 67 ml; p < 0.05, at time 2, and to 586.7 +/- 58.8 ml; p < 0.01, at time 3, the icodextrin administration led to a rise in maltose from 0.02 +/- 0.01 g/l at time 0 to 0.1 +/- 0.1 g/l; p < 0.01, at time 1, to 1.0 +/- 0.09 g/l; p < 0.01, at time 2, and to 1.1 +/- 0.09 g/l; p < 0.01, at time 3, with a fall to zero values at time 4 (NS). Icodextrin administration was followed by a decrease in leptinemia from 34.6 +/- 17.2 ng/ml at time 0 to 21.7 +/- 8.9 ng/ml; p < 0.05, at time 1, to 21.4 +/- 9.5 ng/ml; p < 0.05, at time 2, and to 15.9 +/- 24.1 ng/ml; p < 0.05 at time 4. Insulin and lipid levels were not affected. There was no change in the above parameters in the control group. Icodextrin-treated patients reduced their antihypertensive medication, but not statistically significantly. CONCLUSION: Icodextrin administration significantly increase ultrafiltration thus providing for effective control of hydration status without the need for high-level glucose-based dialysis solutions. The use of a glucose polymer-based dialysis solution is associated with a significant yet reversible rise in serum maltose. The decrease in leptin may signal a reduction in body weight after replacing glucose in dialysis solutions with icodextrin, or enhanced rates of leptin elimination as a result of ultrafiltration-induced convective transport.

Adult↗
PubMedDate not supplied

An exploratory study of a novel peritoneal combination dialysate (1.36% glucose/7.5% icodextrin), demonstrating improved ultrafiltration compared to either component studied alone.

OBJECTIVE: Concerns regarding the impact of ultrafiltration failure on peritoneal dialysis and the effect of hypertonic glucose on the peritoneal membrane have lead to a search for alternative dialysates. Computer simulations based on the three-pore theory suggest that a combination of 1.36% glucose and 7.5% icodextrin (glucose polymer) offers an improved ultrafiltration profile. The aim of the present study was to investigate the ultrafiltration profile of this combination fluid. DESIGN: Prospective open study comparing 1.36% glucose, 3.86% glucose, 7.5% icodextrin, and the combination fluid (1.36% glucose/7.5% icodextrin). SETTING: Sheffield Kidney Institute, Northern General Hospital, Sheffield, UK. PATIENTS: 11 patients currently using peritoneal dialysis not previously exposed to icodextrin. MAIN OUTCOME MEASURE: Intraperitoneal volume was measured using a radioisotope dilution method. RESULTS: The combination fluid showed a biphasic ultrafiltration profile, with a steep initial increase in intraperitoneal volume, then a maintained plateau phase for the duration of the study dwell (7 hours). The final volume was greater than that with the 1.36% glucose dwell and the 7.5% icodextrin dwell. The fluid was well tolerated by the patients. CONCLUSIONS: These findings are in keeping with computer simulations using the three-pore model. The combination fluid offers an improved ultrafiltration profile, with a final volume similar to 3.86% glucose, while avoiding exposing the peritoneal membrane to high glucose concentrations. It may have a role as a long dwell to optimize ultrafiltration and possibly prolong peritoneal dialysis technique survival.

Adult↗
PubMedDate not supplied

Optimization of the drug solution preparation process for a production-scale crossflow ultrafiltration system.

This article describes a new approach to optimizing the drug solution preparation process for a production-scale crossflow ultrafiltration system. Equations were proposed to predict the concentration of the active ingredient and the volume of drug solution in the crossflow ultrafiltration process. These equations take into account the residual water remaining in the process line after the set-up of the ultrafiltration system, the residual drug solution remaining in the process line after ultrafiltration, and the residual Water for Injection (WFI) remaining in the process line after WFI rinsing. Because the residual water or residual drug solution varies slightly for each type of production, it was convenient to define them as preparation parameters. Using the proposed equations, testing was performed during early production in order to collect data on the crossflow ultrafiltration process, and the preparation parameters were then optimized. The concentration of the active ingredient and the weight of the drug solution (which was converted to the drug solution volume using its specific gravity) were calculated accurately with the optimized preparation parameter using the proposed equations. These results indicate that the proposed equations and method of establishing the preparation parameters are useful for a production-scale crossflow ultrafiltration system.

Algorithms↗
PubMed1991

Investigation and management of ultrafiltration failure in CAPD.

Apparent loss of peritoneal ultrafiltration capacity may occur when fluid intake is excessive, residual urine volumes decrease or the patient does not perform exchanges regularly and should be suspected if drain volumes are unchanged. True loss of ultrafiltration capacity (reduced drain volumes) is potentially reversible if due to catheter malposition, internal dialysate leakage or recent peritonitis but is usually permanent if kinetic studies indicate a sustained reduction in net transcapillary ultrafiltration or increased lymphatic drainage. Three types of irreversible ultrafiltration failure have been identified of which high peritoneal solute transport rates resulting in rapid dialysate glucose absorption (Type 1 membrane failure) is the most common. Transcapillary ultrafiltration may also be reduced due to very low peritoneal solute transport rates (Type 2 membrane failure) in patients with sclerosing peritonitis or massive peritoneal adhesions but is now rare. Ultrafiltration failure due to high lymphatic drainage (Type 3 failure) is also uncommon. Treatment strategies in patients with Type 1 failure include achieving the maximum urine output with diuretics, reducing fluid intake to the minimum tolerated by the patient, changing to short dwell exchanges (daytime ambulatory peritoneal dialysis (DAPD) or machine peritoneal dialysis overnight) and temporary hemodialysis which may lead to a spontaneous reduction in peritoneal transport rates in some patients. Patients with Type 2 and Type 3 failure require permanent transfer to hemodialysis.

Biological Transport↗
PubMed1989

Ultrafiltration and absorption characteristics of hydroxyethylstarch and dextran during long dwell peritoneal dialysis exchanges in rats.

Glucose has several disadvantages such as low pH, high osmolality and hyperglycemia. Rapid glucose absorption contributes to hyperlipidemia, obesity and ultrafiltration failure in peritoneal dialysis patients. Two commercially available plasma substitutes 10% hydroxyethylstarch (HES) and 6% dextran were studied for ultrafiltration and absorption patterns. 18 ml of each solution were instilled into the peritoneal cavity of 6 non-uremic rats. HES yielded a significantly (p less than 0.02) greater ultrafiltration after 6 h of dwell, whereas 2.3% glucose solution showed the typical ultrafiltration pattern of an easily absorbable osmotic agent. With 6% dextran ultrafiltration was markedly lower. At the end of cycle time the mean absorption rates for HES were 62.7% and 41.5% for dextran. It is concluded that HES is a potent osmotic agent due to sustained colloidal ultrafiltration. However, despite their high molecular weights both solutions were markedly absorbed probably by lymphatics. However, accumulation in tissues and undefined metabolic pathways might prove disadvantageous in patients with ESRD.

Absorption↗
PubMed1986

Clinical utility of measuring free thyroxin and free triiodothyronine in serum of critically ill patients by ultrafiltration.

Free thyroxin (FT4) measurements by ultrafiltration were compared with results obtained by equilibrium dialysis and commercial RIA methods. In a group of critically ill patients, the mean +/- 2 SD FT4 value by ultrafiltration (26.5 +/- 21.4 ng/L) was higher than in the healthy reference population (19.3 +/- 9.8 ng/L, p less than 0.0001), and correlated well with equilibrium dialysis (23.8 +/- 20 ng/L, r = 0.87). By a two-step RIA method (Clinical Assays), the FT4 value was greater in the critically ill (14.7 +/- 9.6 ng/L) than in the reference population (12.8 +/- 5 ng/L, p less than 0.001) and was also correlated with ultrafiltration results (r = 0.71). FT4 values for the ill patients were lower than for the reference population in two one-step RIA methods (Clinical Assays: 8.6 +/- 7.1 ng/L; Corning Medical: 12.7 +/- 9.4 ng/L), neither of which gave results correlated with ultrafiltration (r = 0.16 and 0.22, respectively). The concentration of free triiodothyronine (FT3), also measured by ultrafiltration, was 4.5 +/- 2.2 ng/L in healthy subjects, 12.5 +/- 14.2 ng/L in hyperthyroidism, 1.7 +/- 2.0 ng/L in hypothyroidism, 2.2 +/- 1.9 ng/L in the critically ill subjects, and 3.8 +/- 0.9 ng/L in pregnancy. Thus, FT4 and FT3 measured by ultrafiltration accurately affects assessment of the thyroid status of the patient except in critical illnesses in which FT3 values are indistinguishable from those in hypothyroidism.

Acute Disease↗