Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Ultrafiltration”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources
PubMed2006

Analysis of fluid transport pathways and their determinants in peritoneal dialysis patients with ultrafiltration failure.

Ultrafiltration failure (UFF) is a serious complication of peritoneal dialysis (PD). The aim of the study was to analyze changes in water transport and their determinants in UFF patients over the time on PD. Standard peritoneal permeability analyses of 50 stable PD patients with UFF were analyzed. Fluid transport through small pores (SPT), free water transport (FWT) at 60 min, their contributions on total ultrafiltration (SPTC and FWTC), and their determinants were assessed. Patients were divided in Group I (UFF) treated for less than 24 months, Group II treated 24-60 months, and Group III treated for more than 60 months. Group I (UFF) was compared with Group I (non-UFF) matched for the duration of PD treatment and age. Transcapillary ultrafiltration (TCUF), SPT, FWT, and FWTC were significantly lower in Group III when compared to the other UFF groups. In this group also, negative relationship was present between FWT, the ultrafiltration coefficient LpA, and osmotic conductance to glucose on one hand and PD duration on the other. FWT was positively related to osmotic conductance to glucose in all groups. Group I (UFF) showed significantly higher solute transport, effective lymphatic absorption rate, lower TCUF, and lower FWT than Group I (non-UFF). The patterns of UFF in PD patients are dependent on the duration of treatment.

Adult↗
PubMed1998

Hyaluronan prevents the decreased net ultrafiltration caused by increased peritoneal dialysate fill volume.

In the present study, we investigated (1) the effect of an increase in dialysate fill volume on peritoneal fluid and solute transport using a 1.36% glucose solution, and (2) the effect of intraperitoneal administration of hyaluronan on peritoneal transport characteristics when different fill volumes were used. A four-hour dwell study with frequent dialysate and blood sampling was performed in 26 male Sprague-Dawley rats with 131I albumin as the intraperitoneal volume marker. Each rat was injected intraperitoneally with 25 ml (group Con25, N = 6) or 40 ml (group Con40, N = 7) of 1.36% glucose dialysis solution alone or 25 ml (group HA25, N = 6) or 40 ml (Group HA40, N = 7) of 1.36% glucose dialysis solution with 0.01% hyaluronan. The peritoneal transport of fluid, glucose, urea, and total protein as well as the intraperitoneal hydrostatic pressure (IPP) with different fill volumes were evaluated. We found that IPP and peritoneal fluid absorption rate significantly increased with the increase in fill volume (P < 0.01), and therefore the net ultrafiltration volume was significantly lower in the Con40 group compared to the Con25 group despite a higher transcapillary ultrafiltration rate in the Con40 group. The addition of hyaluronan to dialysate significantly (P < 0.01) decreased the peritoneal fluid absorption rate (by 22% in HA25 vs. Con25 and by 29% in HA40 vs. Con40) and thus significantly increased the net peritoneal fluid removal. The diffusive mass transport coefficients for glucose, urea and total protein did not differ between the Con25 and Con40 groups or between the two hyaluronan groups as compared to their respective control groups. The peritoneal clearance of urea increased significantly in the high fill volume group (by 58% in Con40 vs. Con25) and in the two hyaluronan groups (by 21% in HA25 vs. Con25 and by 16% in HA40 vs. Con40). We conclude that: (1) An increase in dialysate fill volume using 1.36% glucose dialysis solution results in higher intraperitoneal hydrostatic pressure and higher peritoneal fluid absorption rate, and therefore lower net ultrafiltration. (2) Intraperitoneal addition of hyaluronan significantly decreases the peritoneal fluid absorption rate, and the decreasing effect is even more marked when a high fill volume is used. (3) Small solute clearances increase markedly with increases in fill volume, and then further increase by adding hyaluronan to the dialysate due to the increase in drainage volume. Thus, intraperitoneal administration of hyaluronan during a single peritoneal dialysis exchange may significantly increase the peritoneal fluid and solute removal by decreasing peritoneal fluid absorption, and may thereby prevent the decreased net ultrafiltration caused by an increase in dialysate fill volume.

Animals↗
PubMed2003

Ultrafiltration volume is associated with changes in blood pressure in chronically hemodialyzed patients.

INTRODUCTION: Volume overload is a main factor in development of hypertension in hemodialysis patients. In order to demonstrate impact of ultrafiltration volume on blood pressure during 15-months period in a group of patients undergoing chronic hemodialysis therapy, we conducted this study. We hypothesized that ultrafiltration volume different affects the pre/postdialysis systolic pressure, diastolic pressure, mean arterial pressure (MAP), and pulse pressure (PP) values. SUBJECTS AND METHODS: Study subjects were 23 anuric chronically hemodialyzed patients. The overall study time was 15 months, and 136 single hemodialysis treatments were analyzed. RESULTS: Ultrafiltration was negatively correlated with predialysis systolic blood pressure (r = -0.169, p = 0.025), postdialysis systolic blood pressure (r = -0.292, p < 0.001), postdialysis MAP (r = -0.186, p = 0.015), predialysis PP (r = -0.290, p < 0.001), and postdialysis PP (r = -0.370, p < 0.001). Ultrafiltration/dry body mass (UF/W) ratio was negatively correlated with predialysis PP (r = -0.222, p = 0.005), postdialysis PP (r = -0.340, p < 0.001), and postdialysis systolic blood pressure (r = -0.243, p = 0.002). We found significant difference in postdialysis PP between dialyses with UF/W ratio < or = 0.05 an dialyses with UF/W ratio > 0.05 (63.49 +/- 20.76 vs. 56.27 +/- 16.33 mmHg, p = 0.033). CONCLUSION: The ultrafiltration volume strongly affects postdialysis PP values. Evaluation of elevated blood pressure treatment in patients undergoing chronic hemodialysis therapy must be considered in respect of postdialysis PP values, not just depending on pre/postdialysis systolic and diastolic pressur or MAP values.

Aged↗
PubMed1986

Effects of furosemide versus isolated ultrafiltration on extravascular lung water in oleic acid-induced pulmonary edema.

We studied the effects of no treatment, furosemide treatment, and isolated ultrafiltration on extravascular lung water (ETVL) in mongrel dogs in whom pulmonary edema was induced with oleic acid. In all treatment groups, ETVL was significantly elevated 90 min after oleic acid infusion. At 270 min, we found no difference between nontreatment and furosemide. There was, however, a significant difference between no treatment and ultrafiltration but not between furosemide and ultrafiltration. In spite of observations which suggest that ultrafiltration is of benefit in reducing ETVL, we could not demonstrate superiority of one therapy over another.

Animals↗
PubMed1985

Determination of free valproic acid concentrations using the Amicon Micropartition MPS-1 Ultrafiltration System.

Free valproic acid concentrations were determined using the MPS-1 ultrafiltration device marketed by Amicon with one YMB membrane per device. Valproic acid binding to the membrane was 5.6% of the free valproic acid concentration. The free valproic acid concentration increased as serial ultrafiltrate volumes were collected, suggesting that only small ultrafiltrate volumes should be collected from a large initial sample. The protein content of the ultrafiltrate was acceptable and was within the tolerances stated by Amicon. There was no significant difference between free valproic acid concentrations determined within 3 h of sample collection and those determined after storage at 4 degrees C or -20 degrees C for 1 week. There was no significant difference between free valproic acid concentrations in serum and heparinized plasma samples collected simultaneously.

Humans↗
PubMedDate not supplied

Continuous renal replacement therapy for congestive heart failure: the wearable continuous ultrafiltration system.

Ultrafiltration is effective in the treatment of fluid and sodium overload in congestive heart failure. There is no available device to provide this therapy to ambulatory patients. We built and tested in vivo a wearable belt that can provide continuous ultrafiltration, 168 hours a week. Nine pigs underwent ureteral ligation and subsequently were allowed fluids ad lib, producing fluid overload. Next day, ultrafiltration was performed for 8 hours. The device consists of a hollow-fiber filter, a 9 V battery-operated pulsatile blood pump, a micro pump for heparin infusion, and another micro pump to control ultrafiltration rate. Blood flow was 65 ml/min and the weight of the device is less than 2.5 lb. Fluid removal rate ranged from 0 to 700 ml/h and averaged 106 ml/h. Salt removed was 7.6 g. No complications were observed. The potential impact on the quality of life of these patients by reducing the shortness of breath, leg swelling, and returning their ability to enjoy salt in their food might be significant, and a reduction in morbidity could be expected. The economic impact in reducing hospital admissions and length of stay, intensive care unit utilization, and drug consumption could be significant. Further studies are needed to compare this innovative approach with traditional drug-based therapy.

Animals↗
PubMedDate not supplied

Incorporation of an in-line filter for ultrafiltration or hemodialysis to the Abiomed BVS5000 ventricular assist device.

Multiple organ system dysfunction is an associated finding in patients requiring acute ventricular assist device (VAD) support. In the setting of acute renal failure, percutaneous catheters are placed for hemodialysis and/or ultrafiltration. Incorporation of an ultrafiltration or hemodialysis system in the Abiomed BVS5000 VAD circuit is a simple maneuver that eliminates the need for an additional catheter, thereby reducing the vascular and infectious complications associated with these catheters. We recommend splicing connectors into the outflow tubing of the right VAD circuit for attachment to an ultrafiltration or hemodialysis unit. This technique is a safe, simple, and reliable method by which to perform intermittent or continuous ultrafiltration or hemodialysis.

Acute Kidney Injury↗
PubMed1985

An evaluation of ultrafiltration as treatment of diuretic-resistant oedema in nephrotic syndrome.

Plasma volume, plasma colloid osmotic pressure, creatinine clearance and sodium excretion were measured before and after ultrafiltration treatment in six patients with diuretic-resistant nephrotic syndrome. The mean total ultrafiltrate volume in two sessions on two successive days was 7460 ml, the mean ultrafiltration rate was 22.0 ml/min and the calculated plasma refilling rate was 19.9 ml/min. Plasma volume and creatinine clearance were unchanged and sodium excretion was reduced after treatment. A short-lasting drop in blood pressure was seen in 3 of the 12 treatment sessions. No other complications were noted. Ultrafiltration is a safe and useful alternative in the treatment of the few patients with massive oedema due to nephrotic syndrome not responding to conventional therapy.

Blood↗
PubMed1986

An evaluation of ultrafiltration as treatment of therapy-resistant cardiac edema.

In six patients with therapy-resistant cardiac edema, ultrafiltration on two consecutive days removed on an average 7750 ml fluid and reduced body weight by 7.3 kg. A difference between the mean ultrafiltration rate (17.4 ml/min) and the calculated plasma refilling rate (12.7 ml/min) led to a reduction in plasma volume during treatment together with an increase in plasma colloid osmotic pressure. Systemic blood pressure, heart rate and cardiac output were unchanged during ultrafiltration while systemic vascular resistance increased and pulmonary capillary wedge pressure and right atrial pressure decreased significantly. No complications were recorded during or after treatment. Ultrafiltration is a safe method of fluid removal in patients with therapy-resistant cardiac edema and can be used as preparation for cardiac catheterization or surgery.

Adult↗
PubMed1983

Binding of theophylline in human serum determined by ultrafiltration and equilibrium dialysis.

1 Binding of theophylline (80 mumol/l) was determined in serum from healthy subjects by equilibrium dialysis and by ultrafiltration, using [3H]-theophylline, at 22 degrees C and at different pH-values. pH was regulated by gassing with CO2 or by dialysing the serum against a phosphate buffer before use. 2 Binding of theophylline in serum was 34-38% determined by equilibrium dialysis and 41-45% determined by ultrafiltration at pH 7.4-7.5. The protein concentration in serum decreased by 12-16% during equilibrium dialysis and increased by 20% during ultrafiltration. The intersubject variation in binding was small. 3 Binding of theophylline in serum was pH-dependent with 25-30% bound at pH 7.0 and 58-60% bound at pH 8.1-8.3. Binding was significantly correlated to the fraction of ionized theophylline. 4 The binding of theophylline in normal human serum is about 35-40% at pH 7.4 and 22 degrees C. The difference in binding observed between equilibrium dialysis and ultrafiltration may be explained by the opposite changes in protein concentration during the experiment. 5 Control of pH is necessary to obtain physiologically relevant data on drug binding in serum.

Adolescent↗
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↗
PubMed1978

Clinical evaluation of a pre-set ultrafiltration rate controller available for single pass and hemodiafiltration systems.

Introduction of high flux-type dialyzers, such as the RP-6, makes it necessary to devise an ultrafiltration rate controller for a single pass system. For this purpose, a new pre-set ultrafiltration rate controller has been developed and examined experimentally and clinically. The controller has twin chambers, each of which is divided into two symmetrical parts by a vertically-placed diaphragm. The diaphragm shifts repeatedly from right to left, aspirating in and driving out fresh or used dialysate alternately. If one removes a certain amount of used dialysate from a branch of the efferent line, negative pressure develops and aspirates an equal amount of water from the dialyzer. Therefore, extra dialysate obtained by a pump precisely reflects ultrafiltration rate. The controller has been used on five patients. The scheduled ultrafiltration rate was easily obtainable. The apparatus is also available for hemodiafiltration. Initial clinical trial has been promising.

Body Fluids↗
PubMed1991

Net ultrafiltration may not eliminate backfiltration during hemodialysis with highly permeable membranes.

Backfiltration of dialysis solution can occur during hemodialysis with highly permeable membranes. A method has recently been developed for determining backfiltration rates in vitro at low dialysate flow rates by measuring changes in the local dialysate concentration of a marker macromolecule via sampling ports added to the hemodialyzer housing. In the present study, the influence of net ultrafiltration on backfiltration rates was determined for five commercial dialyzers containing membranes with different water permeabilities. In vitro experiments were performed (n = 3) using freshly donated whole blood at blood flow rates of 200 and 340 ml/min and at a dialysate flow rate of 100 ml/min. At zero net ultrafiltration, backfiltration rates increased with increasing membrane water permeability and ranged from 0.9 to 6.9 ml/min. At a net ultrafiltration rate of 10 ml/min, backfiltration was eliminated for dialyzers containing membranes with water permeabilities of less than 30 ml/h/mm Hg but remained significant for dialyzers with higher membrane water permeabilities. Therefore, despite a significant net ultrafiltration rate, backfiltration may still occur during hemodialysis with highly permeable membranes.

Fluorescein-5-isothiocyanate↗
PubMed1994

Impact of ultrafiltration on back-diffusion in hemodialyzer.

Ultrafiltration of water from blood to dialysate decreases the rate of back-diffusion of solutes from dialysate to blood. Therefore, back-clearance (bK) of hemodialyzers may be expressed as bK = bK0--bTrQu, where bK0 is the diffusive back-clearance, bTr is the "back-"transmittance coefficient, and Qu is the net ultrafiltration rate. A formula for bK was derived from the one-dimensional theory of hemodialyzer, and bTr was described as a function of bK0 and the Staverman reflection coefficient. The transport parameters, bK0 and bTr, for creatinine and vitamin B12 were measured in two types of hemodialyzers with negligible back-filtration, using water solutions, and compared with the transport parameters, K0 and Tr, for the case of both diffusion and ultrafiltration from blood to dialysate. bK0 was in general equal to K0. bTr was not different from Tr for creatinine whereas bTr was lower than Tr for vitamin B12. Experimental values of bTr for vitamin B12 were in general agreement with theoretical predictions. However, experimental values of bTr for creatinine were lower than predicted values. We conclude that the impact of ultrafiltration on back-clearance for slowly diffusing solutes is weaker than on their clearance.

Algorithms↗
PubMed1986

Ultrafiltration in the management of refractory congestive heart failure.

Ultrafiltration was performed in nine patients with congestive cardiac failure that was refractory to conventional medical treatment. A mean of 12 X 7 litres of fluid was removed, and there was a sustained symptomatic improvement in all patients. Weight loss continued after ultrafiltration and a sustained increase in serum sodium concentration was also noted. A transient fall in right atrial pressure was seen only at four hours after ultrafiltration. No adverse haemodynamic effects were seen four and eighteen hours after fluid removal. Intracardiac dimensions measured by echocardiography remained unchanged. Ultrafiltration can be used to relieve symptoms in patients with refractory congestive heart failure and gross oedema.

Blood Pressure↗
PubMed2001

Increase in blood volume during dialysis without ultrafiltration.

Combined dialysis and ultrafiltration leads to more frequent episodes of hypotension than isolated ultrafiltration. It has been suggested that decreased plasma volume preservation could be responsible for this phenomenon. The present study evaluates the effects of diffusive dialysis on the changes in relative blood volume (RBV). Six stable hemodialysis patients, without the need of ultrafiltration, were studied during 10 sessions of diffusive dialysis (bicarbonate) lasting 4 h. RBV was monitored continuously by measurement of hematocrit. During the 1st and 2nd h RBV increased by 2.4+/-1.4 and 2.5+/-0.8% respectively, returning to baseline levels at the end of dialysis. No changes in blood pressure or heart rate were noted. We conclude that during diffusive dialysis without ultrafiltration RBV is increased. A decrease in vascular resistance, or changes in regional blood distribution could explain these findings.

Adult↗
PubMed2006

Is there a competition between urine volume and peritoneal ultrafiltration in peritoneal dialysis patients?

Many peritoneal dialysis patients are overhydrated. Overhydration may lead to hypertension and left ventricular hypertrophy, and may be related to inflammation and malnutrition. The presence of overhydration is not always detected by clinical examination. Especially patients with peritoneal ultrafiltration failure and/or negligible residual renal function are prone to overhydration. Treatment consists of a combination of sodium and fluid restriction, in combination with increased peritoneal ultrafiltration and loop diuretics in patients with residual diuresis. Peritoneal ultrafiltration can be enhanced by the use of hypertonic glucose solutions or icodextrin. In some, but not all, studies, residual renal function or diuresis declined with an increase in peritoneal ultrafiltration. At least in a subset of patients, underhydration might have played a role in this phenomenon. We propose to treat overhydration using both clinical criteria and objective techniques such as vena cava echography or bioimpedance measurements.

Body Water↗
PubMed1991

Effect of high hematocrit and high blood flow rates on transmembrane pressure and ultrafiltration rate in hemodialysis.

Removal of prescribed ultrafiltration volumes in hemodialysis requires knowledge of both the ultrafiltration coefficient of the dialyzer and the average transmembrane pressure (TMP) in the dialyzer. While it has been a fairly common practice to assume that the TMP is constant along the length of the dialyzer, it actually decreases linearly from a maximum value at the blood inlet to a minimum value at the blood outlet. In the past, ignoring the difference between arterial and venous TMPs when calculating the dialysate pressure setting did not result in significant errors in ultrafiltration volume. However, with the introduction of erythropoietin therapy and the trend toward high-efficiency dialysis, increases in hematocrit and blood flow rate have led to axial variations in TMP which, if ignored, can lead to inaccurate fluid removal. The goals of this paper are to provide an understanding of how high hematocrits and high blood flow rates affect TMP and ultrafiltration rate, and to provide simple guidelines for ensuring accurate fluid removal. Sample calculations are given on the last page for easy reference.

Blood Flow Velocity↗