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PubMed1984

Glomerular ultrafiltration and tubular reabsorption of bovine serum albumin and derivatives with increased negative charge in the normal female Wistar rat.

Urinary clearances of bovine albumin derivatives rose with their increasing negative charge. A mathematical model has been developed to assess the relative contributions of glomerular ultrafiltration and tubular reabsorption to overall urinary protein clearance. This model indicates that the increased urinary clearance seen with negatively charged bovine albumin derivatives was due to a large reduction in the amount of protein absorbed by the proximal tubular epithelium, which swamped the effects of a small decrease in glomerular ultrafiltration. Derivatives of bovine albumin with increasing negative charge were also cleared with correspondingly greater rapidity from the blood stream.

Absorption↗
PubMed1986

Change in plasma immunoreactive atrial natriuretic peptide during sequential ultrafiltration and haemodialysis.

Plasma immunoreactive human atrial natriuretic peptide (Ir-ANP) levels were measured in eight patients with chronic renal failure who were volume-expanded and during treatment by sequential ultrafiltration and haemodialysis. One patient was studied at two separate treatment sessions. Plasma Ir-ANP levels were raised in all patients (mean +/- SE 184 +/- 44 pmol/l, n = 9) compared with healthy controls (11 +/- 1.4 pmol/l), but showed considerable inter-patient variability. Plasma Ir-ANP levels fell with fluid removal during ultrafiltration (123 +/- 30 pmol/l, n = 9, P less than 0.02) and again as fluid was removed during haemodialysis (76 +/- 20 pmol/l, n = 9, P less than 0.02). Seven patients studied 48 h later, before their next dialysis treatment, had regained weight and showed a coincident rise in circulating plasma Ir-ANP (130 +/- 33 pmol/l, n = 7). Our data would support the hypothesis that the secretion of ANP is determined by volume or by a stimulus related to volume. However, it does not exclude the possibility that a factor other than extracellular fluid volume expansion contributes to the raised plasma Ir-ANP levels in chronic renal failure.

Adult↗
PubMed1999

Sum of segmental bioimpedance analysis during ultrafiltration and hemodialysis reduces sensitivity to changes in body position.

BACKGROUND: Bioimpedance, a noninvasive technique to analyze body composition, has attracted interest in determining body hydration in hemodialysis patients. However, the so-called whole-body (wrist-to-ankle) bioimpedance analysis (WBIA) is sensitive to changes in regional fluid distribution and tends to underestimate fluid changes during ultrafiltration in hemodialysis patients. The aim of this study was to show that volume changes calculated from a new approach, that is, segmental bioimpedance analysis (SBIA), are not affected by changes in body position. METHODS: Ten male patients (age 44 +/- 8 years, target weight 70.8 +/- 10 kg) were studied during their regular hemodialysis treatment while maintaining either a sitting or a supine body position throughout the study. Extracellular volume was calculated from extracellular resistance obtained from bioimpedance data measured for a range of frequencies (5 to 500 kHz) using the Xitron BIS4000B analyzer. Wrist-to-ankle measurements were compared with segmental arm, trunk, and leg measurements. RESULTS: Changes in extracellular volume estimated from wrist-to-ankle measurements only reached 80 +/- 13% and 65 +/- 17% of the actual change in body mass during sitting and supine dialysis treatments, respectively. However, when segmental measurements were analyzed, the calculated change in extracellular volume was 101 +/- 6% and 100 +/- 3% of the actual change in body mass during the sitting and supine treatments, respectively. CONCLUSIONS: SBIA properly identifies regional fluid changes and provides an appropriate measure of fluid changes caused by ultrafiltration and hemodialysis. The volume estimation based on the sum of segmental bioimpedance measurements is independent of body position, which is a prerequisite for applications in everyday practice.

Adult↗
PubMedDate not supplied

Inflammatory response to intramuscular implantation of polyacrylonitrile ultrafiltration probes in sheep.

Polyacrylonitrile is used in the manufacture of dialysis membranes. These membranes are fundamental to the functioning of implantable probes for microdialysis and ultrafiltration sampling of tissue fluids. Although in vivo experimentation using polyacrylonitrile has been reported to cause little inflammatory response when implanted subcutaneously, such information is not available for intramuscular implantation in sheep. The procaine and benzathine salts of penicillin are formulated for intramuscular injection. These salts of penicillin or the formulation excipients may cause inflammatory reactions. Use of polyacrylonitrile probes to draw samples from sites at which these formulations have been injected may be compromised by inflammation or direct interaction between formulation excipients and the dialysis membrane. The aim of this project was to describe tissue responses to intramuscular implantation of polyacrylonitrile in the presence and absence of either procaine or procaine plus benzathine salts of penicillin G. Each of 20 normal sheep was implanted with two ultrafiltration probes, one at the site of an injection of procaine or benzathine plus procaine penicillin G. Similar injections were also made at remote intramuscular sites. After 8, 9, and 11 days of the experiment, sheep were killed and the injection and implantation site muscle were excised and prepared for histopathological examination. The implantation of the probe alone caused greater inflammatory response than the injection of procaine or procaine plus benzathine penicillin G at remote intramuscular sites. The histopathological lesions were greatest where the implantation site was coupled with the injection of either formulation of penicillin G. Polyacrylonitrile may not be a suitable dialysis membrane material for intramuscular implantation in sheep.

Acrylic Resins↗
PubMed2001

Hyaluronan and peritoneal ultrafiltration: a test of the "filter-cake" hypothesis.

Adding hyaluronan (HA) to the dialysis fluid seems to improve the efficiency of peritoneal dialysis (PD). This effect may be explained by the gradual formation of a HA "filter-cake" that decreases the tissue hydraulic conductivity. A filter cake (concentration hyperpolarization layer) can be formed when a large, slowly diffusible molecule, such as HA, is partly sieved by the pores of a membrane during the process of transmembrane ultrafiltration. The filter cake then forms at the "uphill" membrane-fluid interface, thereby increasing the resistance to fluid flow across the membrane. To test the filter-cake hypothesis, we investigated the effects of intraperitoneal (IP) HA on peritoneal small solute and water transport by administering HA either during the dwells or as incubations before PD dwells in rats. In the first set of experiments, HA, 0.01% (n = 7), 0.05% (n = 6), and 0.1% (n = 7) was given in 20 mL dialysis fluid (3.86% Dianeal). Control group was instilled with 20 mL of dialysis fluid. Evans Blue (EB) albumin was given as an intra-arterial (IA) bolus and (51)Cr-EDTA as an intravenous (IV) infusion. Plasma and dialysate were sampled up to 240 minutes to determine total peritoneal clearance (Cl), clearance from dialysate to plasma (Cl-->P) of (125)I-albumin (RISA), clearance from plasma to dialysate (Cl-->D) of EB-albumin, and mass transfer area coefficients (MTAC or permeability-surface area products, PS) of (51)Cr-EDTA and glucose. Peritoneal ultrafiltration (UF) was determined from RISA dilution. In the second set of experiments, rats were first incubated with 4 mL of phosphate-buffered saline (PBS) or PBS containing 0.1% HA for 120 minutes. Rats were then dialyzed with HA-free PD fluid, and sampling of plasma and dialysate was performed for 60 minutes. For HA concentrations exceeding 0.01%, UF volumes increased with increasing doses of HA. Small solute MTACs and initial UF were unaffected when HA was either given during the dwell or as a preincubation. Compared with control, there was a significant decrease in RISA-Cl for 0.05% HA and 0.1% HA. Also, Cl-->P decreased significantly compared with control for 0.1% HA. In conclusion, the present data clearly demonstrate that small solute MTACs and the glucose-induced osmotic water transport occurring early in the dwell are not affected by HA. Only the back-filtration of fluid from peritoneum to plasma was affected.

Animals↗
PubMed2003

The effect of modified ultrafiltration on the postoperative course in patients with congenital heart disease.

Improvements in the technology of cardiopulmonary bypass have significantly reduced morbidity following repair of congenital cardiac defects. However, the use of cardiopulmonary bypass exposes infants to extremes of hemodilution and hyperthermia, often in association with tissue ischemia. Exposure of the blood to surfaces of the bypass circuit initiates a systemic inflammatory response that may result in organ dysfunction after cardiopulmonary bypass, especially the heart, lungs, and brain. The technique of modified ultrafiltration (MUF) was introduced by Naik and colleagues at the Hospital for Sick Children in London over 10 years ago. Since that time, multiple studies have evaluated the effects of MUF on organ function and postoperative morbidity following repair of congenital heart defects. Use of MUF after cardiopulmonary bypass reverses hemodilution and decreases tissue edema resulting in improved pulmonary function with decreased duration of postoperative ventilation, improved left ventricular function, decreased postoperative bleeding, and a decrease in the incidence and duration of pleural effusions following the Fontan procedure. Despite the increasing evidence that the use of MUF reduces postoperative morbidity, many important questions remain unresolved. The mechanisms by which MUF results in these beneficial effects requires additional investigation. In addition, further studies are necessary to identify patients most likely to benefit from MUF and to define the optimal protocols for its use. In the future, prospective randomized studies incorporating recent advances in the technology of cardiopulmonary bypass will be necessary to define the optimal utilization of ultrafiltration during and after cardiopulmonary bypass.

Blood Loss, Surgical↗
PubMed2001

Cell saver, ultrafiltration and direct transfusion: comparative study of three blood processing techniques.

BACKGROUND: Intraoperative blood salvage is an important part of blood conservation efforts in cardiac surgery. The purpose of this study is to examine the effects of three different circuit blood-salvaging techniques: centrifugation, ultrafiltration and direct infusion. METHODS: Sixty patients undergoing elective coronary bypass graft procedures were randomly assigned in a prospective manner to one of the three blood-salvaging methods. RESULTS: Intra- and postoperative blood samples demonstrated increased hemoglobin values in the direct infusion group and higher platelet count in the ultrafiltration group. There were no significant differences in these results. The analysis of coagulation parameters revealed a similar prolongation of partial thromboplastin time and activated clotting time in all groups. The amount of blood loss was not significantly different between the three blood conservation methods. The effect of direct infusion method does not result in either major disturbance of coagulation parameters or in increased blood loss. CONCLUSION: In a sample of adult patients undergoing coronary artery bypass grafting, direct transfusion is, in consideration of the cost-effective factor, an appropriate approach for returning cardiopulmonary bypass circuit blood.

Adult↗
PubMedDate not supplied

[Sclerosing peritonitis without reduced ultrafiltration as complication of peritoneal dialysis].

UNLABELLED: Peritoneal dialysis (PD) is the preferred method of renal replacement therapy in childhood and adolescence while waiting for a kidney transplant. As major complication, encapsulating peritoneal sclerosis (EPS), sometimes also referred to as "sclerosing peritonitis", may develop after prolonged periods of PD and lead to severe therapeutical problems. CASE REPORT: A 20-year-old patient with a history of three unsuccessful kidney transplants due to recurrence of his focal segmental glomerulosclerosis presented after 9 years of PD with acute abdominal pain and reduced bowel movements. Infectious peritonitis was excluded, ultrafiltration with 800-1 000 ml per day with low (1,36 %) glucose dialysate was not impaired. Plain abdominal X-ray, ultrasound and CT-scan illustrated characteristic peritoneal calcifications. Diagnosis of EPS was confirmed by peritoneal biopsy. The patients was switched to hemodialysis, enteral nutrition was continued, and the follow-up (now 16 months) was uncomplicated with the exception of a sterile ascites, which was twice relieved. Diagnostic and therapeutic options are discussed. CONCLUSION: In contrast to most reports, EPS may develop with unchanged ultrafiltration after prolonged periods of PD. We recommend regular functional and imaging studies in patients at risk.

Adolescent↗
PubMedDate not supplied

Surgical implantation of ultrafiltration probes in ovine bone and muscle.

It may be desirable to collect compounds directly from sites of interest if blood concentrations do not reflect tissue levels. Ultrafiltration and microdialysis probes may be used to do this, but the hollow fibers of these probes are quite fragile. For this reason, we developed a pull-through technique that allows their implantation into the ovine quadriceps muscle and femur. The sheep is placed under anesthesia in lateral recumbency. An incision is made midway between the patella and greater trochanter directly over the lateral femur. A hand drill is used to make a 4.5-mm hole into the medullary cavity through the lateral cortex of the distal femur. A second incision is then made over the greater trochanter. The drill bit is inserted into the trochanteric fossa and a hole is drilled distally through the medullary cavity of the femur to the level of the first hole. A looped 20-gauge wire is then inserted into the femur and removed through the distal hole. Suture is attached, and the wire is withdrawn, leaving the suture in place. The suture is tied to the ultrafiltration probe tubing, allowing the probe to be carefully drawn into position. For implantation into the muscle, a 10-gauge introducer is used. The introducer is placed through the quadriceps muscle and the probe is then threaded through it. This technique has been successfully performed on 18 sheep. All sheep tolerated the procedure well. Up to 2.0 mL/day of interstitial fluid was recovered from each site. The average lifetimes of the bone and muscle probes were 35 and 40 days, respectively.

Animals↗
PubMedDate not supplied

Sample preparation by ultrafiltration for direct gas chromatographic analysis of ethylene glycol in plasma.

The application of ultrafiltration to sample preparation in the detection and quantification of ethylene glycol in plasma by gas chromatography is described. After addition of the butylene glycol internal standard and ultrafiltration, the sample is directly injected, obviating the need for further dilution. This simple, efficient method of sample preparation is also suitable for more sensitive gas chromatographic measurement of other volatiles.

Chromatography, Gas↗
PubMed1993

Analytical method for sugar chain structures involving lectins and membrane ultrafiltration.

A simple and rapid analytical method for the structural identification of sugar chains involving lectins and ultrafiltration was developed. In the procedure, a mixture of fluorogenic sugar chains is mixed with an unmodified lectin. Unbound sugar chains are removed by ultrafiltration. Qualitative differences between sugar chains from the sample and from the filtrate were determined by high performance liquid chromatography. The structures of different sugar chains could be determined from the specificity of the lectins used. Because the lectins used for the procedure were not modified, both the lectins used and sugar chains could be recovered. The method is simple and can be used for structural analysis of sugar chains.

Animals↗
PubMed1998

Disappearance of mitral and tricuspid regurgitation in haemodialysis patients after ultrafiltration.

BACKGROUND: Doppler echocardiography has recently revealed frequent occurrence of valvular (in particular mitral) regurgitation in dialysis (HD) patients. We hypothesized that this may be in part 'functional' and related to the cardiac dilatation which is also frequently present. Thus it would be possible to improve it by ultrafiltration. METHODS: Mitral and tricuspid regurgitation was detected in 21 haemodialysis patients who had cardiomegaly but no manifest cardiac failure. They were treated by intensified ultrafiltration sessions, as much as they could tolerate, while all antihypertensive drugs were stopped. Doppler echocardiograms were then repeated. RESULTS: Mitral regurgitation disappeared in 13 and tricuspid regurgitation in 14 patients, while lesser degrees of either of them persisted in seven. This was accompanied by decreases of body weight (5.4 +/- 2.7 kg) mean arterial pressure (125 +/- 15 to 95 +/- 11 mmHg), cardiothoracic index (from 0.57 to 0.47), and left atrial (28 +/- 4 to 22 +/- 3 mm/m2), left ventricular systolic (25 +/- 5 to 21 +/- 55 mm/m2) and left ventricular diastolic (31 +/- 5 to 27 +/- 5 mm/m2), and mitral annular diameters (19.4 +/- 2 to 16.6 +/- 2 mm/m2). Ejection fraction increased but remained below 50% in 11 patients. CONCLUSION: Most of the mitral and tricuspid regurgitations seen in HD patients are partly or completely functional, due to dilatation of the mitral annulus which is related to volume overload. A more aggressive approach, while discontinuing antihypertensive drugs can correct or improve many of them and also ameliorate cardiac function.

Adolescent↗
PubMed1987

Treatment of acute serum sickness by plasma ultrafiltration.

The clinical value of a scaled-down prototype of an extracorporeal plasma ultrafiltration system for the treatment of acute serum sickness in rabbits was examined. The system uses two filters: the primary separates red cells from plasma, and the secondary filter excludes high molecular weight proteins from plasma. In vitro and in vivo experiments showed that the secondary filters rejected substantially more IgM (80-90%) than IgG (10-30%) or albumin (10%) and totally rejected immune complexes (IC) prepared in vitro. Two groups of rabbits were submitted to either sham filtration with the primary filter only (n = 5), receiving back the remixed components of their blood, or to the complete ultrafiltration protocol (n = 7), with removal of high molecular weight proteins and IC. Several parameters were studied longitudinally, such as circulating IC, which appeared to rise more slowly in animals whose blood was ultrafiltered, and total proteinuria, which appeared to remain at lower levels in the same animals. Histologic examination of the kidneys, collected after killing, showed evidence of glomerular IC deposition in three of five sham-treated animals (a similar frequency to that observed in a separate group of five rabbits with acute serum sickness), while one of six treated animals had evidence of glomerular deposition of IC. These observations are tentative because of the small number of animals in each group, but are encouraging. Further studies with larger groups of animals are needed to determine whether the observed effects are reproducible and to better characterize the factors directly related to the removal of circulating IC.

Acute Disease↗
PubMed1979

A volume controlled apparatus for ultrafiltration and hemofiltration with acetate or bicarbonate solutions.

To meet a growing need, a single dialysis apparatus has been developed that can easily be employed by conventionally trained staff to perform volume programmed ultrafiltration hemodialysis, sequential ultrafiltration-hemodialysis, hemofiltration, or any combination of these with either acetate or bicarbonate based dialysate. Continued studies will be necessary to establish its full suitability for general use. However, we feel that the investigations of the various modes of dialysis therapy that this device makes so readily available show great potential for improving the treatment of ESRD.

Acetates↗
PubMedDate not supplied

Effect of ultrafiltration on priming solution with preserved blood for extracorporeal circulation in infants.

In pediatric cardiac surgery, the initial priming solutions of the extracorporeal circulation include preserved blood. In an effort to eliminate unfavorable effects of preserved blood on the circulation, the authors introduced the preserved blood to ultrafiltration (UF). Seventeen infants with congenital heart defects were included in this study. UF was performed with a polysulfone ultrafiltrator before extracorporeal circulation. The 1600 ml of fluid, consisting of saline, 5% glucose, and maltose, were added to 400 ml of preserved blood, and the same amount of fluid was removed by UF. The concentrations of potassium, NH3, and bradykinin in the priming blood decreased significantly after UF. In the UF group, water balance during extracorporeal circulation and max. Creatinine-phosphokinase levels after surgery were better than controls. These data suggest that UF is able to remove some substances and result in reduction of an unfavorable effect on the circulation.

Blood Preservation↗
PubMed1990

Isolated ultrafiltration in cardiogenic pulmonary edema.

Twenty patients (ten with mitral and/or aortic valve disease and ten with ischemic heart disease, all in the New York Heart Association class IV, aged between 18 and 74 yr, with cardiogenic pulmonary edema unresponsive to drug treatment) were treated with polysulphone membrane ultrafiltration (UF) in a veno-venous circuit. All patients had dyspnea, pulmonary rales, hypoxemia, tachycardia, hypotension, overhydration, radiologic evidence of engorged pulmonary vasculature, and Kerley-B lines. Systemic and pulmonary arterial pressures, cardiac output (by thermodilution), and intrapulmonary shunt fraction (Qsp/Qt) were determined and chest x-ray was obtained at the beginning and the end of UF. Average duration of the treatment was 150 +/- 28 min; UF volume averaged 3000 +/- 170 ml. UF reduced the Qsp/Qt by 58% from control condition, and did not significantly affect hemodynamic variables. Chest x-rays documented clearing of alveolar edema and venous congestion. These changes were associated with unequivocal clinical improvement and no mechanical ventilation was necessary to improve gas exchange. Short-term fluid subtraction did not result in undesired circulatory alternations. Because the ultrafiltrate composition is similar to plasmatic fluid, no modification in the plasma osmolarity was detected. In conclusion, UF may be considered an effective tool for the treatment of acute pulmonary edema refractory to drug therapy, as an alternative to mechanical ventilation, and as a remedy for excessive extravascular lung water.

Adult↗
PubMed1985

Rapid protein determinations on ultrafiltrates prepared for free phenytoin quantification.

Ultrafiltration techniques for the separation of bound and free ligand are dependent on minimal amounts of protein-bound drug leakage through the membrane devices. A dye-impregnated test strip protein assay (Chemstrip-9) provides a rapid, visual assessment of membrane protein leakage. The test strips are sensitive to 200 mg/L of albumin in ultrafiltrates and do not react with as much as 4 mg/L of phenytoin.

Blood Proteins↗
PubMed1985

Determination of free disopyramide plasma concentrations using ultrafiltration and enzyme multiplied immunoassay.

Disopyramide is an antiarrhythmic drug that exhibits nonlinear binding to plasma proteins. As a result, the total body clearance increases with increasing total drug plasma concentration. A rapid and sensitive method for the determination of free (unbound) disopyramide plasma concentrations is described. The procedure employs an ultrafiltration system (Centrifree), which can be used for basic drugs, along with an enzyme multiplied immunoassay system (EMIT) for the measurement of free disopyramide concentrations in plasma water filtrate. The EMIT method was adapted to permit measurement of disopyramide in plasma over a concentration range of 0.02-1.2 micrograms/ml. Plasma storage at -20 degrees C, filtration volume, or the presence of buffer and mono-N-dealkylated metabolite in plasma did not affect the binding determinations. There was no loss of drug during the filtration process. A good correspondence was found between the EMIT assay and a high performance liquid chromatography method, when applied to plasma samples obtained from a human subject who had ingested disopyramide. Furthermore, the extent of protein binding determined by the ultrafiltration system and by equilibrium dialysis were in good agreement. The binding of disopyramide in fortified human plasma decreased from 64 to 52% over a total drug concentration range of 1-5 micrograms/ml.

Blood Proteins↗