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PubMed1979

Hemodynamics during hemodialysis, sequential ultrafiltration and hemofiltration.

Circulatory parameters were determined by cardiac catheterization in patients on maintenance hemodialysis. They were studied in three groups during conventional hemodialysis, sequential ultrafiltration and hemofiltration. All three groups revealed significant reduction of cardiac output, stroke volume, pulmonary artery pressure and plasma volume. In the hemodialysis group hemodynamic parameters were unstable; specifically, hypotension, increased heart rate, and only minimal increase of peripheral resistance were observed. The other two groups showed only minor changes in circulatory parameters despite high ultrafiltration rates. Blood pressure and heart rate remained stable. On the other hand, peripheral vascular resistance increased remarkably. There is compelling evidence that during hemofiltration and sequential ultrafiltration, the patient's ability for vasoconstrictive counterregulation is better maintained than during conventional hemodialysis.

Blood Pressure↗
PubMed1994

On-line continuous venovenous hemodiafiltration: a technique for the control of ultrafiltration and convection during continuous renal replacement therapy.

Continuous renal replacement therapies have been used increasingly in critically ill patients in nephrologic and intensive care units. These techniques are nevertheless time consuming and lack an easy control of ultrafiltration. We conducted continuous venovenous hemodialysis (CVVHD) on a dialysate delivery machine which ensures a volumetric control of ultrafiltration, and which produces both dialysate and infusate with the on-line technique. This new mode of CVVHD was firstly assessed in a feasibility study and was secondly used in a randomized prospective study whose goal was to establish the usefulness of convection. On-line continuous venovenous hemodiafiltration (OL-CVVHDF) appeared safe and time saving, and allowed the fine control of fluid management in critically ill patients. Convective transfers were achieved by a 2 L/h predilutional infusion and increased urea and creatinine clearances twofold. OL-CVVHDF revealed itself to be a valuable method for the control of ultrafiltration and for efficient convective transfers during CVVHD.

Acute Kidney Injury↗
PubMed1988

Virus removal or inactivation in hemoglobin solutions by ultrafiltration or detergent/solvent treatment.

Two procedures to eliminate virus infectivity from hemoglobin solutions at ambient temperature were evaluated. In the first, virus removal was assessed during the ultrafiltration of hemoglobin solutions through a membrane with a nominal molecular weight cut-off of 100,000 Daltons. The results of this study demonstrated that less than 0.1% of any virus originally spiked into the solution was detectable in the ultrafiltrate. In the second procedure the inactivation of viruses in hemoglobin solutions incubated with tri(n-butyl)phosphate mixed with sodium cholate was studied. Greater than 99% of each of the enveloped viruses tested was inactivated during the first 15 minutes of incubation with greater than 10(5) plaque forming units/ml of each being inactivated after one to six hours. No inactivation of the non-enveloped poliovirus was effected by this treatment. The data imply that both ultrafiltration and detergent/solvent incubation may reduce virus infectivity in hemoglobin solutions, but neither method yields a completely virus free product.

Cholic Acid↗
PubMedDate not supplied

Cross flow ultrafiltration studies on solutions of pectin with pulsatile flow in-situ cleaning.

A study was conducted to evaluate the cross flow tubular ultrafiltration behavior of aqueous solutions of pectin. The effectiveness of pulsatile flow as a cleaning-in-place (CIP) technique to improve permeate flux was undertaken on the above mentioned solution. This investigation is part of a study to apply membrane filtration in the clarification of tropical fruit juice. The main variables, which were investigated, include the concentration of pectin, pulse frequency and amplitude. It was found that the amount of pectin in the solution significantly affects its ultrafiltration behavior. From the observed profiles, it is evident that the formation of gel layer on the membrane surface is responsible for the leveling of flux at high pressures. The presence of pectin was found to affect the properties of the solution such as viscosity, pH and the size of pectin colloid. Improvements in the permeate flux for pectin solution were obtained by employing pulsatile flow cleaning-in-place technique. Both pulse frequency and amplitude are important parameters that can improve the improvement of in-situ cleaning method. Similar to several findings reported in the literature, pulsatile flow showed significant effectiveness of about 60% higher flux when the ultrafiltration process is operated under laminar condition.

Detergents↗
PubMed1976

[Peritoneal dialysis, ultrafiltration and hyperosmolarity].

Observation of a patient who developed serious hypernatremia during peritoneal dialysis with a dialysis fluid containing 135 mval Na+/1 prompted investigation of net water, sodium, potassium and chloride transport during 45 peritoneal fluid exchanges with standard dialysis solutions containing 1.5 and 4.5 g% glucose. With both solutions and an equilibration time of 0 min, net ultrafiltration was observed (89 ml and 230 ml per exchange respectively). In both groups the calculated sodium concentration of the ultrafiltrate was considerably lower than plasma sodium concentrations (27.0 mval/1 and 36.9 mval/1 respectively, resulting in a new sieving coefficient of 0.20 and 0.27 respectively. Therefore, the free water deficit resulting from peritoneal ultrafiltration is directly responsible for the hypernatremia observed during peritoneal dislysis. While the potassium and chloride transport observed in these studies can be explained by diffusion processes along a given concentration gradient, sodium transport and sodium concentrations raise the question of more complex mechanisms. The data are discussed with reference to the relative significance of diffusion processes versus bulk flow and solvent drag.

Biological Transport↗
PubMed1998

Analysis of protein fouling during ultrafiltration using a two-layer membrane model.

Protein fouling can significantly alter both the flux and retention characteristics of ultrafiltration membranes. There has, however, been considerable controversy over the nature of this fouling layer. In this study, hydraulic permeability and dextran sieving data were obtained both before and after albumin adsorption and/or filtration using polyethersulfone ultrafiltration membranes. The dextran molecular weight distributions were analyzed by gel permeation chromatography to evaluate the sieving characteristics over a broad range of solute size. Protein fouling caused a significant reduction in the dextran sieving coefficients, with very different effects seen for the diffusive and convective contributions to dextran transport. The changes in dextran sieving coefficients and diffusive permeabilities were analyzed using a two-layer membrane model in which a distinct protein layer is assumed to form on the upstream surface of the membrane. The data suggest that the protein layer formed during filtration was more tightly packed than that formed by simple static adsorption. Hydrodynamic calculations indicated that the pore size of the protein layer remained relatively constant throughout the adsorption or filtration, but the thickness of this layer increased with increasing exposure time. These results provide important insights into the nature of protein fouling during ultrafiltration and its effects on membrane transport.

Adsorption↗
PubMed2001

[The effects of dialysate and ultrafiltration flow rate on solute clearance during continuous renal replacement therapy].

OBJECTIVE: To study the solute clearance during various forms of continuous renal replacement therapy(CRRT) and test the formulas that allow the prediction of the influence of dialysate and ultrafiltration flow rate on small solute removal during CRRT. METHOD: Five patients with acute renal failure were included in the study and were treated by venovenous CRRT using the PRISMA predilution system. Solute clearance of urea nitrogen(UN), creatinine(Cr), uric acid(Ua), phosphate(P) and beta(2)-microglobulin(beta(2)-M) were evaluated during CRRT with different dialysates and ultrafiltration flow rates. RESULTS: The determined clearance of small molecular solutes during continuous venovenous hemofiltration (CVVH) and continuous venovenous hemodialysis(CVVHD) was similar with the following formulas: K(UF) = (Q(UF)/60) x Q(B)/(Q(B) + Q(UF)/60) (in CVVH), Kd = Q(D)/60 (in CVVHD), where K is the clearance, Q(B), Q(D) and Q(UF) are blood, dialysate and ultrafiltration flow rates, respectively. There was very significant correlation between calculated values of K(UF) and observed clearances of small solutes such as UN, Cr, Ua and P during CVVH, between calculated values of Kd and observed clearances of UN, Cr, Ua but not P during CVVHD (P < 0.001). Clearances of UN, Cr, Ua and P during CVVHD were greater than those during CVVH, but clearance of beta(2)-M during CVVHD was less than that during CVVH. Interaction between convection and diffusion was found during continuous venovenous hemodiafiltration (CVVHDF). CONCLUSIONS: The previous formulas can provide with the prediction of the clearance of small molecular solutes during CVVH and CVVHD. The present results demonstrate that diffusion is more efficient in removing small solutes than convection but less efficient in removing large solutes than convection. There is interaction between convection and diffusion during CVVHDF.

Acute Kidney Injury↗
PubMed2002

Effects of dilutional and modified ultrafiltration in plasma endothelin-1 and pulmonary vascular resistance after the Fontan procedure.

BACKGROUND: Pulmonary vascular resistance (PVR) is closely related with patients' hemodynamics after the Fontan procedure and endothelin-1 (ET-1) may play an important role in pulmonary circulation. Modified ultrafiltration (MUF) is known to remove inflammatory mediators after cardiopulmonary bypass (CPB) surgery. The time courses of plasma ET-1 and PVR were examined before and after the Fontan procedure with MUF. METHODS: Twenty-two patients who underwent the Fontan procedure were divided into two groups: a dilutional ultrafiltration/modified ultrafiltration (DUF/MUF) group (n =11) and a control group (n = 11). Conventional ultrafiltration was performed during CPB in the control group. DUF was performed semicontinuously during CPB and MUF was continued until 15 to 20 minutes after the CPB with polyacrylonitonile membrane in the DUF/ MUF group. The plasma ET-1 concentration was measured before and after CPB, after MUF in the DUF/MUF group, and 6 and 24 hours after CPB. PVR was calculated simultaneously using a thermodilutional catheter. RESULTS: Plasma ET-1 levels increased significantly after CPB in the control group but they did not increase immediately after CPB in the DUF/MUF group. Similarly, PVR increased significantly after CPB in the control group but it did not increase after CPB in the DUF/MUF group and remained low at 6 and 24 hours after CPB. CONCLUSIONS: DUF and MUF suppress the increase in the plasma ET-1 concentration that occurs immediately after the completion of the Fontan procedure and may be an effective intervention for maintaining low PVR after the procedure.

Cardiopulmonary Bypass↗
PubMedDate not supplied

[Study of ultrafiltration of trypsin solutions].

The dependence of the rate of trypsin ultrafiltration on the concentration, pressure and structure of membranes was studied. During ultrafiltration of diluted trypsin (0.3 mg/ml), water and sodium chloride the flow rate increased linearly with a pressure increase in the range of 0.4-4.2 kg/cm2. During ultrafiltration of trypsin solutions of a concentration of 1 mg/ml and over at a pressure of 2-3 kg/cm2 deviations from linear proportionality occurred which enhanced with an increase in the protein concentration and a decrease in membrane permeability.

Binding Sites↗
PubMed2002

Peritoneal rest may successfully recover ultrafiltration in patients who develop peritoneal hyperpermeability with time on continuous ambulatory peritoneal dialysis.

Temporary transfer to hemodialysis, as a peritoneal rest, may be a rescue therapy to recover ultrafiltration (UF) in patients who develop peritoneal hyperpermeability as a complication of continuous ambulatory peritoneal dialysis (CAPD). However, peritoneal sclerosis has been reported after peritoneal pause. Since the beginning of our CAPD program in 1985, 12 elective peritoneal pauses have been performed in 11 patients who developed type I ultrafiltration failure (D/P240 creatinine: 0.88 +/- 0.09) after 42 +/- 14 months on CAPD. Eight patients recovered UF and remained on CAPD with standard solutions for 10 +/- 9 months more (minimum: 5 months; maximum: 29 months). Only 3 of those patients were later switched to hemodialysis because of recurring UF failure. One patient remains on CAPD (62 months of follow-up). Four patients failed to respond and were permanently transferred to hemodialysis, without signs of developing encapsulating peritoneal sclerosis. The failed pauses were performed later after the detection of UF failure than were the successful ones (483 +/- 574 days vs. 54 +/- 52 days). In our study, 8 of 12 peritoneal pauses (66.6%) successfully treated type I UF failure and prolonged CAPD retention. If a pause is initiated soon after diagnosis of UF failure, results may improve further. We urge prospective studies to better determine the best and timely therapeutic approach in patients with loss of ultrafiltration.

Creatinine↗
PubMed1992

[Use of ultrafiltration in refractory cardiac decompensation].

Traditional therapy for heart failure (diuretics, digitalic compound, vasodilators, inodilatory ACE-inhibitors) cannot arrest the progressive overloading of the circulatory system so that it is inevitable that a refractory stage to all forms of treatment will be reached when more specialised techniques, such as heart transplant and ultrafiltration will be needed. The paper reports the results obtained in 13 patients in ultrafiltration treatment for refractory heart failure: in the majority of these, a marked improvement in general conditions (edema, dyspnea) was recorded together with a regression from class 5 to class 3 NYHA in 5 patients, and to class 2 for others. The ultrafiltration method in spite of not altering the prognosis which remains negative in these patients, allow those waiting for heart transplant to survive and may improve their chances of surviving heart surgery.

Adult↗
PubMed2004

[Ultrafiltration with different membranes and respiratory function after cardiopulmonary bypass].

OBJECTIVE: To investigate the protective effect of ultrafiltration on pulmonary function after cardiopulmonary bypass (CPB) by comparing two different membranes used in the ultrafiltration. METHODS: Thirty patients undergoing cardiac surgery with CPB were randomly divided into adsorption group (n=15) and control group (n=15), and in the former group, AN69 membrane was used for ultra-infiltration, with polysulfone (PS) membrane adopted in the control group during CPB. Plateau airway pressure (P(Plateau)), peak airway pressure (P(Peak)), static pulmonary compliance (Cst), dynamic pulmonary compliance (Cdyn) and respiratory index (RI) were measured or calculated before and 5, 60, 120, and 240 min after CPB in each group respectively. RESULTS: During the period of 5 to 240 min after CPB, the increase in P(Plateau), P(Peak), RI and decrease in Cst and Cdyn were much more obvious and lasted for longer time in the adsorption group than in the control group (P<0.05). No operative death or hemoglobinuria occurred in these cases. CONCLUSION: Ultrafiltration with AN69 membrane more effectively reduces CPB-induced lung injury and improves the postoperative respiratory function than with PS membrane.

Adult↗
PubMed2004

[Study on the interface of human hepatocyte/micropore polypropylene ultrafiltration membrane].

OBJECTIVE: To found a new interface of human hepatocyte/micropore polypropylene ultrafiltration membrane (MPP) with good cytocompatibility so as to construct bioartificial bioreactor with polypropylene hollow fibers in future. METHODS: MPP ultrafiltration membrane underwent chemical grafting modification through ultraviolet irradiation and Fe(2+) reduction. The contact angles of MPP and the modified MPP membranes were measured. Human hepatic cells L-02 were cultured. MPP and modified MPP membranes were spread on the wells of culture plate and human hepatic cells and cytodex 3 were inoculated on them. Different kinds of microscopy were used to observe the morphology of these cells. RESULTS: The water contact angle of MPP and the modified MPP membranes decreased from 78 degrees +/- 5 degrees to 27 degrees +/- 4 degrees (P < 0.05), which indicated that the hydrophilicity of the membrane was improved obviously after the grafting modification. Human hepatocyte L-02 did not adhere to and spread on the modified MPP membrane surface, and only grew on the microcarrier cytodex 3 with higher density and higher proliferation ratio measured by MTT. CONCLUSION: Grafting modification of acrylamide on MPP membrane is a good method to improve the human hepatocyte cytocompatibility with MPP ultrafiltration membrane.

Bioartificial Organs↗
PubMed2004

The role of microparticles in dead-end ultrafiltration of wwtp-effluent.

Ultrafiltration is considered as an interesting polishing technique for effluent of wastewater treatment plants (wwtp-effluent). Results in pilot-scale experiments indicated that microparticles might dominate the filtration characteristics. In this article the results of investigations on the role of microparticles on the filterability of effluent is described. Calculation effects on particle size distributions of effluent showed that particles smaller than 2.0 microm predominantly influence the filterability of the wwtp-effluent. Additionally, experiments were performed on the filterability of size fractions of effluent. Effluent was fractionated with laboratory filters (pore diameter 5.0, 1.2, 0.45, 0.2 and 0.1 microm). The filterability of this pre-filtered effluent in applying ultrafiltration was evaluated by measurement of the SUR, a new parameter for measurement of the filterability of effluent. The results showed that filterability of the effluent was mainly influenced by 40% to 57% by the fraction larger than 0.1 microm and smaller than 0.2 microm, which is five to twenty times larger than the ultrafiltration membrane pores. Pre-treatment of the effluent by coagulation or sand filtration showed only minor influence on these results.

Particle Size↗
PubMed2006

[Separation of protein and isoflavone in soybean whey by ultrafiltration].

The study on the technical conditions of separating protein and isoflavone in soybean whey by ultrafiltration showed that before ultrafiltration, soybean whey should be pretreated to reduce membrane contamination. The orthogonal experiment of 2 factors and 3 levels indicated that the optimum pretreatment conditions were 5% of CaCl, addition based on the solid substance content in soybean whey, and heating up at 85 degrees C for 15 minutes. Under these conditions, the precipitation rate of whey protein was 49. 8% , while the reservation rate of isoflavone was 90.4%. Single factor experiment showed that the optimum ultrafiltration conditions were poly (ether sulfone) membrane of 10 kDa molecular weight cut-off (MWCO), 51-68 kPa, and 30 degrees C-40 degrees C. Under these conditions, the retention rate of whey protein and isoflavone was 83.9% and 7.6% , respectively.

Isoflavones↗
PubMed1991

Digoxin-like immunoreactivity in serum from neonates and infants reduced by centrifugal ultrafiltration and fluorescence polarization immunoassay.

We evaluated the TDx Digoxin II (Abbott) modified procedure for interference from digoxin-like immunoreactive factors (DLIF) in pediatric patients. The effectiveness of centrifugal ultrafiltration as a means of removing DLIF interference from the serum of such patients was assessed. We used sera from 40 patients who had not received digoxin, whom we divided into two age groups: 30 neonates (less than 34 days postpartum) and 10 infants (younger than six months). Digoxin-like immunoreactivity was detected in 34 of 41 (83%) neonatal specimens (range 0.2-1.0 micrograms/L) and 16 of 25 (60%) infants' specimens (range 0.2-1.3 micrograms/L). Centrifugal ultrafiltration of serum specimens from these patients reduced but did not eliminate the DLIF interference in some specimens. A comparison of concentrations of DLIF in serum with various other patients' characteristics demonstrated a strong correlation (r = 0.915; P = 0.0001) between DLIF and serum bilirubin in the infants. Apparent digoxin concentrations from 19 serum and serum ultrafiltrate samples collected from 13 patients (four neonates and nine infants) who were treated with digoxin showed a good correlation (r = 0.97); however, the serum samples showed a positive bias of 0.39 microgram/L. We conclude that the TDx Digoxin II modified procedure is still subject to considerable DLIF interference in these two pediatric populations. This interference can be reduced in some serum specimens, but cannot be eliminated completely as others reported.

Aging↗
PubMed1989

Increased migration inhibition factor production by leukocytes of patients with herpes zoster given the leukocyte ultrafiltrate.

Using the direct leukocyte migration inhibition assay, the cell-mediated immune response was followed in together 47 patients suffering from herpes zoster. Of these, 19 persons were treated with partially purified and concentrated lysed leukocyte ultrafiltrate. Enhancement and/or earlier production of the leukocyte migration inhibition factor--in the presence of varicella-zoster virus antigen--was observed by leukocytes from patients given the ultrafiltrate on days 2-3 since the onset of the vesicular stage of the disease. Highly significant (alpha = 1%, P less than 0.01) differences in the migration inhibition values were observed between non-treated patients and patients given one dose of the ultrafiltrate during the days 3-12 after appearance of the first herpes zoster vesicles; on days 13-30 these values were not significant.

Adolescent↗
PubMed1989

[Isolated ultrafiltration in refractory cardiac insufficiency].

The efficiency of isolated ultrafiltration was demonstrated in 101 patients with refractory heart failure developing in the presence of myocardial abnormalities. Catheterization of major (femoral or subclavian) veins is shown to be the optimum vascular access for isolated ultrafiltration; patient's blood can be returned through the needle catheter placed into the cubital vein. To prevent possible complications of isolated ultrafiltration, packed cell volume, central venous pressure and end diastolic pressure in the pulmonary artery should be monitored.

Adult↗