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PubMed2006

The oxalate level in ultrafiltrate fluid collected from a dialyzer is useful for estimating the plasma oxalate level in hemodialysis patients.

BACKGROUND: Patients on chronic hemodialysis are likely to develop secondary hyperoxalemia. It is, however, difficult to measure plasma oxalate levels. To measure plasma oxalate levels, rapid plasma separation, deproteinization, and acidification are essential in preventing the formation of oxalate and the deposition of calcium oxalate within the test tube. The present study was undertaken to examine whether the oxalate level in dialyzer ultrafiltrate is potentially useful for estimating plasma oxalate levels. METHODS: In nine patients on chronic hemodialysis, the plasma, after deproteinization with a filter, and the ultrafiltrate from the dialyzer before hemodialysis were acidified to a pH level of less than 3, followed by the measurement of oxalate levels by ion chromatography. Also, oxalate levels were compared between acidified and non-acidified ultrafiltrates from the dialyzer. In the second part of the study, seven patients on chronic hemodialysis receiving erythropoietin therapy, in whom the ferritin level was more than 300 ng/ml and transferrin saturation was less than 25%, were intravenously administered ascorbic acid, 100 mg, three times a week, after each dialysis session to facilitate the utilization of stored iron. This treatment was continued until the serum ferritin level decreased to a level below 300 ng/ml (for 3 months, at a maximum). The oxalate level in the dialyzer ultrafiltrate after this treatment was compared with that before treatment. RESULTS: The mean +/- SE oxalate level in the dialyzer ultrafiltrate was 45 +/- 6 micromol/l, essentially equal to the plasma oxalate level (46 +/- 7 micromol/l). The plasma oxalate level had a significant positive correlation with the dialyzer ultrafiltrate oxalate level (plasma oxalate level = 0.99 x dialyzer ultrafiltrate oxalate level + 1.5; r = 0.95; P < 0.0001). The oxalate level in the acidified ultrafiltrate (45 +/- 6 micromol/l) did not differ significantly from that in the non-acidified ultrafiltrate (45 +/- 6 micromol/l). The mean +/- SE duration of ascorbic acid administration was 64 +/- 13 days. The hemoglobin level remained unchanged at 9.6 +/- 0.4 g/dl, whereas the serum iron level increased significantly, from 34 +/- 2 microg/dl to 43 +/- 4 microg/dl (P < 0.05), and serum ferritin levels decreased significantly, from 645 +/- 219 ng/ml to 231 +/- 30 ng/ml after the treatment (P < 0.05). The oxalate level in the acidified ultrafiltrate showed no significant change after ascorbic acid administration (31 +/- 8 micromol/l vs 47 +/- 7 micromol/l). CONCLUSIONS: In patients on chronic hemodialysis, the oxalate level in acidified ultrafiltrate from the dialyzer was found to be useful for estimating the plasma level of non-protein-bound oxalate. When administering ascorbic acid to hemodialysis patients, the plasma oxalate level can be monitored using this method.

Adult↗
PubMed2006

Ultrafiltration reduces blood transfusions following cardiac surgery: A meta-analysis.

BACKGROUND: Although used routinely in pediatric patients, ultrafiltration techniques that reverse hemodilution are infrequently used in adults. Data from small, unblinded clinical trials suggest that the use of ultrafiltration can reduce inflammatory mediators, improve cardiac function, and reduce hemodilution. We conducted a meta-analysis of randomized trials to evaluate the effects of ultrafiltration on blood transfusions and blood loss following adult cardiac surgery. METHODS: Medline, EMBASE, and Cochrane databases were searched and randomized controlled trials evaluating modified and/or conventional ultrafiltration, meeting pre-determined selection criteria, were obtained. Quality evaluation and data extraction were performed by two independent observers blinded to study source. Random effects models were used to determine pooled effect estimates and sources of heterogeneity were explored using meta-regression. RESULTS: One hundred and thirty two studies were screened and 10 randomized trials evaluating 1004 patients (control, n = 495; ultrafiltration, n = 509) were identified of which only two were double-blinded. The use of ultrafiltration was associated with a reduction in postoperative blood transfusions (weighted mean difference [95% CI] of -0.73 units [-1.16, -0.31]; p = 0.001). This reduction was greater in studies evaluating modified ultrafiltration. Use of ultrafiltration was also associated with reduced postoperative bleeding (-70 ml, [-118, -21]; p = 0.005), which was driven primarily by trials evaluating modified rather than conventional ultrafiltration. CONCLUSIONS: Use of ultrafiltration is associated with a significant reduction in postoperative blood transfusions as well as reduced bleeding in adults undergoing cardiac surgery. The efficacy and cost-effectiveness of ultrafiltration as a blood conservations strategy should be evaluated in a large, randomized, double-blinded study.

Adult↗
PubMed1999

Venovenous modified ultrafiltration after cardiopulmonary bypass in children: a prospective randomized study.

BACKGROUND: Cardiopulmonary bypass is associated with the production of both proinflammatory and anti-inflammatory cytokines, the balance of which leads to varying degrees of postoperative systemic inflammation. Arteriovenous modified ultrafiltration effectively reduces total body water and improves postoperative hemodynamic and homeostatic functions. Venovenous modified ultrafiltration is a modification of this technique, which has the potentially added advantage of eliminating the obligatory left-to-right shunt associated with arteriovenous modified ultrafiltration. We tested the hypothesis that venovenous modified ultrafiltration is a safe and effective method of achieving ultrafiltration in children after cardiopulmonary bypass. METHODS: Thirty-eight pediatric patients were randomly assigned to undergo conventional, venovenous (n = 13), or no ultrafiltration venovenous (n = 13), and controls (n = 12). Perioperative, cardiopulmonary, and cytokine (tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, interleukin-8, and interleukin-10) data were collected for statistical analysis. RESULTS: Compared with patients in the conventional ultrafiltration and control groups, patients undergoing venovenous modified ultrafiltration had the greatest volume of ultrafiltrate removed (46. 9 +/- 8.4 mL/kg vs 20.1 +/- 5.0 mL/kg and 0 mL/kg for conventional ultrafiltration and control groups, respectively; P =.0001), least increase in total body water (1.91% +/- 1.49% vs 3.90% +/- 1.86% and 8.24% +/- 3.41%; P =.05), greatest rise in hematocrit (39.7% +/- 1. 7% vs 33.8% +/- 2.1% and 29.6% +/- 2.3%; P =.006), and shortest length of hospital stay (4.41 +/- 0.28 days vs 6.69 +/- 1.47 days and 8.38 +/- 1.11 days; P =.03, P =.03). CONCLUSIONS: Venovenous modified ultrafiltration is a safe and effective method of reducing the increase in total body water and duration of postoperative convalescence after cardiopulmonary bypass.

Cardiopulmonary Bypass↗
PubMed2005

High flow rates during modified ultrafiltration decrease cerebral blood flow velocity and venous oxygen saturation in infants.

BACKGROUND: The intracranial hemodynamic effects of modified ultrafiltration in children are unknown. We investigated the effects of different blood flow rates during modified ultrafiltration on the cerebral hemodynamics of children with weights above and below 10 kg. METHODS: Thirty-one children (weights: < or = 10 kg, n = 21; > 10 kg, n = 10) undergoing cardiopulmonary bypass were studied. Middle-cerebral artery blood flow velocities and cerebral mixed venous oxygen saturations were measured before, five minutes from the beginning, and at the end of ultrafiltration. Patients were classified according to their blood flow rates during ultrafiltration in three groups: high (> or = 20 mL/kg/min), moderate (10-19 mL/kg/min), and low flow rates (< 10 mL/kg/min). RESULTS: During modified ultrafiltration, blood pressures and hematocrit increased (p < 0.001), but cerebral blood flow velocities and mixed venous oxygen saturations decreased (p < 0.001). A significant correlation was found between blood flow rates of ultrafiltration and the decline in mean cerebral blood flow velocity (r = - 0.48; p = 0.005) and cerebral oxygen saturation (r = - 0.49; p = 0.005) or hematocrit increase (r = 0.59; p = 0.001). Infants exposed to high flow rates had greater reduction of cerebral blood flow velocity and regional mixed venous saturation and higher hematocrit at the end of ultrafiltration compared with those subjected to moderate and low flow rates (p < 0.04). No significant difference was found between moderate and low flow groups. The flow rate of ultrafiltration was the only independent predictor of the changes in cerebral mixed venous oxygen saturation (p = 0.033). CONCLUSIONS: High blood flow rates through the ultrafilter during modified ultrafiltration transiently decrease the cerebral circulation in young infants compared with lower blood flow rates. These effects may be related to an increased diastolic runoff from the aorta into the ultrafiltration circuit that leads to a "stealing" effect from the intracranial circulation, which may be important in infants with dysfunctional cerebral autoregulation.

Blood Flow Velocity↗
PubMed1991

A successful modification of ultrafiltration for cardiopulmonary bypass in children.

Total body water (TBW) is increased after cardiopulmonary bypass (CPB) resulting in tissue oedema and organ dysfunction. Ultrafiltration has been used to reduce this accumulation of water, although conventional ultrafiltration seemed ineffective in reducing the rise in TBW after CPB in our clinical experience. We describe a modified technique in which ultrafiltration is performed in the first 10 minutes after the patient is weaned from bypass, returning nearly all the blood in the circuit to the patient and elevating the haematocrit (Hct) to any predetermined level. We carried out a pilot study on 21 children aged 4-144 months undergoing open-heart surgery and CPB for congenital heart defects. They were divided into three comparable groups: (1) controls (n = 6); (2) conventional ultrafiltration (n = 7); and (3) modified ultrafiltration (n = 8). TBW (bio-impedance), Hct, osmolality, mean corpuscular volume and mean corpuscular haemoglobin concentration were recorded at frequent intervals. Control patients showed elevation of TBW by 18.2% median (range 14.5-20.3), conventional ultrafiltration by 12.4% (7.9-15.0), modified ultrafiltration by 5.7% (4.5-7.1) (p less than 0.0001 compared to controls, p. less than 0.005 compared to conventional ultrafiltration, Mann-Whitney U test). Hct could be elevated to preoperative levels only by the modified method. Mean corpuscular volume, and mean corpuscular haemoglobin concentration osmolality were unaltered. Ultrafiltration by the modified method was more effective than conventional ultrafiltration in reducing the rise in TBW and elevating Hct after CPB.

Blood Volume↗
PubMed1989

Loss of ultrafiltration in continuous ambulatory peritoneal dialysis (CAPD).

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

Biological Transport↗
PubMed2000

Pulmonary function after modified venovenous ultrafiltration in infants: a prospective, randomized trial.

OBJECTIVE: We sought to examine the effects of modified venovenous ultrafiltration after cardiopulmonary bypass on pulmonary compliance in infants. METHODS: We prospectively enrolled 38 infants undergoing their first operation for congenital heart disease. Infants were randomized to receive 20 minutes of modified ultrafiltration after bypass or control. Static and dynamic compliance was measured after induction of anesthesia, before and immediately after filtration in the operating theater, 1 hour after return to the pediatric intensive care unit, and 24 hours after the operation. Length of time on the ventilator, inotropic requirements, and length of stay in the intensive care unit were recorded. RESULTS: Modified ultrafiltration produced a significant immediate improvement in dynamic (pre-ultrafiltration 2.5 +/- 1.9 mL/cm H(2)O to post-ultrafiltration 2.9 +/- 2.7 mL/cm H(2)O, P =.03) and static (pre-ultrafiltration 2.1 +/- 0.9 mL/cm H(2)O to post-ultrafiltration 2.9 +/- 2.1 mL/cm H(2)O, P =.04) compliance. However, there was no significant difference in the change in dynamic (P =.3) or static (P =.7) compliance in the ultrafiltration and control groups when compared before the operation, after the operation, and at 24 hours. There was no significant difference in the time to extubation between patients and control subjects (140 +/- 91 hours vs 90 +/- 58 hours) or the length of intensive care unit stay (10.0 +/- 9.1 days vs 7.4 +/- 5.7 days). CONCLUSIONS: Modified ultrafiltration produces an improvement in pulmonary compliance after bypass in infants. However, these improvements are not sustained past the immediate post-ultrafiltration period and do not lead to a decreased length of intubation or intensive care unit stay.

Cardiopulmonary Bypass↗
PubMed1995

Ultrafiltration and backfiltration during hemodialysis.

Ultrafiltration is the pressure-driven process by which hemodialysis removes excess fluid from renal failure patients. Despite substantial improvements in hemodialysis technology, three significant problems related to ultrafiltration remain: ultrafiltration volume control, ultrafiltration rate control, and backfiltration. Ultrafiltration volume control is complicated by the effects of plasma protein adsorption, hematocrit, and coagulation parameters on membrane performance. Furthermore, previously developed equations relating the ultrafiltration rate and the transmembrane pressure are not applicable to high-flux dialyzers, high blood flow rates, and erythropoietin therapy. Regulation of the ultrafiltration rate to avoid hypotension, cramps and other intradialytic complications is complicated by inaccurate estimates of dry weight and patient-to-patient differences in vascular refilling rates. Continuous monitoring of circulating blood volume during hemodialysis may enable a better understanding of the role of blood volume in triggering intradialytic symptoms and allow determination of optimal ultrafiltration rate profiles for hemodialysis. Backfiltration can occur as a direct result of ultrafiltration control and results in transport of bacterial products from dialysate to blood. By examining these problems from an engineering perspective, the authors hope to clarify what can and cannot be prevented by understanding and manipulating the fluid dynamics of ultrafiltration.

Blood Flow Velocity↗
PubMed1999

[Combined perioperative ultrafiltration in pediatric cardiac surgery. The preliminary results].

INTRODUCTION AND OBJECTIVES: Recently, ultrafiltration techniques are used more and more as a treatment for the inflammatory response of cardiopulmonary bypass. It also provides fine control of fluids. The purpose of this study is to present a technique which combines conventional and modified ultrafiltration and to analyze the obtained results. PATIENTS AND METHODS: 22 patients (mean weight 13.1 +/- 8.4 kg) operated on cardiopulmonary bypass. Combined ultrafiltration was performed during cardiopulmonary bypass (conventional) and after pump (modified ultrafiltration). We analyzed cardiopulmonary bypass variables, the first 24-hour hemodynamics, biological variables (arterial blood gases, cell counts, IL-6, adhesion molecules ICAM-1 and VCAM-1, and coagulation profiles). RESULTS: A total amount of 1,399 +/- 680 ml/m2 of mean combined ultrafiltrate volume was obtained (657 +/- 386 ml/m2 during cardiopulmonary bypass and 845 +/- 358 ml/m2 post-cardiopulmonary bypass). After modified ultrafiltration, hematocrit rose from 23 +/- 2.3 to 32 +/- 4.1, arterial systolic blood pressure rose from 74 +/- 13 to 98 +/- 20 mmHg, heart rate decreased from 133 +/- 22 to 126 +/- 23 bpm, and central versus pressure did not change. A statistically significant relationship (multivariable), was shown between modified ultrafiltration time and VCAM-1 post-ultrafiltration levels. Platelet count was lower and diuresis rose related to cardiopulmonary bypass ultrafiltration volume and diuresis increased. CONCLUSIONS: Perioperative combined ultrafiltration is feasible without undue morbidity and provides adequate hemoconcentration and excellent postoperative hemodynamic results. More studies with control groups are necessary to better define the therapeutic influence in antiinflammatory properties of this technique.

Cardiac Surgical Procedures↗
PubMed1995

Determination of free and liposome-associated doxorubicin and vincristine levels in plasma under equilibrium conditions employing ultrafiltration techniques.

A thorough understanding of the pharmacodynamic relationships associated with toxicity and efficacy behavior of liposome-encapsulated anticancer agents such as doxorubicin and vincristine will rely on the ability to accurately separate and quantify the free and liposome-associated drug fractions in plasma after administration. We have investigated the use of ultrafiltration as a method of isolating free doxorubicin and vincristine from liposomal drug under equilibrium conditions and compared it to previously developed nonequilibrium procedures based on solid-phase extraction. Adsorption of drugs dissolved in saline to the ultrafiltration devices resulted in concentration-dependent ultrafiltrate drug recoveries ranging from 41 to 96%. However, concentration-independent quantitative recovery of vincristine in saline solutions could be obtained by passivating the ultrafiltration devices with PEG-8000 and device drug adsorption was ameliorated for both agents by plasma. The ultrafiltration method provided a more reliable separation of free and protein-bound drug, whereas solid-phase extraction yielded artificially high free drug concentrations due to process-induced protein-bound drug complex dissocation. Also, coelution of liposomes with the free drug fraction using solid-phase extraction was 64- to 418-fold higher than observed with ultrafiltration. Taken together, these properties indicated a significantly increased degree of accuracy in measuring the amount of free doxorubicin and vincristine in samples containing liposomal formulations employing ultrafiltration compared to solid-phase extraction. The importance of this improvement was highlighted by observations that determinations of free drug concentrations in the plasma of mice injected with liposomal doxorubicin and vincristine were 3- to 12-fold higher using solid-phase extraction compared to ultrafiltration. Finally, the ultrafiltration procedure is rapid, versatile, and can be used for a wide range of drug and liposome concentrations and free drug/liposomal drug ratios.

Adsorption↗
PubMed2005

Haemodynamic changes during modified ultrafiltration immediately following the first stage of the Norwood reconstruction.

BACKGROUND: Modified ultrafiltration has been shown to reverse haemodilution and improve ventricular function following cardiopulmonary bypass. There has been concern, however, about the safety and efficacy of modified ultrafiltration after the first stage of Norwood reconstruction for palliation of neonates with hypoplasia of the left heart and its variants. METHODS: We reviewed the intraoperative course of all patients undergoing the first stage of Norwood reconstruction between September 1, 2000, and August 31, 2002. RESULTS: The first stage of reconstruction was performed in 99 neonates, 78 with classical hypoplasia of the left heart, and 21 with variants. Mean weight at surgery was 3.1 plus or minus 0.7 kilograms. Genetic syndromes, weight less than or equal to 2.5 kilograms, and/or major additional cardiac or non-cardiac anomalies, were present in 44 patients. We deemed these patients to constitute the group at high risk. A modified Blalock-Taussig shunt was utilized in 95 patients, and a conduit from the right ventricle to the pulmonary arteries in 4. Deep hypothermic circulatory arrest was used in all patients for a mean period of 45 minutes, plus or minus 15 minutes. Total support time on cardiopulmonary bypass plus deep hypothermic circulatory arrest was 100 minutes plus or minus 26 minutes. Modified ultrafiltration was performed in all patients. The mean duration of modified ultrafiltration was 10 plus or minus 2 minutes, and the total volume of filtrate removed was 104 plus or minus 29 millilitres per kilogram. There were no complications from modified ultrafiltration, and no patient required discontinuation of modified ultrafiltration for haemodynamic instability. During modified ultrafiltration, the haematocrit increased from 31 percent plus or minus 4 to 46 percent plus or minus 6. Heart rate decreased from 170 plus or minus 17 beats per minute to 158 plus or minus 16 beats per minute. Systolic blood pressure increased from 57 plus or minus 12 to 63 plus or minus 13 millimetres of mercury, and diastolic blood pressure from 30 plus or minus 8 to 35 plus or minus 7 millimetres of mercury. All these values are significant at a p value of less than 0.0001. Hospital morality in the patients at low risk was 3 of 55 (5.5 percent), but was 12 of 44 (27.3 percent) in the patients deemed to be at high-risk. CONCLUSIONS: Modified ultrafiltration is safe procedure following the first stage of Norwood reconstruction, with improvement in all haemodynamic parameters measured. Modified ultrafiltration is an additional incremental strategy, which may contribute to the overall improvement in outcome following surgical palliation of patients with hypoplasia of the left heart or its variants.

Cardiac Surgical Procedures↗
PubMed1997

Icodextrin instead of glucose during the daytime dwell in CCPD increases ultrafiltration and 24-h dialysate creatinine clearance.

BACKGROUND AND METHODS: Icodextrin 7.5% is an iso-osmolar, glucose polymer-containing peritoneal dialysis solution with an ultrafiltration potential similar to glucose 3.86%. We compared in an open, randomized, prospective study the ultrafiltration potential of icodextrin with that of glucose during the daytime dwell of 23 patients treated with automated peritoneal dialysis (CCPD). RESULTS: Daytime ultrafiltration volume and 24-h ultrafiltration volume increased significantly in icodextrin-treated patients (n = 11) at 3 and 6 months, allowing patients a less rigid fluid restriction or an adapted treatment schedule. This improved the patients' subjective well-being. Although ultrafiltration at 9 and 12 months also increased it did not reach statistical significance. Similar to the gain in ultrafiltration volume, 24-h dialysate creatinine clearance per 1.73 m2 (DCl/1.73 m2) and DCl/1.73 m2 per litre used dialysate (DCl/1.73 m2/l) increased in icodextrin-treated patients. DCl/1.73 m2/l per litre ultrafiltrate (DCl/1.73 m2/l/UF) did not increase. No side-effects of icodextrin were encountered, although serum disaccharide levels increased. CONCLUSION: Icodextrin enhances ultrafiltration during the daytime dwell in CCPD patients. As a result of an increased 24-h ultrafiltration volume, DCl/1.73 m2 and DCl/1.73 m2/l improve. DCl/1.73 m2/l/UF does not rise, which suggests that the increase in DCl/1.73 m2 and DCl/1.73 m2/l is caused by convective transport.

Creatinine↗
PubMed1983

Plasma protein binding of disopyramide by equilibrium dialysis and ultrafiltration.

An ultrafiltration technique, using Ultrafree Anticonvulsant Drug Filters, was compared to equilibrium dialysis for the determination of disopyramide plasma protein binding. Mean total recovery of drug was 92.4% for ultrafiltration compared with 98.4% for equilibrium dialysis. At initial plasma concentrations spanning the therapeutic range (2-8 micrograms/ml), the percentage binding of disopyramide was concentration dependent for both methods (78-38%). Initial experiments with ultrafiltration (1 ml of plasma) indicated a small (0.14%) but variable loss of total plasma protein in the ultrafiltrate (0.1-ml volume). In ultrafiltration, percentage binding of disopyramide was similar at 22 and 37 degrees C, whereas in equilibrium dialysis, binding was significantly (p less than 0.001) greater (1.4-2.7%) at 22 than at 37 degrees C. Percentage binding for plasma (1-ml volume), assessed at ultrafiltrate volumes of approximately 0.1 and 0.25 ml, was found to be significantly (p less than 0.05) different, but in practical terms the mean difference was less than 1% at any of the concentrations studied and was therefore of little consequence. Absolute values for percentage disopyramide bound by ultrafiltration and equilibrium dialysis were very similar, irrespective of the temperature. However, when these values were related in the usual way to the starting plasma drug concentration for ultrafiltration or to the final dialysed plasma concentration, ultrafiltration gave results that were consistently greater than those with equilibrium dialysis. Reasons for these differences and their implications are discussed.

Blood Proteins↗
PubMed2005

Predictors of a favourable response to icodextrin in peritoneal dialysis patients with ultrafiltration failure.

BACKGROUND AND AIMS: Icodextrin is a starch-derived glucose polymer that causes sustained ultrafiltration in long dwells in peritoneal dialysis. The aim of this study was to assess factors that were predictive of an increment in ultrafiltration following the introduction of icodextrin in patients with refractory fluid overload. METHODS: Thirty-nine patients (20 male/19 female, mean age 57.7 +/- 2.4 years) on peritoneal dialysis were enrolled in a prospective pretest/post-test, open-label study. All patients had symptomatic fluid overload refractory to fluid restriction (<800 mL/day), frusemide doses of 250 mg or more daily, optimization of dwell time and use of hypertonic dextrose. An icodextrin exchange was substituted for a 4.25% dextrose exchange for the long-dwell period. RESULTS: After 1 month, median (interquartile range) 24 h ultrafiltration volume increased by 500 mL (interquartile range: 50-1000). An increase in ultrafiltration volume correlated positively with the dialyate : plasma creatinine ratio at 4 h (r = 0.498, P = 0.001) and negatively with the ratio of dialysate glucose concentrations at 4 and 0 h (r = -0.464, P = 0.003). On multivariate regression analysis, high transporter status was predictive of a greater ultrafiltration response to icodextrin relative to dextrose peritoneal dialysis exchanges. Age, sex, race, peritoneal dialysis duration, peritoneal dialysis modality, diabetes mellitus, baseline albumin, and baseline ultrafiltration volume were not significantly correlated with the change in ultrafiltration volume. CONCLUSION: Icodextrin significantly augments ultrafiltration volumes in patients with refractory fluid overload. A high peritoneal membrane transporter status is the best predictor of a favourable ultrafiltration response to icodextrin.

Adult↗
PubMed1991

Large-volume paracentesis versus dialytic ultrafiltration in the treatment of cirrhotic ascites.

We compared the clinical efficacy and safety of large-volume paracentesis and dialytic ultrafiltration in the treatment of refractory ascites in cirrhotic patients. A group of cirrhotic subjects (age 49-80 years) were randomly allocated to either continuous paracentesis (1-1.5 l/hour) or dialytic ultrafiltration until disappearance of ascites. Each patient was maintained on bed rest, fluid restriction (1 l/day) and a low (25 mmol/day) sodium diet for 14 days. Five patients (three in the paracentesis group and two in dialytic ultrafiltration group) developed massive ascites 3-5 months later, and received the crossover treatment. The average volume of fluid removed was similar in the two groups (4.70 +/- 1.47 l for dialytic ultrafiltration versus 4.69 +/- 1.84 l for paracentesis), but the treatment period was significantly shorter with dialytic ultrafiltration. The plasma creatinine significantly increased three days after paracentesis but did not increase in patients treated with dialytic ultrafiltration. There was an initial fall in mean arterial pressure during the first two hours of either treatment; a further fall in blood pressure was observed with paracentesis but not with dialytic ultrafiltration. Pretreatment plasma renin activity was elevated, but was not altered by either treatment. Plasma atrial natriuretic peptide levels were in the high-normal range before treatment. Paracentesis was associated with a delayed fall in plasma atrial natriuretic peptide, while dialytic ultrafiltration induced a modest but significant rise. No complication was experienced with dialytic ultrafiltration in the two weeks following treatment, but four of the eight patients who underwent paracentesis had developed severe complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1985

Volumetrical microcomputer-based ultrafiltration monitor for hemodialysis.

Uniform and controlled ultrafiltration during hemodialysis can decrease dialysis side effects. One of the prerequisites for this treatment is accurate measurement of ultrafiltration. The best method currently available for ultrafiltration measurement is based on the volumetrically measured change of dialysate flow over the dialyzer. We have developed an ultrafiltration monitor (UFM) for hemodialysis using two micro-oval flowmeters that measure the flow rate of the dialysate entering and leaving the dialyzer. Correction for intrinsic error was achieved with an Acorn microprocessor, in a calibration run without ultrafiltration and constant, equal flow through both flow transducers. The accuracy of the UFM in vitro was 99.4% of the mean total ultrafiltration, with a correlation coefficient of 0.998 (n = 8) with actual ultrafiltration. In vivo, in which UFM was compared with bed scale body weight monitoring, a correlation coefficient of 0.97 (n = 82) was obtained, and an accuracy of 90% of total ultrafiltration as measured by the change in body weight. Therefore, this UFM provides a cheap and reliable method for ultrafiltration measurement.

Humans↗
PubMed1995

Does impaired transcellular water transport contribute to net ultrafiltration failure during CAPD?

OBJECTIVES: To assess the contribution of transcellular water transport in net ultrafiltration failure during continuous ambulatory peritoneal dialysis (CAPD). DESIGN: Retrospective. SETTING: Renal Unit, Academic Medical Center, Amsterdam. PATIENTS: One group of 6 patients with clinical severe ultrafiltration loss and a group of 10 stable CAPD patients without ultrafiltration problems. INTERVENTION: In all patients, two peritoneal permeability tests were done within one week, using glucose 1.36% dialysate on one day and glucose 3.86% on the other day. Dextran 70 was used as a volume marker. RESULTS: The difference in net ultrafiltration between 3.86% glucose and 1.36% glucose dialysate was 569 +/- 51 mL (control) and 153 +/- 103 mL (poor ultrafiltration group; p < 0.005). The dialysate/plasma (D/P) concentration ratios increased in both groups with glucose 1.36%. When using 3.86% glucose, the D/P ratio decreased in the control group with a median minimum value one hour after completion of inflow. It is possible that sieving of sodium was due to transcellular water transport by crystalloid osmosis during the hypertonic dwell, as a dissociation between the transport of water and sodium is unlikely to occur in transport through the much larger intercellular pores. The D/P sodium ratio after one hour was related to the mass transfer area coefficient (MTC) of creatinine and the percentage of glucose absorption in the control group. No decrease in D/P ratio was found in the poor ultrafiltration group. This suggests impairment of transcellular water transport. No significant differences were present between both groups with regard to MTC creatinine (10.2 and 14.0 mL/min), glucose absorption (71% and 71%), effective lymphatic absorption rate (1.34 and 1.01 mL/min), and residual volume (248 and 178 mL). Only 1 patient in the ultrafiltration loss group continued with CAPD. The others had to be transferred to hemodialysis; 1 of them developed sclerosing peritonitis. CONCLUSION: The sieving of sodium during CAPD may be caused by transcellular water transport. Deficient sieving as assessed by the absence of a decreased D/P ratio after one hour of a hypertonic dwell suggests impairment of transcellular water transport. This is associated with severe ultrafiltration failure. It indicates that failure of transcellular water transport, possibly by glycosylation of specific proteins on the cell membrane, may be considered one of the causes of ultrafiltration failure during CAPD.

Biological Transport↗
PubMed1998

Modified ultrafiltration improves left ventricular systolic function in infants after cardiopulmonary bypass.

OBJECTIVE: Our objective was to test the hypothesis that use of modified ultrafiltration after cardiopulmonary bypass improves intrinsic left ventricular systolic function in children. METHODS: Twenty-one infants undergoing cardiopulmonary bypass were instrumented with ultrasonic dimension transducers, to measure the anteroposterior minor axis diameter, and a left ventricular micromanometer. Patients were randomized to modified ultrafiltration (n = 11, age 226 +/- 355 days, weight 6.7 +/- 3.1 kg) or control (n = 10, age 300 +/- 240 days, weight 7.0 +/- 2.5 kg) (all differences p > 0.05 between groups). Left ventricular systolic function was assessed by means of the slope of the preload-recruitable stroke work index. Myocardial cross-sectional area was measured by echocardiography. Data were acquired immediately after separation from bypass, at steady state, and during transient vena caval occlusion. Data acquisition was repeated after 13 +/- 5 minutes of modified ultrafiltration or after 12 +/- 5 minutes without modified ultrafiltration in the control group. Inotropic drug support was the same at both study points. RESULTS: In the modified ultrafiltration group, the filtrate volume was 363 +/- 262 ml. The hematocrit value increased from 26.0% +/- 2.7% to 36.7% +/- 9.5% (p = 0.018), myocardial cross-sectional area decreased from 3.72 +/- 0.35 cm2 to 3.63 +/- 0.36 cm2 (p = 0.04), end-diastolic length increased from 25.6 +/- 9.0 mm to 28.8 +/- 9.9 mm (p = 0.01), and end-diastolic pressure fell from 5.6 +/- 0.8 mm Hg to 4.2 +/- 0.8 mm Hg (p = 0.005), suggesting an improved diastolic compliance. In the control group, the hematocrit value, myocardial cross-sectional area, end-diastolic length, and pressure did not change (all p > 0.05). Mean ejection pressure increased in the ultrafiltration group (p = 0.001) but did not change in the control group (p = 0.22). The slope of the preload-recruitable stroke work index increased after ultrafiltration from 52.3 +/- 52.0 to 74.2 +/- 66.0 (10[3] erg/cm3) (p = 0.02) but did not change in the control group (p = 0.07). One patient from each group died in the postoperative period. Patients in the ultrafiltration group received less inotropic drug support in the first 24 hours after the operation (156.62 +/- 92.31 microg/kg in 24 hours) than patients in the control group (865.33 +/- 1772.26 microg/kg in 24 hours, p = 0.03). CONCLUSIONS: Use of modified ultrafiltration after cardiopulmonary bypass improves intrinsic left ventricular systolic function, improves diastolic compliance, increases blood pressure, and decreases inotropic drug use in the early postoperative period.

Cardiopulmonary Bypass↗