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PubMed1990

Pathophysiology of ultrafiltration in peritoneal dialysis.

Pathophysiology of peritoneal ultrafiltration is analyzed in the present study. Peritoneal equilibration test is the easiest procedure to study in detail the possible causes of failure to control the ultrafiltration rate in patients undergoing peritoneal dialysis. Membrane failure, reduction in peritoneal blood flow, excessive lymphatic reabsorption catheter malposition, and fluid sequestration are the most common causes of ultrafiltration loss. Pharmacologic manipulation of peritoneal membrane, correction of mechanical inconvenients, reduction in peritonitis rate and in the level of immunostimulation of the mesothelial macrophages, together with a careful policy in terms of glucose concentration in the dialysate and dwell times may contribute not only to treat different forms of ultrafiltration loss but also to prevent their incidence.

Algorithms↗
PubMed1990

New ultrafiltration method for free thyroxin compared with equilibrium dialysis in patients with thyroid dysfunction and nonthyroidal illness.

This new ultrafiltration method for free thyroxin in serum [FT4(U)] is based on radioimmunoassay of the free hormone fraction in ultrafiltrates obtained by centrifuging serum samples in Unisep Ultracent-10 ultrafiltration devices. We compared the results obtained with those by an equilibrium dialysis method [FT4(D)]. In 36 euthyroid healthy subjects, the mean FT4(U) concentration was 24.2 pmol/L and the mean FT4(D) concentration 14.8 pmol/L. In hyperthyroid and hypothyroid patients, results by the ultrafiltration method were also approximately twice as high as those obtained by the dialysis method. In 23 patients with various nonthyroidal illnesses, mean FT4(U) was 41.2 pmol/L and mean FT4(D) 19.8 pmol/L. The mean FT4(U)/FT4(D) ratio in patients with nonthyroidal illnesses (1.97) was not significantly higher than in control subjects (1.68), making it unlikely that the increase in serum FT4 is caused by weakly protein-bound and therefore dialyzable inhibitors of thyroxin binding to carrier proteins. However, two nonthyroidally ill patients with a clearly increased FT4(U) but a normal FT4(D) concentration might have had such inhibitors, whereas for two other nonthyroidally ill patients a high molar ratio of free fatty acids to albumin is a more likely explanation for increased FT4(U) and FT4(D) concentrations. On theoretical grounds, we consider the FT4(U) concentrations analytically more nearly accurate than FT4(D) values for all patient groups studied.

Adult↗
PubMed1986

Comparative analysis of two volumetrical ultrafiltration monitors for hemodialysis.

Controlled ultrafiltration (UF) during hemodialysis may prevent dialysis associated hypotension. A prerequisite for controlled ultrafiltration is an accurate measurement of ultrafiltration. Volumetric measurement is the best currently available method for this purpose. In this study we compared in a clinical setting two volumetric ultrafiltration monitors (UFM): one device constructed in our hospital using oval flow-meters (UFM-N) and the other using electromagnetic flow transducers (UFM-G: UFM 10-2, Gambro Lund Sweden). The UF measurements of both UFM's were compared with UF calculated from bed scales weight monitoring and standard scales determinations. During dual needle hemodialysis (n = 8) with a hollow fiber dialyzer the accuracy of the UFM-N was 91% and that of the UFM-G 97%. During dual needle dialysis with a parallel flow dialyzer the UFM-N appeared to be more sensitive for pulsatile changes in the dialysate flow due to the greater compliance of this type of dialyzer. The accuracy of the UFM-N in this setting was 80%, while that of the UFM-G was 87% (n = 11). During single needle dialysis with a parallel flow dialyzer (n = 14) only the UFM-G was tested and it measured UF with an accuracy of 92%. Finally the UFM-G can control UF actively by adjusting the TMP to obtain a given UF rate. The accuracy of the UFM-G in this setting was 94%, and the linear regression correlation coefficient between planned UF and actually obtained UF was 0.974 (n = 61). In conclusion volumetric monitoring of UF is accurate and reliable, but its accuracy is dependent on the type of dialyzer used.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Weight↗
PubMed1986

Effect of ultrafiltration on plasma concentrations of atrial natriuretic peptide in haemodialysis patients.

We have investigated the influence of body fluid volume status on plasma levels of immunoreactive atrial natriuretic peptide (irANP) in eight uraemic patients on chronic haemodialysis, including two diabetics with severely impaired reflex control of the heart. IrANP was significantly higher in volume-expanded uraemic patients (36 +/- 16 pg/ml) than in a group of seven age and sex-matched normal subjects (14 +/- 2 pg/ml), and fell consistently, approaching the normal range after the removal of 2.0-4.3 litres of isotonic plasma ultrafiltrate (by isolated ultrafiltration). Plasma levels of the hormone were strictly related to right atrial pressure. The irANP response to ultrafiltration in the two diabetics was similar to that of the other uraemic patients. The results suggest that the elevated irANP levels found in volume-expanded uraemic patients depend largely on fluid overload per se. The preserved irANP response to ultrafiltration of the two diabetics with severe autonomic neuropathy indicates that in chronic renal failure irANP secretion may be regulated independently from autonomic influences.

Adult↗
PubMed1988

CAPD with preservation of ultrafiltration capacity in infants and young children during the first 18 months of treatment.

Prolonged CAPD is reported to cause a gradual loss of ultrafiltration capacity. The composition of the dialysis fluid and the occurrence of recurrent peritonitis episodes are assumed to be responsible for this diminished ultrafiltration. A group of 22 infants and young children (mean age 3.8 years) is described. CAPD was performed in these children for a mean period of 17.8 months. There was no loss of ultrafiltration capacity, determined by the repeated volume method, in the first 18 months of treatment. Urea clearance remained stable. These data could be calculated in half of the patients, the other patients behaved clinically in the same way. In one patient ultrafiltration capacity decreased after 4 years of treatment. It is concluded that, in young children, CAPD is a reliable renal replacement therapy, although peritonitis remains a matter of concern.

Child↗
PubMedDate not supplied

Technical and clinical evaluation of a new system for ultrafiltration control during hemodialysis.

A new system for ultrafiltration control during hemodialysis is described. The apparatus consists of a computer operated system of load cells that register variations in weight of the outlet dialysate versus inlet dialysate. Once the weight loss of the patient has been established, the gravimetric control operates on the dialysate circuit to obtain the transmembrane pressure adequate to achieve the desired ultrafiltration rate and patient weight loss. The system can be used as a complete dialysis machine or as a separate module that can be adapted to any standard dialysis machine. This module was tested in more than 220 dialysis sessions, using different membranes and ultrafiltration rates. The difference between the scheduled and the real weight loss was always less than 100 g at the end of the dialysis session. The number of technical interventions required were few, as was the rate of complications related to the system. The system is safe and reliable and offers a low cost opportunity to improve dialysis tolerance by accurate and progressive ultrafiltration during the session.

Body Weight↗
PubMed1987

Ultrafiltration by hemofilter--a new therapeutic measure in intractable ascites.

The clinical efficacy of ultrafiltration (UF) of ascitic fluid with hemofilter in the treatment of intractable ascites associated with chronic liver disease or intraabdominal malignancy was studied in fifteen patients. The ascitic fluid was reinfused into the peritoneal cavity after ultrafiltration. An average of 6.2 liters of fluid was removed during 4.4 hours of ultrafiltration with no significant change in blood pressure, central venous pressure, hemoglobin, platelets or plasma creatinine. Ascitic fluid albumin rose significantly immediately after the procedure (from 5.2 +/- 4.3 gm/L to 31.9 +/- 30.0 gm/L, P less than 0.01). The plasma albumin concentration increased significantly at the end of UF (P less than 0.001). Also there was a significant increase in urine output (P less than 0.001), urinary sodium excretion (P less than 0.001), and endogenous creatinine clearance (P less than 0.01) during the 48 hours following UF. There was no evidence of hemodynamic, renal or hematological dysfunction, and other complications, including encephalopathy, peritonitis and variceal bleeding were not experienced. Ultrafiltration of ascitic fluid with hemofilter may be safely used in the temporary relief of refractory ascites due to cirrhosis or intra-abdominal malignancy.

Adolescent↗
PubMedDate not supplied

Modification of peritoneal ultrafiltration capacity in children undergoing peritoneal dialysis.

Eleven children (7 girls and 4 boys) 2 1/2 to 17 years and 8 months of age were treated with CAPD for periods ranging from 6 to 31 months. All children were treated with commercially available dialysate solutions containing lactate. Peritoneal ultrafiltration capacity (PUFC) decreased progressively in all children without accompanying decrease in peritoneal urea and creatinine clearances. Five children developed membrane failure with negative ultrafiltration. One episode of peritonitis occurred in one of these 5 children and in 4 of them only 1.5% glucose solutions had been used. After an initial period (ranging from 14 to 31 months) of CAPD, 2 children were treated with Intermittent Ambulatory Peritoneal Dialysis (IAPD) and two others with Intermittent Cycling Peritoneal Dialysis (ICPD). In these 4 children, PUFC increased within one month from -3.75 ml/kg/day to + 5 ml/kg/day. By providing a shorter dwell time, IAPD and ICPD may allow a reduction in net inward transport of glucose, the maintenance of osmolar gradient and preservation of ultrafiltration capacity. Furthermore, periods of rest may allow some recovery from the progressive deterioration of the peritoneum resulting from long-term irrigation of the peritoneal cavity. These results indicate that IAPD and CPD may be superior to CAPD to maintain the ultrafiltration capacity of the peritoneum.

Adolescent↗
PubMed1985

Ultrafiltrate and total platinum in plasma and cerebrospinal fluid in a patient with neuroblastoma.

Ultrafiltrate and total plasma and cerebrospinal fluid (CSF) platinum concentrations were examined in a patient with neuroblastoma following a 2-hour infusion of 120 mg/m2 of cisplatin. Total plasma platinum was 93.4% bound, while the ultrafiltrate of plasma accounted for the remaining 6.6%. The CSF ultrafiltrate resulted in equivalent concentrations of platinum to total CSF platinum. CSF concentrations were 2.9% of the total plasma platinum and 43.5% of the ultrafiltrate plasma platinum 2 hours after the end of the infusion.

Brain Neoplasms↗
PubMed1985

[Continuous arteriovenous hemofiltration in acute renal failure. Value of regulating the rate of ultrafiltration].

Continuous arteriovenous hemofiltration (CAVH) requires constant supervision and frequent readjustment of the rate of infusion of the substitution fluid because of variable filtration rate. In order to lighten the management of patients treated with CAVH, an ultrafiltration-pump assisted CAVH was used in 16 patients with oliguric renal failure and cardiovascular instability treated in the intensive care unit. A plate hemofilter (Biospal) was used which is equipped with the high hydraulic permeability AN 69 S membrane. The driving pump was set in order to modulate the ultrafiltration rate from 400 to 1000 ml/h. Ultrafiltration-pump assisted CAVH was given for 8.1 +/- 5.3 days and the filtration volume was 16.3 +/- 3.1 l/day. The mean life span of the hemofilter was 36.4 +/- 27.3 hours. No adverse reaction toward the artificial membrane was detected. Adequate control of fluid balance and electrolyte and acid-base homeostasis were obtained allowing parenteral nutrition. However, in two instances additional hemodialysis was required to adequately control urea generation. Ultrafiltration-pump assisted CAVH proved to be a simple and effective method of fluid removal and urea subtraction by convective transport. Maintenance of stable fluid balance and parenteral nutrition without osmotic disequilibrium was allowed. The pump driven hemofiltration allows optimal use of the filter.

Acute Kidney Injury↗
PubMed1977

Experience with a low volume ultrafiltration cell in small children*.

A low volume (16 ml) ultrafiltration cell was used ten times in two small, fluid overloaded children to remove plasma water. The device was simple to use and, at slow blood flow rates (25-50 ml/minutes) and low transmembrane pressures (10-30 mm Hg), provided controlled removal of excess fluid. Although no major complications were encountered, hypothermia and hypotension (at ultrafiltrate flux rates exceeding 0.5 ml/kg/minute) were observed. The ultrafiltrate solute concentration was similar to plasma and no significant shifts in serum electrolytes were induced. The ultrafiltrate protein concentration of 64 to 2,760 mg/dl was much higher than previously reported.

Blood Flow Velocity↗
PubMed1979

[Hemodynamic changes during ultrafiltration and hemodialysis in uremia].

1. The ultrafiltration causes a reduction of blood pressure and minute output of the heart which is compensated by vasoconstriction and thus a decrease of blood pressure is prevented. 2. Changes in the salt concentrations with reduction of the osmolarity during the dialysis without simultaneous ultrafiltration lead to vasodilation and hypotension despite increase of the minute output of the heart. 3. During a usual haemodialysis (i.e. dialysis with simultaneous ultrafiltration) the vasodilating effect of the dialysis may abolish the vasoconstrictive effect of the ultrafiltration and thus may be the cause of the hypotension.

Adult↗
PubMed1978

Ultrafiltration without dialysis for removal of fluid and solutes in uremia.

A review is presented of the use of sequential ultrafiltration and dialysis to facilitate asymptomatic fluid removal in dialysis patiens, and the use of ultrafiltration as a method to remove uremic compounds. In sequential ultrafiltration and dialysis, the two physical principles in hemodialysis are separated in time. Hypotension and other side-effects which may be encountered when the two procedures take place simultaneously are eliminated or minimized by sequential treatment. Hemofiltration is an entirely new form of treatment, which mimics the performance of the human kidney better than hemodialysis. The blood is purified by ultrafiltration and fluid replacement either before or after the ultrafilter device. Preserved well-being or improvement in clinical condition have been reported after prolonged treatment with hemofiltration in spite of relatively inefficient elimination of small molecules as urea and creatinine. The most consistent beneficial effect of hemofiltration appears to be better blood pressure control in severely hypertensive patients than with conventional hemodialysis.

Humans↗
PubMed1984

A pressure ultrafiltration method for serum free drug determination. Comparison with equilibrium dialysis using normal and uraemic sera.

The clinical methods most frequently used for serum free drug determinations are equilibrium dialysis and ultrafiltration. Both methods have usually been considered equal when comparisons have been made on normal sera. The purpose of the study was to develop a reliable and rapid method for serum free drug determinations especially for disease states where there is an increased free fraction. This modification of the pressure ultrafiltration method proved to meet these demands. The method was tested in vitro by adding radiolabelled phenytoin in different concentrations to normal and uraemic sera. The within-run and between-run variation coefficients were both under 5%. In comparison with equilibrium dialysis the values obtained by the ultrafiltration method were 0.65% lower (p less than 0.001, Student's paired t-test) in normal and 0.37% lower (non-significant) in uraemic sera. There are some theoretical grounds to presume that the results obtained by means of the pressure ultrafiltration method would better reflect the real values than those obtained by means of equilibrium dialysis.

Dialysis↗
PubMed1982

An improved ultrafiltration method for determining free testosterone in serum.

In this method, we use the Amicon MPS-1 centrifugal ultrafiltration device and the YMB membrane in measuring free testosterone in serum. Two independent assays are combined: total testosterone and the ultrafiltrable fraction of added [3H]testosterone. The unbound fraction is determined in 0.15-0.5 mL ultrafiltrates of 0.6 to 1 mL of variably diluted serum that has been equilibrated with [3H]testosterone at 37 degrees C. The assay is rapid (less than 1 h), practicable (requires 0.6 mL of serum), and reproducible (CV 3.2% within assay, 3.9% between assays). Accuracy was evaluated as the fraction of free testosterone in the ultrafiltrate of dialyzed serum vs that in a prior dialysate; they were the same confirming the validity of the free testosterone measurement. Samples from ostensibly healthy men and women and from hirsute and pregnant women gave results that agreed with those obtained by equilibrium dialysis. Total testosterone concentrations for normal and hirsute women showed considerable overlap, but data on free testosterone concentrations in these populations were better resolved.

Adult↗
PubMed1980

An improved ultrafiltration method for free thyroxine and triiodothyronine in serum.

We describe an ultrafiltration technique for rapidly and directly determining free triiodothyronine or free thyroxine, or both. After equilibrating serum at 37 degrees C with purified tracer of high specific activity, we placed 0.15 mL of serum in 2.8 mL of phosphate buffer (0.1 mol/L, pH 7.4) in the ultrafiltration cell and obtained successive 0.2- and 0.6-mL fractions of protein-free ultrafiltrate. Under our conditions free ligand concentration was independent of flow rate. After purifying the second fraction with protein-coated charcoal, we could determine the proportion of free triiodothyronine or free thyroxine. Samples from normal adult men and women, including women who were taking oral contraceptives or were pregnant, and from hypo- and hyperthyroid patients gave results that agreed with those obtained by equilibrium dialysis. Speed is the main advantage of the method: one technologist can complete the procedure in 2 h and, using a multi-micro-ultrafiltration system, can process many samples in one day. For laboratories where index-type reactions are performed routinely and direct free triiodothyronine or free thyroxine is determined only on selected specimens, this method is superior to dialysis. It is also very convenient for rapidly purifying tracers, to at least 97% radiochemical purity, with 94% recovery and no dilution.

Dialysis↗
PubMed1978

Importance of the plasma refilling rate in the genesis of hypovolaemic hypotension during regular dialysis and controlled sequential ultrafiltration-haemodialysis.

The effects of ultrafiltration (UF) on plasma volume (PV) have been studied in eight patients using regular dialysis (RD) and controlled sequential ultrafiltration-haemodialysis (CSU) performed with a Rhodial 75 dialysis system. For a given value of UF the reduction of PV is determined by the plasma refilling rate. During CSU ultrafiltration induces a rapid increase in oncotic pressure without decreasing plasma osmolality. The high plasma refilling rate which can reach 1500 ml/hr allows moderate hypovolaemia despite high rates of UF and contributes to the usual good clinical tolerance of CSU. During RD a rapid decrease in plasma osmolality contributes to a water shift from the vascular space towards the interstitial and intracellular spaces and severe hypovolaemia can occur despite moderate ultrafiltration. CSU offers an adequate treatment for sodium overloaded patients with hypervolaemia, but is of no benefit in routine conditions.

Humans↗
PubMed1980

[Experimental studies of the treatment of hypotensive blood circulation disorders during sequential ultrafiltration hemodialysis].

Particularly in risk patients who in the condition of hyperhydration underwent sequential ultrafiltrations-haemodialysis treatment the decrease of blood pressure which appears in individual cases under the treatment is negatively decisive for the success in therapy. In 33 hyperhydrated patients who underwent dialysis, therefore, with the help of the fourfold concentrated human dry plasma DAB 7 the influence of a combined osmo- and substitution therapy on this circulatory complication was investigated. Under the sequential ultrafiltration by means of application of human dry plasma also at an initial decrease of blood pressure not only a stabilisation, but also an increase of blood pressure is achieved. This favourable circulatory behaviour continues also during the following haemodialysis, Apparently by the application of the human dry plasma physiological compensation mechanisms are evoked by various factors such as pharmacological effects on the excitable structures by sodium, potassium and catecholamines and physical effects on the plasma volume by increase of the osmolality and increase of the oncotic pressure. The use of human dry plasma allows the performance of an ultrafiltration treatment as well as of a haemodialysis in hyperhydrated risk patients who are in a circulatory collapse and thus considerably enlarges the area of indication of the sequential ultrafiltration dialysis treatment.

Adult↗