Artificial Kidney Treatment Research Articles

Importance of convection in artificial kidney treatment.

Importance of convection in artificial kidney treatment.

Adaptive modelling of creatinine concentration in human blood

The need and importance of modelling and evaluation of renal function has grown with the increasing need for kidney replacement, design of artificial kidney and proper diagnosis and treatment of kidney disorders. This paper explores a fuzzy model of the creatinine concentration ( C r ) in human blood using adaptive Neurofuzzy Inference System (NFIS). This model aims to predict blood creatinine using blood urea, sodium and potassium without a need for actual measurement of C r in blood. The creatinine level in blood is an efficient tool for evaluation and assessment of renal function. The proposed model was validated by comparing the predicted creatinine values from the model with the experimental creatinine values. The obtained results showed that the developed model is capable of estimating the blood creatinine with a Root-Mean Square Error (RMSE) of 0.76 and also the predicted C r values agree closely with the experimentally measured C r values. Practically, this implies that the developed neurofuzzy model is adequate one for prediction of creatinine concentration in human blood and consequently will lead to a proper evaluation of renal function.

Effect of the skin nursing care to enhance the combined artificial kidney treatment of skin itching caused by uremia

Objective To investigate the effect of the skin nursing care to enhance the combined artificial kidney treatment of skin itching caused by uremia, in order to improve the quality of life of patients. Methods Forty patients of uremic pruritus were randomly divided into two groups. The patients of the control group took combination of artificial kidney treatment. The patients of the curative group took skin care besides the combination-type artificial kidney treatment. The visual analog scale (VAS) between the two groups were compared after 1 week nursing. Results The 16 patients of the control group needed artificial kidney-line combination treatment to cure skin itching after one week. The 1 patients of the curative group needed artificial kidney-line combination treatment to cure skin itching after one week. The scores between two groups showed no significantly different after 1 and 3 day's nursing, while those showed significantly different after 5 and 7 day's nursing. Conclusions The combination of artificial kidney-treatment Uremic itching skin of patients with skin care will not only enhance the implementation of full-bedy skin comfort, to alleviate symptoms of itching, but also to enhance the treatment of patients with comphance. Key words: Pruritus; Uremia; Skin care; Kidney,artificial

Bioartificial liver support anno 2001.

Despite maximal intensive care, mortality of acute fulminant hepatic failure is high: 60%-75% in several studies. In addition patients with chronic liver insufficiency suffer from a bad quality of life: all patients suffer from fatigue; symptoms of hepatic encephalopathy, jaundice, and itching are often present. Analogous to artificial kidney treatment in patients with renal failure, an artificial liver assist device is needed not only to bridge patients with fulminant hepatic failure to liver transplantation or own liver regeneration, but also to improve the quality of life of patients with chronic liver insufficiency. Several modalities of artificial liver support are under investigation, like plasma exchange, haemodialysis, haemadsorption, albumin dialysis, liver cell transplantation, and the bioartificial liver. Artificial livers based on only supportive detoxification function do not show significant improvement of survival in controlled studies. Bioartificial liver support systems have also the potential to support hepatic synthetic functions. Bioreactors can be charged with freshly isolated or cryopreserved porcine hepatocytes, but also by human hepatoma cell lines. Several uncontrolled studies in humans show safety of such a treatment, even by using porcine cells. Transmission of porcine endogenous retrovirus to recipients has not been found. Furthermore, beneficial effects have been reported on symptoms of hepatic encephalopathy, on the height of intracranial pressure and on hemodynamic parameters. By using porcine cells immunological problems (e.g., serum sickness) can be expected during treatments longer than one week. However, "proof of the pudding" in the sense of improvement of survival is not yet available. The creation of a "liver dialysis unit" in the near future depends mainly on the development of well-differentiated immortalized human hepatocytes. Some progress in this field has already been obtained.

Solute fluxes in different treatment modalities.

The principles governing solute flux or transport in different artificial kidney treatment modalities are reviewed. Solute clearance profiles were calculated for identical artificial kidney membranes during haemodialysis, haemofiltration and haemodiafiltration. It was shown that the clearance of small solutes depends largely on the dialysate flow rate and is similar when using either haemodialysis or haemodiafiltration. In contrast, clearance of middle molecules, especially low-molecular-weight proteins, depends largely on convective transport induced by high ultrafiltration rates and is maximized when using either haemofiltration or haemodiafiltration. Optimal fluxes for both small solutes and middle molecules can be achieved by using postdilution haemodiafiltration. Recent work has shown that use of the reduction in plasma concentration, even after normalization for changes in extracellular volume during therapy, is not an exact measure of beta2-microglobulin (and other low-molecular-weight proteins) clearance. It is proposed that beta2-microglobulin clearance be reported in future studies instead of the normalized reduction in beta2-microglobulin plasma concentration. Additional studies are necessary to determine the effects of postdialysis rebound on the calculated clearance for beta2-microglobulin and other high-molecular-mass uraemic toxins.

Continuous Hematocrit Monitoring Method in an Extracorporeal Circulation System and Its Application for Automatic Control of Blood Volume during Artificial Kidney Treatment

A two-frequency electrical conductivity method for measuring hematocrit has been developed for use in the continuous monitoring of circulating blood volume during artificial kidney treatment. Using this method, an algorithm for programmed control of blood volume also has been developed. This hematocrit measurement method is based on the beta-dispersion of blood conductivity, and the values measured during hemodialysis are in good agreement with the laboratory hematocrit values obtained by a Coulter counter. Programmed control of blood volume was used 29 times on 11 patients undergoing long-term dialysis. In each case, the blood volume was maintained within 2.5% of the desired level, and stable control was achieved even with disturbances caused by eating, change in body position, and so on. These methods can be used to study the relationship between blood volume and dialysis-induced hypotension during artificial kidney treatment and to achieve adequate ultrafiltration without clinical adverse effects.

Biochemical Definition of the Uremic Syndrome and Possible Therapeutic Implications

Renal failure is characterized by the progressive decline in the capacity of the kidneys to eliminate toxic solutes. In parallel, the “uremic syndrome” is depicted by a functional disturbance of enzymes, organelles, cells, and organs. This leads to an overall malaise that ultimately ends in coma and death unless artificial kidney treatment (dialysis) is started (1). The current conception of dialysis is highly aspecific. Emphasis has been on the elimination of small, water-soluble compounds such as creatinine and urea; however, the toxicity of the latter substances is still debatable. Uremic biological fluids are in fact complex mixtures containing innumerable interfering compounds that are the basis of the “uremic syndrome.” The uremic toxin probably does not exist (2). Despite several decades of study, the pathophysiology of the uremic syndrome remains ill defined. The possibilities in this domain have been improved recently by the introduction of new techniques for biochemical and biological evaluation and for separation and identification of the contents of complex biological fluids. The latter steps were made possible by the introduction of high-performance liquid chromatography (HPLC). In our laboratory, a stepwise strategy has been developed whereby complex uremic mixtures (sera or ultrafiltrates) are fractionated in several fractions (eluates). By evaluating the effect of uremic biological fluids on functional systems that are known to be disturbed in renal failure, we can pursue a fractionation of these biological fluids to identify the responsible compounds. This approach has already enabled us to identify the sub

人工腎臓における"ながれ"の問題

人工腎臓における"ながれ"の問題

Heterogeneity of the cardiovascular response to hemofiltration

Twenty-one stable maintenance hemodialysis patients were studied in a crossover format with hemofiltration to determine whether the lower incidence of symptomatic hypotension noted with hemofiltration could be correlated with changes in baroreflex function as tested using the cold pressor test and amyl nitrite inhalation study. Baroreflex function remained abnormal and unchanged in all patients in the face of a reduced incidence of symptomatic hypotension. Subdivision of the patients into frequent (greater than 1 episode/treatment) and infrequent (less than 1 episode/treatment) reactors during the hemodialysis control period resulted in the infrequent reactors, showing a significant increase in episodes of symptomatic hypotension/hemofiltration treatment where a significant reduction was noted with the frequent reactors. No clear correlation could be made between the incidence of symptomatic hypotension and the pre- to post-treatment change in body temperature. The presence of pretreatment hypertension, another previously identified correlate of symptomatic hypotension with hemodialysis, also could not be corroborated. Further, changes from baseline predialysis values in mean arterial pressure noted with hemofiltration could not be correlated with a changed incidence of symptomatic hypotension. We conclude that previously identified correlates of symptomatic hypotension noted in the hemodialysis setting may be dissociated during treatment with hemofiltration and that there is a heterogeneous patient response to this treatment. These data suggest that there are additional, as yet undetermined, pathophysiologic events that underly the symptomatic hypotension of artificial kidney treatment.

Screening of UV-absorbing solutes in uremic serum by reversed phase HPLC — Change of blood levels in different therapies

In order to screen UV-absorbing solutes in large numbers of uremic serum samples, an automated liquid Chromatographic method was developed. The method proved to be reliable and reproducible in more than 500 analyses. HPLC separation was performed using gradient elution on a 25-cm Ultrasphere Octyl reversed phase column, with 5 jiim particles. Characteristic profiles for the uremic state were obtained in the analyses of serum samples of 43 uremic patients before and just after artificial kidney treatment; hemodialysis ( n = 14), hemodiafiltration ( n = 13) and hemofiltration ( n = 16). In these profiles 20–40 peaks were resolved of which nine were ‘quantitated’ by peak height relative to a standard. Of these solutes creatinine, uracil, uric acid, hypoxanthine, indoxylsulfate, tryptophan and hippuric acid were identified. The heterogeneity of the population of uremic patients, with respect to the UV-absorbing solutes, was estimated. Significant differences of solute blood level changes during hemodialysis, hemodiafiltration and hemofiltration, were observed.

Urea movement across erythrocyte membrane during artificial kidney treatment

Previous work by other investigators indicates that erythrocyte urea and creatinine in uremic whole blood leaving the hemodialyzer do not move down the concentration gradients established by loss of these solutes across the dialyzer membrane. This puzzling disequilibrium is at odds with work indicating ready movement of both solutes across the erythrocyte membrane of nonuremic erythrocytes studied in vitro. The present study shows that contact with the dialyzer does not noticeably alter the erythrocyte membrane of the uremic patient, so that urea distribution between plasma and erythrocyte water is the same as that in the blood of normal control subjects. Furthermore, urea does not show a disequilibrium in concentration across the erythrocyte membrane in response to 50% dilution with a modified Ringer's solution but rather equilibrates swiftly and completely.

Long-term Follow up in Chronic Hemofiltration

The course of treatment is demonstrated in 72 patients with chronic renal insufficiency who were undergoing regular hemofiltration for more than 6 months. 29 patients were treated for more than 5 years and 8 for more than 6 years with hemofiltration exclusively, total experience comprising 2,985 patient months. Thus, 16% of all patients accepted for artificial kidney treatment were selected for this form of therapy. Main reasons for transfer from hemodialysis to hemofiltration were hypotension, hypertension and/or repeated episodes of overhydration. In 12 patients with severe drug- and dialysis-resistant hypertension, blood pressure was normalized within 6 weeks after transfer to hemofiltration. Whereas some parameters of lipid and bone metabolism showed a tendency towards normalization, a favourable effect of hemofiltration on neuropathy was not observed. Main causes of death were encephalomalacia and cardiac infarction. Contraindications for post-dilution hemofiltration are vascular access problems resulting in a reduced blood flow and severe catabolism with accumulation of low molecular protein metabolites or potassium.

Ultrafiltration monitor and automatic controller

An apparatus for automatic regulation and monitoring of ultrafiltration during artificial kidney treatment has been constructed on the basis first described in 1967 (Bier et al., A.S.A.I.O. 13, 227, 1967). Two concentric reservoirs, for fresh and spent dialyzate, respectively, are suspended from a balancing beam, capable of automatic taring. Circulation through the kidney is maintained by a positive displacement pump, and negative pressure regulated by a valve. The dialyzate flows through the kidney in a closed loop; the net weight of the two reservoirs does not change unless there is gain or loss of water across the membranes in the kidney. This is registered by the balancing beam, causing an impulse pump to reestablish the equilibrium of the beam. The desired rate of ultrafiltration can be preselected, and a feedback mechanism will adjust automatically the valve regulating the negative pressure, maintaining the desired rate. The sensitivity of the apparatus is 0·1 ml of ultrafiltration per min, which is probably in excess of even the most critical clinical needs. Rustrack recorders register continuously the rate of ultrafiltration and the negative pressure, while a totalizer gives a digital measure of total ultrafiltration from beginning of run.

Past, Present, and Future of Artificial Kidney Treatment

Abstract The past has seen the evolution of hemodialysis from a very complex operation to a systematized approach which allows the procedure to be instituted by minimally trained individuals. The first big advance in the application of hemodialysis to the problem of chronic renal insufficiency came in 1960 when a permanently implanted arteriovenous plastic fistulae was established. Improvements in dialyzer design and the logistics of hemodialysis since then have resulted in expansion of hemodialysis facilities. There is still a deficit between facilities available and suitable patients in need of therapy. Closure of this gap will depend upon a cheap, small, disposable dialyzer which most patients can operate themselves. In addition, an improvement in kidney transplantation results will remove many patients from the pool of those needing hemodialysis. It is likely that other medical applications of hemodialysis will be discovered in the future.

Alwall's Artificial Kidney Modified for the Treatment of Infants

We report the construction of a modified Alwall artificial kidney and hemodialysis treatment of a 9½-month-old infant.

Artificial Kidney Treatment of Bromism

Artificial Kidney Treatment of Bromism