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International Urology and Nephrology Jul 2014Dialysis-dependent patients are particularly susceptible to the toxic effects of aluminum (Al) because of their impaired ability to eliminate it. Al contamination of... (Review)
Review
PURPOSE
Dialysis-dependent patients are particularly susceptible to the toxic effects of aluminum (Al) because of their impaired ability to eliminate it. Al contamination of dialysis fluid remains a threat in this population. The mechanism for Al diffusion across dialysis membranes is not well established. Our objective is to verify, in AL-exposed patients, the postulate that the direction of Al transfer is predicted by the concentration gradient between free diffusible plasma Al and dialysate Al.
METHODS
A systematic review of the literature was performed. Only papers which included Al plasma concentration ([Al]p), Al dialysate concentration ([Al]d) and direction of Al transfer (positive = from dialysate to plasma, negative = from plasma to dialysate) were selected. We also included four patients from our own cohort. Assuming that [Al]p has an ultrafiltrable fraction between 17 and 23%, cases were considered in keeping with our hypothesis if any of the following scenarios was present: negative Al transfer when [Al]d < [Al]p*23% and positive Al transfer when [Al]d > [Al]p*17%.
RESULTS
The search yielded 409 articles, of which 12 were selected for review. When reviewing individual patients for analysis, 108 out of 115 (94%) patients followed our hypothesis. By further excluding cases in which Al transfer could not be determined, only three out of 111 patients were contrary to out hypothesis.
CONCLUSION
Comparing ultrafiltrable Al to dialysate Al permits to accurately predict the direction of Al transfer. The optimal [Al]d should be <20% of the maximally acceptable [Al]p. In order to follow K/DOQI guidelines ([Al]p < 20 μg/L), the [Al]d should therefore not exceed 4 μg/L. At the level presently supported by K/DOQI ([Al]d < 10 μg/L), [Al]p could realistically reach 50 μg/L and potentially cause toxicity.
Topics: Aluminum; Dialysis Solutions; Humans; Membranes, Artificial; Renal Dialysis; Ultrafiltration
PubMed: 24938693
DOI: 10.1007/s11255-014-0752-8 -
Seminars in Dialysis 2015The control of serum phosphorus by dialysis is made difficult by the fact that intradialytic blood levels tend to be low, and because phosphorus is removed almost... (Review)
Review
The control of serum phosphorus by dialysis is made difficult by the fact that intradialytic blood levels tend to be low, and because phosphorus is removed almost exclusively from the plasma during its passage through the dialyzer. The most practical way to increase phosphorus removal is to extend dialysis time, although attention to dialysis efficiency (surface area, advanced membrane, and higher blood and dialysate flow rates) also plays a role. Benefits of hemodiafiltration in helping control serum phosphorus have been claimed, but not found in all studies. Because serum phosphorus levels tend to plateau during the later parts of a dialysis session, extending weekly dialysis time is of greater benefit for phosphorus removal than for urea removal. Increasing dialysis frequency also probably has a small benefit. It appears that 18-30 hours of dialysis per week are required to obviate the need for phosphorus binders. Several promising models of phosphorus kinetics are under development. These may help predict the change in treatment on serum phosphorus levels, but their ability to do so has not yet been critically assessed.
Topics: Dialysis Solutions; Humans; Kidney Failure, Chronic; Phosphorus; Renal Dialysis
PubMed: 26358370
DOI: 10.1111/sdi.12439 -
Seminars in Dialysis Mar 2021For three-weekly hemodialysis, a single-pool Kt/V target of at least 1.4 together with a minimal dialysis dose Kt at 45 L for men and 40 L for women per each session is... (Review)
Review
For three-weekly hemodialysis, a single-pool Kt/V target of at least 1.4 together with a minimal dialysis dose Kt at 45 L for men and 40 L for women per each session is currently recommended. Fully automatic online calculation of Kt and Kt/V from conductivity or UV-absorbance measurements in the dialysate is standardly implemented on some hemodialysis monitors and makes it possible to estimate the dialysis dose without the need for blood or dialysate samples. Monitoring the UV-absorbance of the spent dialysate is the most direct method for estimating Kt/V as it does not require an estimate of V. Calculation of ionic dialysance from conductivity measurements is the most direct method for estimating Kt and BSA-scaled dialysis dose. Both ionic dialysance monitoring and UV-absorbance monitoring may help detect a change in urea clearance occurring during the session, but this change must be interpreted differently depending on the monitoring being considered. An abrupt decrease in urea clearance results in a decrease in ionic dialysance but, paradoxically, a sudden increase in estimated urea clearance provided by dialysate UV-absorbance monitoring. Healthcare teams who monitor both ionic dialysance and UV-absorbance in their hemodialysis units must be clearly informed of this difficulty.
Topics: Blood Urea Nitrogen; Dialysis Solutions; Female; Humans; Ions; Male; Monitoring, Physiologic; Renal Dialysis; Urea
PubMed: 33529406
DOI: 10.1111/sdi.12949 -
Seminars in Dialysis Sep 2022HDF prescription should be able to satisfy the delivery of an optimal dialytic convective dose. Several factors are implicated in this endeavor. High blood flow rate is...
HDF prescription should be able to satisfy the delivery of an optimal dialytic convective dose. Several factors are implicated in this endeavor. High blood flow rate is crucial to warranty processing an adequate blood volume and to ensure the highest shear rate per fiber needed to cleanse and prevent membrane fouling. A highly permeable dialyzer is needed with a surface area aligned to blood flow and performance needs. Anticoagulation requires specific adaptation in case of low molecular weight heparin use. By default, HDF prescription modality should ideally start by postdilution mode with a stepwise increment of convective dose by probing patient tolerance and efficacy. Alternative substitution modality should be considered if dialytic convective dose could not be achieved in the usual time frame. Convective dose prescription relies either on a manual mode (pressure control or volume control) or on automated mode (ultrafiltration control) depending on the technical options of the HDF machines. Dialysate flow rate is regulated by the HDF machine but should preferably keep constant dialysis fluid flowing the dialyzer with a Qb:Qd ratio of 1.4. Treatment time should not be reduced with HDF prescription. Treatment time should fit with patient tolerance (hemodynamic, osmotic, and solute shifts) and overall solute removal efficiency. Electrolytic prescription does not require specific adjustments as compared with conventional dialysis, but the patient needs to be monitored regularly and dialysate electrolyte adjusted to lab tests. A stepwise approach for implementing ol-HDF is preferable depending on the initial condition of the patient. Three particular cases may be considered: late-stage chronic kidney disease patient transitioning to renal replacement therapy, stable dialysis patient switching to HDF, and unstable or fragile patient or specific treatment schedule. Optimal dosing of HDF and personalized care to ensure treatment adequacy is the main goal for renal replacement therapy to improve patient outcomes. That should be ensured with HDF treatment.
Topics: Anticoagulants; Dialysis Solutions; Hemodiafiltration; Heparin, Low-Molecular-Weight; Humans; Kidney Failure, Chronic; Prescriptions; Renal Dialysis
PubMed: 35297521
DOI: 10.1111/sdi.13070 -
Nature Reviews. Nephrology Nov 2011The results of several studies assessing dialysis dose have dampened the enthusiasm of clinicians for considering dialysis dose as a modifiable factor influencing... (Review)
Review
The results of several studies assessing dialysis dose have dampened the enthusiasm of clinicians for considering dialysis dose as a modifiable factor influencing outcomes in patients with acute kidney injury. Powerful evidence from two large, multicenter trials indicates that increasing the dialysis dose, measured as hourly effluent volume, has no benefit in continuous renal replacement therapy (CRRT). However, some important operational characteristics that affect delivered dose were not evaluated. Effluent volume does not correspond to the actual delivered dose, as a decline in filter efficacy reduces solute removal during therapy. We believe that providing accurate parameters of delivered dose could improve the delivery of a prescribed dose and refine the assessment of the effect of dose on outcomes in critically ill patients treated with CRRT.
Topics: Acute Kidney Injury; Dialysis Solutions; Humans; Renal Dialysis
PubMed: 22045240
DOI: 10.1038/nrneph.2011.172 -
Giornale Italiano Di Nefrologia :... Feb 2020In Italy, over the last 50 years, dialysis has been the driving force of research in nephrology. The work of many Italian nephrologists has fueled progress in dialytic...
In Italy, over the last 50 years, dialysis has been the driving force of research in nephrology. The work of many Italian nephrologists has fueled progress in dialytic techniques worldwide, improving dramatically the quality of dialytic therapy. Our foreign colleagues unanimously agree that we have been the first to look into the complexities of dialysis, into the many differences between dialytic patients and how to best address this diversity. This has allowed us to adopt a holistic approach, deeply connected to technological innovation, with the aim of putting the patient center stage and creating a "precision dialysis".
Topics: Dialysis Solutions; Holistic Health; Humans; Italy; Nephrology; Peritoneal Dialysis, Continuous Ambulatory; Precision Medicine; Renal Dialysis
PubMed: 32068355
DOI: No ID Found -
Seminars in Dialysis Sep 2022Standard high-flux hemodialysis (HD) clears urea very efficiently but is less efficient at clearing uremic toxins with larger molecule size, which diffuse more slowly.... (Review)
Review
Standard high-flux hemodialysis (HD) clears urea very efficiently but is less efficient at clearing uremic toxins with larger molecule size, which diffuse more slowly. Hemodiafiltration (HDF) provides much higher convection rates, thereby reliably increasing the clearance of these larger toxins. However, the high ultrafiltration volumes employed by HDF significantly increase the concentration of proteins and lipids in the dialyzer blood compartment. This has the effect of increasing plasma viscosity, which opposes solute diffusion, and increasing plasma oncotic pressure, which opposes convection. The negatively charged plasma proteins also influence the equilibration of ions between dialysate and blood compartments. These effects result in varying conditions for solute transport along the length of the dialyzer and along the radial distance from the membrane within the dialyzer fibers. High-flux dialyzers can be designed to augment solute diffusion and internal filtration, so that their performance approaches that of HDF. This avoids some of the mechanical complexity of HDF, but such enhanced dialyzers may be more difficult to manufacture, control and monitor. Here, we present and discuss the most important physical phenomena associated with HDF therapy, providing an overview of its main concepts and principles. In particular, we discuss the physics of solute diffusion and convection and the factors affecting them, and we compare predilution or postdilution HDF with enhanced HD.
Topics: Blood Proteins; Dialysis Solutions; Hemodiafiltration; Humans; Lipids; Physics; Renal Dialysis; Urea
PubMed: 35869627
DOI: 10.1111/sdi.13111 -
Nephrology, Dialysis, Transplantation :... 1996Profiled dialysis is a new conceptual approach to patient intradialytic vascular instability. It is based on the continuous modulation of dialysis operative parameters,... (Review)
Review
Profiled dialysis is a new conceptual approach to patient intradialytic vascular instability. It is based on the continuous modulation of dialysis operative parameters, such as dialysate sodium and UF rate, according to pre-established profiles. The points to be defined for profiled dialysis are: (a) the patient's individual sodium and masses already stated; (b) the patient's individual algorithms to fit the clinically effective intradialytic variations in plasma sodium and sodium mass; (c) a mathematical model from which sodium and UF profiles are automatically worked out at the beginning of each session. The basic concept of profiled dialysis should evolve towards an ongoing "profiling' programme. This is based on the continuous on-line intradialytic adjustment of profiles according to the patient's emerging clinical requirements.
Topics: Biotechnology; Dialysis Solutions; Hemofiltration; Humans; Renal Dialysis; Sodium
PubMed: 9044344
DOI: 10.1093/ndt/11.supp8.63 -
Current Opinion in Nephrology and... Nov 2012Intradialytic hypotension (IDH) produces uncomfortable symptoms for the patient and reduces the efficiency of dialysis. (Review)
Review
PURPOSE OF REVIEW
Intradialytic hypotension (IDH) produces uncomfortable symptoms for the patient and reduces the efficiency of dialysis.
RECENT FINDINGS
IDH may be an important cause of vascular access thrombosis. Automatic biofeedback-controlled dialysis changes dialysate conductivity and ultrafiltration during dialysis. A number of trials suggest that automatic feedback-controlled dialysis improves IDH in part by improvement in myocardial stunning and preservation of cardiac function. However, the effects of automatic biofeedback dialysis are inconsistent between studies and sample sizes are small. Acetate even in small amounts may trigger IDH especially in predisposed patients. Cool temperature dialysate causes vasoconstriction, activates the sympathetic nervous system, preserves central blood volume, and mitigates IDH. Increasing the treatment time to at least 4 h three times a week and limiting dialysate and dietary sodium intake are effective ways to reduce IDH. Ultrafiltration profiling needs further work, but it appears that removing more fluid during the first hour of dialysis and reducing the rate later on may also reduce IDH.
SUMMARY
Adequate prescription and frequency of dialysis treatments, limiting dietary and dialysate sodium, ultrafiltration profiling, automatic biofeedback-controlled dialysis, avoidance of acetate, and cool temperature dialysate may be effective strategies to reduce IDH.
Topics: Automation, Laboratory; Dialysis Solutions; Equipment Design; Feedback; Humans; Hypotension; Kidney Failure, Chronic; Kidneys, Artificial; Renal Dialysis; Risk Factors; Time Factors; Treatment Outcome
PubMed: 22914686
DOI: 10.1097/MNH.0b013e3283588f3c -
Seminars in Dialysis 2010The 180 l of glomerular filtrate formed each day contain some 1100 g (2.5 pounds) of sodium chloride, of which only 5-10 g are excreted in the urine--95% is reabsorbed...
The 180 l of glomerular filtrate formed each day contain some 1100 g (2.5 pounds) of sodium chloride, of which only 5-10 g are excreted in the urine--95% is reabsorbed by the tubules. Some 425 g (nearly a pound) of sodium bicarbonate and 145 g of glucose are filtered, and more than 99% of both are reabsorbed. Also filtered, only to be reabsorbed, are substantial quantities of potassium, calcium, magnesium, phosphate, sulfate, amino acids, vitamins, and many other substances valuable to the body. It is no exaggeration to say that the composition of the blood is determined not by what the mouth takes in but by what the kidneys keep: they are the master chemists of our internal environment, which, so to speak, they manufacture in reverse by working it over completely some fifteen times a day…Our bones, muscles, glands, even our brains are called upon to do only one kind of physiological work, but our kidneys are called upon to perform an innumerable variety of operations. Bones can break, muscles can atrophy, glands can loaf, even the brain can go to sleep, without immediately endangering our survival; but should the kidneys fail to manufacture the proper kind of blood neither bone, muscle, gland nor brain could carry on (1).
Topics: Dialysis Solutions; Homeostasis; Humans; Kidney; Minerals; Renal Dialysis
PubMed: 21175830
DOI: 10.1111/j.1525-139X.2010.00788.x