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Pietribiasi M, Waniewski J, Leypoldt JK. Mathematical modelling of bicarbonate supplementation and acid-base chemistry in kidney failure patients on hemodialysis. PLoS One 2023; 18:e0282104. [PMID: 36827348 PMCID: PMC9955675 DOI: 10.1371/journal.pone.0282104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 02/07/2023] [Indexed: 02/25/2023] Open
Abstract
Acid-base regulation by the kidneys is largely missing in end-stage renal disease patients undergoing hemodialysis (HD). Bicarbonate is added to the dialysis fluid during HD to replenish the buffers in the body and neutralize interdialytic acid accumulation. Predicting HD outcomes with mathematical models can help select the optimal patient-specific dialysate composition, but the kinetics of bicarbonate are difficult to quantify, because of the many factors involved in the regulation of the bicarbonate buffer in bodily fluids. We implemented a mathematical model of dissolved CO2 and bicarbonate transport that describes the changes in acid-base equilibrium induced by HD to assess the kinetics of bicarbonate, dissolved CO2, and other buffers not only in plasma but also in erythrocytes, interstitial fluid, and tissue cells; the model also includes respiratory control over the partial pressures of CO2 and oxygen. Clinical data were used to fit the model and identify missing parameters used in theoretical simulations. Our results demonstrate the feasibility of the model in describing the changes to acid-base homeostasis typical of HD, and highlight the importance of respiratory regulation during HD.
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Affiliation(s)
- Mauro Pietribiasi
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Warsaw, Poland
- * E-mail:
| | - Jacek Waniewski
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Warsaw, Poland
| | - John K. Leypoldt
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Warsaw, Poland
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Gennari FJ, Marano M, Marano S. Replenishing Alkali During Hemodialysis: Physiology-Based Approaches. Kidney Med 2022; 4:100523. [PMID: 36032503 PMCID: PMC9411655 DOI: 10.1016/j.xkme.2022.100523] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The acid-base goal of intermittent hemodialysis is to replenish buffers consumed by endogenous acid production and expansion acidosis in the period between treatments. The amount of bicarbonate needed to achieve this goal has traditionally been determined empirically with a goal of obtaining a reasonable subsequent predialysis blood bicarbonate concentration ([HCO3-]). This approach has led to very disparate hemodialysis prescriptions around the world. The bath [HCO3-] usually chosen in the United States and Europe causes a rapid increase in blood [HCO3-] in the first 1-2 hours of treatment, with little change thereafter. New studies show that this abrupt increase in blood [HCO3-] elicits a buffer response that removes more bicarbonate from the extracellular compartment than is added in the second half of treatment, a futile and unnecessary event. We propose that changes in dialysis prescription be studied in an attempt to moderate the initial rate of increase in blood [HCO3-] and the magnitude of the body buffer response. These new approaches include either a much lower bath [HCO3-] coupled with an increase in the bath acetate concentration or a stepwise increase in the bath [HCO3-] during treatment. In a subset of patients with low endogenous acid production, we propose reducing the bath [HCO3-] as the sole intervention.
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3
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Sargent JA, Yamamoto T, Yamakawa T, De Waal D, Gennari FJ. Hemodialysis using a low bicarbonate dialysis bath: Implications for acid‐base homeostasis. Semin Dial 2020; 33:402-409. [DOI: 10.1111/sdi.12902] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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4
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Park S, Paredes W, Custodio M, Goel N, Sapkota D, Bandla A, Lynn RI, Reddy SM, Hostetter TH, Abramowitz MK. Intradialytic acid-base changes and organic anion production during high versus low bicarbonate hemodialysis. Am J Physiol Renal Physiol 2020; 318:F1418-F1429. [PMID: 32308019 DOI: 10.1152/ajprenal.00036.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The use of high dialysate bicarbonate for hemodialysis in end-stage renal disease is associated with increased mortality, but potential physiological mediators are poorly understood. Alkalinization due to high dialysate bicarbonate may stimulate organic acid generation, which could lead to poor outcomes. Using measurements of β-hydroxybutyrate (BHB) and lactate, we quantified organic anion (OA) balance in two single-arm studies comparing high and low bicarbonate prescriptions. In study 1 (n = 10), patients became alkalemic using 37 meq/L dialysate bicarbonate; in contrast, with the use of 27 meq/L dialysate, net bicarbonate loss occurred and blood bicarbonate decreased. Total OA losses were not higher with 37 meq/L dialysate bicarbonate (50.9 vs. 49.1 meq using 27 meq/L, P = 0.66); serum BHB increased in both treatments similarly (P = 0.27); and blood lactate was only slightly higher with the use of 37 meq/L dialysate (P = 0.048), differing by 0.2 meq/L at the end of hemodialysis. In study 2 (n = 7), patients achieved steady state on two bicarbonate prescriptions: they were significantly more acidemic when dialyzed against a 30 meq/L bicarbonate dialysate compared with 35 meq/L and, as in study 1, became alkalemic when dialyzed against the higher bicarbonate dialysate. OA losses were similar to those in study 1 and again did not differ between treatments (38.9 vs. 43.5 meq, P = 0.42). Finally, free fatty acid levels increased throughout hemodialysis and correlated with the change in serum BHB (r = 0.81, P < 0.001), implicating upregulation of lipolysis as the mechanism for increased ketone production. In conclusion, lowering dialysate bicarbonate does not meaningfully reduce organic acid generation during hemodialysis or modify organic anion losses into dialysate.
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Affiliation(s)
- Sarah Park
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York
| | - William Paredes
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York
| | - Matthew Custodio
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York
| | - Narender Goel
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York
| | - Deepak Sapkota
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York
| | - Anusha Bandla
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York
| | - Robert I Lynn
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York.,Kidney Medical Associates, Bronx, New York
| | | | - Thomas H Hostetter
- Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Matthew K Abramowitz
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York.,Institute for Aging Research, Albert Einstein College of Medicine, Bronx, New York.,Diabetes Research Center, Albert Einstein College of Medicine, Bronx, New York.,Fleischer Institute for Diabetes and Metabolism, Albert Einstein College of Medicine, Bronx, New York
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5
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Feriani M, Passlick-Deetjen J, La Greca G. Factors Affecting Bicarbonate Transfer with Bicarbonate-Containing CAPD Solution. Perit Dial Int 2020. [DOI: 10.1177/089686089501500409] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Objective To evaluate bicarbonate fluxes across the peritoneal membrane and bicarbonate gain in patients treated with continuous ambulatory peritoneal dialysis (CAPD) using dialysis solutions with different bicarbonate concentrations. Patients and Design Ninety-seven exchanges, using different dwell times and glucose and bicarbonate concentrations were performed in 43 stable CAPD patients. Dialysate effluent bicarbonate concentration and volumes were measured at different dwell times. Net dialytic bicarbonate gain was calculated. Patients’ acid-base status was determined at the middle of the dwell. Results In prolonged dwells (6 –12 hours)thedialysate effluent bicarbonate concentration correlated with arterial plasma bicarbonate concentration (F = 129, p < 0.0001), but not with ultrafiltration rate or dialysis solution bicarbonate concentration. In 4-hour dwells, effluent bicarbonate concentration correlated with both plasma bicarbonate concentration and ultrafiltration rate (F = 32.52, p < 0.0001 and F = 4.4, p < 0.05, respectively). The effluent bicarbonate concentration may be predicted from the patient's plasma bicarbonate concentration and net ultrafiltration rate for either a 4-hour or prolonged (6 –12 hours) dwell time. Net bicarbonate gain by the patient correlated with ultrafiltration rate, plasma bicarbonate, and dialysis solution bicarbonate concentration (F = 100.56, p < 0.0001 at 4 hours and F = 108.08, p < 0.0001 at 6 12 hours), with the ultrafiltration rate being the predominant parameter. Conclusions The effluent bicarbonate concentration is related to plasma bicarbonate concentration, with ultrafiltration playing a marginal role only during short dwells. However, the ultrafiltration rate has a profound effect on net patient bicarbonate gain. Multiple linear regression analysis allows the prediction of the effect of acid-base status, ultrafiltration, dwell time, and dialysis solution bicarbonate content on net patient bicarbonate gain. It seems that bicarbonate content in the CAPD dialysis solution should be progressively increased with increasing solution osmolality.
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Affiliation(s)
- Mariano Feriani
- Department of Nephrology, St. Bortolo Hospital, Vicenza, Italy
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6
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Richardson RM, Roscoe JM. Bicarbonate, L-Lactate and D-Lactate Balance in Intermittent Peritoneal Dialysis. Perit Dial Int 2020. [DOI: 10.1177/089686088600600404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Systemic acid-base values and bicarbonate and lactate balance were measured during dialysis in seven patients on chronic intermittent peritoneal dialysis (IPD). Dialysate contained 40 mM lactate, including 20 mM D-Iactate and 20 mM L-Iactate. Mean predialysis plasma bicarbonate concentration was 22 mM and rose to 25 mM after dialysis. The average net alkali gain during dialysis, calculated as lactate gain minus bicarbonate loss, was 80 mmoles/ treatment or 34 mmoles/day. There was considerable variability in alkali gain between patients and between treatments in the same patient. The major factors influencing alkali gain were peritoneal solute clearance and dialysate effluent volume, or ultrafiltration. Both in the balance study, and in a shorter study comparing the effects of consecutive 4.25% or 0.5 % glucose exchanges on net alkali gain, the authors demonstrated that increasing ultrafiltration reduced net alkali gain by about 26 mmoles/liter ultrafiltrate. D-Iactate appears to be quantitatively as important as Llactate in bicarbonate generation. Further longitudinal studies are required to define the relationship between net alkali gain, dietary hydrogen-ion generation and blood acid-base values.
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Affiliation(s)
- Robert M.A. Richardson
- From the Department of Medicine, Toronto General Hospital and Wellesley Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Janet M. Roscoe
- From the Department of Medicine, Toronto General Hospital and Wellesley Hospital, University of Toronto, Toronto, Ontario, Canada
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7
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Sargent JA, Marano M, Marano S, Gennari FJ. Changing dialysate composition to optimize acid‐base therapy. Semin Dial 2019; 32:248-254. [DOI: 10.1111/sdi.12779] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Marco Marano
- Hemodialysis Unit Maria Rosaria Clinic Pompeii, Naples Italy
| | - Stefano Marano
- Department of Information and Electrical Engineering and Applied Mathematics University of Salerno Fisciano, Salerno Italy
| | - F. John Gennari
- University of Vermont College of Medicine Burlington Vermont
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8
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Sargent JA, Marano M, Marano S, Gennari FJ. Acid-base homeostasis during hemodialysis: New insights into the mystery of bicarbonate disappearance during treatment. Semin Dial 2018; 31:468-478. [PMID: 29813184 DOI: 10.1111/sdi.12714] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In patients receiving hemodialysis, it has long been recognized that much more bicarbonate is delivered during treatment than ultimately appears in the blood. To gain insight into this mystery, we developed a model that allows a quantitative analysis of the patient's response to rapid alkalinization during hemodialysis. Our model is unique in that it is based on the distribution of bicarbonate in the extracellular fluid and assesses its removal from this compartment by mobilization of protons (H+ ) from buffers and other sources. The model was used to analyze the pattern of rise in blood bicarbonate concentration ([HCO3- ]), calculated from measurements of pH and PCO2 , in patients receiving standard bicarbonate hemodialysis. Model analysis demonstrated two striking findings: (1) 35% of the bicarbonate added during hemodialysis was due to influx and metabolism of acetate, despite its low concentration in the bath solution, because of the rapidly collapsing gradient for bicarbonate influx. (2) Almost 90% of the bicarbonate delivered to the patients was neutralized by H+ generation. Virtually all the new H+ came from intracellular sources and included both buffering and organic acid production. The small amount of added bicarbonate retained in the extracellular fluid increased blood [HCO3- ], on average, by 6 mEq/L in our patients. Almost all this rise occurred during the first 2 hours. Thereafter, blood [HCO3- ] changed minimally and always remained less than bath [HCO3- ]. This lack of equilibrium was due to the continued production of organic acid. Release of H+ from buffers is a reversible physiological response, restoring body alkali stores. By contrast, organic acid production is an irreversible process during hemodialysis and is metabolically inefficient and potentially catabolic. Our analysis underscores the need to develop new approaches for alkali repletion during hemodialysis that minimize organic acid production.
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Affiliation(s)
| | - Marco Marano
- Hemodialysis Unit, Maria Rosaria Clinic, Pompeii, Naples, Italy
| | - Stefano Marano
- Department of Information and Electrical Engineering and Applied Mathematics, University of Salerno, Salerno, Fisciano, Italy
| | - F John Gennari
- University of Vermont College of Medicine, Burlington, VT, USA
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9
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Heineken F, Brady-Smith M, Haynie J, Van Stone J. Prescribing Dialysate Bicarbonate Concentrations for Hemodialysis Patients. Int J Artif Organs 2018. [DOI: 10.1177/039139888801100111] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A rearranged equation of Sargent and Gotch (1) was used to determine dialysate bicarbonate concentrations for hemodialysis patients. Parameters in this equation include an estimate of the acid generated by each patient between treatments, an estimate for the dialyzer dialysance for bicarbonate, ultrafiltration rate, blood flow rate and a targeted mid-dialysis plasma bicarbonate concentration of 25 mEq/L. Nine patients were studied over a 35 week period to verify this method of determining each patient's dialysate bicarbonate concentration. Prescribed dialysate bicarbonate concentrations for the nine patients varied from 29 to 38 mEq/L with five patients having a prescribed value of 35 mEq/L. After a baseline period of five weeks, five patients switched from a 37 mEq/L acetate dialysate to their prescribed dialysate bicarbonate concentration. Four patients who had already been on bicarbonate dialysis at a concentration of 35 mEq/L were dialyzed with their prescribed dialysate bicarbonate concentrations. Patients were then followed for a study period of 30 weeks. The prescribed dialysate bicarbonate concentration resulted in more normal acid/base chemistries for both groups of patients. The results also demonstrate that chronic hemodialysis patients require individualization of dialysate bicarbonate concentrations.
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Affiliation(s)
- F.G. Heineken
- Research and Development, Medical Systems Division, COBE Laboratories, Inc. Lakewood, Colorado
- Department of Medicine, School of Medicine, University of Missouri, Columbia, Missouri, U.S.A
| | - M. Brady-Smith
- Research and Development, Medical Systems Division, COBE Laboratories, Inc. Lakewood, Colorado
- Department of Medicine, School of Medicine, University of Missouri, Columbia, Missouri, U.S.A
| | - J. Haynie
- Research and Development, Medical Systems Division, COBE Laboratories, Inc. Lakewood, Colorado
- Department of Medicine, School of Medicine, University of Missouri, Columbia, Missouri, U.S.A
| | - J.C. Van Stone
- Research and Development, Medical Systems Division, COBE Laboratories, Inc. Lakewood, Colorado
- Department of Medicine, School of Medicine, University of Missouri, Columbia, Missouri, U.S.A
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10
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Thews O. Model-Based Decision Support System for Individual Prescription of the Dialysate Bicarbonate Concentration in Hemodialysis. Int J Artif Organs 2018. [DOI: 10.1177/039139889201500801] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A decision support system has been developed that determines the optimal dialysate bicarbonate concentration in hemodialysis therapy for each patient individually. The knowledge about the behavior of the acid-base state during treatment has been provided by a mathematical model for the description of dynamic exchange processes during hemodialysis. This model simulates the sodium and water distribution, the acid-base state as well as the ventilation. The decision support system uses the model for the prediction of the end-dialysis acid-base state and calculates by means of linear optimization the dialysate bicarbonate concentration which is necessary to reach a specified end-dialysis state. If the aspired acid-base state can not be reached, the system varies the dialysate sodium concentration and the treatment time. The whole program can be used on a PC and is easy to use. One decision making process lasts between 10 seconds and 5 minutes depending on the computer.
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Affiliation(s)
- O. Thews
- Institute of Physiology and Pathophysiology, Johannes Gutenberg-Universität, Mainz - Germany
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11
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Abstract
The optimal approach to managing acid-base balance is less well defined for patients receiving hemodialysis than for those receiving peritoneal dialysis. Interventional studies in hemodialysis have been limited and inconsistent in their findings, whereas more compelling data are available from interventional studies in peritoneal dialysis. Both high and low serum bicarbonate levels associate with an increased risk of mortality in patients receiving hemodialysis, but high values are a marker for poor nutrition and comorbidity and are often highly variable from month to month. Measurement of pH would likely provide useful additional data. Concern has arisen regarding high-bicarbonate dialysate and dialysis-induced alkalemia, but whether these truly cause harm remains to be determined. The available evidence is insufficient for determining the optimal target for therapy at this time.
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Affiliation(s)
- Matthew K Abramowitz
- Division of Nephrology, Department of Medicine, and
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York
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12
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Kohn OF, Kjellstrand CM, Ing TS. Dual-concentrate bicarbonate-based hemodialysis: know your buffers. Artif Organs 2012; 36:765-8. [PMID: 22924819 DOI: 10.1111/j.1525-1594.2012.01524.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Klaboch J, Opatrná S, Matousovic K, Sefrna F, Havlín J, Schück O. Acid-base balance in peritoneal dialysis patients: a Stewart-Fencl analysis. Ren Fail 2009; 31:625-32. [PMID: 19817518 DOI: 10.3109/08860220903134076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Evaluation of acid-base disorders using the Stewart-Fencl principle is based on assessment of independent factors: strong ion difference (SID) and the total concentration of non-volatile weak acids (Atot). This approach allows for a more detailed evaluation of the cause of acid-base imbalance than the conventional bicarbonate-centered approach based on the Henderson-Hasselbalch principle, which is a necessary yet insufficient condition to describe the state of the system. The aim of our study was to assess acid-base disorders in peritoneal dialysis (PD) patients using both of these principles. METHODS A total of 17 patients with chronic renal failure (10 men), aged 60.7 (22-84) years, treated by PD for 25.7 (1-147) months were examined. A control group included 17 healthy volunteers (HV) (8 males), with a mean age of 42.7 (22-77) years and normal renal function. Patients were treated with a solution containing bicarbonate (25 mmol/L) and lactate (15 mmol/L) as buffers; eleven of them used, during the nighttime dwell, a solution with icodextrin buffered by lactate at a concentration of 40 mmol/L. The following equations were employed for calculations of acid-base parameters according to the Stewart-Fencl principle. The first is SID = [Na+] + [K+] + 2[Ca(2+)] + 2[Mg(2+)] - [Cl-] - [UA-], where SID is the strong ion difference and [UA-] is the concentration of undetermined anions. For practical calculation of SID, the second equation, SID = [HCO3-] + [Alb-] + [Pi-], was used, where [Alb-] and [Pi-] are the charges carried by albumin and phosphates. The third is Atot, the total concentration of weak non-volatile acids, albumin [Alb] and phosphates [Pi]. RESULTS The capillary blood pH in PD group was 7.41 (7.27-7.48), [HCO3-] levels 23.7 (17.6-29.5) mmol/L, SID 36.3 (29.5-41.3) mmol/L, sodium-chloride difference 39.0 (31.0-44.0) mmol/L, [Pi] 1.60 (0.83-2.54) mmol/L, and [Alb] 39.7 (28.8-43.4) g/L (median, min-max). Bicarbonate in blood correlated positively with SID (Rho = 0.823; p < 0.001), with the sodium-chloride difference (Rho = 0.649; p < 0.01) and pH (Rho = 0.754; p < 0.001), and negatively with residual renal function (Rho = -0.517; p < 0.05). Moreover, the sodium-chloride difference was also found to correlate with SID (Rho = 0.653; p < 0.01). While the groups of PD and HV patients did not differ in median bicarbonate levels, significantly lower median value of SID were observed in PD patients, 36.3 vs. 39.3 mmol/L (p < 0.01); additionally, PD patients were shown to have significantly lower mean value of serum sodium levels, 138 vs. 141 mmol/L (p < 0.01), and serum chlorides levels, 100 vs. 104 mmol/L (p < 0.001). Despite the higher [UA-] levels in PD patients, 9.1 vs. 5.4 mmol/L (p < 0.001), this parameter was not found to correlate with bicarbonate levels. CONCLUSIONS The results suggest that the decreased bicarbonate in PD patients results from a combination of decreased sodium-chloride difference and mildly increased unmeasured anions.
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Affiliation(s)
- Jan Klaboch
- Department of Medicine I, Charles University, Medical School and Teaching Hospital, Plzen 304 60, Czech Republic
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Graham KA, Goodship THJ. Does Metabolic Acidosis Have Clinically Important Consequences in Dialysis Patients? Semin Dial 2007. [DOI: 10.1111/j.1525-139x.1998.tb00200.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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20
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Uribarri J, Oh MS. Acid-Base Balance in Dialysis Patients: A Reassessment. Semin Dial 2007. [DOI: 10.1111/j.1525-139x.1995.tb00339.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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21
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Kraut JA, Madias NE. Treatment of Metabolic Acidosis in End-Stage Renal Failure: Is Dialysis with Bicarbonate Sufficient? Semin Dial 2007. [DOI: 10.1111/j.1525-139x.1996.tb00869.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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22
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Gotch FA. Definitions of dialysis dose suitable for comparison of daily hemodialysis and continuous ambulatory peritoneal dialysis to conventional thrice weekly dialysis therapy. Hemodial Int 2004; 8:172-82. [DOI: 10.1111/j.1492-7535.2004.01092.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Pedrini LA, De CV, Pagliari B. Effects of the infusion mode on bicarbonate balance in on-line hemodiafiltration. Int J Artif Organs 2002; 25:100-6. [PMID: 11905512 DOI: 10.1177/039139880202500204] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Electrolyte and acid-base balance may be differently affected by the infusion mode in on-line hemodiafiltration (HDF). We studied the effects of the different infusion modes on bicarbonate transport across the dialyzer membrane, and thus on the final bicarbonate balance of the HDF sessions. METHODS Instantaneous HCO3- transfer across the dialyzer membrane, blood bicarbonate profile and the total balance of the sessions were studied in six dialysis patients under the same operating conditions over 36 HDF sessions, in order to compare the effects of predilution HDF (pre-HDF), postdilution HDF (post-HDF), and mixed HDF on the final bicarbonate balance. RESULTS The final HCO3- balance was more positive in post-HDF vs pre-HDF (142 +/- 36 vs 99 +/- 41 mmol/session, p<0.05), with a final blood HCO3- concentration of 26.6 +/- 1.0 vs 25.4 +/- 1.1 mmol/L, (p<0.05). Mixed HDF yielded intermediate results (balance: 119 +/- 42 mmol/session, final HCO3- 26.2 (1.2 mmol/L). These differences were seen to result from the increased HCO3- concentration of blood entering the filter in predilution, due to the infused HCO3-, enhancing convective loss and reducing the driving force for diffusive HCO3- gain. CONCLUSIONS Bicarbonate concentration in dialysate-reinfusate is critical in order to obtain an adequate end of session HCO3- balance in on-line HDF. The predilution method produced the lowest cumulative net HCO3- gain between the three studied infusion modes. Our data suggest that, under the same operating conditions and excluding the effect of ultrafiltration, dialysate HCO3- should be increased by about 2 mmol/L in pre-HDF, and 1 mmol/L in mixed HDF, to yield the same final balance as in post-HDF.
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Affiliation(s)
- L A Pedrini
- Nephrology and Dialysis Unit, Department of Internal Medicine, Hospital of Sondrio, Italy.
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Abstract
Our interest in urea kinetic modeling (UKM) was stimulated some 30 years ago at the time of the advent of hollow fiber kidneys with greatly improved urea transport. This led to examination of the interaction between time and clearance in computing the dialysis dose. In early studies a fixed-volume single-pool UKM was used but this frequently gave spurious high volumes and led to the advent of the variable-volume single-pool model. The role of volume calculation in assessment of the delivered dialysis dose and the value of normalized protein catabolic rate (nPCR) calculation are reviewed. More recently quantification of double-pool effects has become simplified and now is widely used for UKM. The National Cooperative Dialysis Study (NCDS) resulted in the concept of dose quantification by Kt/V. This is reviewed, including the controversy surrounding interpretation of the NCDS. Currently there is great interest in more frequent dialysis, 4-6 days/week. The development of a new dose parameter, the standard Kt/V (stdKt/V), to enable quantitative comparison of dose with widely varying dose schedules is discussed.
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Affiliation(s)
- F A Gotch
- Department of Medicine, Franklin Hospital and University of California-San Francisco, San Francisco, CA, USA
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Chauveau P, Fouque D, Combe C, Laville M, Canaud B, Azar R, Cano N, Aparicio M, Leverve X. Acidosis and nutritional status in hemodialyzed patients. French Study Group for Nutrition in Dialysis. Semin Dial 2000; 13:241-6. [PMID: 10923352 DOI: 10.1046/j.1525-139x.2000.00066.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In a cross-sectional study of more than 30% of French dialysis patients (N = 7,123), we evaluated the relationships between predialysis plasma bicarbonate concentration and nutritional markers. Data including age, gender, cause of end-stage renal disease (ESRD), time on dialysis, body mass index (BMI), blood levels of midweek predialysis albumin, prealbumin, and bicarbonate were collected. Normalized protein catabolic rate (nPCR), dialysis adequacy parameters, and estimation of lean body mass (LBM) were computed from pre- and postbicarbonate-dialysis urea and creatinine levels according to the classical formulas of Garred. Average values (+/- 1 SD) were age 61 +/- 16 years, BMI 23.3 +/- 4.6 kg/m2, dialysis time 12.4 +/- 2.7 h/week, HCO3 22.8 +/- 3.5 mmol/L, albumin 38.7 +/- 5.3 g/L, prealbumin 340 +/- 90 mg/L, Kt/V 1.36 +/- 0.36, nPCR 1.13 +/- 0.32 g/kg BW/day, and LBM 0.86 +/- 0.21% of ideal LBM. A highly significant negative correlation was observed between predialysis bicarbonate levels (within a range of 16-30 mmol/L, 95% of this population) and nPCR confirmed by analysis of variance using bicarbonate classes (p < 0.0001). Bicarbonate was also negatively correlated with albumin, prealbumin, BMI, and LBM. No relationship was noted between bicarbonate and Kt/V despite a positive correlation between Kt/V and nPCR. It is likely that a persistent acidosis observed despite standard bicarbonate dialysis was caused by a high dietary protein intake which results in an increased acid load, but also overcomes the usual catabolic effects of acidosis.
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Affiliation(s)
- P Chauveau
- Department of Nephrology, Hôpital Edouard Herriot, Lyon.
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Abstract
In recent years there has been increasing evidence for the deleterious effect of acidosis on a number of fundamental systems of the body including nutrition [1, 2]. Approximately 70 mmol of hydrogen ions are produced daily by the body, and to maintain acid-base balance there must be an equivalent net acid secretion by the kidney. It is remarkable that extracellular fluid (ECF) pH is maintained within a very narrow range of 7.35-7.45 (35-45 nM), reflecting the fundamental importance of pH on many aspects of basic cellular function particularly proteins. It is important to differentiate between the terms acidosis and acidemia. The former is a pathophysiologic process tending to acidify body fluids, whereas the latter occurs when the ECF hydrogen ion concentration is above the normal range. It is possible to be acidotic (with a reduced serum bicarbonate) but not acidemic because of appropriate buffering of hydrogen ions. The major extracellular buffer is the carbonic acid/hydrogen carbonate system with plasma proteins and hemoglobin contributing significantly less. The major intracellular buffer is protein followed by bone [3]. The type of acidosis seen in patients with chronic renal failure changes with decreasing GFR; initially a non-anion gap acidosis is observed secondary to the loss of bicarbonate from the proximal tubule and impaired excretion in the distal tubule. With increasing severity of renal impairment, failure to excrete organic and inorganic acids results in an increased anion gap [4, 5].
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Affiliation(s)
- J D Louden
- Department of Nephrology, School of Clinical Medical Sciences, University of Newcastle upon Tyne, United Kingdom
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Affiliation(s)
- D A Bushinsky
- Strong Memorial Hospital, University of Rochester, New York, USA
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Abstract
Endogenous acid production has never been measured directly in dialysis patients and an empiric formula is used to estimate acid production from their protein catabolic rate. We have studied acid-base balance in 19 stable CAPD patients attending the peritoneal dialysis clinic of Mount Sinai Hospital. They obtained a 24 hour collection of peritoneal dialysis fluid and urine while consuming their usual diet and performing their usual activities. Total alkali gain was calculated from net GI alkali absorption plus urinary net acid excretion plus alkali gain from dialysate, while total acid production was measured directly from the urinary and dialysate excretions of sulfate and organic anions. Net GI alkali absorption was estimated from the difference between cations (Na + K+Ca + Mg) and anions (Cl + 1.8P) in the 24 hour dialysate and urine collections minus the daily total amount of lactate infused. All of our patients had a normal or high serum bicarbonate concentration, which was stable with time. Total alkali gain was virtually identical to total acid production (54.2 vs. 52.4 mEq/day) which suggests that these patients were in neutral acid-base balance. Net GI alkali absorption (22.7 mEq/day) was one of the same range as that of chronic renal failure patients not on dialysis and represented almost one half of the total daily alkali gain. The daily acid production of 52.4 mEq/day was numerically equal to 84% of the protein catabolic rate expressed as g/day, which is similar to the predicted value of 77% of PCR reported in the literature.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J Uribarri
- Department of Medicine, Mount Sinai Medical Center, New York, New York, USA
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Symreng T, Flanigan MJ, Lim VS. Ventilatory and metabolic changes during high efficiency hemodialysis. Kidney Int 1992; 41:1064-9. [PMID: 1513087 DOI: 10.1038/ki.1992.162] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Ventilatory and metabolic changes were measured in seven patients undergoing high efficiency hemodialysis using a cuprophane dialyzer and bicarbonate-containing dialysate. At an HCO3 concentration of 35 mEq/liter and a mean in vivo urea clearance of 3.6 ml/kg/min, hypoxemia was not detected during dialysis (PaO2 was 14.00 and 13.60 kPa before and during dialysis). The new findings, related to high efficiency bicarbonate dialysis, include a sustained rise in minute ventilation (VE, 6.1 to 6.8 liter/min, P less than 0.01), an increase in CO2 excretion (VCO2, 194 to 214 ml/min, P less than 0.05), and O2 consumption (VO2, 215 to 246 ml/min, P less than 0.05). The increment in VE and VCO2 was attributed to the high flux rate of bicarbonate while the rise in VO2 is likely the result of metabolic alkalosis. Arterial pH rose from 7.40 to 7.49 mm Hg and serum HCO3 increased from 23.8 to 29.2 mEq/liter, while pCO2 remained normal at 5.07 kPa throughout the study. The acid-base status of the blood changed from that of a metabolic acidosis to that of a respiratory acidosis across the dialyzer where the pH decreased from 7.47 to 7.41 and pCO2 rose from 5.31 to 7.72 kPa. These data indicate that a healthy ventilatory response is needed to excrete the excess CO2 generated during high efficiency bicarbonate hemodialysis. The significance and etiology of the elevated O2 consumption is undetermined.
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Affiliation(s)
- T Symreng
- Department of Internal Medicine, University of Iowa College of Medicine, Iowa City
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Feriani M, Ronco C, Biasioli S, Bragantini L, La Greca G. Effect of dialysate and substitution fluid buffer on buffer flux in hemodiafiltration. Kidney Int 1991; 39:711-7. [PMID: 2051728 DOI: 10.1038/ki.1991.86] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effect of differing dialysate and substitution fluid buffer types and concentrations on acid-base balance have not been assessed in patients treated with hemodiafiltration for ESRD. To determine bicarbonate, acetate, lactate and total buffer flux, mass balance studies were performed in patients treated with hemodiafiltration using four different combinations of dialysate and substitution fluids. Driving force for bicarbonate flux was assessed in all treatments. Bicarbonate flux depended on bicarbonate driving force and ultrafiltration rate. Bicarbonate flux was negative in all treatment combinations, even when the driving force was positive. Acetate flux was positive in all treatment combinations, but the net magnitude was small. Lactate flux, when lactate containing substitution fluid was used, varied with dialysate buffer employed during treatment. Overall buffer flux depended on the bicarbonate driving force, ultrafiltration rate, and varied with the type of substitution and dialysate buffer employed. The types and concentrations of buffer used in dialysate and substitution fluid have important effects on the acid-base balance of patients treated with hemodiafiltration. The long-term implications of different therapeutical choices in these patients is unknown.
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Affiliation(s)
- M Feriani
- Department of Nephrology, St. Bortolo Hospital, Vicenza, Italy
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Davenport A, Aulton K, Payne RB, Will EJ. Hyperlactatemia and increasing metabolic acidosis in hepatorenal failure treated by hemofiltration. Ren Fail 1990; 12:99-101. [PMID: 2236733 DOI: 10.3109/08860229009087125] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We report a case of increasing hyperlactatemia in the course of repeated treatment by machine hemofiltration (MHF) using a lactate-buffered replacement solution. The hyperlactatemia was associated with a reduction in mean arterial pressure, and in the majority of treatments a metabolic acidosis developed. Hyperlactatemia due to exogenous lactate may not be as benign as previously discussed.
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Affiliation(s)
- A Davenport
- Department of Renal Medicine, St. Jame's University Hospital, Leeds, England
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Santoro A, Ferrari G, Spongano M, Badiali F, Zucchelli P. Acetate-free biofiltration: a viable alternative to bicarbonate dialysis. Artif Organs 1989; 13:476-9. [PMID: 2803060 DOI: 10.1111/j.1525-1594.1989.tb01561.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Eight patients were studied during four sessions of acetate-free biofiltration (AFBF). AFBF is a new dialysis technique with no base replacement agents in the dialysate and with the addition in postdilution mode of bicarbonate (HCO3) solution directly into the extracorporeal blood circuit. In this study the effects on acid-base balance of different infusions of sodium bicarbonate (NaHCO3) ranging from 751 to 1,002 mEq per session was evaluated. There were significant positive correlations between the HCO3 infused and net HCO3 gained (r = 0.776, p less than 0.0001) and between HCO3 infused and plasma intratreatment HCO3 changes (n = 0.562, p less than 0.001). Stepwise multiple linear regression analysis demonstrated that HCO3 infused and plasma predialysis HCO3 values played the major role in HCO3 balance in AFBF. The best correction of metabolic acidosis was obtained with the infusion of 900-1,000 mEq of HCO3. The use of substitution fluid with 145 mEq/L of Na concentration avoids the risk of a positive intratreatment Na balance.
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Affiliation(s)
- A Santoro
- Division of Nephrology and Dialysis, Malpighi Hospital, Bologna, Italy
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Santoro A, Ferrari G, Spongano M, Cavalli F, Zucchelli P. Effects of pK variability on bicarbonate balance evaluation in dialysis patients. Artif Organs 1987; 11:491-5. [PMID: 3125820 DOI: 10.1111/j.1525-1594.1987.tb02715.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Bicarbonate balance is usually calculated from the Henderson-Hasselbalch equation under the assumption that pK is constant. To evaluate the pK variability and its effects on bicarbonate computed with autoanalyzers in dialysis patients, we studied 44 patients on maintenance hemodialysis. The pH, PCO2, total CO2, and pK were determined in each patient before and after the dialysis session. The mean total CO2 calculated (22.5 +/- 2.7 meq/L) from pH and PCO2 values was significantly higher (p less than 0.001) than that directly measured (20.4 +/- 3.0 meq/L) with total CO2 analyzer. The mean (+/- SD) pK value was 6.14 +/- 0.06 (range 6.05-6.28). The percentage error in computed bicarbonate due to pK variations from the traditional pK value of 6.1 ranged between -11% and 52%. The pK value changed during dialysis in the majority of our patients, thereby confirming that pK consistency does indeed vary. Thus, investigation of acid-base balance based on pH and PCO2 determination may lead to erroneous results determined by pK abnormalities.
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Affiliation(s)
- A Santoro
- Division of Nephrology and Dialysis, Malpighi Hospital, Bologna, Italy
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Ward RA, Wathen RL, Williams TE, Harding GB. Hemodialysate composition and intradialytic metabolic, acid-base and potassium changes. Kidney Int 1987; 32:129-35. [PMID: 3306095 DOI: 10.1038/ki.1987.182] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We compared the effects of dialysate composition on changes in intermediary metabolites, acid-base balance, and potassium removal during hemodialysis. Patients were dialyzed against dialysates containing acetate or bicarbonate, each with or without glucose, in a four-way cross-over study. Dialysates containing acetate were associated with significant perturbations in intermediary metabolism, including increases in blood citrate, acetoacetate and beta-hydroxybutyrate and a decrease in pyruvate. In contrast, bicarbonate-containing dialysates caused minimal perturbations in intermediary metabolism. Addition of glucose to the dialysate decreased the changes in intermediary metabolites; however, the magnitude of this effect was less than that observed for the change from acetate to bicarbonate. Use of acetate also resulted in lower post-dialysis blood-concentrations of base equivalents than obtained with bicarbonate; this difference was unaffected by the presence or absence of glucose. Although pre- and post-dialysis potassium concentrations were unaffected by the dialysate formulation, total potassium removal was significantly greater when glucose was omitted from the dialysate. Our results suggest that both bicarbonate and glucose should be included in the dialysate, particularly for those patients whose capacity for metabolism may be limited because of highly efficient dialysis, intercurrent illness, or starvation. However, addition of glucose to the dialysate may require a reduction in dialysate potassium to maintain proper potassium homeostasis.
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