Theoretical Basis for and Improvement of Daugirdas' Second Generation Formula for Single-Pool Kt/V

Dialysis Adequacy: A Cross-Sectional Study to Assess the Reliability of the Online Clearance Monitor to Measure Dialysis Dose

Background Frequent assessment of the dialysis dose delivered to hemodialysis patients might help improve morbidity and mortality. Daugirdas' second-generation formula is the recommended method for calculating dialysis doses. However, urea reduction ratios (URRs) and online clearance monitors (OCMs) are frequently used to assess dialysis adequacy due to their more straightforward concept and ease of use. This study was conducted to determine the most reliable method for measuring dialysis adequacy by comparing the correlation of urea reduction ratio and online clearance monitor measurements with the dialysis dose measured using the recommended Daugirdas' second-generation formula. Methods This study was an observational, cross-sectional, single-center study. The dialysis dose was measured as a urea reduction ratio and by an online clearance monitor simultaneously for 50 patients. It was compared to the dialysis dose measurements obtained using Daugirdas' second-generation formula. Results There was a statistically significant strong positive correlation (r = 0.929; p ≤ 0.001) of the urea reduction ratio and a poor concordance (ρC = 0.401; p ≤ 0.001) of online clearance monitor measurements with the dialysis dose measured using Daugirdas' second generation formula. Conclusion Our findings illustrate that the urea reduction ratio may be a more straightforward and reliable means for assessing the adequacy of intermittent hemodialysis with minimal errors in patients compared to online clearance monitors. Online clearance monitors offer easy estimation and practicality with minimal effort but are prone to multiple errors and may not be accurate in some settings.

Effects of Oral Sodium Bicarbonate Supplementation on Protein Metabolism and Inflammation in Iraqi Hemodialysis Patients: An Open-Label Randomized Controlled Trial

Background

The effect of correcting metabolic acidosis on protein metabolism in hemodialysis patients is controversial.

Objectives

To study the effects of oral sodium bicarbonate on protein metabolism and markers of inflammation in acidotic hemodialysis patients. Patients and Methods. An open-label randomized controlled trial was conducted at a single center. Sixty-six clinically stable adult hemodialysis patients were recruited with an average predialysis serum bicarbonate level of <22 mmol/l and a dialysate bicarbonate concentration of 35 mmol/l. Forty-nine participants have completed the study. Oral sodium bicarbonate tablets of 500 mg were given daily in the intervention group (n = 25) for 12 weeks versus the standard of care in the control group (n = 24). Outcomes compared intervention versus nonintervention in both groups at equivalent time points (0 and 3 months). The clinical data, anthropometry, dialysis adequacy, albumin, normalized protein catabolism rate, blood gas analysis, and bicarbonate were recorded at 0 and 3 months. In addition, muscle mass and handgrip strength were measured. Finally, IL-6 as a marker of inflammation was measured at randomization and three months.

Results

Serum bicarbonate and pH increased significantly from 17.57 ± 3.34 mmol/L to 20.69 ± 2.54 mmol/L and from 7.26 ± 0.06 to 7.34 ± 0.04, respectively (p < 0.0001). Serum albumin was significantly higher in the intervention group at three months than in the control group, 4.11 ± 0.45 vs. 3.79 ± 0.47 (p value 0.011). Serum potassium significantly decreased in the intervention group at three months compared to the control group, 5.00 ± 0.43 mEq/l vs. 5.33 ± 0.63 mEq/l (p value 0.03). Muscle strength expressed as handgrip has improved significantly in the intervention group at three months compared to the control group, 45.01 ± 19.19 vs. 33.93 ± 15.06 (p value 0.03). The IL-6 values were less in the intervention group at 3 months with a p value of 0.01. The interdialytic weight of the intervention group at three months was 2.42 ± 0.64 compared to the 2.20 ± 1.14 control group, but this did not reach statistical significance (p value of 0.4). The composite of (albumin + nPCR) at three months was achieved in 59.18% of the intervention group compared to 14.28% with a p value of 0.01.

Conclusions

Correcting metabolic acidosis in hemodialysis patients improved serum albumin and nPCR without hypokalemia or significant interdialytic weight gain. This was particularly evident in patients with minimal inflammation with low IL-6 values.

Modeling Factors Associated with Dialysis Adequacy Using Longitudinal Data Analysis: Generalized Estimating Equation Versus Quadratic Inference Function

BACKGROUND

In hemodialysis patients, changes in dialysis adequacy (DA) are examined longitudinally. The aim of this study was to determine factors affecting DA using the generalized estimating equation (GEE) and to compare them with the quadratic inference function (QIF).

STUDY DESIGN

A longitudinal study.

METHODS

This longitudinal study examined the records of 153 end-stage renal disease (ESRD) patients. The longitudinal data on the DA and baseline demographic and clinical characteristics were obtained from patients' files. The GEE1, GEE2, and QIF models were fitted with different correlation structures, and then the best correlation structure was selected using the quasi-likelihood information criterion (QIC), Akaike information criterion (AIC), and Bayes information criterion (BIC) fitting criteria.

RESULTS

The majority of patients (59.5%) had unfavorable DA (KT/V<1.2). Women and patients<60 years had more favorable DA. In the GEE model, the coefficients of female gender (β=0.079, 95% confidence interval [CI]: 0.032, 0.062), age at starting dialysis (β=-0.002, 95% CI: -0.004, -0.0001), hypertension (HTN, β=-0.055, 95% CI: -0.007, -0.103), diabetes (β=-0.088,95% CI: -0.021, -0.155), dialysis duration (β=0.132, 95% CI: 0.085, 0.178), and weight (β=-0.004, 95% CI: -0.006, -0.003) demonstrated a significant relationship with DA. The three models resulted in a similar estimate of regression coefficients. The relative efficiencies of QIF versus GEE1, QIF versus GEE2, and GEE2 versus GEE1 were 1.175, 1.056, and 1.113, respectively.

CONCLUSION

DA is not optimal in most hemodialysis patients, and gender, age at the start of dialysis, HTN, diabetes, dialysis duration, and weight had a significant association with DA. The three different models yielded quite similar coefficient estimates, but the QIF model resulted more efficient than GEE1 and GEE2.

Chronic kidney disease-associated pruritus significantly impacts on quality of life of patients on haemodialysis and associates with increased levels of serum calcium and phosphorus

PURPOSE OF THE STUDY

Chronic kidney disease-associated pruritus (CKD-aP) is common among patients on maintenance haemodialysis (HD). We performed a study to explore the clinical features of patients with CKD-aP and evaluate the impact of CKD-aP on the quality of life of HD patients.

STUDY DESIGN

Patients who were receiving regular HD over 3 months were recruited. Quality of life was quantified by the Short Form-12 (SF-12) questionnaire. Pruritus was evaluated by the 5D-Itch Scale. Demographic characteristics and biochemical indicators were obtained from the medical record system. Multiple linear regression was used to assess the association between pruritus and targeting factors. The relationship between the scores on the 5D-Itch Scale and SF-12 was analysed using multiple linear regression, adjusted for other factors, to demonstrate the impact of CKD-aP on the quality of life of HD patients.

RESULTS

In total, 269 out of 301 (89.4%) patients accomplished all investigations. The prevalence of CKD-aP in our cohort was 40.9%. Age (B=0.339, p=0.042), treatment with haemoperfusion (B=1.853, p=0.018), and serum level of calcium (B=3.566, p=0.008) and phosphorus (B=1.543, p=0.002) were independently associated with pruritus. Score on the 5D-Itch Scale negatively impacted on physical component summary (B=-0.778, p<0.001) and mental component summary (B=-0.675, p<0.001).

CONCLUSIONS

Pruritus significantly aggravates the quality of life of HD patients. Irregularity in the metabolism of calcium and phosphorus may partially explain the mechanism of CKD-aP. More effective treatment of CKD-MBD may help to prevent pruritus and improve patients' mental and physical health conditions.

A novel method to rapidly calculate the urea clearance index and urea reduction rate based on parameters obtained during hemodialysis

Background

The efficacy of hemodialysis (HD) is closely associated with patient survival time and quality of life. The classical method (CLM) to calculate the urea clearance index (Kt/V) and urea reduction rate (URR) requires multiple blood tests. A novel method that may be used as a noninvasive alternative to CLM is required.

Methods

Based on the urea kinetic model, a new method, named the “assessment method” (ASM), was established to calculate blood urea nitrogen after HD, based on parameters obtained during HD. The consistency of the Kt/V and URR values between the ASM and CLM was evaluated in 41 patients from the China–Japan Friendship Hospital between September 2017 and December 2018.

Results

Forty-one patients (24 males and 17 females; mean age, 55.7 ± 14.2 years) undergoing regular HD in our hospital were randomly selected for this study. The blood flow rate was 244.5 ± 19.6 mL/min and the dialysate flow rate was 500 mL/min. We obtained Kt/V (CLM = 1.40 ± 0.06, ASM = 1.37 ± 0.07) and URR (CLM = 68.6 ± 6.4%, ASM = 67.7 ± 7.2%) values. Paired t-test indicated no significant differences between the ASM- and CLM-derived values. The intraclass correlation coefficients were 0.907 and 0.916 for Kt/V and URR, respectively. Similarly, Bland–Altman plots suggested good concordance between the 2 methods.

Conclusions

The Kt/V and URR values calculated using the ASM and CLM were in significant agreement, and both can be used to effectively assess the adequacy of HD in patients undergoing maintenance HD. The ASM is an effective, rapid, inexpensive, and noninvasive alternative to the CLM for obtaining Kt/V and URR values. The ASM has good potential for clinical application, particularly for patients in areas of low socioeconomic status.

Hemodialysis With the Quanta SC+: Efficacy and Safety of a Self-care Hemodialysis Machine

Rationale & Objective

Most patients with kidney failure receive hemodialysis 3 times per week in a facility. More frequent and longer duration dialysis prescriptions improve a number of key outcome measures. These prescriptions are best suited to self-care and home regimens. The Quanta SC+ hemodialysis system is a novel device with demonstrated ease of use for patients and health care practitioners through human factors testing. The primary objective of this study is to report the efficacy and safety of the SC+ system using conventional hemodialysis prescriptions.

Study Design

Nonrandomized observational study.

Setting & Participants

Prevalent hemodialysis patients in 4 sites in the United Kingdom were recruited to switch from their current device to the SC+ system with no other changes to their prescription.

Interventions

SC+ hemodialysis system.

Outcomes

Efficacy data were collected in terms of dialysis adequacy, urea reduction ratios, and net fluid removal accuracy.

Results

60 patients were enrolled in the study, resulting in 1,333 evaluable treatments. The threshold single-pool Kt/V of 1.2 was exceeded in 96.6% of treatments in patients receiving 3-times-weekly regimens, whereas the threshold standard Kt/V of 2.1 was exceeded in 94% of treatments and 97.6% of treatments in patients without significant residual kidney function. Ultrafiltration accuracy was determined by measuring net fluid removal and validated to be within acceptable limits. The adverse event profile during treatment was typical of hemodialysis. There were no serious adverse events.

Limitations

Few patients on high-frequency treatment regimens were enrolled.

Conclusions

The SC+ system delivers safe and effective hemodialysis across a range of patients and dialysis prescriptions. It is one of the smallest systems available and has validated usability for patients to perform self-care safely with minimal training. This device may encourage patients to feel empowered to take on home hemodialysis, unlocking beneficial clinical and patient-reported outcomes associated with these modalities.

Oxidized Low-Density Lipoprotein Serum Concentrations and Cardiovascular Morbidity in End Stage of Renal Disease

Introduction: Oxidized low-density lipoprotein (ox-LDL) is considered a main biomarker of oxidative stress, a common characteristic in end stage renal disease. We examined the relationship between ox-LDL serum concentrations and cardiovascular disease in permanent hemodiafiltration therapy patients. Methods: Ox-LDL values were measured by ELISA and were corrected for LDL-cholesterol (LDL-C) in 96 participants and in 45 healthy control subjects. We performed chi-square tests and adjusted models for the role of ox-LDL on cardiovascular morbidity including coronary artery disease, left ventricular hypertrophy, systolic, diastolic dysfunction and peripheral arterial disease. Results: ox-LDL/LDL-C values were significantly higher in patients than in control group (p = 0.02), due to increased ox-LDL serum levels rather than to low LDL-C. The unadjusted relationship between high ox-LDL/LDL-C and low ejection fraction was found significant (x2 = 9.04, p = 0.003), although the association with the other cardiovascular manifestations was found non-significant. In the adjusted model for the prediction of systolic cardiac dysfunction, high ox-LDL/LDL-C, old age and non-administration of vitamin D supplementation during dialysis session were found to be significant predictors after adjustment to the confounder. Moreover, the association between systolic cardiac dysfunction and non-administration of vitamin D derivatives during dialysis sessions was found significant (x2 = 6.9, p = 0.008). Conclusions: This study showed a significant association between high ox-LDL and systolic cardiac dysfunction in permanent hemodiafiltration therapy patients. This relationship seems to be influenced by aging and pharmaceutical therapy during dialysis sessions, including vitamin D derivatives.

Oxidized Low-Density Lipoprotein Serum Concentrations and Cardiovascular Morbidity in End Stage of Renal Disease

INTRODUCTION

Oxidized low-density lipoprotein (ox-LDL) is considered a main biomarker of oxidative stress, a common characteristic in end stage renal disease. We examined the relationship between ox-LDL serum concentrations and cardiovascular disease in permanent hemodiafiltration therapy patients.

METHODS

Ox-LDL values were measured by ELISA and were corrected for LDL-cholesterol (LDL-C) in 96 participants and in 45 healthy control subjects. We performed chi-square tests and adjusted models for the role of ox-LDL on cardiovascular morbidity including coronary artery disease, left ventricular hypertrophy, systolic, diastolic dysfunction and peripheral arterial disease.

RESULTS

ox-LDL/LDL-C values were significantly higher in patients than in control group (p = 0.02), due to increased ox-LDL serum levels rather than to low LDL-C. The unadjusted relationship between high ox-LDL/LDL-C and low ejection fraction was found significant (x² = 9.04, p = 0.003), although the association with the other cardiovascular manifestations was found non-significant. In the adjusted model for the prediction of systolic cardiac dysfunction, high ox-LDL/LDL-C, old age and non-administration of vitamin D supplementation during dialysis session were found to be significant predictors after adjustment to the confounder. Moreover, the association between systolic cardiac dysfunction and non-administration of vitamin D derivatives during dialysis sessions was found significant (x² = 6.9, p = 0.008).

CONCLUSIONS

This study showed a significant association between high ox-LDL and systolic cardiac dysfunction in permanent hemodiafiltration therapy patients. This relationship seems to be influenced by aging and pharmaceutical therapy during dialysis sessions, including vitamin D derivatives.

Mathematical Representation of Standard Kt/V Including Ultrafiltration and Residual Renal Function

A new formula for calculating standard Kt/V from clinical data has been derived mathematically. It is based on using the relation between eKt/V and the pre- and postdialysis concentrations in order to find the steady state concentrations. The resulting expression for standard Kt/V depends on the treatment schedule (number, length, and spacing of treatments), residual renal function, and eKt/V and relative ultrafiltration volume of each individual treatment. These results include the effects of ultrafiltration and residual renal function also in the case with unequal treatments that may be arbitrarily distributed over the week. The new formula is found to agree, within small fractions of a percentage, with standard Kt/V from simulations of 3 and 5 days per week schedules. Several approximations are also suggested and their accuracies analyzed. It is shown that the use of the midweek eKt/V and ultrafiltration for all treatments of the week is an acceptable approximation. In the presence of residual renal function, the timing of the treatments is an important factor, and particularly in this case, the new formula shows improved accuracy over previously published formulas.

The Relationship of Residual Renal Function with Cardiovascular Morbidity in Hemodialysis Patients and the Potential Role of Monocyte Chemoattractant Protein-1

BACKGROUND

Residual renal function (RRF) provides several benefits to patients on dialysis. Monocyte chemoattractant protein-1 (MCP-1) plays an important role in atherosclerotic lesions. We considered the relationship between RRF and cardiovascular morbidity and the significant role of MCP-1 serum concentrations in hemodiafiltration (HDF) patients.

METHODS

We enrolled 76 patients on on-line HDF. RRF was defined by interdialytic urine output, and we studied the patients in two groups according to the preservation or not of urine output. MCP-1 levels were measured using enzyme-linked immunosorbent assay. χ2 tests were applied for the association between RRF and left ventricular hypertrophy (LVH), coronary artery disease (CAD), peripheral artery disease (PAD), and systolic and diastolic cardiac dysfunction. We built an adjusted model using logistic regression analysis for the factors which might impact on the loss of urine output.

RESULTS

χ2 tests showed a significant association between the loss of urine output and LVH, diastolic dysfunction, and PAD (χ2 = 7.4, p = 0.007; χ2 = 14.3, p = 0.001; χ2 = 4.2, p = 0.03, respectively), although the association with CAD and systolic dysfunction was found to be nonsignificant. The patients without RRF had significantly higher MCP-1, and the urine volume was inversely associated with MCP-1 (r = -465, p = 0.03). In the built adjusted model, the elevated MCP-1 was found to be a significant predictor for the loss of RRF.

CONCLUSION

The loss of RRF was significantly associated with LVH, diastolic dysfunction, and PAD in HDF patients. The increased MCP-1, affected by the lack of urine, may act as an additional underlying factor on this relationship, reflecting a progressive inflammation/oxidative stress condition.

Metabolic acidosis status and mortality in patients on the end stage of renal disease

BACKGROUND AND OBJECTIVES

Uncorrected metabolic acidosis leads to higher death risk in dialysis patients. We observed the relationship between metabolic acidosis status and mortality rate in patients on renal replacement therapy during a median follow up time of 60 months.

METHODS

We studied 76 patients on an on-line hemodiafiltration. The dialysis adequacy was defined by Kt/V for urea. The Framingham risk score (FRS) points were used to determine the 10-year risk for coronary heart disease. We examined the impact of high or low serum bicarbonate concentrations on mortality rate and on 10-year risk for coronary heart disease via the Kaplan-Meier method. Cox's model was used to evaluate a combination of prognostic variables, such as dialysis adequacy defined by Kt/V for urea, age and serum bicarbonate concentrations.

RESULTS

We divided the enrolled patients in three groups according to serum bicarbonate concentrations (< 20 mmol/L, 20-22 mmol/L and > 22 mmol/L). Kaplan-Meier survival curve for the impact of serum bicarbonate concentrations on overall mortality was found significant (log-rank = 7.8, P = 0.02). The prevalence of serum bicarbonate less or more than 20 mmol/L on high FRS (> 20%) by Kaplan-Meier curve was also found significant (log-rank = 4.9, P = 0.02). Cox's model revealed the significant predictive effect of serum bicarbonate on overall mortality (P = 0.006, OR = 1.5, 95% CI = 1.12-1.98) in combination to Kt/V for urea and age.

CONCLUSION

Uncorrected severe metabolic acidosis, defined by serum bicarbonate concentrations less than 20 mmol/L, is associated with a 10-year risk for coronary heart disease more than 20% and high overall mortality in patients on renal replacement therapy.

Finite-element modeling of time-dependent sodium exchange across the hollow fiber of a hemodialyzer by coupling with a blood pool model

INTRODUCTION

Hollow fiber models describe the exchange of solutes between blood and dialysate across the membrane of a single fiber of the hemodialysis filter (hemodialyzer). This work aims to develop a new approach to simulate the solute exchange in a hollow fiber in a dynamic and realistic way. Sodium was chosen as our solute of interest due to its importance in hemodialysis as an osmotic regulator.

METHODS

A 2-dimensional (2D) hollow fiber model based on the finite element method (FEM) is coupled to a simple blood pool model to dynamically update the concentration of the solute entering the dialyzer. The resulting coupled model maintains the geometrical detail of the 2D fiber representation and gains a dynamic, blood-side inlet solute concentration. In vitro dialysis sessions were carried out for model validation, by implementing a combination of blood volume loss and/or sodium concentration steps. Plasmatic sodium concentration was recorded by blood gas sampling. Dialysate inlet and outlet conductivities were continuously recorded.

RESULTS

Simulated plasmatic sodium concentration was compared with data from the blood gas samples. A mean error of 1.76 ± 1.03 mM was found for the complete dataset, along with a 3.87 mM maximum error. The simulated outlet dialysate sodium concentration was compared with the recorded outlet dialysate conductivity: a very high correlation was found on the whole dataset (R2 = 0.992).

CONCLUSIONS

Coupling our FEM hollow fiber model to a simple blood pool model proved to be an effective approach for dynamical analysis of the properties of the hemodialyzer.