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.

The Impact of Medical Nutrition Intervention on the Management of Hyperphosphatemia in Hemodialysis Patients with Stage 5 Chronic Kidney Disease: A Case Series

The treatment and interdisciplinary management of patients with chronic kidney disease (CKD) continue to improve long-term outcomes. The medical nutrition intervention's role is to establish a healthy diet plan for kidney protection, reach blood pressure and blood glucose goals, and prevent or delay health problems caused by kidney disease. Our study aims to report the effects of medical nutrition therapy-substituting foods rich in phosphorus-containing additives with ones low in phosphates content on phosphatemia and phosphate binders drug prescription in stage 5 CKD patients with hemodialysis. Thus, 18 adults with high phosphatemia levels (over 5.5 mg/dL) were monitored at a single center. Everyone received standard personalized diets to replace processed foods with phosphorus additives according to their comorbidities and treatment with prosphate binder drugs. Clinical laboratory data, including dialysis protocol, calcemia, and phosphatemia, were evaluated at the beginning of the study, after 30 and 60 days. A food survey was assessed at baseline and after 60 days. The results did not show significant differences between serum phosphate levels between the first and second measurements; thus, the phosphate binders' initial doses did not change. After 2 months, phosphate levels decreased considerably (from 7.322 mg/dL to 5.368 mg/dL); therefore, phosphate binder doses were diminished. In conclusion, medical nutrition intervention in patients with hemodialysis significantly reduced serum phosphate concentrations after 60 days. Restricting the intake of processed foods containing phosphorus additives-in particularized diets adapted to each patient's comorbidities-and receiving phosphate binders represented substantial steps to decrease phosphatemia levels. The best results were significantly associated with life expectancy; at the same time, they showed a negative correlation with the dialysis period and participants' age.

Using the Intelligent System to Improve the Delivered Adequacy of Dialysis by Preventing Intradialytic Complications

Acute kidney failure patients while detoxificated by hemodialysis (HD) mostly or continuously faced regular problems such as low blood pressure (hypotension), muscle cramps, nausea, or vomiting. Higher intradialytic symptom leads to low-quality HD treatment. Although more known therapeutic interventions are used to relieve the HD side effects, this study was designed to investigate how intelligent systems can make highly beneficial alterations in dialysis facilities and equipment to ease intradialytic complications and help the staff deliver high-quality treatment. A search was performed among relevant research articles based on nonpharmacological intervention methods considered to prevent adverse effects of renal replacement therapy until 2020 in the PubMed databases using the terms “intradialytic complications,” “intradialytic complication interventions,” “nonpharmacological interventions,” “intradialytic exercises,” and “adequacy calculation methods.” Studies included the prevalence of intradialytic complications, different strategies with the aim of preventing complications, the outcome of intradialytic exercises on dialysis symptoms, and dialysis dose calculation methods. The results showed the incidence of hypotension varying between 5% and 30%, fatigue, muscular cramps, and vomiting as the most common complications during dialysis, which greatly affect the outcome of HD sessions. To prevent hypotension, ultrafiltration profiling, sodium modeling, low dialysate temperature, and changing the position to Trendelenburg are some strategies. Urea reduction ratio (URR), formal urea kinetic modeling (FUKM), formal single-pool urea kinetics, and online clearance monitoring (OCM) are methods for calculating the delivered dose of dialysis in which OCM is a low-cost and accessible way to monitor regularly the quality of dialysis delivered. Integration of the chair and HD machine which is in direct contact with the patient provides an intelligent system that improves the management of the dialysis session to enhance the quality of healthcare service.

Integrating Monitoring of Volume Status and Blood Volume-Controlled Ultrafiltration into Extracorporeal Kidney Replacement Therapy

Purpose

Volume management in hemodialysis (HD) requires the ability to assess volume status objectively and determine treatment strategies that achieve euvolemia without compromising hemodynamic stability. The aim of this study was to compare dialysis with and without blood volume-controlled ultrafiltration (UF) in combination with body composition monitoring, and to evaluate indicators for adequate dialysis (Kt/V), ultrafiltration volume, fluid status, and the occurrence of intradialytic morbid events (IME).

Patients and Methods

Patients undergoing hemodialysis or on-line hemodiafiltration with support of a blood volume monitor (BVM) - a feedback control device integrated into the 5008 and 6008 HD systems - were enrolled. Patients received treatment for four weeks using the 6008 CAREsystem and the BVM (6008+). Data on dialysis dose (Kt/V), UF volume and predialysis fluid status were documented. This data was also documented retrospectively for four weeks with (5008+) and without (5008-) the use of the BVM with the 5008 system. Comparisons were analyzed using linear mixed models.

Results

Twenty-four patients were enrolled. Kt/V was unaffected by blood volume-controlled UF (5008- vs 5008+: p=0.230) and was equally achieved with both HD systems (5008+ vs 6008+: p=0.922). The UF volume and fluid status achieved were comparable, independent of the use of UF control with BVM (5008- vs 5008+; UF volume: p=0.166; fluid overload: p=0.390) or the HD system (5008+ vs 6008+: UF volume: p=0.003; fluid overload: p=0.838), except for UF volume being higher in the 6008+ phase. IMEs occurred in less than 3% of treatments, with no difference between study phases.

Conclusion

This study demonstrates that a clinical approach to kidney replacement therapy that tracks volume status and manages intradialytic fluid removal by blood volume-controlled UF delivers adequate dialysis without compromising fluid removal. It maintains volume status and ensures low incidence of IMEs.

Dialysis dose and mortality in hemodialysis: Is higher better?

BACKGROUND

The effect of dialysis dose on mortality remains unsettled. Current guidelines recommend to target a spKt/V at 1.20 to 1.40 per tri-weekly dialysis session. However, the optimal dialysis dose remains mostly disputed.

METHODS

In a nationwide registry of all incident patients receiving thrice-weekly hemodialysis, 32 283 patients had available data on dialysis dose, estimated by Kt/V and its variants Kt and Kt/A. Survival was analyzed with a multivariate Cox model and a concurrent risk model accounting for renal transplantation. A predictive model of Kt in the upper quartile was developed.

RESULTS

Regardless of the indicator, a higher dose of dialysis was consistently associated with better survival. The survival differential of Kt was the most discriminating, but marginally, compared to the survival differential according to Kt/V and Kt/A. Patient survival was higher in the upper quartile of Kt (> 69L/s), then deteriorated as the Kt decreased with a difference in survival between the upper and lower quartile of 23.6% at five years. Survival differences across Kt distribution were similar after accounting for kidney transplantation as a competing risk. Predictive factors for Kt in the upper quartile were arteriovenous fistula versus catheters and graft, hemodiafiltration versus hemodialysis, scheduled dialysis start versus emergency start, long weekly dialysis duration, spKt/V measurement versus double pool eKt/V.

CONCLUSION

Our data confirm the existence of a relationship between dialysis dose and survival, which persisted despite correcting for known confounders. A model for predicting a high dose of dialysis is proposed with practical relevance.

Routine online assessment of dialysis dose: Ionic dialysance or UV-absorbance monitoring?

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.

Continuing education: online monitoring of haemodialysis dose

BACKGROUND

Kt/Vurea reflects the efficacy of haemodialysis scaled to patient size (urea distribution volume). The guidelines recommend monthly Kt/V measurements based on blood samples. Modern haemodialysis machines are equipped with accessories monitoring the dose online at every session without extra costs, blood samples and computers.

OBJECTIVE

To describe the principles, devices, benefits and shortcomings of online monitoring of haemodialysis dose.

DESIGN

A critical literature overview and discussion.

RESULTS

UV absorbance methods measure Kt/V, ionic dialysance Kt (product of clearance and treatment time; cleared volume without scaling). Both are easy and useful methods, but comparison is difficult due to problems in scaling of the dialysis dose to the patient's size.

CONCLUSIONS

The best dose estimation method is the one which predicts the quality of life and survival most accurately. There is some evidence on the predictive value of ionic dialysance Kt, but more documentation is required on the UV method. Online monitoring is a useful tool in everyday quality assurance, but blood samples are still required for more accurate kinetic modelling.

LEARNING OUTCOMES

After reading this article the reader should be able to: Understand the elements of the Kt/V equation for dialysis dose. Compare and contrast different methods of measurement of dialysis dose. Reflect on the importance of adequate dialysis dose for patient survival and life quality.

Body composition monitoring-derived urea distribution volume in children on chronic hemodialysis

BACKGROUND

Modern hemodialysis (HD) machines are able to measure ionic dialysance online and thereby continuously monitor Kt/V. The accuracy of measurement depends on the input of the correct urea distribution volume (V), available from anthropometric equations and body composition monitoring (BCM). The latter method, however, has not been validated in children.

METHODS

We compared V determined by BCM to that calculated using four different anthropometric formulas (Morgenstern, Mellits and Cheek, Hume-Weyers and Watson equations) in 23 pediatric HD patients. We also compared online Kt/V using BCM-derived V with the Kt/V calculated from pre- and post-dialytic urea concentrations using the single-pool second-generation Daugirdas equation.

RESULTS

The V calculated by the Morgenstern equation was similar to that derived by BCM, with a mean difference of -0.7% (95% limits of agreement -11.7 to 10.3%). In contrast, the V calculated by the other equations was 5.4, 6.2 and 18%, respectively higher than the BCM-derived V. The mean difference between Kt/V calculated using the Daugirdas equation and online Kt/V determination based on BCM-derived V data was 0.10 (95% limits of agreement -0.50 to 0.70%).

CONCLUSIONS

In our pediatric HD patients the V measured by BCM was in agreement with that calculated using the Morgenstern equation, which is the only equation which has been validated to date in children on dialysis. Online determination of Kt/V using a BCM-derived V largely agreed with that calculated by the Daugirdas equation. We therefore conclude that the former approach is suitable for frequent online assessment of dialytic small solute clearance.

Serum free 1,25-dihydroxy-vitamin D is more closely associated with fibroblast growth factor 23 than other vitamin D forms in chronic dialysis patients

BACKGROUND

Mineral bone disorder (MBD) is prevalent among chronic dialysis patients. However, relationship between different forms of vitamin D and fibroblast growth factor 23 (FGF-23) remains unclear in this population.

METHODS

A multicenter hemodialysis cohort was assembled. We evaluated 25-OH-D and 1,25-(OH)2-D, vitamin D-binding protein, and FGF-23, in this cohort. Multiple regression analyses were performed to investigate the relationship and stewardship between different vitamin D forms and FGF-23 concentrations.

RESULTS

Chronic dialysis patients presented significantly higher FGF-23 concentrations. 25-OH-D concentrations of <20 ng/ml (deficiency), 20-30 ng/ml (insufficiency), and ≥30 ng/ml (sufficiency) were associated with progressively lower FGF-23 concentrations (p<0.01). Serum FGF-23 concentrations were significantly correlated with total (p=0.02), free (p<0.01) and bioavailable (p<0.01) 25-OH-D and total (p=0.04), free (p=0.02), and bioavailable (p=0.03) 1,25-(OH)2-D concentrations. With all 25-OH-D and 1,25-(OH)2-D forms in the regression model, we found that free 1,25-(OH)2-D outweighed all other vitamin D forms regarding its association with FGF-23 (p=0.03).

CONCLUSION

The relationship between FGF-23 and vitamin D is stronger using free forms of 25-OH-D and 1,25-(OH)2-D. Subsequent studies aiming at MBD should consider including free 25-OH-D and 1,25-(OH)2-D in the analysis.

Quantification of Hemodialysis Dose: What Kt/V to Choose?

Background

Quantification of hemodialysis became more accurate and easier after the advent of ionic dialysance and the use of methods for estimating urea distribution volume (V). The aim of this study was to compare different methods of hemodialysis dose assessment: Kt/VDau (Daugirdas 2nd generation), Kt/VOCM (Kt by OCM (Online Clearance Monitor) and V by Watson), and Kt/VBCM (Kt by OCM and V by bio-impedance); and to assess the dialysis adequacy, defined by a Kt/V≥1.4.

Design

Prospective, observational study.

Methods

35 hemodialysis sessions were evaluated in 35 chronic hemodialysis patients. During each session, we measured simultaneously, Kt/VOCM, Kt/VBCM and calculated Kt/VDau by performing blood samples before and after each session.

Results

35 patients, gender (M/F: 19/16), mean age of 50.49 years, were evaluated. We noted a difference between the three methods of evaluating Kt/V index: Kt/VDau, Kt/VOCM and Kt/VBCM (1.82 ± 0.29; 1.45 ± 0.23; 1.8 ± 0.33, p<0.001). Comparison of Kt/VOCM with Kt/VDau and Kt/VBCM leads to a significant systematic underestimate of Kt/V by 22% and 20.5% respectively. Better agreement between Kt/VDau and Kt/VBCM was observed. The adequate hemodialysis was achieved, according to three methods: Kt/VDau, Kt/VOCM and Kt/VBCM respectively in 100%, 57,1% and 88.6% of the cases.

Conclusions

The Kt/V index is different depending on the method used for its evaluation. The three methods can be used for quantification of hemodialysis with a better agreement between Kt/VDau and Kt/VBCM. In this study, Kt/VOCM results underestimate hemodialysis efficiency. This difference has to be considered when applying quantification of hemodialysis to clinical practice.