Practical aspects of volume control in chronic kidney disease using whole body bioimpedance

Lung Ultrasound Estimates the Overhydration and Benefits Blood Pressure Control in Normal or Mild Symptomatic Hemodialysis Patients

Introduction

Lung ultrasound (LUS) is used for dry weight guidance by assessment of pulmonary congestion in hemodialysis (HD) patients. The aim of this study was to estimate amounts of accumulated fluid by total LUS scores (TLUSS), which were scarcely reported in HD patients who were normal or had a mild functional abnormality. In addition, the correlations between the LUS score of each area and TLUSS were determined to suggest fewer specific areas valuable to shorten the examination time of LUS.

Methods

This cohort study was conducted in adult HD patients who have New York Heart Association Classes I-II. LUS and multifrequency bioimpedance (BIA) were performed at baseline and the individual prescribed dry weight was set. Then each LUS was conducted at 28 areas of bilateral intercostal spaces and calculated as TLUSS weekly for eight weeks in which dry weight was adjusted. The second BIA was also measured at week eight. The difference of pre-HD weight and target weight (weight gain; WG) represented the amount of fluid accumulation.

Results

Twenty patients with a mean age of 62.2±14.0 years were enrolled. One hundred and sixty-six LUS were performed in which forty episodes of them were simultaneously measured with BIA. Optimum dry weight adjusted by TLUSS which benefited in mean reductions of blood pressure, and cardiothoracic ratios. WG amounts were significantly correlated with TLUSS (r=0.38), and with extracellular fluid (r=0.35) and overhydration fluid (r=0.39) assessed by BIA. Estimations of mean fluid overload were 2.18 (TLUSS ≤15), 2.72 (TLUSS 16-24), 3.17 (TLUSS 25-33), 3.65 (TLUSS 34-38) and 5.03 (TLUSS ≥39) in liters. The cut-off points of sum scores of 12 specific lung areas represented the none-mild were <8, moderate at 8-16, and severe pulmonary congestions were >16.

Conclusion

TLUSS estimated accumulated fluid useful for volume and blood pressure controls. Performance of LUS in 12 specific lung areas may reduce spending time and support routine uses of LUS in clinical practice.

Bioimpedance spectroscopy: Is a picture worth a thousand words?

Volume status can be difficult to assess in dialysis patients. Peripheral edema, elevated venous pressure, lung crackles, and hypertension are taught as signs of fluid overload, but sensitivity and specificity are poor. Bioimpedance technology has evolved from early single frequency to multifrequency machines which apply spectroscopic analysis (BIS), modeling data to physics-based mixture theory. Bioimpedance plots can aid the evaluation of hydration status and body composition. The challenge remains how to use this information to manage dialysis populations, particularly as interventions to improve over hydration, sarcopenia, and adiposity are not without side effects. It is therefore of no surprise that validation studies for BIS use in peritoneal dialysis patients are limited, and results from clinical trials are inconsistent and conflicting. Despite these limitations, BIS has clinical utility with potential to accurately evaluate small changes in body tissue components. This article explains the information a BIS plot ("picture") can provide and how it can contribute to the overall clinical assessment of a patient. However, it remains the role of the clinician to integrate information and devise treatment strategies to optimize competing patient risks, fluid and nutrition status, effects of high glucose PD fluids on membrane function, and quality of life issues.

Patient perspectives of target weight management and ultrafiltration in haemodialysis: a multi-center survey

Background

Decisions around planned ultrafiltration volumes are the only part of the haemodialysis prescription decided upon at every session. Removing too much fluid or too little is associated with both acute symptoms and long-term outcomes. The degree to which patients engage with or influence decision-making is not clear. We explored patient perspectives of prescribing ultrafiltration volumes, their understanding of the process and engagement with it.

Methods

A questionnaire developed for this study was administered to 1077 patients across 10 UK Renal Units. Factor analysis reduced the dataset into factors representing common themes. Relationships between survey results and factors were investigated using regression models. ANCOVA was used to explore differences between Renal Units.

Results

Patients generally felt in control of their fluid management and that they were given the final say on planned ultrafiltration volumes. Around half of the respondents reported they take an active role in their treatment. However, respondents were largely unable to relate signs and symptoms to fluid management practice and a third said they would not report common signs and symptoms to clinicians. A fifth of patients reported not to know how ultrafiltration volumes were calculated. Patients responded positively to questions relating to healthcare staff, though with significant variation between units, highlighting differences in perception of care.

Conclusions

Despite a lack of formal acknowledgement in fluid management protocols, patients have significant involvement in decisions regarding fluid removal during dialysis. Furthermore, substantial gaps remain in patient knowledge and engagement. Formalizing the role of patients in these decisions, including patient education, may improve prescription and achievement of target weights.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02399-7.

Cost-effectiveness and value of information analysis of multiple frequency bioimpedance devices for fluid management in people with chronic kidney disease having dialysis

Background

Among people with chronic kidney disease (CKD) on dialysis, sub-optimal fluid management has been linked with hospitalisation, cardiovascular complications and death. This study assessed the cost-effectiveness using multiple-frequency bioimpedance guided fluid management versus standard fluid management based on clinical judgment.

Methods

A Markov model was developed to compare expected costs, outcomes and quality adjusted life years of the alternative management strategies. The relative effectiveness of the bioimpedance guided approach was informed by a systematic review of clinical trials, and focussed reviews were conducted to identify baseline event rates, costs and health state utility values for application in the model. The model was analysed probabilistically and a value of information (VOI) analysis was conducted to inform the value of conducting further research to reduce current uncertainties in the evidence base.

Results

For the base-case analysis, the incremental cost-effectiveness ratio (ICER) for bioimpedance guided fluid management versus standard management was £16,536 per QALY gained. There was a 59% chance of the ICER being below £20,000 per QALY. Form the VOI analysis, the theoretical upper bound on the value of further research was £53 million. The value of further research was highest for parameters relating to the relative effectiveness of bioimpedance guided management on final health outcomes.

Conclusions

Multiple frequency bioimpedance testing may offer a cost-effective approach to improve fluid management in patients with CKD on dialysis, but further research would be of value to reduce the current uncertainties.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12962-021-00276-6.

Are there any further modalities for prediction of subclinical volume overload in advanced stages of chronic kidney disease?

BACKGROUND

Subclinical volume overload in chronic kidney disease (CKD) patient represents a debatable issue. Although many tools were used to detect volume overload in such patients, many non-specific results were due to presence of comorbidities. Bioimpedance spectroscopy is an objective fluid status assessment method, which is shown superior to classical methods in many studies. Combining some of these tools may improve their accuracy and specificity. Inferior vena cava collapsibility index (IVCCI) with brain natriuretic peptide (BNP) can be combined for more specific volume assessment. This study was performed to assess the usage of combined IVCCI and BNP levels in CKD patients to predict subclinical volume overload.

METHODS

One hundred and ten patients with CKD (stages 4 and 5) not on dialysis and having normal left ventricular systolic function were included in this study. Exclusion criteria were: (1) patients with other causes of raised BNP than volume overload and (2) patients on diuretics. A complete medical history was obtained, and thorough examination and laboratory tests were performed for all included patients. IVCCI and BNP serum levels were evaluated. The patients who exhibited an overhydration (OH)/extracellular water (ECW) ratio of >15% were considered to have volume overload.

RESULTS

Twenty-six patients (23.6%) had subclinical hypervolemia as diagnosed by OH/ECW ratio of >15%. IVCCI ≤ 38% had higher diagnostic performance than BNP ≥ 24 pg/mL. Combining both IVCCI ≤ 38% and BNP ≥ 24 pg/mL increased the specificity and positive predictive value for detection of subclinical hypervolemia.

CONCLUSION

Combined elevated BNP level and decreased IVCCI are more precise tools for subclinical volume overload detection in CKD patients.

Classification of Hydration in Clinical Conditions: Indirect and Direct Approaches Using Bioimpedance

Although the need to assess hydration is well recognized, laboratory tests and clinical impressions are impractical and lack sensitivity, respectively, to be clinically meaningful. Different approaches use bioelectrical impedance measurements to overcome some of these limitations and aid in the classification of hydration status. One indirect approach utilizes single or multiple frequency bioimpedance in regression equations and theoretical models, respectively, with anthropometric measurements to predict fluid volumes (bioelectrical impedance spectroscopy-BIS) and estimate fluid overload based on the deviation of calculated to reference extracellular fluid volume. Alternatively, bioimpedance vector analysis (BIVA) uses direct phase-sensitive measurements of resistance and reactance, measured at 50 kHz, normalized for standing height, then plotted on a bivariate graph, resulting in a vector with length related to fluid content, and direction with phase angle that indexes hydration status. Comparison with healthy population norms enables BIVA to classify (normal, under-, and over-) and rank (change relative to pre-treatment) hydration independent of body weight. Each approach has wide-ranging uses in evaluation and management of clinical groups with over-hydration with an evolving emphasis on prognosis. This review discusses the advantages and limitations of BIS and BIVA for hydration assessment with comments on future applications.

Perspectives on clinical use of bioimpedance in hemodialysis: focus group interviews with renal care professionals

Background

Inadequate volume control may be a main contributor to poor survival and high mortality in hemodialysis patients. Bioimpedance measurement has the potential to improve fluid management, but several dialysis centers lack an agreed fluid management policy, and the method has not yet been implemented. Our aim was to identify renal care professionals’ perceived barriers and facilitators for use of bioimpedance in clinical practice.

Methods

Qualitative data were collected through four focus group interviews with 24 renal care professionals: dieticians, nephrologists and nurses, recruited voluntarily from a nation-wide selection of hemodialysis centers, having access to a bioimpedance-device. The participants were connected to each other and a moderator via equipment for telemedicine and the sessions were recorded. The interviews were semi-structured, focusing on the participants’ perceptions of use of bioimpedance in clinical practice. Thematic content analysis was performed in consecutive steps, and data were extracted by employing an inductive, interactive, comparative process.

Results

Several barriers and facilitators to the use of bioimpedance in clinical practice were identified, and a multilevel approach to examining barriers and incentives for change was found to be applicable to the ideas and categories that arose from the data. The determinants were categorized on five levels, and the different themes of the levels illustrated with quotations from the focus groups participants.

Conclusions

Determinants for use of bioimpedance were identified on five levels: 1) the innovation itself, 2) the individual professional, 3) the patient, 4) the social context and 5) the organizational context. Barriers were identified in the areas of credibility, awareness, knowledge, self-efficacy, care processes, organizational structures and regulations. Facilitators were identified in the areas of the innovation’s attractiveness, advantages in practice, and collaboration. Motivation, team processes and organizational capacities appeared as both barriers and facilitators.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-0907-4) contains supplementary material, which is available to authorized users.

Multiple-frequency bioimpedance devices for fluid management in people with chronic kidney disease receiving dialysis: a systematic review and economic evaluation

BACKGROUND

Chronic kidney disease (CKD) is a long-term condition requiring treatment such as conservative management, kidney transplantation or dialysis. To optimise the volume of fluid removed during dialysis (to avoid underhydration or overhydration), people are assigned a 'target weight', which is commonly assessed using clinical methods, such as weight gain between dialysis sessions, pre- and post-dialysis blood pressure and patient-reported symptoms. However, these methods are not precise, and measurement devices based on bioimpedance technology are increasingly used in dialysis centres. Current evidence on the role of bioimpedance devices for fluid management in people with CKD receiving dialysis is limited.

OBJECTIVES

To evaluate the clinical effectiveness and cost-effectiveness of multiple-frequency bioimpedance devices versus standard clinical assessment for fluid management in people with CKD receiving dialysis.

DATA SOURCES

We searched major electronic databases [e.g. MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, Science Citation Index and Cochrane Central Register of Controlled Trials (CENTRAL)] conference abstracts and ongoing studies. There were no date restrictions. Searches were undertaken between June and October 2016.

REVIEW METHODS

Evidence was considered from randomised controlled trials (RCTs) comparing fluid management by multiple-frequency bioimpedance devices and standard clinical assessment in people receiving dialysis, and non-randomised studies evaluating the use of the devices for fluid management in people receiving dialysis. One reviewer extracted data and assessed the risk of bias of included studies. A second reviewer cross-checked the extracted data. Standard meta-analyses techniques were used to combine results from included studies. A Markov model was developed to assess the cost-effectiveness of the interventions.

RESULTS

Five RCTs (with 904 adult participants) and eight non-randomised studies (with 4915 adult participants) assessing the use of the Body Composition Monitor [(BCM) Fresenius Medical Care, Bad Homburg vor der Höhe, Germany] were included. Both absolute overhydration and relative overhydration were significantly lower in patients evaluated using BCM measurements than for those evaluated using standard clinical methods [weighted mean difference -0.44, 95% confidence interval (CI) -0.72 to -0.15, p = 0.003, I2 = 49%; and weighted mean difference -1.84, 95% CI -3.65 to -0.03; p = 0.05, I2 = 52%, respectively]. Pooled effects of bioimpedance monitoring on systolic blood pressure (SBP) (mean difference -2.46 mmHg, 95% CI -5.07 to 0.15 mmHg; p = 0.06, I2 = 0%), arterial stiffness (mean difference -1.18, 95% CI -3.14 to 0.78; p = 0.24, I2 = 92%) and mortality (hazard ratio = 0.689, 95% CI 0.23 to 2.08; p = 0.51) were not statistically significant. The economic evaluation showed that, when dialysis costs were included in the model, the probability of bioimpedance monitoring being cost-effective ranged from 13% to 26% at a willingness-to-pay threshold of £20,000 per quality-adjusted life-year gained. With dialysis costs excluded, the corresponding probabilities of cost-effectiveness ranged from 61% to 67%.

LIMITATIONS

Lack of evidence on clinically relevant outcomes, children receiving dialysis, and any multifrequency bioimpedance devices, other than the BCM.

CONCLUSIONS

BCM used in addition to clinical assessment may lower overhydration and potentially improve intermediate outcomes, such as SBP, but effects on mortality have not been demonstrated. If dialysis costs are not considered, the incremental cost-effectiveness ratio falls below £20,000, with modest effects on mortality and/or hospitalisation rates. The current findings are not generalisable to paediatric populations nor across other multifrequency bioimpedance devices.

FUTURE WORK

Services that routinely use the BCM should report clinically relevant intermediate and long-term outcomes before and after introduction of the device to extend the current evidence base.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016041785.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Bioimpedance monitoring of cellular hydration during hemodialysis therapy

Introduction The aim of this paper is to describe and demonstrate how a new bioimpedance analytical procedure can be used to monitor cellular hydration of End Stage Renal Disease (ESRD) patients during hemodialysis (HD). Methods A tetra-polar bioimpedance spectroscope (BIS), (UFI Inc., Morro Bay, CA), was used to measure the tissue resistance and reactance of the calf of 17 ESRD patients at 40 discrete frequencies once a minute during dialysis treatment. These measurements were then used to derive intracellular, interstitial, and intravascular compartment volume changes during dialysis. Findings The mean (± SD) extracellular resistance increased during dialysis from 92.4 ± 3.5 to 117.7 ± 5.8 Ohms. While the mean intracellular resistance decreased from 413.5 ± 11.7 to 348.5 ± 8.2 Ohms. It was calculated from these data that the mean intravascular volume fell 9.5%; interstitial volume fell 33.4%; and intracellular volume gained 20.3%. Discussion These results suggest that an extensive fluid shift into the cells may take place during HD. The present research may contribute to a better understanding of how factors that influence fluid redistribution may affect an ESRD patient during dialysis. In light of this finding, it is concluded that the rate of vascular refill is jointly determined with the rate of "cellular refill" and the transfer of fluid from the intertitial compartment into the intravascular space.

Fluid volume expansion and depletion in hemodialysis patients lack association with clinical parameters

BACKGROUND

Achievement of normal volume status is crucial in hemodialysis (HD), since both volume expansion and volume contraction have been associated with adverse outcome and events.

OBJECTIVES

The objectives of this study are to assess the prevalence of fluid volume expansion and depletion and to identify the best clinical parameter or set of parameters that can predict fluid volume expansion in HD patients.

DESIGN

This study is cross-sectional.

SETTING

This study was conducted in three hemodialysis units.

PATIENTS

In this study, there are 194 HD patients.

METHODS

Volume status was assessed by multifrequency bio-impedance spectroscopy (The Body Composition Monitor, Fresenius) prior to the mid-week HD session.

RESULTS

Of all patients, 48 % (n = 94) were volume-expanded and 9 % of patients were volume-depleted (n = 17). Interdialytic weight gain was not different between hypovolemic, normovolemic, and hypervolemic patients. Fifty percent of the volume-expanded patients were hypertensive. Paradoxical hypertension was very common (31 % of all patients); its incidence was not different between patient groups. Intradialytic hypotension was relatively common and was more frequent among hypovolemic patients. Multivariate regression analysis identified only four predictors for volume expansion (edema, lower BMI, higher SBP, and smoking). None of these parameters displayed both a good sensitivity and specificity.

LIMITATIONS

The volume assessment was performed once.

CONCLUSIONS

The study indicates that volume expansion is highly prevalent in HD population and could not be identified using clinical parameters alone. No clinical parameters were identified that could reliably predict volume status. This study shows that bio-impedance can assist to determine volume status. Volume status, in turn, is not related to intradialytic weight gain and is unable to explain the high incidence of paradoxical hypertension.