Fresenius Medical Care The BCM – Body Composition Monitor allows the detection of overhydration by determining the quantitative amount of excess fluid in. Fresenius Medical Care SUPPORT. For further information on the BCM – Body Composition Monitor, please see the following downloads: General Information. Download scientific diagram | The Fresenius’ Body Composition Monitor (BCM) is an example of multi-frequency Bio-impedance analysis technology. Picture.
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Bioimpedance measurements with the Body Composition Monitor BCM have been shown to improve fluid management in haemodialysis.
Body composition monitor (BCM)
However, there is a lack of a sufficiently robust evidence-base for use of the BCM outside of standard protocols. This study aims to characterise BCM measurement variation to allow users to make measurements and interpret the results with confidence in a range of clinical scenarios.
BCM measurements were made in 48 healthy controls and in 48 stable haemodialysis patients before and immediately after dialysis. The effect of utilising alternative measurement paths was assessed using mixed effects models and the effect of frezenius post-dialysis was assessed by comparing changes in BCM-measured overhydration OH with weight changes over dialysis.
The data from healthy controls suggest that there freseniuus no difference in BCM-measured OH between all the whole-body paths other than the foot-to-foot measurement.
Dialysis patients showed dresenius results other than having higher BCM-measured OH when measured across the site of a vascular access. There was good agreement between BCM-measured OH and change in weight, suggesting post-dialysis measurements can be utilised. These results suggest BCM protocols can be flexible regarding measurement paths and timing of measurement to ensure as many patients as possible can benefit from the technology.
Fluid management is an important part of care for haemodialysis patients Wizemann et al. There is growing evidence that the use of bioimpedance measurements with the body composition monitor BCM; Fresenius Medical Care, Germany can help guide fluid management and improve outcomes Moissl et al.
However, there are few pragmatic studies that can help to inform freseenius use of BCM outside of the strict protocol recommended for fresnius and used in interventional studies, which can exclude a significant number of patients when BCM is used as part of routine care. This is related to the effect that ultrafiltration Abbas et al. Measurements should also be made from hand-to-foot — as bvm is the only validated measurement path — and should avoid peripheral access sites, due to the presence of anatomical changes.
However, in practice these requirements would exclude a relatively large number of patients from having BCM measurements. fresnius
The haemodialysis population is highly comorbid and is disproportionately prone to amputations and tissue viability problems. Heavily bandaged limbs, damaged skin and amputations can prevent the use of the standard measurement path, while some complications may not prevent a measurement but will significantly affect the quality of fresenisu measurement — e.
Validated alternative pathways would allow measurements to be made on patients who would have otherwise have been managed without BCM or managed based on poor quality data. There are also a number of situations where it would be helpful to make post-dialysis BCM measurements. Practicalities and staffing levels can sometimes make it difficult to carry out all necessary BCM measurements at the same time as putting patients on dialysis, while post-dialysis measurements also allow immediate action to be taken when intradialytic symptoms prompt a review of target weights.
The potential for the fesenius of impedance rresenius different paths was demonstrated two decades ago using bioimpedance analysis BIA measurements Lukaski et al. The only investigation to consider alternative paths with BIS measurements was in preliminary work for this study, where it was shown that BCM-measured overhydration OH from the hand-to-hand path is an acceptable alternative to the standard path Keane and Lindley, When considering post-dialysis measurements, it is accepted that haemodialysis induced changes in fluid distributions affect whole-body bioimpedance Zhu et al.
Ethical approval was granted by a local ethics committee and all participants provided informed consent. Routine target weights were defined on the basis of clinical examination and BCM on indication.
Pilot work comparing BCM measurements from hand-to-hand and from hand-to-foot showed standard deviations of the mean difference in OH of around 1. Recruiting 48 subjects into each cohort would allow differences fresenihs 0.
This is deemed an acceptable sample size; differences below 0. Healthy controls had height measured using a stadiometer and weight measured using calibrated scales. For haemodialysis patients, height was taken from their clinical notes and pre- and post-dialysis weights were obtained as part of normal care.
BCM measurements were made with a standard BCM and also with a modified BCM – the 8-lead BCM – which had four additional cables allowing leads to be connected to electrodes on both hands and both feet.
This gave the possibility of making BCM measurements across a number of paths and also allowed the isolation of individual segments for measurement see figure 1. Standard and 8-lead BCM measurements were made on healthy subjects on one occasion while dialysis patients had measurements made pre- and post-dialysis.
All BCM measurements were checked visually for artefacts, and repeated until the difference in measured OH was no greater than 0. The 8-lead device does not display Cole-plots or body composition data to allow real-time assessment of artefacts or consistency, so repeat measurements were not made. Measurements of resistance, reactance and phase angle were made at cresenius same 50 frequencies as in the standard BCM, ffesenius seventeen combinations of voltage and current see fig.
Programmes were written in Matlab v. For each of the 17 paths, the measured data was fitted to the Cole equation as described by De Lorenzo et al. De Lorenzo et al. This provided equivalent data to the standard BCM device, which was validated by processing standard BCM impedance data with the custom analysis programme and comparing the results with those from the standard BCM see appendix 1.
The use of mixed-effects regression allowed a model to be built that could account for the repeated measures on an individual from the 8-lead BCM. This characterises the individual differences in fluid status and body composition and accounts for this when describing the differences between the paths at the cohort level.
For healthy controls, subject was taken as the random effect and path, sex and age were taken as fixed effects. The paths included in the model were limited to the 6 whole-body paths: For haemodialysis patients, the same model set up was used, only with the addition of measurement time pre- or post-dialysiswhich was added as a simple frezenius variable for the models of LTM and ATM freseniud as an interaction term for the model of OH, to allow assessment of ultrafiltration associated changes in fluid distributions between the paths.
To present the data, results for a 60 year old female measured on the standard path acted as a reference standard path was taken as hand-to-foot on the dominant side of the body for controls and on and the contralateral side of the body to the most recently used vascular access VA for dialysis patients.
Adjustments for age and sex in each model are given and also for measurement time in the models assessing LTM and ATM. Significance levels were set at 0.
To examine each model, plots of standardised residuals against fitted values were used to check the assumption of homoscedasticity and a Q-Q plot of the residuals was used to assess normality. To investigate the validity of post-dialysis measurements, the agreement between change in BCM-measured OH from the reference path and change in weight was assessed using Bland-Altman analysis.
Furthermore, the consistency of LTM and ATM from the start to end of dialysis was assessed based on the effect of measurement time in each of the mixed-effects models.
The estimate of R E from the curve-fitting routine was used as a marker of relative changes in fluid status during dialysis for comparisons between the five body segments, where the whole-body analysis models are not appropriate. Bland Altman analysis was done using Analyse-it for Microsoft Excel version 2. Patient characteristics can be seen in table 1. Details of model checking can be seen in Appendix 2. For the models of LTM and ATM, including measurement time as an interaction term did not make a difference to the model, suggesting that the effect of measurement time on LTM and ATM was not different between the paths.
For these models, measurement time was included as a predictor variable to investigate the validity of post-dialysis measurements of LTM and ATM. The data from healthy controls show that there is no difference in BCM-measured OH between all the whole-body paths other than the foot-to-foot measurement, which had a difference of 0.
Considering LTM and ATM, there was a significant difference between the reference path and most other paths, apart from the cross measurements, including higher LTM and lower ATM in the dominant arm and in the hand-to-hand path as compared to the reference path.
Haemodialysis patients showed different pre-dialysis patterns than subjects with normal renal function. In particular, there was a significant difference in pre-dialysis BCM-measured OH between the side of the body where vascular access was situated as compared to the contralateral side 0. Unlike controls, there was no difference in LTM or ATM between the sides Appendix 3despite the fact that vascular access is usually on the non-dominant side. Using the 8-lead BCM, the impedances of each limb individually can be isolated figure 1which can support the results of the frseenius models.
Estimation of RI has much greater uncertainty and for segmental measurements, especially, in the trunk, the data were largely uninformative. The use of measurement time as an interaction term in the models for dialysis patients showed that measured-OH changed by a different amount between freseniuz paths.
The only statistically significant interaction was for the foot-to-foot path, which suggests that there is a greater change in BCM-measured OH across this path compared to the other paths.
This is supported by looking at the segmental fresrnius data. If relative changes in R E over dialysis are used to indicate changes in fluid status, it can be seen that the greatest relative change is in the leg segments table 5. At a population level, it is becoming well accepted that using BCM as an aide in guiding fluid management in haemodialysis improves outcomes Onofriescu et al.
In an uncomplicated individual with relatively common characteristics, standard measurement protocols – from hand to foot on one side of the body avoiding vascular access sites – and decision making algorithms are likely to be beneficial.
Yet there is a lack of data to support use fresenisu BCM outside this standardised approach and there remains a great deal of uncertainty in utilisation of the technology in certain individuals.
By making 8-lead BCM measurements on healthy controls and dialysis patients, the effect of a number of simple alterations to BCM measurements are characterised which will allow these measurements to be made with greater confidence.
Measurements on healthy controls suggest there is no significant difference in OH from any whole-body path other than across the legs. In principle the models that were generated and validated for the standard path freseenius be employed with alternate paths. Changing from a whole-body measurement to a hand-to-hand or cross measurement will involve substitution of one limb for another and a change in the pathway through the trunk.
Using the segmental resistances in table 4the different path resistances can be built from the segments and referenced to the standard path figure 3.
Body Composition Monitor
For measurements of R Esubstituting limbs and trunk paths does not significantly alter the overall path R Efor any of the whole body paths except the leg to leg path which is noticeably lower, consistent with results from the regression model. For the arm to arm path, the higher resistance of the arms seems to be compensated by a lower measured resistance for a current crossing the trunk from arm to arm than from arm to leg.
The evidence supporting this recommendation comes from studies using different bioimpedance with different analysis techniques to the BIS used in the BCM. More recently, two studies from a single centre using segmental BIA SBIA have reported that water and lean tissue content is different in the fistula and non-fistula arms Panorchan et al. However, neither BIA or SBIA can adequately distinguish excess fluid from lean and adipose tissue, which left the possibility that the differences observed relate to differences in lean tissue alone rather than excess fluid, particularly given that fistulae tend to be placed in the non-dominant arm of patients.
The results here confirm that the presence of a vascular access does tend to increase OH. However, the effect mean: Considering the model results for LTM and ATM in controls, it is important to note that the equivalence of OH across different paths does not translate to these compartments. Where accurate monitoring of body composition is important, the standard pathway is preferred and consistency is important. This is consistent with previous work using BIA on controls that demonstrated decreased resistance in the dominant arm compared to the non-dominant arm Bedogni et al.
Considering the use of post-dialysis BCM measurements, change in body weight was compared to change in BCM-measured OH as there is no accepted gold standard measure of OH to validate post-dialysis measurements. However, dialysis has been shown to perturb fluid distributions Shulman et al. Fluid shifts from the limbs into the trunk manifest as an apparent decrease in ECF when measured by whole-body techniques and shifts from the trunk to the limbs as an increase in ECF Lundvall et al.
This supports the validation literature of the BCM which has shown that the change in BCM-measured OH over dialysis is comparable to the ultrafiltration volume Wabel et al. There are reasonably large limits of agreement which should be taken into account when making post-dialysis measurements, but these measurements were taken immediately after dialysis and it is reasonable to assume that they would be reduced if there was a time delay introduced between dialysis end and BCM measurement, as recommended by the manufacturer.
This discrepancy seems likely to be due to artefactual BCM measurements and highlights the need for some expertise when making measurements Lindley et al. The BCM validation literature also suggests that a bias is introduced into measurements of LTM and ATM when measurements are made immediately after dialysis but within 30 minutes this becomes non-significant. Despite the good agreement between change in BCM-measured OH and change in weight, the model for OH did suggest there was a degree of ultrafiltration induced changes in fluid distribution, with a larger change in the lower limbs than the upper.
This would suggest that relatively more fluid is recruited from the legs than the upper body which is largely in agreement with previous work. Measurements over the first 75 minutes of dialysis using BIS Shulman et al. Abbas et al Abbas et al. One of the implications of preferential removal of fluid from the legs than arms could be that the legs are the last segment that fluid is recruited from. If that is true, techniques for fluid management based on normalising calf ECF Seibert et al.