Rapid development in the field of tissue engineering necessitates implementation of monitoring methods for evaluation of the viability and characteristics of the cell cultures in a real-time, ...non-invasive and non-destructive manner. Current monitoring techniques are mainly histological and require labeling and involve destructive tests to characterize cell cultures. Bioimpedance measurement technique which benefits from measurement of electrical properties of the biological tissues, offers a non-invasive, label-free and real-time solution for monitoring tissue engineered constructs. This review outlines the fundamentals of bioimpedance, as well as electrical properties of the biological tissues, different types of cell culture constructs and possible electrode configuration set ups for performing bioimpedance measurements on these cell cultures. In addition, various bioimpedance measurement techniques and their applications in the field of tissue engineering are discussed.
Background. In the modern world, much attention is paid to the early diagnosis and prevention of diseases of patients, which is associated with the need to develop and improve non-invasive, easily ...accessible and accurate biomedical devices in order to monitor the parameters of the functioning of the human body. Bioimpedance is a noninvasive technique that has a variety of applications. Biological tissue in contact with electrodes under the influence of alternating current exhibits complex impedance behavior, which requires the creation of accurate biophysical and electrical models. Materials and methods. In this paper, the models of interaction between electrode-tissue contacts are considered, and the factors influencing the result of impedance measurement are analyzed. Results. Based on the considered models of electrode-tissue contact interaction, a method for increasing the sensitivity of measurement and the accuracy of impedance measurement is proposed. Conclusions. The successful implementation of bioimpedance diagnostics depends on the basic biophysical and electrical model of the system, as well as the interaction of the electrode with the tissue. The methods of interaction between the electrode and the tissue studied in the work make it possible to increase the sensitivity, as well as to reduce the measurement errors.
Objective:
to determine a component body composition of students specializing in volleyball and athletics and to conduct a comparative analysis of the results.
Materials and methods:
the study was ...conducted at the Department of physical training and sports at the Yaroslavl State Medical University of the Ministry of Health of the Russian Federation. The study included students from different groups of physical training: volleyball (10 men and 10 women), athletics (10 women) (experimental groups), and firstyear students that attended physical training classes (14 men and 16 women) (control group).
Results:
significant differences were revealed between the anthropometric measurements in the experimental groups of the studied women and between the results of anthropometric measurements in the female volleyball players, female athletes, and students from the control group. Significant differences were revealed in the component body composition of the studied women from the experimental and control groups. The analysis of the results of anthropometric measurements in the experimental and control groups of men did not reveal any significant differences between the parameters. Bioimpedancemetry revealed significant differences in the composition of the internal milieu of volleyball players in comparison with the control group.
Conclusions:
1. differences were revealed in the component composition of the body of female athletes involved in gamebased and cyclic kinds of sport as well as in the parameters of bioimpedance of female volleyball players and the control group. Female volleyball players had higher parameters of total body fluids, intracellular and extracellular fluids, fatfree, fat, and active cell mass in comparison with female light athletes and the control group. The differences in the obtained results were more significant in the experimental groups. 2. Bioimpendance analysis of men showed significant differences in the component body composition of volleyball players in comparison with untrained students. The parameters of total body fluids, fatfree, fat, and active cell mass in sportsmen exceeded the same parameters in the control group. 3. Differences were established in the anthropometric parameters depending on the sportoriented specialization of female students. Female volleyball players had higher values of mass, length, body weight index, and body surface area, the circumferences of the pelvis, thighs, and wrists in comparison with the results obtained in female light athletes. Similar differences were revealed in the anthropometric parameters of female volleyball players and students from the control group. Significantly lower values of the body weight index, circumference of the chest and pelvis of female athletes were registered in comparison with students from the control group. Male volleyball players did not have significant differences in the anthropometric parameters. They tended to have an increase in the body mass, length and surface area of the body, circumference of the chest, thighs, and wrists.
In low frequency dosimetry the variability in the electrical conductivity values assigned to body model tissues represents a major source of uncertainty. The aim of this study is to propose a method ...for estimating the conductivity of human anisotropic skeletal muscle and fat
in the frequency range from 10 kHz to 1 MHz.
A method based on bounded electrical impedance tomography was used. Bioimpedance measurements were performed on the legs of ten subjects. Anatomically realistic models of the legs were then created using magnetic resonance images. The inverse problem of the tissue conductivities was solved using the finite element method. The results were validated using resampling techniques. These findings were also used to study the effects of muscle anisotropy on magnetic field exposure.
The estimated conductivities for anisotropic muscle were found to be in good agreement with values found in existing literature and the anisotropy was shown to decrease with increasing frequency, with the ratio of lateral to longitudinal conductivity increasing from 37% to 64%. The conductivity of fat was found to be almost a constant 0.07 S m
in the frequency range considered.
The proposed method was shown to be a viable option when estimating
conductivity of human tissue. The results can be used in numerical dosimetry calculations or as limits in future investigations studying conductivity with bioimpedance measurements.
Body composition reflects the dynamic processes in a child’s development. The recommended restrictive diets for patients with advanced chronic kidney disease (CKD) contribute to a high risk of ...sarcopenic muscle wasting as diagnosed by bioimpedancemetry.
The aim of the study
. To assess BMI and body composition in children with CKD, to identify features of body composition in patients with different BMI Z-score values.
Materials and methods.
The physical development of 110 children with CKD of different stages was assessed. Patients were divided into two clusters: Group 1 (92 children) with BMI from 10.95 to 21.5 kg/m
2
, BMI Z-score did not exceed +2.0 (without obesity); Group 2 (18 children) – BMI from 24.11 to 37.2 kg/m
2
, Z-score BMI – more than +2.0 (obese). All underwent bioimpedancemetry, the proportion of fat and active cell mass was assessed. The comparison was carried out by nonparametric statistics methods.
Results.
Changes in body composition were revealed: children without obesity had severe protein-energy deficiency in 7 cases (7.6 %). The difference in the proportion of fat mass in children of different groups, Me Q1; Q3: Group 1 – 18.00 % 14.00; 22.00, Group 2 – 35.00 % 21.98; 41.00, (Mann – Whitney U-test: U = 279.5, p = 0.00001). In Group 1, the active cell mass was 53.50 % 51.00; 56.00, in Group 2 – 41.50 % 39.00; 47.00 (U = 174.5, p = 0.000001), there were no significant differences in other parameters of bioimpedancemetry.
Conclusions.
The proportion of active cell mass is lower in overweight children, with a significant predominance of the proportion of fat mass, which indicates the depletion of protein reserves due to their redistribution and possible insufficient alimentary intake in advanced stages of CKD.
The aim of this study was to examine an association of individual and combined pulse waveform parameters derived from bioimpedance measurements, that is pulse waves from a distal impedance ...plethysmographic (IPG), a whole-body impedance cardiographic (ICG) and transformed distal impedance plethysmographic (tIPG) signals, with markers of subclinical atherosclerosis, i.e. carotid intima-media thickness (cIMT), brachial artery flow-mediated dilation (FMD) and carotid artery distensibility (Cdist). The level of the association was also compared for arterial pulse wave velocity (PWV) and cIMT, FMD, and Cdist.
IPG, ICG, tIPG signals were measured from 1741 Finnish adults aged 30–45 years. The association between pulse wave parameters and cIMT, FMD and Cdist was studied using bootstrapped stepwise Akaike's Information Criterion method resulting in selection of parameters other than PWV, i.e. parameters having stronger association with cIMT, FMD and Cdist than PWV, in the model. Then risk scores were calculated from the selected pulse wave parameters and their association between cIMT, FMD and Cdist was studied with multivariable linear regression analysis.
The risk score was found to be the third strongest predictor of subclinical atherosclerosis as indicated by cIMT measurement, the second strongest predictor of FMD and the strongest predictor of Cdist. These findings show that several individual pulse wave parameters were associated more strongly with cIMT, FMD, and Cdist than PWV when adjusted with clinical risk factors.
Impedance based pulse waveform analysis provides a useful tool for assessing cardiovascular risk and estimating presence of structural changes in the vasculature.
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•Pulse wave (PW) parameters were derived from bioimpedance measurements.•PW parameters were used to calculate risk scores for subclinical atherosclerosis.•Several PW parameters have stronger association with carotid intima-media thickness (cIMT), brachial artery flow-mediated dilation (FMD) and carotid artery distensibility (Cdist) than PWV.•PWV was not selected among the most relevant predictors in the risk scores.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Background
Lumbar puncture is a common clinical procedure that can occasionally be difficult. Various needle guidance methods can facilitate performing this procedure, but at the expense of special ...expertise, equipment and facility. In the present study, we evaluated the clinical feasibility of a novel bioimpedance needle system regarding its ability to detect cerebrospinal fluid (CSF) in paediatric lumbar punctures.
Methods
We performed 40 lumbar puncture procedures using the bioimpedance needle system in 37 paediatric patients, aged from 0 days to 17 months, as a part of their prescribed examinations in two university hospitals. The bioimpedance needle is similar to a conventional 22G cutting‐edge spinal needle with a stylet, except the needle and stylet are configured as a bipolar electrode with high spatial resolution. The system measures in real‐time when the needle tip reaches the subarachnoid space containing CSF. The procedure was considered successful when the erythrocyte count was determined from the obtained CSF sample.
Results
Subarachnoid space was verifiably reached in 28 out of 40 procedures (70%). Bioimpedance needle system detected CSF in 23 out of these 28 successful procedures (82%) while failed in 3 out of 28 procedures (11%). No adverse events were reported.
Conclusion
Bioimpedance spinal needle system was found clinically feasible in paediatric lumbar punctures, and it may offer an objective and simple means to detect the time point when the needle tip is in contact with the cerebrospinal fluid.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Background Assessment of hydration status in patients with chronic kidney failure treated by dialysis is crucial for clinical management decisions. Dilution techniques are considered the gold ...standard for measurement of body fluid volumes, but they are unfit for day-to-day care. Multifrequency bioimpedance has been shown to be of help in clinical practice in adults and its use in children and adolescents has been advocated. We investigated whether application of multifrequency bioimpedance is appropriate for total-body water (TBW) and extracellular water (ECW) measurement in children and adolescents on dialysis therapy. Study Design A study of diagnostic test accuracy. Setting & Participants 16 young dialysis patients (before a hemodialysis session or after peritoneal dialysis treatment) from the Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy, and the Emma Children’s Hospital−Academic Medical Center, Amsterdam, the Netherlands. Index Test TBW and ECW volumes assessed by multifrequency bioimpedance. Reference Tests TBW and ECW volumes measured by deuterium and bromide dilution, respectively. Results Mean TBW volumes determined by multifrequency bioimpedance and deuterium dilution were 19.2 ± 8.7 (SD) and 19.3 ± 8.3 L, respectively; Bland-Altman analysis showed a mean bias between the 2 methods of −0.09 (95% limits of agreement, −2.1 to 1.9) L. Mean ECW volumes were 8.9 ± 4.0 and 8.3 ± 3.3 L measured by multifrequency bioimpedance and bromide dilution, respectively; mean bias between the 2 ECW measurements was +0.6 (95% limits of agreement, −2.3 to 3.5). Limitations Participants ingested the deuterated water at home without direct supervision by investigators, small number of patients, repeated measurements in individual patients were not performed. Conclusions Multifrequency bioimpedance measurements were unbiased but imprecise in comparison to dilution techniques. We conclude that multifrequency bioimpedance measurements cannot precisely estimate TBW and ECW in children receiving dialysis.
An important component in bioimpedance measurements is the current driver, which can operate over a wide range of impedance and frequency. This paper provides a review of integrated circuit analog ...current drivers which have been developed in the last 10 years. Important features for current drivers are high output impedance, low phase delay, and low harmonic distortion. In this paper, the analog current drivers are grouped into two categories based on open loop or closed loop designs. The characteristics of each design are identified.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Electrical impedance tomography (EIT) may have potential to overcome existing limitations in stroke differentiation, enabling low-cost, rapid, and mobile data collection. Combining bioimpedance ...measurement technologies such as EIT with machine learning classifiers to support decision-making can avoid commonly faced reconstruction challenges due to the nonlinear and ill-posed nature of EIT imaging. Therefore, in this work, we advance this field through a study integrating realistic head models with clinically relevant test scenarios, and a robust architecture consisting of nested cross-validation and principal component analysis. Specifically, realistic head models are designed which incorporate the highly conductive layers of cerebrospinal fluid in the subarachnoid space and ventricles. In total, 135 unique models are created to represent a large patient population, with normal, haemorrhagic, and ischemic brains. Simulated EIT voltage data generated from these models are used to assess the classification performance of support vector machines. Parameters explored include driving frequency, signal-to-noise ratio, kernel function, and composition of binary classes. Classifier accuracy at 60 dB signal-to-noise ratio, reported as mean and standard deviation, are (79.92% ± 10.82%) for lesion differentiation, (74.78% ± 3.79%) for lesion detection, (77.49% ± 15.90%) for bleed detection, and (60.31% ± 3.98%) for ischemia detection (after ruling out bleed). The results for each method were obtained with statistics from 3 independent runs with 17,280 observations, polynomial kernel functions, and feature reduction of 76% by PCA (from 208 to 50 features). While results of this study show promise for stroke differentiation using EIT data, our findings indicate that the achievable accuracy is highly dependent on the classification scenario and application-specific classifiers may be necessary to achieve acceptable accuracy.
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