Bioimpedance Measurements Research Articles

Improved Estimation of Left Ventricular Volume from Electric Field Modeling.

Volume measurement is beneficial in left ventricular assist device (LVAD) therapy to quantify patient demand. In principle, an LVAD could provide a platform that allows bioimpedance measurements inside the ventricle without requiring additional implants. Conductance measured by the LVAD can then be used to estimate the ventricular radius, which can be applied to calculate ventricular volume. However, established methods that estimate radius from conductance require elaborate individual calibration or show low accuracy.This study presents two analytical calculation methods to estimate left ventricular radius from conductance using electric field theory. These methods build on the established method of Wei, now considering the dielectric properties of muscle and background tissue, the refraction of the electric field at the blood-muscle boundary, and the changes of the electric field caused by the measurements.The methods are validated in five glass containers of different radius. Additional bioimpedance measurements are performed in in-vitro models that replicate the left ventricle’s shape and conductive properties. The proposed analytical calculation methods estimate the radii of the containers and the in-vitro models with higher accuracy and precision than Wei’s method. The lead method performs excellently in glass cylinders over a wide range of radii (bias: 1.66%–2.48%, limits of agreement < 16.33%) without calibration to specific geometries.

Bandwidth and Common Mode Optimization for Current and Voltage Sources in Bioimpedance Spectroscopy.

Bioimpedance measurements use current or voltage sources to inject an excitation signal into the body. These sources require a high bandwidth, typically from 1 kHz to 1 MHz. Besides a low common mode, current limitation is necessary for patient safety. In this paper, we compare a symmetric enhanced Howland current source (EHCS) and a symmetric voltage source (VS) based on a non-inverting amplifier between 1 kHz and 1 MHz. A common mode reduction circuit has been implemented in both sources. The bandwidth of each source was optimized in simulations and achieved a stable output impedance over the whole frequency range. In laboratory measurements, the output impedance of the EHCS had its -3 dB point at 400 kHz. In contrast, the VS reached the +3 dB point at 600 kHz. On average over the observed frequency range, the active common mode compensation achieved a common mode rejection of -57.7 dB and -71.8 dB for the EHCS and VS, respectively. Our modifications to classical EHCS and VS circuits achieved a low common mode signal between 1 kHz and 1 MHz without the addition of complex circuitry, like general impedance converters. As a conclusion we found VSs to be superior to EHCSs for bioimpedance spectroscopy due to the higher bandwidth performance. However, this only applies if the injected current of the VS can be measured.

Thoracic, Peripheral, and Cerebral Volume, Circulatory and Pressure Responses To PEEP During Simulated Hemorrhage in a Pig Model: a Case Study.

Positive end-expiratory pressure (PEEP) is a respiratory/ventilation procedure that is used to maintain or improve breathing in clinical and experimental cases that exhibit impaired lung function. Body fluid shift movement is not monitored during PEEP application in intensive care units (ICU), which would be interesting specifically in hypotensive patients. Brain injured and hypotensive patients are known to have compromised cerebral blood flow (CBF) autoregulation (AR) but currently, there is no non-invasive way to assess the risk of implementing a hypotensive resuscitation strategy and PEEP use in these patients.The advantage of electrical bioimpedance measurement is that it is noninvasive, continuous, and convenient. Since it has good time resolution, it is ideal for monitoring in intensive care units (ICU). The basis of its future use is to establish physiological correlates. In this study, we demonstrate the use of electrical bioimpedance measurement during bleeding and the use of PEEP in pig measurement.In an anesthetized pig, we performed multimodal recording on the torso and head involving electrical bioimpedance spectroscopy (EIS), fixed frequency impedance plethysmography (IPG), and bipolar (rheoencephalography – REG) measurements and processed data offline. Challenges (n=16) were PEEP, bleeding, change of SAP, and CO2 inhalation. The total measurement time was 4.12 hours.Systemic circulatory results: Bleeding caused a continuous decrease of SAP, cardiac output (CO), and increase of heart rate, temperature, shock index (SI), vegetative - Kerdo index (KI). Pulse pressure (PP) decreased only after second bleeding which coincided with loss of CBF AR. Pulmonary arterial pressure (PAP) increased during PEEP challenges as a function of time and bleeding.EIS/IPG results: Body fluid shift change was characterized by EIS-related variables. Electrical Impedance Spectroscopy was used to quantify the intravascular, interstitial, and intracellular volume changes during the application of PEEP and simulated hemorrhage. The intravascular fluid compartment was the primary source of blood during hemorrhage. PEEP produced a large fluid shift out of the intravascular compartment during the first bleeding period and continued to lose more blood following the second and third bleeding. Fixed frequency IPG was used to quantify the circulatory responses of the calf during PEEP and simulated hemorrhage. PEEP reduced the arterial blood flow into the calf and venous outflow from the calf.Head results: CBF AR was evaluated as a function of SAP change. Before bleeding, and after moderate bleeding, intracranial pressure (ICP), REG, and carotid flow pulse amplitudes (CFa) increased. This change reflected vasodilatation and active CBF AR. After additional hemorrhaging during PEEP, SAP, ICP, REG, CFa signal amplitudes decreased, indicating passive CBF AR. 1) The indicators of active AR status by modalities was the following: REG (n=9, 56 %), CFa (n=7, 44 %), and ICP (n=6, 38 %); 2) CBF reactivity was better for REG than ICP; 3) REG and ICP correlation coefficient were high (R2 = 0.81) during CBF AR active status; 4) PRx and REGx reflected active CBF AR status. CBF AR monitoring with REG offers safety for patients by preventing decreased CBF and secondary brain injury.We used different types of bioimpedance instrumentation to identify physiologic responses in the different parts of the body (that have not been discussed before) and how the peripheral responses ultimately lead to decreased cardiac output and changes in the head. These bioimpedance methods can improve ICU monitoring, increase the adequacy of therapy, and decrease mortality and morbidity.

Multi-Channel Bioimpedance System for Detecting Vascular Tone in Human Limbs: An Approach.

Vascular tone plays a vital role in regulating blood pressure and coronary circulation, and it determines the peripheral vascular resistance. Vascular tone is dually regulated by the perivascular nerves and the cells in the inside lining of blood vessels (endothelial cells). Only a few methods for measuring vascular tone are available. Because of this, determining vascular tone in different arteries of the human body and monitoring tone changes is a vital challenge. This work presents an approach for determining vascular tone in human extremities based on multi-channel bioimpedance measurements. Detailed steps for processing the bioimpedance signals and extracting the main parameters from them have been presented. A graphical interface has been designed and implemented to display the vascular tone type in all channels with the phase of breathing during each cardiac cycle. This study is a key step towards understanding the way vascular tone changes in the extremities and how the nervous system regulates these changes. Future studies based on records of healthy and diseased people will contribute to increasing the possibility of early diagnosis of cardiovascular diseases.

Межгрупповая изменчивость обхватных размеров тела и подкожного жироотложения у молодых мужчин различных этнических групп

Introduction. This study is devoted to intergroup variability of body circumferences, degree and to-pography of subcutaneous fat deposition in samples of young men of different ethnic backgrounds. Materials and Methods. We used anthropometric survey data from Russian men from various regions of Russia, indigenous Altaians and Tuvans from the Altai and Tyva Republics measured in the period from 2015 to 2019. Anthropometric measurements were performed according to standard methods of the Re-search Institute and the Museum of Anthropology of Moscow State University using GPM (DKSH, Switzer-land) and Holtain (Holtain Ltd, UK) anthropometric instruments. Body composition was assessed by bioelec-trical impedance analysis using ABC-02 Medass (Medass, Russia). We analyzed body circumferences, the value of fat and skin folds in various points of the body, bioimpedance measurements, and central fat dep-osition indices. Mathematical processing of the data was performed using the standard Statistica 10 soft-ware package. Discriminant (canonical) analysis was performed to study the topography of subcutaneous fat deposition. The materials have been collected from the population of these territories randomly and anonymously, according to the rules of bioethics and protocols of informed consent. Results. A comparative analysis of the main statistical parameters in three ethnic samples of men showed no significant differences in body mass index, the amount of fat mass, and most circumferences measurements. Intergroup variability was clearly evident in the thickness of fat and skin folds, in the index of central obesity (waist-to-height ratio), in the waist-to-hip ratio, and in the body adiposity index (BAI). In Tuvans, the value of fat and skin folds in the abdominal area and on the inner surface of the shoulder is significantly greater than in Russians and Altaians; in Russians, the mean values of all fat deposition indices are significantly lower than in Altaians and Tuvans. The canonical analysis of the set of body circumferences and fat and skin folds showed the predominant development of waist and shoulder circumferences and subcutaneous fat deposition on the body in Altaians and Tuvans as compared to Russians. Conclusions. The nature of intergroup variability indicates a predisposition of the Altaians and Tu-vans to the central type of fat deposition, which can be regarded as a result of adaptation under environ-mental stress in most Mongoloid populations of Southern Siberia.

Anthropometric Profile Assessed by Bioimpedance and Anthropometry Measures of Male and Female Rugby Players Competing in the Spanish National League

Different rugby positions make different demands on players. It therefore follows that optimum body composition may vary according to the position played. Using anthropometry and bioimpedance analysis (BIA) to assess body composition, the present study aimed to compare the effect of sex and position on body composition variables using anthropometry and BIA methods. A total of 100 competitive rugby players (35 women and 65 men) competing in the First Spanish National League were recruited voluntarily and for convenience for this study. In the laboratory, body composition was assessed by anthropometry, following the recommendations established by the International Society for the Advancement of Kinanthropometry (ISAK), and by direct segmental multi-frequency BIA, following the guidelines established by the Spanish Group of Kinanthropometry (GREC) of the Spanish Federation of Sports Medicine (FEMEDE). We found sex-related differences in height, weight, body mass index and body fat (%) by anthropometry and in body lean mass (%) by DSM-BIA, in 4 of the 6 skinfolds assessed (p &lt; 0.05). We also observed position-related differences in all the variables assessed (p &lt; 0.05) except for lean body mass, as measured by both methods of determining body composition, and front thigh skinfold. Body composition and ∑6skinfolds differs according to sex and playing position, backs (16.6 ± 3.8% and 92.3 ± 33.9 mm,) vs. forwards (20.0 ± 6.7 and 115.3 ± 37.6 mm), and the muscle-adipose (meso-endomorphic somatotype) development predominated in both sexes. Thus, forwards of both sexes are taller, heavier and fatter, possibly due to the specific demands of this position. In addition, body composition measurements vary according to the method used (DSM-BIA vs. anthropometry), indicating that anthropometry is probably the best body composition assessment method.

Early assessment of body composition in patients with liver transplantation

Rationale: Patients with liver cirrhosis frequently present alterations in body composition consisting of decreased muscle mass, increased body water and variable alterations in fat mass. The objective was to study body composition in the immediate postoperative period of liver transplantation, as well as 1 month later by bioimpedance measurement.

Assessing Ischemic Injury in Human Intestine Ex Vivo with Electrical Impedance Spectroscopy.

Electrical impedance spectroscopy is a well-established tool for monitoring changes in the electrical properties of tissue. Most tissue and organ types have been investigated in various studies. As for the small intestine, there are several published studies conducted on pig and rat models. This study investigates the changes in passive electrical properties of the complete wall of the human intestine non-invasively during ischemia. We aim to use the passive electrical properties to assess intestinal viability. The bioimpedance measurements were performed using a two-electrode set-up with a Solartron 1260 Impedance/gain-phase analyser. The small intestinal samples were resected from patients who underwent pancreaticoduodenectomy. Impedance measurements were conducted following resection by placing the electrodes on the surface of the intestine. A voltage was applied across the intestinal sample and the measured electrical impedance was obtained in the ZPlot software. Impedance data were further fitted into a Cole model to obtain the Cole parameters. The Py value was calculated from the extracted Cole parameters and used to assess the cell membrane integrity, thus evaluate the intestinal viability. Eight small intestinal segments from different patients were used in this study and impedance measurements were performed once an hour for a ten-hour period. One hour after resection, the impedance decreased, then increased the next two hours, before decreasing until the end of the experiment. For all the intestinal segments, the Py values first increased and reached a plateau which lasted for 1 - 2 hours, before it decreased irreversibly. The time interval where Py value reached the maximum is consistent with reported viable/non-viable limits from histological analysis.

The Association between Anthropometry Indices and Serum Concentrations of Gamma-Glutamyl Transferase, Alkaline Phosphatase, Alanine Aminotransferase, and Aspartate Aminotransferase.

Background Nowadays, metabolic syndrome (MetS) has become a great public health crisis that threatens too many lives worldwide. Many previous studies have been investigated the association between MetS and anthropometric indices. This study is aimed at investigating the association between anthropometric indices with gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). We were using data from a large population-based cohort of seemingly healthy women and men. Methods A total of 7216 participants were included in this study. The serum levels of GGT, ALP, ALT, and AST with bioimpedance measures were obtained at the time of enrollment. Multiple regression analysis was performed to assess the relationship between anthropometric indices and serum levels of the aforementioned laboratory tests. Results Serum levels of GGT, ALP, ALT, and AST significantly correlated with body mass index (BMI). Only ALP had a significant association with visceral fat area (VFA). AST, ALT, and ALP levels had a positive correlation with 50 kHz whole-body phase. Conclusion From the findings of this study, body mass index consistently appeared a good predictor of elevated hepatic enzymes and triglycerides. Thus, it can be helpful in clinical settings to identify patients at risk of nonalcoholic fatty liver disease, which is closely related to metabolic syndrome.

Abstract 12455: Comparison of Clinical Symptoms and Bioimpedance to Pulmonary Capillary Wedge Pressure in Heart Failure

Introduction: Clinical symptoms of heart failure commonly include fatigue, edema, and shortness of breath. Unfortunately, clinical monitoring has proven to be unreliable for the assessment of congestion and predicting the need for hospitalization. Biosensing wearables have been developed as a potential adjunct to clinical signs and symptoms. Hypothesis: This report hypothesis a correlation between clinicians’ signs and symptoms of heart failure along with bioimpedance measurements (ZOE ® ), and pulmonary capillary wedge pressure (PCWP). Methods: One hundred and fifty-five subjects undergoing right heart catheterization (RHC) at Vanderbilt University Medical Center (VUMC) were prospectively enrolled. A Zo value (ohms) was obtained, jugular venous pressure (JVP) was estimated, edema graded, and dyspnea assessed in all subjects. RHC was performed by scheduled cardiologist per routine. One-way ANOVA was performed to assess relationship between dependent and independent variables. A Pearson correlation coefficient was used to compare Zo value and PCWP. Results: Neither estimated JVP (cmH 2 O) (p = 0.65, n=110) nor edema scores (p = 0.12, n=110) demonstrated a significant relationship to PCWP (Figure 1). The presence of subjective SOB also did not demonstrate significant association with PCWP (p = 0.99, n=110; Figure 1). There was no correlation between ZOE ® and PCWP (r = -0.08, p = 0.56, n=56; Figure 2). Conclusions: These findings support the idea that traditional measures for monitoring heart failure patients are limited.

Short Term Caloric Restriction and Biofeedback Enhance Psychological Wellbeing and Reduce Overweight in Healthy Women.

Obesity is highly prevalent, causing substantial cardiovascular and mental health morbidity. Women show increased risk for mental health disorders, that is multiplied in obesity and related to cellular and psychological stress that can be targeted by non-pharmacological interventions. A total of 43 women underwent two weeks of caloric restriction, half of which also received 7 h of individualized clinical psychological intervention including psychoeducation, mindfulness, and heart-rate-variability biofeedback. Effects on body mass index (BMI), fatty liver index (FLI), bioimpedance measures, serum parameters, perceived stress (PSS), burn-out susceptibility (burn out diagnostic inventory) and dimensional psychiatric symptom load (brief symptom inventory, BSI) were analyzed with linear mixed effects models. Caloric restriction led to a reduction in BMI, body fat and FLI, decreased serum concentrations of leptin, PSS score, BSI dimensions and global severity index (all p ≤ 0.0001, withstanding Bonferroni–Holm correction). Benefits of add-on biofeedback were observed for BMI reduction (p = 0.041). Caloric restriction was effective in ameliorating both psychological wellbeing and metabolic functions following a BMI reduction. Biofeedback boosted effects on BMI reduction and the combinative therapy may be protective against common progression to mental health and cardiovascular disorders in overweight women while comparing favorably to pharmacological interventions in terms of side-effects and acceptability.

Development of a tissue discrimination electrode embedded surgical needle using vibro-tactile feedback derived from electric impedance spectroscopy.

Some tumours may not be detected by ultrasound during biopsy, but recent evidence has shown that different tissues can be discerned by electric impedance. This paper explores the application of vibrotactile feedback in an electrode embedded needle to help classify tissue during fine-needle aspiration biopsy from bioimpedance measurements. The process uses electric impedance spectroscopy from 10 Hz to 349 kHz to fit the double-dispersion Cole model through the Newton-Raphson algorithm. A Naive Bayes classifier is then used on the equivalent circuit parameters to estimate the tissue at the needle tip. The method is validated through a series of experiments and user trials. The results show that the vibrotactile feedback is able to help the operator in determining the tissue the needle is in, suggesting that this may prove to be a useful supplement to the standard procedure used today. Graphical Abstract This paper explores the application of vibrotactile feedback for an electrode embedded needle to help classify tissue from electric impedance measurements. The data is fit to an equivalent circuit using Newton- Raphon's method. A Naive Bayes classifier is trained and later used in an experiment to estimate the tissue at the needle tip and provide an assigned vibrotacticle feedback to the user.

The Association of Circulating CD14++CD16+ Monocytes, Natural Killer Cells and Regulatory T Cells Subpopulations With Phenotypes of Cardiovascular Disease in a Cohort of Peritoneal Dialysis Patients

The altered expression of immune cells including monocyte subsets, natural killer (NK) cells and CD4+CD25+ regulatory T cells (Tregs) in end-stage kidney disease, affect the modulation of inflammation and immunity with significant clinical implications. The aim of this study was to investigate the profile of specific immune cells subpopulations and their correlations with phenotypes of established cardiovascular disease (CVD), including coronary artery disease (CAD) and heart failure (HF) in peritoneal dialysis (PD) patients.Materials and Methods: 29 stable PD patients and 13 healthy volunteers were enrolled. Demographic, laboratory, bioimpedance measurements, lung ultrasound and echocardiography data were collected. The peripheral blood immune cell subsets analysis was performed using flow cytometry.Results: PD patients compared to normal controls had lower total lymphocytes (22.3 ± 6.28 vs. 31.3 ± 5.54%, p = <0.001) and B-lymphocytes (6.39 ± 3.75 vs. 9.72 ± 3.63%, p = 0.01) as well as higher CD14++CD16+ monocytes numbers (9.28 ± 6.36 vs. 4.75 ± 2.75%, p = 0.0002). PD patients with prevalent CAD had NK cells levels elevated above median values (85.7 vs. 40.9%, p = 0.04) and lower B cells counts (3.85 ± 2.46 vs. 7.2 ± 3.77%, p = 0.03). Patients with increased NK cells (>15.4%) had 3.8 times higher risk of CAD comparing with patients with lower NK cell levels (95% CI, 1.86 – 77.87; p = 0.034). B cells were inversely associated with the presence of CAD (increase of B-lymphocyte by 1% was associated with 30% less risk for presence of CAD (95% CI, −0.71 – 0.01; p = 0.05). Overhydrated patients had lower lymphocytes counts (18.3 ± 4.29% vs. 24.7 ± 6.18%, p = 0.006) and increased NK cells [20.5% (14.3, 23.6) vs. 13.21% (6.23, 19.2), p = 0.04)]. In multiple logistic regression analysis the CRP (OR 1.43; 95% CI, 1.00 – 2.05; p = 0.04)] and lymphocytes counts (OR 0.79; 95% CI, 0.63–0.99; p = 0.04)] were associated with the presence of lung comets. Patients with higher NK cells (>15.4%, n = 15) were more likely to be rapid transporters (D/P creatinine 0.76 ± 0.1 vs. 0.69 ± 0.08, p = 0.04). Patients displaying higher Tregs (>1.79%) were older (70.8 ± 10.7 years vs. 57.7 ± 14.7years, p = 0.011) and had higher nPCR (0.83 ± 0.14 vs. 0.91 ± 0.17, p = 0.09).Conclusion: Future research is required to evaluate the role of immune cells subsets as potential tools to identify patients at the highest risk for complications and guide interventions.

Bioimpedance Sensors: A Tutorial

Electrical bioimpedance entails the measurement of the electrical properties of tissues as a function of frequency. It is thus a spectroscopic technique. It has been applied in a plethora of biomedical applications for diagnostic and monitoring purposes. In this tutorial, the basics of electrical bioimpedance sensor design will be discussed. The electrode/electrolyte interface is thoroughly described, as well as methods for its modelling with equivalent circuits and computational tools. The design optimization and modelling of bipolar and tetrapolar bioimpedance sensors is presented in detail, based on the sensitivity theorem. Analytical and numerical modelling approaches for electric field simulations based on conformal mapping, point electrode approximations and the finite element method (FEM) are also elaborated. Finally, current trends on bioimpedance sensors are discussed followed by an overview of instrumentation methods for bioimpedance measurements, covering aspects of voltage signal excitations, current sources, voltage measurement front-end topologies and methods for computing the electrical impedance.

Relationships between parameters of cardiorespiratory function and bioimpedance analysis in young patients with type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) triggers disruption of oxygen transport system in patients. The maximum oxygen consumption (VO2 max) during spiroergometry depends on the functional capabilities and composition of the body. Moreover, VO2 max may be considered a predictor of pathological changes in cardiovascular system.Aim. The purpose of the study was to investigate the compositional body characteristics and functional cardiorespiratory parameters in T1DM patients.Material and Methods. The study comprised 30 patients with T1DM (average age of 25.5 ± 8.1 years) and 10 patients of control group (average age of 27 ± 9 years). Patients received spiroergometry examination according to B. Bruce protocol and bioimpedansometry using the Inbody 770 apparatus. The study showed that T1DM patients reached anaerobic threshold faster (p = 0.032) and had significantly lower VO2 max and carbon dioxide emission compared to patients without diabetes (p = 0.021; p = 0.034) whereas exercise tolerance did not significantly differ compared with the corresponding value in control group. Patients with higher muscle mass i.e. muscle tissue weight (kg) according to bioimpedance measurements had higher values of VO2 max (L) in control group (p = 0.017) and in group of T1DM patients (p = 0.028).Conclusions: Young T1DM patients without cardiovascular diseases had significantly less effective cardiorespiratory system compared with that in people without diabetes even in those with high exercise tolerance. Rapid achievement of anaerobic threshold with preserved performance efficiency was a sign of unfavorable prognosis. Body mass index and lean body mass did not significantly affect the performance parameters in young T1DM patients. Screening of spiroergometry parameters may be used for identification of young T1DM patients at high risk of unfavorable cardiovascular diseases including chronic heart failure.

Development of Bioimpedance Sensors and Measurement System for Biomedical In-Vitro Applications

Abstract Bioimpedance analysis is a label-free and easy approach to obtain information on cellular barrier integrity and cell viability more broadly. In this work, we introduce a small, low-cost, portable in vitro impedance measurement system for studies where a shadow-free exposure of the cells is a requirement. It can be controlled by a user-friendly web interface and can perform measurements automated and autonomously at short intervals. The system can be integrated into an existing IoT network for remote monitoring and indepth analyses. A single-board computer (SBC) serves as the central unit, to control, analyze, store and forward the measurement data from the single-chip impedance analyzer. Various materials and manufacturing methods were used to produce a purpose-built lid on top of a modified 24-well microtiter plate in a “do it yourself” fashion. Furthermore, three different sensor designs were developed utilizing anodic aluminum oxide (AAO) membranes and gold-plated electrodes. Preliminary tests with potassium chloride (KCl) showed first promising results.

Pilot Study of Anti-Th2 Immunotherapy for the Treatment of Breast Cancer-Related Upper Extremity Lymphedema.

Simple SummaryLymphedema is a common complication of cancer, and patients with lymphedema have substantially decreased quality of life and suffer from lifelong symptoms. This study aimed to examine the effect of inhibition of Th2 inflammation in lymphedema by using QBX258, a combination of IL4/13 neutralizing antibodies. QBX258 treatment increased quality of life and reduced pathologic changes in skin including hyperkeratosis, cytokine production, fibrosis and immune cell recruitment. In conclusion, this study suggested that immunotherapy against IL4/13 improved patients’ daily life which might be related with reduced pathological skin changes.Recent studies suggest that Th2 cells play a key role in the pathology of secondary lymphedema by elaborating cytokines such as IL4 and IL13. The aim of this study was to test the efficacy of QBX258, a monoclonal IL4/IL13 neutralizing antibody, in women with breast cancer–related lymphedema (BCRL). We enrolled nine women with unilateral stage I/II BCRL and treated them once monthly with intravenous infusions of QBX258 for 4 months. We measured limb volumes, bioimpedance, and skin tonometry, and analyzed the quality of life (QOL) using a validated lymphedema questionnaire (Upper Limb Lymphedema 27, ULL-27) before treatment, immediately after treatment, and 4 months following treatment withdrawal. We also obtained 5 mm skin biopsies from the normal and lymphedematous limbs before and after treatment. Treatment was well-tolerated; however, one patient with a history of cellulitis developed cellulitis during the trial and was excluded from further analysis. We found no differences in limb volumes or bioimpedance measurements after drug treatment. However, QBX258 treatment improved skin stiffness (p < 0.001) and improved QOL measurements (Physical p < 0.05, Social p = 0.01). These improvements returned to baseline after treatment withdrawal. Histologically, treatment decreased epidermal thickness, the number of proliferating keratinocytes, type III collagen deposition, infiltration of mast cells, and the expression of Th2-inducing cytokines in the lymphedematous skin. Our limited study suggests that immunotherapy against Th2 cytokines may improve skin changes and QOL of women with BCRL. This treatment appears to be less effective for decreasing limb volumes; however, additional studies are needed.

Study differentiating fish oocyte developmental stages using bioimpedance spectroscopy

Fish oocyte development monitoring is a mandatory operation when studying breeding in captivity as well as in the wild. In aquaculture, it is required to determine the best fertilization time. In the wild, it helps to detect spawning grounds, the distribution of fish species and the interaction between animals and their environment. In both settings, the conventional technique for developmental stage identification consists of handling the fish for oocyte sampling and sample observation using a binocular zoom head. Such an operation is difficult for the operator as well as for the fish. There is a need for repeated anesthesia and oocyte sampling, and it relies on operator expertise to identify the developmental stage. In this context, this publication proposes, for the first time, to study the potential of bioimpedance measurement as an alternative in fish breeding studies. We have set up an experiment combining the in vitro bioimpedance measurement of sampled oocytes with the conventional estimation technique for 69 sampled collected on farmed European sea bass. The statistical analysis has demonstrated that three of the four main developmental stages can be identified using bioimpedance measurement. The integrability of the bioimpedance technique with its implantable sensor makes this potential alternative approach very promising. Thanks to this sensor it could be possible, for the first time ever, to monitor in vivo the oocyte developmental stage in captivity as well as in the wild.

A Goertzel Filter-Based System for Fast Simultaneous Multi-Frequency EIS

Bioimpedance measurement is a non-invasive, radiation-free, and inexpensive method for measuring the electrical properties of biological tissues. In applications where transients occur, the commonly used swept sinewave is replaced with broadband signals such as multisine. This makes the signal generation and the extraction of the real and imaginary parts of the impedance challenging. In this brief, an alternative to traditional fast Fourier transform (FFT) or coherent demodulation is presented. Based on the Goertzel filter, this alternative is simpler and requires very few digital resources. Its robustness to the harmonic fold back phenomenon, enables simple ternary current pulses to be used for excitation. The developed digital architecture is capable of simultaneous demodulation of 16 frequencies with an accuracy of 97% and 96% on the magnitude and phase measurement respectively. Employing a ternary sequence allows the use of a low power H-bridge current driver. The analog front-end and demodulation algorithm were implemented in an ASIC using a 180-nm CMOS technology. The system was tested on an isolated pig heart distinguishing edema from non-edema tissue by impedance changes.

Influence of experimental metabolic syndrome on bioimpedance spectroscopy indicators of rat body

The objective of this experiment was to establish sex-related differences in the parameters of bioimpedance spectroscopy of the Wistar rat’s bodies in the experimental metabolic syndrome (endocrine-salt model).&#x0D; Sexual dependencies of bioimpedance measurements in intact animals have been determined for the first time: males have higher amount of total fluid, but lower one of total fat. The intra/extracellular fluid balance in males is characterized with ratio 2:1, while in females is the other one - 1:1.&#x0D; For the first time the formation of the metabolic syndrome has already been determined on the seventh day in females which lead to decreasing in the percentage of total fat and to changing of the intra / extracellular fluid balance to ‘male’ type - 2:1. The last one should be considered as a sign of intracellular hyperhydration. In males the examined parameters have been being within the control values ​​throughout 21 days of experiment.