Bioimpedance Measurements Research Articles

Bioimpedance Measurement under Feature Combination of Time-Frequency Domain and Application for E. coli Detection

Electrochemical impedance sensors are widely used for bacterial detection and interpreted by the equivalent circuit model (ECM) to evaluate the concentration changes on the electrode interface. However, this method is mainly based on prior models and focuses on frequency domain analysis which cannot precisely describe unknown dynamic processes and a fractional surface coverage of electrode. Distribution of Relaxation Times (DRT) method, as an alternative to interpret impedance spectra can be applied to solve the problem. In this research, two electrode schemes with different modification steps were designed to collect impedance data. An Ensemble Tree-SHAP model was then adopted to quantitatively analyze the impedance data processed by ECM-DRT method in time-frequency domain and applied for the detection of Escherichia coli (E. coli). The results showed that using a dataset integrated with time-frequency domain features significantly improved the accuracy of bacterial concentration prediction. As a result, the RMSE of untrained concentration with LightGBM model was 6.4×10−4 log CFU ml−1, with the sensor detection limit about 2.69 log CFU ml−1. The research provided a tool combining time-frequency analysis for accurate prediction of bacterial concentration, which is crucial for evaluation of the antibacterial effect of long-term antibiotics on E. coli in future.

The Feasibility of Semi-Continuous and Multi-Frequency Thoracic Bioimpedance Measurements by a Wearable Device during Fluid Changes in Hemodialysis Patients.

Repeated single-point measurements of thoracic bioimpedance at a single (low) frequency are strongly related to fluid changes during hemodialysis. Extension to semi-continuous measurements may provide longitudinal details in the time pattern of the bioimpedance signal, and multi-frequency measurements may add in-depth information on the distribution between intra- and extracellular fluid. This study aimed to investigate the feasibility of semi-continuous multi-frequency thoracic bioimpedance measurements by a wearable device in hemodialysis patients. Therefore, thoracic bioimpedance was recorded semi-continuously (i.e., every ten minutes) at nine frequencies (8-160 kHz) in 68 patients during two consecutive hemodialysis sessions, complemented by a single-point measurement at home in-between both sessions. On average, the resistance signals increased during both hemodialysis sessions and decreased during the interdialytic interval. The increase during dialysis was larger at 8 kHz (∆ 32.6 Ω during session 1 and ∆ 10 Ω during session 2), compared to 160 kHz (∆ 29.5 Ω during session 1 and ∆ 5.1 Ω during session 2). Whereas the resistance at 8 kHz showed a linear time pattern, the evolution of the resistance at 160 kHz was significantly different (p < 0.0001). Measuring bioimpedance semi-continuously and with a multi-frequency current is a major step forward in the understanding of fluid dynamics in hemodialysis patients. This study paves the road towards remote fluid monitoring.

Improving multidisciplinary management of patients living with obesity: The evaluation of seated bioimpedance measures and relationship to functional performance following targeted intervention.

Management of obesity requires a multidisciplinary approach including physical activity interventions, which have significant impacts on overall health outcomes. Greater levels of lean muscle mass are significantly associated with improved health and reduced risk of comorbidities and should be preserved where possible when undertaking rapid weight loss. This article reports on the physical and functional outcomes achieved during a 12-week intensive multidisciplinary intervention targeting obesity and evaluates correlations between body composition and functional outcomes. We additionally aimed to investigate the test-retest reliability and levels of agreement in body composition measurements using bioimpedance spectroscopy between seated and standing positions. Of the 35 participants included in analysis, significant differences were observed between baseline and post-intervention measures. These included weight loss of 12.6 kg, waist circumference reduction of 10.5 cm, fat mass reduction by 2.9%, muscle mass increase by 1.6%, 54.5 m improvement in the 6-minute walk test and 3.8 rep improvement in the 30-second sit-to-stand test. No significant correlations were observed between physical and functional outcome measures. Excellent test re-test reliability was observed in bioimpedance spectroscopy seated measurements (ICC >.9). Significant differences were observed between seated and standing bioimpedance spectroscopy measurements, however they are regarded as small differences in a clinical setting.

Localized hamstring bioimpedance in marathon runners is related to muscle high-energy enzyme serum levels and predicts race time.

Introduction: The aim was to analyze the response of serum levels of inflammatory, high-energy muscle biomarkers and hamstring localized bioimpedance (L-BIA) measurements to marathon running and to ascertain whether they correlate with each other or with race time. Methods: Blood samples and hamstrings tetra-polar L-BIA measurements from 14 Caucasian male recreational athletes at the Barcelona Marathon 2019 were collected at base line, immediately after and 48 h post-race. Serum C reactive protein (sCRP), creatinine kinase (sCK) and lactate dehydrogenase (sLDH) were determined using an AU-5800 chemistry analyzer. L-BIA was obtained at 50 kHz with a Quantum V Segmental phase-sensitive bioimpedance analyzer. Results: Median sCRP increased (4-fold) after 48 h post-race. Median sCK and sLDH levels increased immediately post-race (3-fold, 2-fold) and 48h post-race (5-fold, 1-fold). Left, right and combined hamstring reactance (Xc) and phase angle (PhA) increased immediately post-race. Xc combined hamstring pre- and immediately post-race correlated with race-time and with sCK and sLDH median levels pre-race. Xc combined hamstring pre- and immediately post-race > 15.6 Ω and 15.8 Ω, respectively, predicted the race time of 3:00:00 h. Conclusion: L-BIA reactance (Xc) is an objective direct, real time, easy, noninvasive bioelectrical parameter that may predict muscle and marathon athlete performance.

Soft electrodes for simultaneous bio-potential and bio-impedance study of the face

The human body’s vascular system is a finely regulated network: blood vessels can change in shape (i.e. constrict, or dilate), their elastic response may shift and they may undergo temporary and partial blockages due to pressure applied by skeletal muscles in their immediate vicinity. Simultaneous measurement of muscle activation and the corresponding changes in vessel diameter, in particular at anatomical regions such as the face, is challenging, and how muscle activation constricts blood vessels has been experimentally largely overlooked. Here we report on a new electronic skin technology for facial investigations to address this challenge. The technology consists of screen-printed dry carbon electrodes on soft polyurethane substrate. Two dry electrode arrays were placed on the face: One array for bio-potential measurements to capture muscle activity and a second array for bio-impedance. For the bio-potential signals, independent component analysis (ICA) was used to differentiate different muscle activations. Four-contact bio-impedance measurements were used to extract changes (related to artery volume change), as well as beats per minute (BPM). We performed concurrent bio-potential and bio-impedance measurements in the face. From the simultaneous measurements we successfully captured fluctuations in the superficial temporal artery diameter in response to facial muscle activity, which ultimately changes blood flow. The observed changes in the face, following muscle activation, were consistent with measurements in the forearm and were found to be notably more intricate. Both at the arm and the face, a clear increase in the baseline impedance was recorded during muscle activation (artery narrowing), while the impedance changes signifying the pulse had a clear repetitive trend only at the forearm. These results reveal the direct connection between muscle activation and the blood vessels in their vicinity and start to unveil the complex mechanisms through which facial muscles might modulate blood flow and possibly affect human physiology.

Modeling Anisotropic Electrical Conductivity of Blood: Translating Microscale Effects of Red Blood Cell Motion into a Macroscale Property of Blood.

Cardiovascular diseases are a leading global cause of mortality. The current standard diagnostic methods, such as imaging and invasive procedures, are relatively expensive and partly connected with risks to the patient. Bioimpedance measurements hold the promise to offer rapid, safe, and low-cost alternative diagnostic methods. In the realm of cardiovascular diseases, bioimpedance methods rely on the changing electrical conductivity of blood, which depends on the local hemodynamics. However, the exact dependence of blood conductivity on the hemodynamic parameters is not yet fully understood, and the existing models for this dependence are limited to rather academic flow fields in straight pipes or channels. In this work, we suggest two closely connected anisotropic electrical conductivity models for blood in general three-dimensional flows, which consider the orientation and alignment of red blood cells (RBCs) in shear flows. In shear flows, RBCs adopt preferred orientations through a rotation of their membrane known as tank-treading motion. The two models are built on two different assumptions as to which hemodynamic characteristic determines the preferred orientation. The models are evaluated in two example simulations of blood flow. In a straight rigid vessel, the models coincide and are in accordance with experimental observations. In a simplified aorta geometry, the models yield different results. These differences are analyzed quantitatively, but a validation of the models with experiments is yet outstanding.

P442 Renal lithogenic risk in patients with Inflammatory Bowel Diseases correlates with microbiota composition, urinary profile and dietary intake

Abstract Background Nephrolithiasis (NL) is a common extra-intestinal complication of inflammatory bowel diseases (IBD), often related to enteric hyperoxaluria. Growing evidence highlights the association between NL and gut microbiota, but no data are available on the urinary microbiota in IBD patients. Our study aims to analyse the relationship between diet, urinary lithogenic profile, and gut and urinary microbiota in patients with IBD. Methods We prospectively enrolled consecutive adult patients with IBD. All patients underwent abdominal ultrasound, blood tests and 24h-urine collection for lithogenic profile analysis. Moreover, a nutritional evaluation was performed, and all patients underwent bioimpedance measurement. Urinary and gut microbiota were analysed through 16S rRNA sequencing. Results 60 patients were enrolled: 32 with Crohn’s disease (CD) and 28 with ulcerative colitis (UC). NL was more frequent in CD than in UC (28% vs 14%). In patients with NL, gut microbiota analysis showed a lower relative abundance of Agathobacter (p&amp;lt;0.05) and a reduction in alpha diversity (p&amp;lt;0.05) [figure 1]. No statistically significant difference was found in urinary microbiota composition comparing patients with the presence or absence of NL. Protein (g/die) and phosphorus (mg/die) dietary intake were significantly associated with oxaluria (mg/L) (p=0.032 and p=0.007, respectively). At the same time, protein and calcium (mg/day) intake were significantly associated with NL (p= 0.018 and p= 0.023, respectively). Oxaluria and calcium oxalate relative saturation ratio (RSRCaOx) were significantly higher in CD compared to UC [Table 1]. Conclusion Patients with IBD and NL have distinctive gut microbiota features. CD patients showed a higher prevalence of NL and oxaluria levels than UC. In addition, NL occurrence and oxaluria correlated with some nutritional parameters. Further studies are needed to identify patients with IBD at greater risk of NL by connecting the parameters of the gut microbiota, urinary profile and dietary intake to act on modifiable factors aiming to reduce this risk.

Body Composition Changes in Male and Female Elite Soccer Players: Effects of a Nutritional Program Led by a Sport Nutritionist.

Soccer is a game in constant evolution and the intensity of play is increasing. Nutrition can play a role in the physical performance of elite players, maintaining their health and facilitating recovery. It is important to cover players' energy demands, and low energy availability may therefore result in impaired performance. This study aimed to evaluate alterations in body composition to determine the effects of a nutritional program led by a sport nutritionist. A group of 88 elite soccer players from a Serie A club in Italy (44 males aged 26.5 ± 3.0 years and 44 females aged 27.1 ± 5.2 years) were enrolled. To evaluate changes in body composition, bioimpedance and anthropometric measurements were obtained following the protocol of the International Society for the Advancement of Kinanthropometry (ISAK). Compared with females, males had more muscle mass and less fat mass in both seasons evaluated. Comparing the first and last seasons, the male soccer players showed increased muscle mass and decreased fat mass while the female soccer players only showed decreased fat mass. The presence of a specialist sport nutritionist on the staff of professional soccer clubs could be important to ensure energy availability and evaluate body composition during the season.

Abstract B001: Impedance based biomarker for “smart ROSE” pancreatic cancer detection: Initial results from an ongoing clinical trial with nsCanary

Abstract Pancreatic cancer (PC) accounts for half a million new cases and 4.7% of cancer-related deaths globally in 2020. Endoscopic ultrasound (EUS) guided fine needle biopsies (FNB) are the current standard for confirming suspicious lesions, although their diagnostic accuracy remains below 70% with a non-diagnostic rate of the first procedure as high as 40%. Rapid on-site evaluation (ROSE) was introduced to improve diagnostic accuracy via on-site pathology assessment. However, ROSE availability is often limited due to resource constraints. NovaScan has developed the nsCanary, a ”smart ROSE” device, which uses a bioimpedance spectroscopy biomarker based on the Cole Relaxation Frequency (CRF) to detect cancer in biopsy samples in real-time and on-site. The aim of this study is to present initial results from a clinical trial that validates the nsCanary’s ability to detect PC in biopsy samples. Data were collected with the nsCanary device in an IRB approved double-blind study including a cohort of 44 patients (20 males, 24 females; average age of 63 years; 66% White, 22% African American, 12% Hispanic) undergoing EUS procedures with FNB sampling for suspected PC at the Texas International Endoscopy Center in Houston, TX. The nsCanary is a small desktop instrument that performs spectral bioimpedance analysis to extract the CRF based biomarker in less than 30 seconds without altering the biopsied tissue. A touch panel user interface allows for the user to input information and start the measurement. Obtained biopsy samples were flushed in a disposable strainer in order to drain any excess fluid. A circular disposable electrode, consisting of an interdigitated array with alternating polarities was placed in contact with the sample to perform measurements of complex bioimpedance in the 1 kHz - 10 MHz frequency range. The design of the electrode allows it to sense the signal from samples as small as FNB cores. Samples with CRF value below 1 MHz for every scan were considered noncancerous. Samples with at least one CRF value above 1MHz or absence of CRF reading (i.e., CRF out of range) were considered cancerous. PC assessment provided by nsCanary was validated against histopathology outcomes for each biopsy sample. Pathology results indicated that out of the cancerous lesions observed, there were 7 cases of pancreatic adenocarcinoma, 2 cases of invasive adenocarcinoma, 1 case of ductal adenocarcinoma, and 1 case of metastatic renal cell carcinoma. Findings showed a sensitivity of 81.8%, specificity of 84.8%, PPV of 64.3% and NPV of 93.3% for a total of n=44 patients. The device is low cost, portable, and can be used in the surgical suite without interfering with the standard workflow or affecting the sample for following pathological assessment. The implementation of the nsCanary device into the clinic will adjunctively support the decision-making process by providing immediate feedback on cancer detection and sample adequacy. This will enable endoscopists to diagnose PC on the first biopsy procedure, ultimately facilitating prompt treatment of patients. Citation Format: Federica Dibennardo, Martina Guidetti, Onur Fidaner, Daniel S. Gehrke, Donato Ceres, Margaret C. John, Constantine H. Bovalis, Isaac Raijman, Les Bogdanowicz. Impedance based biomarker for “smart ROSE” pancreatic cancer detection: Initial results from an ongoing clinical trial with nsCanary [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B001.

Noninvasive Urinary Bladder Volume Estimation With Artifact-Suppressed Bioimpedance Measurements

Noninvasive Urinary Bladder Volume Estimation With Artifact-Suppressed Bioimpedance Measurements

Bioimpedance measurement: a non-invasive diagnosis of limb compartment syndrome.

The methods for diagnosing compartment syndrome non-invasively remain under debate. Bioimpedance measurements offer a promising avenue in clinical practice, detecting subtle changes in organ impedance due to volume shifts. This study explores bioimpedance measurement as a novel, painless method for diagnosing compartment syndrome, potentially enabling continuous monitoring. This work aims to develop a prototype device for non-invasive diagnosis of compartment syndrome based on bioimpedance changes and assess initial results through in vitro experiments on inanimate biological material. We assume a change in the bioimpedance value after the application of physiological solution. Between 2018 and 2022, a prototype device for diagnosing limb compartment syndrome was collaboratively developed with the Department of Cybernetics and Biomedical Engineering at the Technical University of Ostrava, Czech Republic. This device operates by comparing bioimpedance between two compartments, one of which is pathologically affected (experiencing compartment syndrome). The Bioimpedance Analyzer for Compartment Syndrome (BACS) has been utilized to conduct measurements on inanimate biological material in laboratory settings. Two samples of duck and chicken tissue, as well as piglets, were employed for these experiments. According to the size of sample was compartment syndrome simulated by injecting 20-120mL saline into one limb (breast) while leaving the other as a control. Invasive intramuscular pressure measurements were conducted post-saline injection using a conventional device (Stryker). Changes in bioimpedance were evaluated following saline application. The non-invasive bioimpedance measurement instrument has been developed. It meets the safety requirements of European standard EN 60601-1. Measurement of accuracy showed minimal deviation for both channels (1.08% for the left channel and 1.84% for the right channel) when measuring on resistors. Ten measurements were conducted using the BACS prototype - two on chicken legs, two on duck breasts, two on duck legs, and four on piglets. Compartment syndrome simulation was achieved for all 10 measurements (IMP variance 31-45mmHg). Following saline application, a notable decrease in bioimpedance was observed in the compartment simulating compartment syndrome (decrease by 12-78Ω). Non-invasive methods could revolutionize limb compartment syndrome diagnosis, offering advantages such as non-invasiveness and continuous monitoring of compartment swelling.

Bioimpedance as an alternative tool for subjective, visual scoring of a prevalent ham quality defect.

The detection of meat quality defects can involve both subjective and objective methods. PSE-like meat is linked to a common pork defect and can be caused by rapid post-mortem damage of muscle fibers. This damage can again be linked to various factors, such as a low ultimate pH or a higher slaughter weight. PSE-like defects are characterized by discoloration, structural damage, and excessive moisture loss. However, the lack of suitable instrument-based methods makes the detection of PSE-like defects difficult, and subjective methods typically suffer from poorer reproducibility. The objective of this study was to establish how subjective visual evaluation correlates with electrical impedance spectroscopy and with traditional quality parameters. To do so, visual scoring was performed together with measurements of bioimpedance, color, and pH in two ham muscles (Adductor, Semimembranosus) for 136 animals 24-hours post-mortem. When comparing with visual scoring, Pearson correlation analysis shows the strongest correlation for bioimpedance (Py , r = -0.46, R2 = 21%), followed by pHu (r = 0.44, R2 = 19%). When using all five quality measures, i.e., Py , pHu, and CIELAB L * a * b *, the multivariate regression model had a prediction error of 0.76 for the visual scores. This was close to the error describing the subjective bias of visual scoring, more specifically the prediction error between the two observers (0.85). In all, Py showed the strongest correlation among instrument-based quality tests and alone may be used for predicting pork ham structural defects, i.e., as an instrument-based alternative for subjective, visual scoring. However, an instrument that combines Py with pH and/or L*a*b* would improve the prediction of PSE-like quality defects.

Effect of body orientation and joint movement on local bioimpedance measurements.

The purpose of this pilot study was to determine if body orientation, skin treatment, joint angle, and shoulder arch movements affect localized bioimpedance spectroscopy (BIS) measurement. Nowadays, there are various wearable and portable impedance measurement tools in different shapes and sizes. Therefore, the body position and orientation of the subject during measurement may be of great importance for the comparability of the results. Ultrasound machine was used to measure the thickness of the skin layers and then bioimpedance measurements were performed for ten young men (age=23 ± 5) at room temperature (22°C) for different body orientations, skin treatments, joint angle, and shoulder arch movements. The results were analyzed using statistical methods and graphical presentation using Python and MatLab. Our observations indicate that there is a significant difference between standing straight up, supine and sitting positions. The results show that there is a significant difference between the two skin treatments (alcohol vs tape stripping). Moreover, joint angle and shoulder arch movements also have an impact on the impedance data. Therefore, to be able to control these factors can potentially improve the quality and comparability of the measured impedance data.

Натрийуретический пептид при ожирении и неалкогольной жировой болезни печени в молодом возрасте

The purpose — to study the relationship of increased natriuretic peptide (NUP) with obesity and non-alcoholic fatty liver disease (NAFLD) in young people. Material and methods. 142 patients, including 74 men and 68 women aged Me = 35 [31–39] years, were examined at the consulting and diagnostic center of the Aviastroiyelny district of Kazan. The study design is an observational clinical case-control study based on the criterion of constitutional obesity. A questionnaire was conducted, as well as a clinical examination with anthropometry, bioimpedance measurement, assessment of the level of N-terminal cerebral natriuretic peptide (NUP), ultrasound examination of the liver with detection of NAFLD, echocardiography. The indices of liver steatosis Non-Alcoholic Fatty Liver Disease – Liver Fat Score (NAFLD-LFS), Hepatic Steatosis Index (HSI) and Triglyceride and glucose Index (TyG) were calculated. The data is processed in IBM SPSS Statistics 26. Results. According to ultrasound data, NAFLD was found in 12.6% of the examined patients. Patients with NAFLD and exogenous constitutional obesity tended to have a higher incidence of elevated levels of NUP when compared with the group of obese people without NAFLD. The prognostic model results showed that NAFLD, HSI index &gt; 36, as well as female gender were associated with an increase in NUP. At the same time, obesity and male gender reduced the likelihood of NUP increase. Conclusion. NAFLD and obesity have a multidirectional effect on the likelihood of NUP increase among young people without diabetes mellitus and cardiovascular diseases. The presence of NAFLD is associated with an increase in NUP, while exogenous constitutional obesity reduces the likelihood of NUP increase.

Neuroinflammation in Obese Children.

Obesity is associated with chronic persistent inflammation due to a pool of tissue macrophages that can penetrate the blood-brain barrier and cause neuroinflammation. The analysis of the association of CD14+CD163+ monocytes in the peripheral blood with cognitive functions in 56 obese children (mean age 11.95 (9.45; 14.45) years) was carried out. The control group consisted of 10 children (mean age 10.4 (9.3; 13.8) years). Standard deviation of the body mass index (SDS BMI) and height (SDS height) were calculated using WHO AnthroPlus software (for children of 6-19 years). Body composition was assessed using bioimpedance measurement. Mononuclear cells were isolated from whole blood by centrifugation on a Ficoll-Urografin density gradient (ρ=1.077 g/ml). The content of CD14+CD163+ monocytes in the peripheral blood was assessed by flow cytometry. To analyze cognitive functions, the intelligence coefficient (IQ) was calculated and a Russian adaptation of the Rey test was performed. We found an increase in the number of M2-polarized CD14+CD163+ monocytes in the peripheral blood with an increase in the obesity degree and in the presence of cognitive decline, as well as a negative correlation of the level of M2-polarized monocytes and IQ, taking into account the excess of visceral fat. The revealed data on the relationship of M2-polarized CD14+CD163+ peripheral blood monocytes with obesity in children and the development of neuropsychological deficiency confirm the role of peripheral visceral obesity and neuroinflammation.

Improving sensitivity in the deep regions of a volume conductor using electrical focused impedance methods.

Bioimpedance measurements are becoming important in probing the human body for diagnosis and monitoring. An age old 4-electrode technique called tetrapolar impedance measurement (TPIM), giving transfer impedance, cannot localize a specific zone besides having large zones of negative sensitivity. A new technique named the focused impedance method (FIM) from Dhaka University (DU), Bangladesh used the algebraic average of two concentric and orthogonal TPIMs, localizing a zone of interest and having reduced magnitudes of negative sensitivity. Earlier, this was implemented with electrodes applied from one side of the human body giving information to shallow depths only. To get information from deeper regions, specifically, of the thorax, the same DU group placed two electrodes of a 4-electrode version of FIM at the front and two at the back in a horizontal plane of the thorax, using physics-based visualization. This was followed by a few quantitative studies using point sensitivity, which supported the concept. However, more quantitative studies still need to be performed, particularly using objects of finite sizes, in order to establish the technique on a stronger footing. The present study was taken up with this objective. A simplified approach was used in which the volume conductor was a rectangular non-conducting container filled with saline of uniform conductivity with an embedded spherical object - first an insulator and then a conductor. Electrodes were placed at specific chosen positions following the above visualization. Percentage change in transfer impedance with the object placed at different internal positions, compared to that without the object was obtained first using COMSOL simulation and then through experimental measurements. These were performed for both TPIM and FIM. The new configuration of 4-electrode FIM gave good depth sensitivity supporting the effectiveness of the new placement of electrodes.

Sensitivity study of a locally developed six electrode focused impedance method.

The Focused Impedance Method (FIM) is a new technique of electrical bioimpedance measurements in the human body. The idea originated in Bangladesh and provides an opportunity for localized measurement of bioimpedance down to reasonable depths from the body surface using skin surface electrodes. This has potential applications for physiological studies of targeted organs in the body and in detecting or diagnosing diseases and disorders. FIM is based on the age-old Tetra-Polar Impedance Measurement (TPIM) but provides a few significant improvements. Technology must be developed indigenously to obtain long-term benefits, particularly in Low and Medium Income countries (LMIC). This paper presents an experimental sensitivity study of the six-electrode version of the Focused Impedance method (FIM-6) with the circuit and phantom indigenously designed in Nepal. The work involved sensitivity studies of both FIM-6 and TPIM with the necessary circuit blocks developed through experimental validation. The sensitivity studies were performed on a simple 2D phantom with different electrode arrangements for FIM-6 and linear TPIM. A cylindrical object was placed at different positions for this study. The FIM-6 gave a high sensitivity in the central part, which remained almost constant within a small region that may be termed as the focused region. On the other hand, TPIM results fell off sharply away from the central point, making it unsuitable for practical measurements on target organs. Besides, there were areas with large negative sensitivities in TPIM, which were much smaller in FIM. The results obtained through this work clearly show the improvement offered by FIM over TPIM.

Влияние дулаглутида на метаболическую адаптацию у больных сахарным диабетом 2 типа и ожирением

Aim. To evaluate the effect of dulaglutide, a glucose-lowering drug from the group of glucagon-like peptide 1 receptor (GLP-1) agonists, on indicators of fat metabolism and irisin. Design. Open pilot study. Materials and methods. 85 people (56 women, 29 men) with type 2 diabetes mellitus and obesity of varying severity took part in the study. 17 of them had a history of myocardial infarction, 2 patients had stroke (acute cerebrovascular accident), and all the rest had arterial hypertension. All patients were prescribed dulaglutide, a GLP-1 agonist, for ongoing glucose-lowering therapy for the purpose of intensification. Results. After 12 months of therapy, a statistically significant (р &lt; 0.05) decrease in anthropometric parameters was obtained: body weight decreased from 110 (70–185) to 105.5 (60–159) kg, waist circumference decreased from 124.5 (46.4–150) to 119 (90–146) cm. The levels of glycated hemoglobin statistically significantly decreased — from 7.1% (5.4–10.6%) to 6.5% (6.2–12.4%) (р &lt; 0.05), total cholesterol — from 4.89 (2.07–15) to 4.55 (2.19–8.33) mmol/l (р &lt; 0.05), leptin — from 32.9 (14.9–127.6) to 24.5 (13.5–133.7) ng/ml (р &lt; 0.05), C-reactive protein — from 3.37 (0.01–64.2) to 2.24 (0.01–54.1) mg/ml (р &lt; 0.05), the HOMA β level statistically significantly increased — from 80 (4–359) to 110 (12.2–755) (р &lt; 0.05). In addition, the thickness of epicardial fat according to echocardiography significantly decreased — from 11 (2.5–20) to 10 (7–15) mm (р &lt; 0.05), as well as the amount of adipose tissue according to bioimpedance measurements from 52.3 (26.6–99.8) to 44.7 (28.2–73.9) kg (р &lt; 0.05). Conclusion. In patients with type 2 diabetes and obesity, therapy with GLP-1 agonist dulaglutide after 12 months contributed to a significant improvement in glycemic control and pancreatic β-cell function. In patients with type 2 diabetes and obesity, therapy with GLP-1 agonist the dulaglutide after 12 months, a significant decrease in body weight, the amount of adipose tissue, and epicardial fat was observed. Regression of adipose tissue according to bioimpedansometry data was accompanied by a significant decrease in the level of leptin, a marker of inflammation C-reactive protein, and a tendency to increase the level of adiponectin and irisin. Keywords: dulaglutide, obesity, type 2 diabetes mellitus, irisin, fat metabolism.

Load in the Loop Dual Howland Current Source for Wide Frequency Bandwidth and Wide Load Range Bioimpedance Measurements

Load in the Loop Dual Howland Current Source for Wide Frequency Bandwidth and Wide Load Range Bioimpedance Measurements

Use of bioimpedance in prevention of sarcopenia in the elderly.

Physiological ageing is associated with major and progressive changes in body composition, particularly in the decline of fat-free mass, which puts older individuals at risk of geriatric syndromes such as sarcopenia and sarcopenic obesity. Bioimpedance analysis noninvasively allows the determination of body composition, thus being able to rapidly assess primary risk factors leading to sarcopenia prediction. We conducted a study of 180 probands, 120 females (66.7%) with a mean age of 76.23 (SD = 9.29) years and 60 males (33.3%) with a mean age of 74.01 (SD = 8.99) years in cooperation with facilities for the elderly and with the inpatient department of the clinics of J.A. Reimann Hospital in Prešov. Body height, body weight, hip circumference, and waist circumference were determined by the anthropometric method, from which the values of the body mass index and waist-to-hip ratio were calculated. Active body mass, total body water, extracellular body water, intracellular body water, cell mass, body mass fat, body fat index, fat-free mass index, impedance at frequencies of 50 kHz, resistance, reactance, and phase angle were determined using the Quadscan 4000 Touch bioimpedance instrument. Appendicular skeletal muscle mass (ASMM) and muscle mass (ASMM/Ht2) were calculated. The data obtained from anthropometric and bioimpedance measurements were processed in MS Excel 2000 and STATISTICA ver. 12. The difference of means in the studied groups was tested by the t-test. Presarcopenia was diagnosed in 12 (6.66%) probands out of 180 probands, of which were 3 (5%) men and 9 women (7.5%). Phase angle, ASMM and ASMM/Ht2 values were significantly lower (p < 0.001) in men and women with presarcopenia. By introducing bioimpedance measurements into practice, it is possible to obtain results in a non-invasive way revealing possible presarcopenia in the elderly.