Bioimpedance Measurements Research Articles

Multi-channel EMG manifestations of upper-extremity muscle coordination imbalance among community-dwelling sarcopenic seniors

BackgroundSarcopenia is an age-related, insidious, crippling but curable degenerative disease if diagnosed and treated early. However, no accessible and accurate early screening method is available for community settings that does not require specialized personnel. One of the hallmarks of sarcopenia is the pathological changes of muscle fiber type composition and motor unit firing patterns. Surface electromyography (sEMG) may serve as an effective tool for detecting differences between healthy and sarcopenic individuals due to its superior wearability and accessibility compared to other screening methods such as medical imaging and bioimpedance measurements, making it ideal for community-based sarcopenic screening. Our study aims to explore sEMG biomarkers that can be used for screening or diagnosis of sarcopenia.ResultsWe collected multi-channel sEMG signals from six forearm muscles of 98 healthy and 55 sarcopenic community-dwelling older adults. Participants performed grasp tasks at 20% and 50% of maximum voluntary contraction (MVC). Hexagons created by various EMG features, normalized with respect to respective MVC, and symmetry analyses were performed to estimate multi-muscle coordination patterns. An innovative index, namely incenter–circumcenter distance of muscle coordination (ICDMC), is proposed to discriminate between the healthy and sarcopenic groups. We utilized non-parametric tests to compare the ICDMC between the two groups, considering a p-value less than 0.05 statistically significant. The results showed that at 20% MVC, ICDMCs from root mean square (RMS), mean absolute value (MAV), slope sign changes (SSC) and wavelength (WL) showed statistically significant differences. More insights of this sEMG manifestation of sarcopenia were revealed by gender- and age-stratifications analyses.ConclusionsOur results demonstrated that there are clear sEMG manifestations of altered muscle coordination in sarcopenic patients. More consistent force generation patterns were observed in the sarcopenic group, especially at lower contraction intensities. The novel ICDMC can quantify differences between sarcopenic and healthy muscle. These results warrant further research to further develop more accessible sarcopenia screening strategies in community settings based on electrophysiological measurements such as sEMG.

Comparative Effects of Sleeve Gastrectomy vs. Roux-en-Y Gastric Bypass on Phase Angle and Bioelectrical Impedance Analysis Measures: A Systematic Review and Meta-Analysis.

Background/Objectives: The objective of this meta-analysis was to determine the impact of bariatric surgery on phase angle (PhA) and other bioimpedance measures among adults with obesity, comparing the effects of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG). Methods: A systematic review and meta-analysis were conducted following PRISMA guidelines, including studies up to May 2024 from MEDLINE, Scopus, Cochrane Library, and Web of Science. Eligible studies assessed PhA changes pre- and post-bariatric surgery in adults with BMI ≥ 30 kg/m2. Data on PhA, fat mass (FM), fat-free mass (FFM), body cell mass (BCM), weight, and BMI were extracted and analyzed. Results: Thirteen studies with a total of 1124 patients were included. Significant PhA reductions were observed at 6 months post-surgery (effect size: -1.00; 95% CI: -1.11 to -0.89; p < 0.001), with a more substantial reduction in RYGB patients compared to SG. FM and FFM decreased significantly at 12 months (FM: -27.58; 95% CI: -32.58 to -22.57; p < 0.001; FFM: -10.51; 95% CI: -12.81 to -8.94; p < 0.001). Weight and BMI showed marked reductions at 6 months (Weight: -31.42 kg; 95% CI: -37.28 to -25.26; p < 0.001; BMI: -11.39; 95% CI: -12.60 to -10.18; p < 0.001), with sustained decreases at 12 and 24 months. Conclusions: Bariatric surgery significantly reduces PhA, FM, FFM, weight, and BMI, with initial greater impacts observed in RYGB compared to SG. PhA shows potential as a marker for monitoring post-surgical recovery and nutritional status. Further long-term studies and standardized measurement protocols are recommended to optimize patient management.

Thirty-five years of personalized promotion. The contribution of medicine in the workplace

Abstract Issue/problem Occupational medicine has always had the task of identifying and solving problems caused by exposure to occupational risks and improving the health conditions of workers. This traditional prevention task can be advantageously associated with promotional activities to reduce the incidence of non-communicable diseases. Description of the problem Since the end of the 1980s we have conducted health promotion interventions in the workplace, integrated into the company’s occupational prevention plan. The results, discussed internationally, have allowed the improvement of projects such as the one presented here, aimed at the prevention of cardiovascular and metabolic risks. Results Workers carry out a clinical check integrated with blood chemistry tests, actigraphic measurement of physical activity and sleep, bioimpedance measurement and plicometry, to objectify the data of interest. Furthermore, they keep a food diary and answer questionnaires on lifestyle, stress, and sleep. They receive personalized non-pharmacological treatment aimed at making salutogenic changes to diet, sleep, physical activity, and relaxation methods. They are monitored monthly and carry out a follow-up after six months. The pilot study, conducted on 20 healthcare workers with previously undiagnosed metabolic problems, indicates a significant improvement in abdominal circumference, systolic blood pressure and sleep duration in the third month. Workers report a high level of satisfaction with the initiative, a lower level of occupational stress and a higher quality of sleep. Lessons Accumulated experience demonstrates that projects of this type are feasible, sustainable, and advantageous and can be applied to companies of all sizes, regardless of the quantity of resources available. Key messages • Health promotion in the workplace can contribute to the reduction of chronic non-communicable diseases. • The active participation of workers in health promotion activities contributes to improving job engagement and satisfaction derived from work.

Оценка нутритивного статуса и рисков его нарушения у детей с болезнью Крона: одномоментное исследование

Children with Crohn's disease (CD) are at high risk for developing nutritional deficiencies. According to studies in adult patients with CD, loss of lean and skeletal muscle mass and decreased bone mineral density (BMD) are unfavorable prognostic factors for the course of the disease; among children, the prevalence of these changes has not been sufficiently studied as yet. The purpose of this research was to study the frequency and correlation between disorders of body composition and decreased bone mineral density in children with CD. Materials and methods used: medical records of 163 aged 5 to 17 y/o with a confirmed CD diagnosis were assessed for the risk of nutritional deficiency using STRONGkids screening tool, anthropometric parameters, body composition with bioimpedance measurements as well as the disease activity index with PCDAI and endoscopic activity with SES-CD. BMD was assessed in 145 using densitometry. Results: depending on the degree of risk of malnutrition, children were divided into 2 groups as follows: G1 with high and G2 with moderate risks for malnutrition. G1 patients had significantly lower values of both anthropometric indices (Z-scores BMI/age, mid-upper arm circumference/age) and lean and skeletal muscle mass (p&lt;0.001) along with more severe course of CD according to PCDAI (p&lt;0.001). According to bioimpedansometry data, a significant increase in catabolic processes was found in G1 children as a decrease in Z-scores for both the phase angle (p&lt;0.001) and the active cell mass (p&lt;0.001). A decrease in BMD was detected in 9 (37%) of G1 and 26 (21.4%) of G2. A correlation was found between Z-scores lean body mass/age and BMD/age (p&lt;0.001, Rs=0.612). Among children with reduced BMD values, the indicators for BMI, lean, skeletal muscle and active cell mass according to bioimpedance measurements were significantly lower (p&lt;0.001). Conclusion: the data obtained during the study proposes high incidence of decreased bone mineral density along with pathological changes in body composition in children with CD. The use of STRONGkids tool to identify children at high risk of developing malnutrition, especially in the absence of the technical ability to conduct a detailed assessment of nutritional status with determination of body composition and BMD indicators, makes it possible to timely identify patients requiring individual nutritional support aiming to optimizing diets and, if necessary, prescribing addition of specialized food supplements.

Changes of the microbiome as a predictor of comorbidity in gastrostomy patients

Dysphagia as a symptom of dysfunction of the digestive system occurs in patients with various pathologies and in severe cases requires the formation of a nutrient fistula. The presence of a stoma is a source of additional pathological changes. Changes in the microbiota of gastrostomy patients is an issue that is practically not covered in the scientific literature. The purpose of the study is to determine characteristic changes in the microbiota of the oral cavity, stomach and intestines caused by nutritional stoma and their clinical significance. Materials and methods. The study included 20 children fed through a gastrostomy tube and 10 children fed by mouth. Group 1 consisted of patients with a gastrostomy installed in less than 1 year, group 2 - in periods of more than 1 year, group 3 - children without gastrostomy. All patients underwent a standard examination in a gastroenterological hospital and 16S rRNA sequencing of aspirates from 3 biotopes - mouth, stomach and intestines. An assessment of physical development and bioimpedance measurements was carried out, and a group of patients with sarcopenia was identified. Results. In all three biotopes of patients with gastrostomies, a pronounced disturbance of microbiological homeostasis was found. In the oral cavity, the number of anti-carious microorganisms is reduced and, on the contrary, the level of periodontogenic strains is increased. This fact is the cause of the occurrence of comorbid conditions and requires the appointment of local therapy with probiotic strains approved for use. Changes in the gastric microbiome after gastrostomy placement are characterized by a high degree of H. pylori contamination against the background of a decrease in anti-inflammatory protection. Determining the level of bacteria of the genera Prevotella, Parabacteroides, Porphyromonas in the stomach can become a marker of concomitant chronic inflammatory changes in the mucous membrane of the upper gastrointestinal tract, a high risk of developing peptic ulcers and its complications. The state of the gut microbiome correlates with underweight, BMI, proportion of fat mass and active cell mass. The development of sarcopenia in gastrostomy patients is one of the possible dangerous comorbid conditions, one of the diagnostic criteria of which is a decrease in the level of Phylum Fusobacteriota bacteria.

Signal Acquisition and Algorithm Design for Bioimpedance-Based Heart Rate Estimation from the Wrist

Background: Heart rate (HR) is a critical biomarker that provides insights into overall health, stress levels, and the autonomic nervous system. Pulse wave signals contain valuable information about the cardiovascular system and heart status. However, signal acquisition in wearables poses challenges, particularly when using electrical sensors, due to factors like the distance from the heart, body movement, and suboptimal electrode placement. Methods: Electrical bioimpedance (EBI) measurements using bipolar and tetrapolar electrode systems were employed for pulse wave signal acquisition from the wrist in both perpendicular and distal configurations. Signal preprocessing techniques, including baseline removal via Hankel matrix methods, normalization, cross-correlation, and peak detection, were applied to improve signal quality. This study describes the combination of sensor-level signal acquisition and processing for accurate wearable HR estimation. Results: The bipolar system was shown to produce larger ΔZ(t), while the tetrapolar system demonstrated higher sensitivity. Distal placement of the electrodes yielded greater ΔZ(t) (up to 0.231 Ω) when targeting both wrist arteries. Bandpass filtering resulted in a better signal-to-noise ratio (SNR), achieving 3.6 dB for the best bipolar setup and 4.8 dB for the tetrapolar setup, compared to 2.6 and 3.3 dB SNR, respectively, with the Savitzky–Golay filter. The custom HR estimation algorithm presented in this paper demonstrated improved accuracy over a reference method, achieving an average error of 1.8 beats per minute for the best bipolar setup, with a mean absolute percentage error (MAPE) of 8%. Conclusions: The analysis supports the feasibility of using bipolar electrode setups on the wrist and highlights the importance of electrode positioning relative to the arteries. The proposed signal processing method, featuring a preprocessing pipeline and HR estimation algorithm, provides a proof-of-concept demonstration for HR estimation from EBI signals acquired at the wrist.

Prediction of Thrombus Formation within an Oxygenator via Bioimpedance Analysis.

Blood clot formation inside the membrane oxygenator (MO) remains a risk in extracorporeal membrane oxygenation (ECMO). It is associated with thromboembolic complications and normally detectable only at an advanced stage. Established clinical monitoring techniques lack predictive capabilities, emphasizing the need for refinement in MO monitoring towards an early warning system. In this study, an MO was modified by integrating four sensor fibers in the middle of the hollow fiber mat bundle, allowing for bioimpedance measurement within the MO. The modified MO was perfused with human blood in an in vitro test circuit until fulminant clot formation. The optical analysis of clot residues on the extracted hollow fibers showed a clot deposition area of 51.88% ± 14.25%. This was detectable via an increased bioimpedance signal with a significant increase 5 min in advance to fulminant clot formation inside the MO, which was monitored by the clinical gold standard (pressure difference across the MO (dp-MO)). This study demonstrates the feasibility of detecting clot growth early and effectively by measuring bioimpedance within an MO using integrated sensor fibers. Thus, bioimpedance may even outperform the clinical gold standard of dp-MO as a monitoring method by providing earlier clot detection.

Digitally Controllable Multifrequency Impedance Emulator for Bioimpedance Hardware Validation

ABSTRACTThe accurate emulation of the electrical impedance of biological tissues is crucial for the development and validation of bioimpedance measurement devices and algorithms. This paper describes a digitally controllable impedance emulator capable of reproducing values representative of tissue bioimpedance in user‐specified resistance, reactance, and frequency ranges up to 1 MHz. The presented solution uses a 2R‐1C impedance model to emulate the impedance characteristics of a biological tissue. Specific selection of each element value in this model is achieved using analog multiplexers with low resistance. A MATLAB algorithm was developed for value estimation using target impedance requirements. An example design to emulate impedance from 1 kHz to 1 MHz with 10 to 400 resistance and maximum reactance is provided. The nonideal behavior of this design was evaluated and compared against experimentally collected impedance measurements. Deviations of &lt;1% were observed between experimental and theoretical resistances for values up to 100 kHz (with approximately 5% deviations up to 1 MHz) and reactance deviations were also &lt;1% up to 10 kHz. High frequency deviations are attributed to the parasitic capacitance in the realization of the design. The experimental results validate the design approach and realization for low frequencies. Overall, the innovation of the proposed approach is the control of both resistance and reactance for emulating electrical impedance representative of biological tissues.

Cancer predictive model derived from bioimpedance measurements using machine learning methods

Cancer predictive model derived from bioimpedance measurements using machine learning methods

Sea Bass (Dicentrarchus labrax) Tail-Beat Frequency Measurement Using Implanted Bioimpedance Sensing

Estimating tailbeat frequency (TBF) is a crucial component of fish swimming kinematics and performance, particularly because it provides information about energetics and behavioral responses to environmental cues. The most commonly used technique for TBF estimation is based on accelerometers. This paper proposes a novel approach using bioimpedance technology. This is the first time bioimpedance has been measured in a freely moving animal. This was made possible by implanting a flexible electrode in the back muscle of seabasses and having them in a swimming tunnel. The experiment first demonstrates that it is possible to measure bioimpedance in an immersed fish despite the high conductivity of seawater. An agreement analysis was then performed to compare a video-based reference measurement of TBF with the newly proposed approach. Several bioimpedance settings, such as the configuration and the extracted electrical parameters, were considered. Data analysis highlights that a 4-point setup for modulus impedance measurement at frequencies over 10 kHz provides the best agreement (r &gt; 0.98 and CCC &gt; 0.97) with the video-based approach. These results attest to the significant benefits of integrating bioimpedance sensors in biologgers, especially considering the complementary parameters that can be extracted from bioimpedance measurements, such as length, weight, condition index, and fat content.

Cost-effectiveness of bioimpedance-guided fluid management in patients undergoing haemodialysis: the BISTRO RCT.

The BioImpedance Spectroscopy to maintain Renal Output randomised controlled trial investigated the effect of bioimpedance spectroscopy added to a standardised fluid management protocol on the risk of anuria and preservation of residual kidney function (primary trial outcomes) in incident haemodialysis patients. Despite the economic burden of kidney disease, the cost-effectiveness of using bioimpedance measurements to guide fluid management in haemodialysis is not known. To assess the cost-effectiveness of bioimpedance-guided fluid management against current fluid management without bioimpedance. Within-trial economic evaluation (cost-utility analysis) carried out alongside the open-label, multicentre BioImpedance Spectroscopy to maintain Renal Output randomised controlled trial. Thirty-four United Kingdom outpatient haemodialysis centres, both main and satellite units, and their associated inpatient hospitals. Four hundred and thirty-nine adult haemodialysis patients with > 500 ml urine/day or residual glomerular filtration rate > 3 ml/minute/1.73 m2. The study intervention was the incorporation of bioimpedance technology-derived information about body composition into the clinical assessment of fluid status in patients with residual kidney function undergoing haemodialysis. Bioimpedance measurements were used in conjunction with usual clinical judgement to set a target weight that would avoid excessive fluid depletion at the end of a dialysis session. The primary outcome measure of the BioImpedance Spectroscopy to maintain Renal Output economic evaluation was incremental cost per additional quality-adjusted life-year gained over 24 months following randomisation. In the main (base-case) analysis, this was calculated from the perspective of the National Health Service and Personal Social Services. Sensitivity analyses explored the impact of different scenarios, sources of resource use data and value sets. The bioimpedance-guided fluid management group was associated with £382 lower average cost per patient (95% CI -£3319 to £2556) and 0.043 more quality-adjusted life-years (95% CI -0.019 to 0.105) compared with the current fluid management group, with neither values being statistically significant. The probability of bioimpedance-guided fluid management being cost-effective was 76% and 83% at commonly cited willingness-to-pay threshold of £20,000 and £30,000 per quality-adjusted life-year gained, respectively. The results remained robust to a series of sensitivity analyses. The missing data level was high for some resource use categories collected through case report forms, due to COVID-19 disruptions and a significant dropout rate in the informing BioImpedance Spectroscopy to maintain Renal Output trial. Compared with current fluid management, bioimpedance-guided fluid management produced a marginal reduction in costs and a small improvement in quality-adjusted life-years. Results from both the base-case and sensitivity analyses suggested that use of bioimpedance is likely to be cost-effective. Future work exploring the association between primary outcomes and longer-term survival would be useful. Should an important link be established, and relevant evidence becomes available, it would be informative to determine whether and how this might affect longer-term costs and benefits associated with bioimpedance-guided fluid management. This article presents independent research funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme as award number HTA 14/216/01 (NIHR136142).

The relationship between diabetes mellitus and non-alcoholic fatty liver disease: a clinical and instrumental paired study

To study the impact of type 2 diabetes mellitus (DM2) on the severity of liver steatosis and fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). To conduct a paired case-control study 2989 patients were examined at the Federal Research Center of Nutrition, Biotechnology and Food Safety. Pairs were matched by gender and age and distributed into groups: NAFLD + DM2+ (n=313), NAFLD + DM2- (n=313) and a control group of patients without NAFLD and without DM2 (n=313). The severity of liver steatosis was determined by measuring the controlled attenuation parameter. The severity of liver fibrosis was determined by measuring the liver stiffness measurement. Body composition of the patients was determined using bioimpedance measurements. Indicators of lipid and carbohydrate metabolism, and the serum activity of liver enzymes was determined by standard biochemical methods. In NAFLD + DM2+ group compared to NAFLD + DM2- group, and in NAFLDM + DM2-compared to the control group, weight, BMI, waist and hip circumference, waist-to-hip ratio were higher, while in all. In NAFLD + DM2+ and NAFLD + DM2- groups the volume of fat mass directly correlated with the level of blood triglycerides (r=0.21), HbA1с (r=0.32) and fasting blood glucose (r=0.35), and inversely correlated with high-density lipoproteins (r=-0.19). In NAFLD + DM2+ group versus NAFLD + DM2- group severe steatosis (S3, 78% versus 59.4%; p<0.001) and severe fibrosis (F4, 8% vs 2.6%; p<0.001) was more common; 70% of patients in the NAFLD + DM2- group had no liver fibrosis according to elastography (F0), while in the NAFLD + DM2+ group only 43.2% of patients had no liver fibrosis (p<0.0001). When NAFLD is accompanied by DM2, there is an increase in total fat mass, the severity of steatosis and liver fibrosis, and an associated deterioration of lipid metabolism. More than half of these patients have various stages of liver fibrosis, which indicates the progressive nature of the disease.

Ex vivo electrical bioimpedance measurements and Cole modelling on the porcine colon and rectum

Different pathological changes in the large intestine wall, associated with the development of different chronic diseases, including colorectal cancer, could be reflected in electrical bioimpedance readings. Thickness and composition of the mucus bilayer covering it in the luminal side, abundance of bacteria of the intestinal microbiota, the permeability of the epithelium and inflammation are some of these. However, scientific literature on electrical passive properties of the large intestine is scarce. In this study, complex impedance measurements at 8 frequencies were carried out on 6 specimens of porcine colorectal tissue, within half ab hour post-mortem, obtained from a local abattoir. For 5 different distances, measured proximally from the border of the anus, 3 readings were taken at 3 different points with a tetrapolar probe. The results show 2 different dielectric dispersions in the α and β regions and it seems that there is a relationship between the values of resistivities and the thickness of the wall. Also, parameter values both for the Cole and the geometrical models are given. Another set of electrical bioimpedance readings was carried out in order to assess the effect of the mucus layer on electrical properties of the tissue. It seems that these layers are related to the low frequency dispersion. Finally, electrical passive properties of porcine colorectal tissue, reported in this work, give reference values and behaviour patterns that could be applied for further research in human medicine, based on bioimpedance measurements.

Electrical Bioimpedance in Milk Adulterated with Water: Measurement Methodology for Quantification, Influence of Temperature, and Mathematical Modelling

Milk has a high nutritional value and is also one of the most versatile products in the food industry. Unfortunately, fraud involving the product is constant and needs to be combated. This work presents a measurement methodology to perform the electrical impedance analysis in food. The influence of temperature on the measurements has been evaluated through mathematical models specially developed for identifying the fraudulent activity of adding water to milk. The bioimpedance measurements have been performed in a sample container with a four-electrode measurement system and a digital oscilloscope. Samples of 150 mL were analysed, prepared using whole UHT milk adulterated with distilled water in different % by volume (V/V), at temperatures of 16, 28, and 37 °C. The proposed measurement methodology has been validated and showed sensitivity for analysis in milk, revealing the influence of temperature on the impedance values; from the results mathematical models were proposed for investigating adulteration in milk. This work deals with the design of a device capable of measuring bioimpedance in milk with a view to its application in physicochemical analyses. The influence of temperature on the impedance values was also evaluated to propose mathematical models to facilitate analysis with complex factors and matrices.

Anthropometric and Body Composition Changes during Pre-Season of Spanish Professional Female Soccer Players According to Playing Position.

In professional soccer, body composition analysis is crucial to assess preparation and optimize performance. Different playing positions have different physical demands, which can lead to variations in body composition. However, there are few studies on women's soccer that consider the playing position. This study aims to fill that gap by examining position-specific differences in anthropometric and body composition characteristics among Spanish professional female soccer players at the beginning and end of pre-season. Furthermore, it investigates the possible changes during the pre-season period between positions and correlates the data obtained from anthropometric equations with bioimpedance (BIA) measurements. Thirty-four female soccer players: 8 midfielders, 12 defenders, 11 forwards, and 3 goalkeepers (age: 23.06 ± 4.29 years, height: 164.15 ± 5.84 cm, weight: 58.39 ± 6.62 kg, and ∑6 skinfolds: 74.57 ± 18.48 mm) completed the study that lasted 4 weeks (pre-season) where they were measured anthropometrically and by bioimpedance twice. Goalkeepers showed greater wingspan (176.60 ± 7.06 p < 0.05) compared to other positions. Regarding differences during pre-season, midfielders had the greatest decrease in ∑6 skinfolds compared to other positions (∆ -12.10 ± 5.69 p < 0.05). There was a correlation of % fat between Faulkner's equation and BIA (Pearson's r = 0.817). It seems that there are no significant differences in terms of positions and body composition, except for the wingspan and ankle diameter. During pre-season, midfielders are the ones who improve their body composition the greatest. The anthropometric equation for body fat that shows the highest correlation with BIA is Faulkner's equation, followed by Durnin's equation.

The effect of changes in intra-compartmental bioimpedance measurements with early intra-dialytic hypotension during haemodialysis.

Intra-dialytic hypotension (IDH) remains the commonest problem associated with routine haemodialysis treatments. Fluid shifts from intracellular(ICW) and extracellular(ECW) compartments to refill plasma volume during haemodialysis with ultrafiltration. We studied the effect of relative changes in ICW and ECW indifferent body segments using multifrequency segmental bioimpedance during haemodialysis and IDH episodes. Of 42 haemodialysis patients,16 patients (38.1%) developed IDH within the first hour of dialysis. Patients with and without early IDH were well-matched for demographics and starting bioimpedance measurements. However, after 60 min, the relative change in in ECW/ICW ratio between the non-fistula arm and leg was significantly different for the early IDH group median -1.07 (-3.33 to 0.8) versus 0.61 (-0.78 to 1.8), p < 0.05, whereas there no differences in ultrafiltration rate, relative blood volume monitoring or on-line clearance. Monitoring serial changes in fluid status in different body compartments with bioimpedance may potentially prevent IDH in the future.

Conductivity at varying frequencies as a method for differentiating strawberry ripeness and association with colour acceptance of strawberry nectars.

Identifying the best strawberries to produce colour stable nectars is a priority for the juice industry. Although riper strawberries produce nectars with better colour stability, variability between cultivars means that surface colour cannot be used as a single quality attribute to determine stability. Conductivity and bio-impedance measurements can be used to differentiate ripeness of strawberries. The commercially available PEF Control System (ELEA) can measure cell disruption by measuring conductivity at different frequencies. Updated software measured strawberry conductivity at 121 frequencies between 100 Hz and 1 MHz to determine whether conductivity at these frequencies could differentiate ripeness, and be compared with the colour acceptance and stability of nectars produced from these strawberries. A high-low ratio (HLR) was calculated by dividing the conductivity at frequency 1 MHz by conductivity at 1 kHz. HLR could be used to separate five strawberry ripeness stages, with decreasing HLR associated with increasing ripeness. HLR was then compared with the colour of nectars produced from these strawberries. Although there was a good correlation between HLR and an acceptable colour to consumers on initial production (r = -0.823, P < 0.001) and after 12 weeks of storage (-0.759, P < 0.001), cultivars differed greatly in both HLR and colour stability. Additionally, HLR had a strong correlation with firmness. The PEF Control System could be used to differentiate ripeness of strawberries by HLR, and therefore was associated with colour stability. However, no additional information on colour stability was gained from conductivity beyond what could already be deduced from differentiating ripeness based on surface colour. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Bioimpedance sensor array for monitoring chronic wounds: Validation of method feasibility.

In an ageing society, the incidence of hard-to-heal wounds is rising. Chronic wound healing is a complex process, which requires specialised treatment. Clinical assessment of the wound is essential to establish care approaches but is usually based on visual evaluation and it remains challenging. Therefore, innovative quantitative methods for the assessment of chronic wounds are needed. We conducted a single-centre observational study designed to assess the feasibility of a bioimpedance measurement method conducted with a multielectrode sensor array to monitor the wound healing process in patients with chronic wounds of venous, mixed venous-arterial and diabetic aetiology. In total, 104 measurements of bioimpedance were conducted in 18 ulcers during the study. Across all 7 patients analysed, the bioimpedance of the ulcers was consistently increasing as the wound surface was decreasing. The variables had significant (p < 0.001) and strong negative correlation (r = -0.86). We validated the feasibility of the bioimpedance measurement method for the monitoring of the wound healing process on the lower legs. It may be a promising quantitative method for monitoring the status of the wounds. However, long-term measurements are needed to show the usability of the electrode dressing and bioimpedance measurement in the assessment of chronic wounds.

Prognostic value of electrical bioimpedance measured with a portable and wireless device in acute heart failure

Introduction and objectivesThe current evaluation of acute heart failure (HF) does not allow an adequate prediction of its evolution. The electrical bioimpedance (BI) allows knowing the state of blood volume, until now only with fixed equipment. We have developed and validated a portable and wireless device to measure BI at the ankle (IVOL). The objective of the study is to know the long-term prognostic value of the point measurement of BI with IVOL in patients with acute HF. MethodsA prospective cohort study of unselected patients admitted for acute HF in a tertiary hospital. The association between BI and different clinical, analytical and echocardiographic variables on admission and clinical evolution were analyzed. Results76 patients were included (mean age 66.1 years, 71.1% men, 68.4% hypertensive, 34.2% diabetic, mean NT-ProBNP: 7,103 pg/ml). Of these, 52.6% with non-preserved left ventricular ejection fraction (LVEF) (<50%) and 56.6% with right ventricular (RV) dysfunction. 26.3% died during a mean follow-up of 35.8 months. Survival in patients with BI ≤ 21,8 Ω was lower, globally and in the subgroups of patients without preserved LVEF and with RV dysfunction, p < 0.008). In the multivariate analysis, a BI ≥ 21.8 Ω was an independent survival factor (HR 0.242, 95% CI:0.86−0.681, p = 0.007). ConclusionsBI values ​​measured with IVOL may be an independent predictor of long-term mortality in patients hospitalized for acute HF. This prognostic value is maintained in patients without preserved LVEF function and with RV dysfunction.

Assessment of Intraday Variations in Skin Indentation Resistance.

Information about the mechanical properties of skin and their changes with age and other conditions is important to help characterize skin physiology and pathological changes. One method to obtain this information is to measure the force required to indent the skin to a specified indentation depth (FORCE). This process measures the tissue's resistance to indentation or its compressibility and is related to the tissue's elastic modulus. Since such measurements are made in clinical and other settings at various times of day (TOD), it is useful to estimate the extent of intraday variations in FORCE that may be expected. This report focuses on this issue. FORCE was self-measured on the volar forearm, 5 cm distal to the antecubital fossa, every two hours from 08:00 to 24:00 hours on two consecutive days by 12 medical students (six females and six males) who were trained in the measurement process using an indentation device (SkinFibroMeter). Variability in FORCE versus TOD was analyzed using the nonparametric Friedman test and differences between genders by the nonparametric Wilcoxon test. Differences between the first day (day 1) and the second day (day 2) were tested at each TOD. The whole-body fat percentage (FAT%) and water percentage (H2O%) were determined for each participant via bioimpedance measurements at 50 KHz. The age and BMI of the combined group (mean ± SD) were 24.5 ± 1.5 years and 23.2 ± 3.3 kg/m2.The overall average FORCE (mean ± SD) for the day over the 16 hours was 84.1 ± 22.7 mN and for day 2, it was 83.4 ± 28.5 mN with no significant difference between day 1 and day 2. For females, the overall two-day average FORCE (mean ± SD) over the 16 hours was 81.8 ± 20.3 mN and for males, it was 85.7 ± 30.1 mN with no significant difference between them (p = 0.271). Overall, there was no statistically significant difference in FORCE among TOD (p = 0.568). FORCE was not correlated with either FAT%, HTO%, or BMI. The findings indicate no statistically significant variation in indentation force in females, males, or combined concerning the TODof the measurement or differences between consecutive days at corresponding times. This suggests that whether such measurements are done in a research setting or within a clinic, they can be done at various TODwith minimal expected variation for a given subject. However, an extension of these findings to persons with skin conditions or ages not herein evaluated must await further study.