Bioimpedance Measurements Research Articles

A Case Study in Breast Density Evaluation Using Bioimpedance Measurements.

(1) Background: As breast cancer studies suggest, a high percentage of breast density (PBD) may be related to breast cancer incidence. Although PBD screening is one of the strongest predictors of breast cancer risk, X-ray-based mammography evaluation is subjective. Therefore, new objective PBD measuring techniques are of interest. A case study analyzing the PBD of thirteen female participants using a bioimpedance-based method, the anomalies tracking circle (ATC), is described in this paper. (2) Methods: In the first stage, the breast bioimpedance of each participant was measured. Then, the participant breast density was determined by applying a mammogram just after the breast bioimpedance measurement stage. In the third stage, the ATC algorithm was applied to the measured bioimpedance data for each participant, and a results analysis was done. (3) Results: An ATC variation according to the breast density was observed from the obtained data, this allowed the use of classification techniques to determine the PBD. (4) Conclusions: The described breast density method is a promising approach that might be applied as an auxiliary tool to the mammography in order to obtain precise and objective results for evaluation of breast density and with that determine potential breast cancer risk.

БИОФИЗИЧЕСКИЕ ПАРАМЕТРЫ ОРГАНИЗМА МУЖЧИН-ЯКУТОВ ЗРЕЛОГО ВОЗРАСТА

Statistical data indicate a high level of morbidity in the main classes of diseases and mortality among the male population of older age groups, which requires a comprehensive study. The purpose of this study was to determine the biophysical parameters of the body in mature Yakut men. A total of 41 men of the first and second periods of adulthood, workers and employees of various enterprises of Yakutsk were examined. An anthropometric and bioimpedancmetric examination was carried out. The overall dimensions of the body (length and body weight), waist circumference and hip circumference were measured, BMI and the ratio of waist circumference to hip circumference were calculated. Bioimpedance measurement was carried out using the analyzer of body composition and balance of water sectors of the body ABC – 01 “Medass”. Statistical analysis of the data obtained was carried out using the SPSS 17.0 software package. An anthropometric survey revealed that according to the BMI, most men are overweight and obese, according to the ratio of waist circumference to hip circumference a larger proportion of the surveyed men have visceral obesity. Bioelectric indicators and parameters of the component composition of the body were established. In men of mature age, higher relative indicators of fat mass, extracellular fluid and reduced values of musculoskeletal mass were revealed in comparison with similar parameters of Yakut young males.

Plant stem tissue modeling and parameter identification using metaheuristic optimization algorithms

Bio-impedance non-invasive measurement techniques usage is rapidly increasing in the agriculture industry. These measured impedance variations reflect tacit biochemical and biophysical changes of living and non-living tissues. Bio-impedance circuit modeling is an effective solution used in biology and medicine to fit the measured impedance. This paper proposes two new fractional-order bio-impedance plant stem models. These new models are compared with three commonly used bio-impedance fractional-order circuit models in plant modeling (Cole, Double Cole, and Fractional-order Double-shell). The two proposed models represent the characterization of the biological cellular morphology of the plant stem. Experiments are conducted on two samples of three different medical plant species from the family Lamiaceae, and each sample is measured at two inter-electrode spacing distances. Bio-impedance measurements are done using an electrochemical station (SP150) in the range of 100 Hz to 100 kHz. All employed models are compared by fitting the measured data to verify the efficiency of the proposed models in modeling the plant stem tissue. The proposed models give the best results in all inter-electrode spacing distances. Four different metaheuristic optimization algorithms are used in the fitting process to extract all models parameter and find the best optimization algorithm in the bio-impedance problems.

The role of bioimpedance spectroscopy method in severity and stages of breast cancer-related lymphedema.

The correlation between lymphedema severity and stages determined by standard diagnostic methods and Bioimpedance Spectroscopy (BIS) technique was examined in breast cancer-related lymphedema (BCRL) patients. The bioimpedance analyzer device was connected to the 1.0 cm disc electrodes which were connected to the affected and unaffected (healthy) arm of the patients. We evaluated the performance of the impedance (Z) at multiple frequencies (5-50-100-200 kHz) and phase angle (PA), resistance (R), and reactance (XC) at 50 kHz on the lymphedema severity and stages. Bioimpedance measurements were applied to all volunteers in cooperation with the Physical Therapy and Rehabilitation Department. In this study, the correlation between BCRL severity and stages and bioimpedance values was examined. A total of 31 female patients were recruited to compare the BIS technique with standard diagnostic techniques. The severity of lymphedema was found among the patients as follows; mild 14 (45.2%), moderate 10 (32.3%), and severe 7 (22.6%). The stage distribution of volunteers was; 15 (48.4%) patients in Stage 0, 10 (32.3%) patients in Stage 1, 5 (16.1%) patients in Stage 2, and 1 (3.2%) patient in Stage 3. The ratio of affected and unaffected arm bioimpedance mean values were calculated. Although, this ratio at 50-100-200 kHz Z and 50kHz R were significantly correlated with the lymphedema stages (p <0.05), there was no correlation and significant difference between the ratio of the bioimpedance values and lymphedema severity (p> 0.05). The BIS technique is timesaving and can determine lymphedema stages. We found a significant correlation between BCRL stages and BIS, and it appears that BIS is an appropriate, inexpensive, simple, and noninvasive technique for detecting the stages of BCRL.

Comparison of clinical symptoms and bioimpedance to pulmonary capillary wedge pressure in heart failure

IntroductionClinical symptoms of heart failure commonly include fatigue, edema, and shortness of breath. Unfortunately, clinical monitoring has proven unreliable in predicting congestion and the need for hospitalization. Biosensing wearables have been developed as a potential adjunct to clinical signs and symptoms to detect congestion before it becomes severe thus preventing a heart failure hospitalization. HypothesisClinical signs and symptoms of heart failure will correlate with thoracic bioimpedance measurements (ZOE®) and pulmonary capillary wedge pressure (PCWP). MethodsOne hundred and fifty-five subjects undergoing right heart catheterization (RHC) were prospectively enrolled. A Zo value (ohms) was obtained, jugular venous pressure (JVP) was estimated, edema graded, and shortness of breath (SOB) assessed in all subjects. RHC was performed by a scheduled cardiologist per routine. One-way ANOVA was performed to assess the relationship between variables. A Pearson correlation coefficient was used to compare the Zo value and PCWP. ResultsNeither estimated JVP (cmH2O) (p = 0.65, n = 110) nor edema scores (p = 0.12, n = 110) demonstrated a significant relationship to PCWP. The presence of subjective SOB also did not demonstrate a significant association with PCWP (p = 0.99, n = 110). There was no correlation between ZOE® and PCWP (r = −0.08, p = 0.56, n = 56). ConclusionsThese findings support the idea that traditional measures for monitoring heart failure patients are limited.

Characteristics of Frailty in Haemodialysis Patients.

Background: Both frailty and cachexia increase mortality in haemodialysis (HD) patients. The clinical frailty score (CFS) is a seven-point scale and less complex than other cachexia and frailty assessments. We wished to determine the characteristics of frail HD patients using the CFS. Methods: Single centre cross-sectional study of HD patients completing physical activity questionnaires with bioimpedance measurements of body composition and hand grip strength (HGS). Results: We studied 172 HD patients. The CFS classified 54 (31.4%) as frail, who were older (70.4±12.2 vs 56.2 ± 16.1 years, p < 0.001), greater modified Charlson co-morbidity (3 (2–3) versus 1.5 (0–3), p < 0.001), and body fat (33 (25.4–40.2) versus 26.2 (15.8–34) %, p < 0.01), but lower total energy expenditure (1720 (1574–1818) versus 1870 (1670–2194) kcal/day, p < 0.01), lean muscle mass index (9.1 (7.7–10.1) versus 9.9 (8.9–10.8) kg/m2), and HGS (15.3 (10.3–21.9) versus 23.6 (16.7–34.4) kg), both p < 0.001. On multivariable logistic analysis, frailty was independently associated with lower active energy expenditure (odds ratio (OR) 0.98, 95% confidence limits (CL) 0.98–0.99, p = 0.001), diabetes (OR 5.09, CL 1.06–16.66) and HGS (OR 0.92, CL 0.86–0.98). Discussion: Frail HD patients reported less active energy expenditure, associated with reduced muscle mass and strength. Frail patients were more likely to have greater co-morbidity, particularly diabetes. Whether physical activity programmes can improve frailty remains to be determined.

BODY COMPOSITION IN PERSONS OF THE FIRST PERIOD OF ADULTHOOD WITH DIFFERENT AGING RATES

The aim of the study was to find out the body composition features in persons of the first period of adulthood with different aging rates.&#x0D; Methods. The 2404 patient (607 men and 1797 women) of the first period of adulthood were observed. Body length, body weight, waist and hip circumferences were recorded according to generally accepted methods. The body composition was studied by the bioimpedance measurement. The biological age and the aging rate were calculated using the formulas of A.G. Gorelkin and B.B. Pinkhasov.&#x0D; Results. The majority of men (57.5%) had an accelerated aging rate, the majority of women (51.2%) had a delayed aging. The biological age of 19.1% men and 15.2% women coincided with the calendar age. Body composition differed statistically significantly in group with different aging rates and sex groups. The content of the relative fat mass increased and the relative lean, musculoskeletal, active cell masses decrease with increasing aging rate. The proportion of men and women with accelerated aging in the group with increased fat mass was 92.5% and 98.4% respectively. Excess fat mass increases the chances of premature aging by 5.5 times in men and 1.3 times in women in compared to individuals with optimal fat mass.&#x0D; Conclusion. The aging rate in men was highly correlated with fat, musculoskeletal masses and total body water, in women - with fat mass and total body water. High fat mass contributed to premature aging.

Features of modeling fatty liver disease in rats of different ages based on a high-calorie diet

BACKGROUND: The problem of diagnosis, treatment and prevention of fat liver disease (FLD) is one of the actual problems of modern medicine. In this regard, the need for the creation of reliable experimental models of the FLD, which would be as close as possible to the pathogenetic patterns of the development of this disease in humans.AIM: To create an experimental model of FLD and compare the efficiency of its reproduction in rats of different ages.MATERIALS AND METHODS: The study was conducted on male Wistar rats, whose ages at the beginning of the experiment were 3 and 18 months. Control animals were fed a standard diet. The experimental rats were kept on a diet with excess fat (45 %) and carbohydrates (31 %) for 12 weeks. The liver tissue samples were taken for morphological studies of FLD. Histological preparations were made according to the standard technique. Morphometry on digital images of micropreparations was conducted using the computer program «IMAGE J». The concentration of lipids, cholesterol, and triglecerides in the liver tissue was determined, and the concentration of ALT in the blood serum was determined. To assess the biophysical properties of the liver tissue, the method of multifrequency bioimpedance measurement was used.RESULTS: The transfer of animals to a high-calorie diet developed by us led to the development of FLD. This was evidenced by an increase of the liver mass, its pale shade and soft consistency. Morphometric signs of FLD were also revealed. Hypertrophy of hepatocytes was observed with a simultaneous decrease in the nuclear-cytoplasmic ratio; accumulation of numerous lipid inclusions in the cytoplasm and the appearance of large lipid droplets replacing the voids of dead hepatocytes. The number of binuclear hepatocytes and nucleolus in the nucleus, the relative area of the sinusoid network were decreased. An increase in the concentration of lipids, cholesterol and triglecerides in the liver tissue of experimental rats, as well as the activity of ALT in the blood serum, was observed. Changes in the bioimpedance measurements of the liver tissue also indicated the development of severe fatty degeneration of the liver in both young (to a greater extent) and old rats.CONCLUSION: The model of FLD we have advanced based on a combined (fat-carbohydrate) high-calorie diet. It leads to the development of pronounced morphological, biochemical and biophysical signs of this pathology in all experimental rats. The most pronounced manifestations of FLD are observed in young animals.

Protocol of a pilot-scale, single-arm, observational study to assess the utility and acceptability of a wearable hydration monitor in haemodialysis patients

BackgroundFluid overload has a high prevalence in haemodialysis patients and is an important risk factor for excess mortality and hospitalisations. Despite the risks associated with chronic fluid overload, it is clinically difficult to assess and maintain fluid status adequately. Current methods of fluid status assessment are either imprecise or time intensive. In particular, to date, no method exists to accurately assess fluid status during the interdialytic interval.ObjectivesThis pilot study aimed to evaluate whether a prototype wearable hydration monitor can accurately and reproducibly detect fluid overload in the haemodialysis population when compared to haemodialysis and bioimpedance data.MethodsA prospective, open-label, single-arm observational trial of 20 patients commenced in January 2021 in a single haemodialysis centre in Ireland, with a wearable hydration monitor, the Sixty device. The Sixty device uses diffuse reflectance spectroscopy to measure fluid levels at the level of the subdermis and uses machine learning to develop an algorithm that can determine fluid status. The Sixty device was worn at every dialysis session and nocturnally over a three-week observational period. Haemodialysis parameters including interdialytic weight gain, ultrafiltration volume, blood pressure, and relative blood volume were collected from each session, and bioimpedance measurements using the Fresenius body composition monitor were performed on 4 occasions as a comparator. The primary objective of this trial was to determine the accuracy and reproducibility of the Sixty device compared to bioimpedance measurements.ConclusionIf the accuracy of the wearable hydration monitor is validated, further studies will be conducted to integrate the device output into a multi-parameter machine learning algorithm that can provide patients with actionable insights to manage fluid overload in the interdialytic period.Trial registrationwww.clinicaltrials.govNCT04623281. Registered November 10th, 2020.

Evaluating Research Grade Bioimpedance Hardware Using Textile Electrodes for Long-Term Fluid Status Monitoring

Fluid overload is a chronic medical condition that affects over six million Americans with conditions such as congestive heart failure, end-stage renal disease, and lymphedema. Remote management of fluid overload continues to be a leading clinical challenge. Bioimpedance is one technique that can be used to estimate the hydration of tissue and track it over time. However, commercially available bioimpedance measurement systems are bulky, expensive, and rely on Ag/AgCl electrodes that dry out and can irritate the skin. The use of bioimpedance today is therefore limited to clinical and research settings, with measurements performed at daily intervals or over short periods of time rather than continuously and long-term. This paper proposes using wearable calf bioimpedance measurements integrated into a compression sock for long-term fluid overload management. A PCB was developed using standard measurement techniques that measures the calf bioimpedance using a custom analog front-end built around an AD8302 gain-phase detection chip. Data is transmitted wirelessly via Bluetooth Low Energy to an iOS device using a custom iOS app. Bioimpedance data were collected both from the wearable system and a commercial measurement system (ImpediMed SFB7) using RRC networks, Ag/AgCl electrodes, and the textile compression sock. Bioimpedance data collected from the wearable system showed close agreement with data from the SFB7 when using RRC networks and in five healthy human subjects with Ag/AgCl electrodes. However, when using the textile compression sock the wearable system had worse precision than the SFB7 (4% run to run compared to &lt;1% run to run) and there were larger differences between the two systems than when using the RRC networks and the Ag/AgCl electrodes. Wearable system precision and agreement with the SFB7 was improved by pressure or light wetting of the current electrodes on the sock. Future research should focus on reliable elimination of low-frequency artifacts in research grade hardware to enable long-term calf bioimpedance measurements for fluid overload management.

Quality of life improvement in breast cancer survivors affected by upper limb lymphedema through a novel multiperspective physical activity methodology: a monocentric pilot study.

Chronic lymphedema causes psychophysical sequelae jeopardizing quality of life (QoL) of breast cancer (BC) survivors, and lack of effective therapies represents a major challenge for healthcare professionals. Structured adapted physical activity (APA) may represent an effective strategy to attenuate cancer treatment-related impairments and improve QoL. Here, we describe the effects of a specific APA intervention based on a novel multiperspective methodology in counteracting lymphedema-related morphofunctional alterations and improving QoL of BC survivors. BC survivors with chronic moderate/severe lymphedema attending the Cancer Rehabilitation Center in Florence were assessed before and after 8-week APA. The protocol consisted of both APA specialist-supervised and self-leaded sessions using a tailor-designed proprioceptive board. Body mass index, bioimpedance parameters, indirect upper limb volume measurement, and ultrasonography were performed. Wrist flexion/extension and hand strength functional tests were also executed. QoL, depression/anxiety and pain intensity were evaluated by ULL27, HADS, distress thermometer and NRS questionnaires, respectively. Although bioimpedance, ultrasound and volumetric measures remained mostly unchanged, wrist mobility, pain perception, depression, and QoL were all significantly ameliorated after APA. Our findings suggest that a multidisciplinary treatment approach involving APA professionals should be employed in the management of BC-related lymphedema to improve patient psychophysical outcomes and QoL.

Comprehensive assessment of the physical development of children and adolescents at the outpatient stage

The article highlights one of the current issues of pediatrics - the study of the dynamics of Physical Development (PD) in children and adolescents. The numerous methods of assessment are used. The methods contain one-dimensional, two-dimensional and / or trimeric indicators. They do not fully give an idea of the level of the child's PD and do not reflect the patterns of his growth and development. In some cases, a pediatrician at the outpatient stage requires a comprehensive assessment of PD including age determination and compliance of biological age with the real age, determination of the PD harmony, somatotype determination, assessment of the direction of growth and development along with the calculation of indexes, functional state assessment, assessment of the degree of fat deposition or bioimpedance measurement, which allows determining the risk group. The assessment of PD indicators must be carried out according to regional tables.

Relationship between anthropometric indices and arterial stiffness: Insights from an epidemiologic study.

BackgroundObesity and arteriosclerosis are both independently associated with cardiovascular disease risk. Obesity also may increase arterial stiffness.AimsThis study aimed to investigate the association between anthropometric indices and non‐invasive arterial stiffness parameters, using data from a large population‐based cohort of seemingly healthy women and men.MethodsA total of 5023 eligible participants were included in the study. The pulse wave velocity (PWV), central blood pressures, and bio‐impedance measures were obtained at the time of enrollment. Multiple regression analysis was performed to assess the relationship between anthropometric indices with arterial stiffness parameters.ResultsThe mean age of participants was 45.3 ± 8.8 years, 2368 (47.1%) were males and 2655 (52.8%) were females. The prevalence of participant with underweight, normal weight, overweight, and obesity were 0.73%, 33.2%, 48.7%, and 17.2% respectively. Systolic and diastolic blood pressure, fatty liver, and hypertension were significantly higher in overweight/obesity participants. The overweight/obesity participants had significantly higher PWV than the normal‐weight group (471.5 ± 42.6/496.7 ± 47.5 cm/s vs. 448.1 ± 41.4 cm/s, p < 0.001).ConclusionThe prevalence of diabetes, hypertension, fatty liver disease, chronic lung disease, and also kidney stones were significantly higher in overweight and individuals with obesity. Body mass index, body fat mass, waist–hip ratio abdominal circumference, neck circumference, visceral fat area, total body water, 50‐kHz whole body phase angle are positively correlated with PWV. Augmentation index had no significant correlation with body mass index, arm, hip, and abdominal circumferences.

Towards Artefact-Free Bio-Impedance Measurements: Evaluation, Identification and Suppression of Artefacts at Multiple Frequencies

Objective: The bio-impedance (BI) of the body is a powerful parameter to assess the tissue composition and fluid content. Widespread implementation of BI measurement systems is limited due to the inability to detect, interpret and suppress frequently occurring artefacts during continuous use. A major proportion of the artefacts in BI measurements are caused at the skin electrode (SE) interface. Perturbations at the SE interface due to motion, applied pressure, temperature and posture change introduce distortions in the measured data which impede accurate interpretation for physiological monitoring. This paper investigates and accurately presents the effects of the aforementioned actions on the SE interface to develop effective algorithms for artefact identification and suppression at multiple frequencies in-field. Methods: Data collected from 20 subjects is used to analyze artefact associated features due to SE perturbations in BI measurements between 10kHz to 100kHz. Results: High variance noise, concept drifts and abrupt changes in measured BI baselines were identified as the main characteristics associated with artefacts due to SE interface perturbation. Artefacts were identified with a precision of upto 95% and a recall of upto 96% for all observed artefact labels. Conclusion: The characterization of artefacts due SE interface perturbations and high performance algorithms for artefact identification and suppression allow artefact free continuous monitoring of BI. Significance: The presented work enables continuous measurement of BI for non-invasive monitoring with wearable low power devices and permits accurate interpretation of many physiological processes, such as, edema onset, dehydration or urinary bladder filling, even in the presence of artefacts.

Bioelectrical impedance of the lung in rats under chronic exposure to doxorubicin

Changes in lung bioelectric impedance were revealed in male Wistar rats exposed chronically to doxorubicin. Bioimpedance measurements were performed in rats two months after the first injection of doxorubicin (a cumulative dose of 10 mg/kg divided into 4 injections for 4 weeks) or saline. Bioimpedance was analysed at multiple frequencies (10, 30, 70 and 150 kHz) of electric current. Electrodes were placed on the surface of the lung. Significantly lower absolute values of the reactance and phase angle of bioelectrical impedance of the myocardium, liver (noted by us earlier) and lung in rats treated with doxorubicin compared with control animals indicated toxic damage to organs. Significantly higher amplitude (at a frequency of 70 kHz) of bioelectrical impedance of the rat’s lung may be associated with emphysematous changes and inflammation in the lung in the group with chronic exposure to doxorubicin compared to the rats in the control group.

ДИАГНОСТИКА НА ФАБРИКАХ РАСТЕНИЙ: ОБЗОР НЕИНВАЗИВНЫХ МЕТОДОВ МОНИТОРИНГА СОСТОЯНИЯ РАСТЕНИЙ ДЛЯЗАКРЫТЫХ РЕГУЛИРУЕМЫХ АГРОЭКОСИСТЕМ

Under the conditions of growing crops in plant factories, timely information about the physiological state of plants makes it possible to maintain crop yields at a high level. In crop production, non-invasive methods of plant diagnostics are most widely used, which helps identify plant stress conditions at an early stage. In the theoretical study applied to plant factories, the authors compared electrophysical monitoring methods (the measurement of biopotential and bioimpedance), thermography methods (the method of registration of xylem sap fl ow and infrared thermography), optical methods (the measurement of refl ective characteristics of leaves, hyper- and multispectral imaging), and the method for measuring chlorophyll fl uorescence. The studied methods were classifi ed and analyzed according to several criteria: measurable indicators, the assessment of plant parameters, the portability of the measuring instrument, the ability to scan at the canopy level. It was concluded that non-invasive methods for diagnosing the physiological state of plants are capable of signaling negative changes at an early stage, provide for indirect assessing plant stress, transpiration, photosynthesis, pigment and elemental composition, and the electrical resistance of tissues. Among the technologies for non-invasive diagnostics of the physiological state of plants for closed regulated agroecosystems, the method of spectral analysis of plant leaves, in particular, spectral visualization, and the fl uorescence method are particularly eff ective. In further studies to evaluate photosynthesis and compose “light recipes”, the authors are planning to compare the fl uorescence method and the spectral imaging method in practical conditions

Bioimpedance Spectroscopy Helps Monitor the Impact of Electrical Stimulation on Muscle Cells

In this study, we present a first-of-a-kind biological-hardware-software tool to evaluate the physiological condition of in vitro myotubes in response to electrical stimulation. We demonstrate that impedance spectroscopy on a microelectrode array can testify for physiological changes of muscle cells under electrical stimulation. The platform is designed for simultaneous bioimpedance spectroscopy, electrical stimulation, and optical microscopy. It includes a microelectrode array, a custom hardware-software interface, and a commercial impedance analyzer. We used a well-established muscle cell model (C2C12) and developed a culture protocol suited for long-term recordings on microelectrode arrays. Electrical stimulation was applied with carbon electrodes and ad hoc electronics for current stimulation. Muscle cell bioimpedance measurement was complemented with optical microscopy video to record contractions. Then, the influence of electrical stimulation on the contractile activity of myotubes and on their bioimpedance was analyzed. Results validated the functionality of the hardware/software platform when used with our contractile muscle model. A bioimpedance-based metric was defined to evaluate changes in myotubes’ physiology. After playing multiple stimulation scenarios, analysis showed that the bioimpedance metric decreases as duration or frequency of stimulation increase.

Minimally Invasive Lung Tissue Differentiation Using Electrical Impedance Spectroscopy: A Comparison of the 3- and 4-Electrode Methods

Multiple imaging techniques are used for the diagnosis of lung diseases. The choice of a technique depends on the suspected diagnosis. Computed tomography (CT) of the thorax and positron emission tomography (PET) are imaging techniques used for the detection, characterization, staging and follow-up of lung cancer, and these techniques use ionizing radiation and are radiologist-dependent. Electrical impedance spectroscopy (EIS) performed through a bronchoscopic process could serve as a minimally invasive non-ionizing method complementary to CT and PET to characterize lung tissue. The aim of this study was to analyse the feasibility and ability of minimally invasive EIS bioimpedance measures to differentiate among healthy lung, bronchial and neoplastic lung tissues through bronchoscopy using the 3- and 4-electrode methods. Tissue differentiation was performed in 13 patients using the 4-electrode method (13 healthy lung, 12 bronchial and 3 neoplastic lung tissues) and the 3-electrode method (9 healthy lung, 10 bronchial and 2 neoplastic lung tissues). One-way analysis of variance (ANOVA) showed a statistically significant difference (P < 0.001) between bronchial and healthy lung tissues for both the 3- and 4-electrode methods. The 3-electrode method seemed to differentiate cancer types through changes in the cellular structures of the tissues by both the reactance (Xc) and the resistance (R). Minimally invasive measurements obtained using the 3-electrode method seem to be most suitable for differentiating between healthy and bronchial lung tissues. In the future, EIS using the 3-electrode method could be a method complementary to PET/CT and biopsy in lung pathology diagnosis.

Effect of Calibration for Tissue Differentiation Between Healthy and Neoplasm Lung Using Minimally Invasive Electrical Impedance Spectroscopy

This study proposes a calibration method and analyses the effect of this calibration in lung measures, using minimally invasive electrical impedance spectroscopy with the 3-electrode method, for tissue differentiation between healthy and neoplasm lung tissue. Tissue measurements were performed in 99 patients [54 healthy tissue and 15 neoplastic tissue samples obtained] with an indicated bronchoscopy. Statistically significant difference (P < 0.001) were found between healthy lung tissue and neoplasm lung tissue in bioimpedance parameters. The calibration of the bioimpedance measures with respect to a measure performed in bronchi reduces the inter-patient dispersion, increasing the sensitivity, decreasing the specificity and increasing the area below the ROC curve for three out of four impedance-derived estimators. Results also show that there are no significant differences between healthy lung tissue among smoker, non-smoker and ex-smoker samples, which was initially stated as a possible cause of EIS measurement dispersion in lungs.

Accuracy of Bioimpedance Modalities for Fluid Assessment in Hemodialysis Patients: A Randomized Observational Study

Aim Fluid overload is a major contributor to mortality in critically ill patients but is difficult to estimate clinically. Bioimpedance has been used to estimate fluid volumes with three different methods of analysis:1. single-frequency; 2. multi-frequency; 3. bioimpedance spectroscopy. The aim of this study is to assess the accuracy of different types of bioimpedance analysis in detecting changes in fluid volumes. Methods Prospective observational study, in end-stage renal disease patients requiring dialysis, in a tertiary care center. During hemodialysis, we assessed the correlation between change in estimated total body water volumes, as measured by all three methods of bioimpedance, and fluid volumes removed, as measured by changes in body weight. Results Twenty-four pediatric and adult patients were included in the study (median age 42.4 years) with a total of 30 study assessments performed. There was a weak correlation between change in body weight and change in estimated total body water volumes (R=0.15, 0.41, and 0.38, respectively). In the Bland-Altman analysis, the mean biases along with their associated 95% confidence limits of agreement were -0.23 L (-4.1 to 3.5 L) for single-frequency; -1.1 L (-4.1 to 1.9 L) for multi-frequency; and -0.6 L (-6.1 to 4.8 L) for bioimpedance spectroscopy. Conclusion In this study of end-stage renal disease patients requiring dialysis, the accuracy of bioimpedance measurement to evaluate fluid changes was poor, regardless of bioimpedance modality.