Body Impedance Research Articles

Complex assessment of athletes’ operative status and its correction during competitions, based on the body impedance analysis

Background and Study Aim. The aim of this research was assessment and correction of highly skilled swimmers’ operative status during competitions. Material and Methods. The authors carried out complex assessment of 46 high-skilled swimmers during competition period. The body impedance analysis and functional status express diagnosis were conducted before and after competitions. Results. The components limiting the operational state of swimmers were determined: “component composition of the body” (44.83% of the total load), “functional” (19.97%). Correlation relationships were established between the main indicators that determine the level of the operational state of athletes. The multiple regression equation was calculated, which made it possible to determine the influence of individual significant parameters on the level of the operational state of athletes and the confidence interval. A group of athletes with operational status indicators below the confidence interval received sport supplementation. Conclusion. The main characteristics of the athletes’ operative status are cellular biomarker phase, fat free mass, extracellular water, intracellular water, strength index. These characteristics should be used in assessment of both operative status and complex functional diagnosis of highly-skilled swimmers during competitions.

Body composition assessment using bioelectrical impedance analysis (BIA) in a wide cohort of patients affected with mild to severe obesity

Obesity is characterized by fat mass excess (FM), extra cellular water increase (ECW) and, with ageing, decrease in fat free mass (FFM). The validity of body impedance analysis (BIA) in patients with mild to severe obesity is still debated. The purpose of this study is to describe the Resistance (Rz) and Reactance (Xc) values obtained by Body Impedance Analysis (BIA) in a wide cohort of Italian patients with mild to severe obesity. The secondary endpoint is to describe the resulting body composition values (as percentage and indexes) in this population. The study enrolled adult in-patients with mild to severe obesity (classified with class I, II and III obesity) undergoing clinical care rehabilitation program for obesity complications and weight loss. BIA values were grouped by sex, BMI and age classes. A total of 8303 patients with obesity, aged 18 to 90y, were studied. The Resistance (Rz) and Reactance (Xc) were reported by sex, age and BMI classes. In women and men both, the phase angle (PhA) decreases with increasing BMI (kg/m2) and the resulting BIA vector was significantly shifted. The FM index (FMI) was higher (p<0.0001) in women while FFM index (FFMI) was higher in men (p<0.0001) and significantly associated with BMI. FFMI decreased with age in both sex (p<0.0001). Skeletal mass (SM) presents a progressive reduction in relation to age and gender both. The present BIA-based body composition analysis in a wide cohort of mild to severe obese patients revealed a significantly decreased Rz and Xc values with a consequent significant decrease of PhA in a BMI-dependent manner. The body compartments estimation with available equations was BMI, sex and age dependent. These observational results could be the basis for the development of new equations adapted for patients suffering from obesity.

A New Model for Human Body Impedance

The impedance of the human body is strongly voltage-dependent, and exhibits substantial variation among individuals. We introduce a new statistical model that separates body impedance into three terms (internal tissue, skin, and contact impedances in series). Advantages over simpler models include a physically plausible monotonicity with respect to voltage and the ability to simulate the impedance characteristics of individuals.

Optimal current frequency for the detection of changes in extracellular water in patients on hemodialysis by measurement of total body electrical resistance.

Measurement of total body electrical resistance (TBER) to an alternating current is useful to monitor extracellular water (ECW) in patients on hemodialysis (HD). Which current frequency is preferable is subject of ongoing debate. The aim of this study was to quantify the implications of TBER measurements at current frequencies ranging from 0 to 1000kHz for ECW monitoring in patients on HD. Bioimpedance spectroscopy measurements were performed in 39 patients on HD using the Body Composition Monitor (BCM, Fresenius Medical Care). TBER data at 5, 50, 200, 500, and 1000kHz were compared with the extrapolated TBER at 0kHz (TBER0) assessed by Cole-Cole analysis. Sensitivity of each TBER configuration was evaluated at individual level, by assessment of the smallest ultrafiltration (UF) volume that induced a significant change in TBER, i.e. a change in TBER≥2.7%. TBER precision was very high for all frequencies, with coefficients of variation of 0.25%-0.28%. Baseline TBER decreased with increasing current frequency. TBER was 2.9% lower at 5kHz(P<0.001), 11.6% lower at 50kHz, and up to 22.0% lower at 1000kHz. This pattern is attributed to a progressive increase in intracellular current conduction at higher frequencies. Sensitivity to volume changes induced by UF also decreased with increasing current frequency. At 0 and 5kHz, an UF volume≤0.5L was sufficient to induce a significant increase in TBER in 87% of patients. This decreased to 69% at higher frequencies. ECW monitoring by TBER requires measurement at 5kHz or less to ensure optimal performance.

Optimal Skeletal Muscle Mass Index Cut-Off Values for Presarcopenia Evaluated by Computed Tomography against Dual-Energy X-ray Absorptiometry in Patients with Chronic Liver Disease.

Although dual-energy X-ray absorptiometry (DXA) and body impedance analysis are commonly used to measure skeletal muscle mass (SMM), a computed tomography (CT) scan is preferred in clinical practice. We aimed to propose the cut-off values of skeletal muscle mass index (SMI) calculated using CT scans, using DXA as the reference method. We retrospectively assessed 589 patients with chronic liver disease. The SMI was assessed using appendicular SMM by DXA and total muscle area at the level of the third lumbar vertebra (L3) calculated by CT. The cut-off value was determined with reference to the Asian Working Group for Sarcopenia criteria. DXA identified 251 (42.6%) patients as having presarcopenia. In men, the cut-off value of SMI for presarcopenia was determined to be 45.471 cm2/m2, with an area under the curve (AUC) of 0.863 (95% confidence interval (CI): 0.823 to 0.903), and in women, this value was determined to be 35.170 cm2/m2, with an AUC of 0.846 (95% CI: 0.800 to 0.892). Cohen’s kappa coefficient was 0.575 (95% CI: 0.485–0.665) in men and 0.539 (95% CI: 0.438–0.639) in women.

Poor Taste and Smell Are Associated with Poor Appetite, Macronutrient Intake, and Dietary Quality but Not with Undernutrition in Older Adults

BackgroundAge-related declines in taste and smell function are widely assumed to contribute to the decrease in appetite and the development of undernutrition in older adults. ObjectivesHere we aim to assess the associations of both taste and smell function with several nutrition-related outcomes in a single study, with poor appetite and undernutrition as primary outcomes. MethodsThis is a cross-sectional cohort study of 359 community-dwelling Dutch older adults, aged 65–93 y. Taste function was measured for all 5 basic tastes. Smell function was assessed with 3 tests: for odor identification, discrimination, and threshold. Self-reported taste and smell, appetite, energy (kcal/d) and macronutrient (% energy) intake, and covariates were assessed with extensive questionnaires. Dietary quality was calculated using the Dutch Healthy Diet index 2015, Alternative Healthy Eating Index 2010, and Mediterranean Diet Score. Body measurements included body weight (current and 2 y prior), height, and body impedance analysis. Data were analyzed via multiple logistic and linear regression. ResultsOf our sample, 9.2% had poor taste and 17.0% poor smell, 6.1% had poor appetite, and 21.4% were undernourished. Self-reported poor taste (OR: 8.44; 95% CI: 1.56, 45.56; P = 0.013) was associated with poor appetite, but no other taste or smell score was associated with either poor appetite or undernutrition. Some associations were found of individual taste and smell scores with macronutrient intake and dietary quality. Self-reported poor taste and smell were both consistently associated with poorer dietary quality. ConclusionsIn community-dwelling older adults, specific taste and smell impairments may have diverse consequences for appetite, food intake, or dietary quality. However, this does not necessarily result in undernutrition. The consistent associations of self-reported poor taste and smell with poor dietary quality do underline the usefulness of this information when screening for nutritional risk.

Prediction of total body electrical resistance normal values based on limb muscle thickness assessed by ultrasound.

Recently, a new model has been proposed to assess hydration in patients by measurement of total body electrical resistance (TBER), with results expressed in ohm rather than in liter body water. According to this approach, hydration is considered to be normal if TBER is within the normal range. As TBER is inversely related to the size of the limb muscle compartment, this relationship can be used to calculate the patient-specific TBER normal value (TBERnorm). The present study investigates whether the prediction of TBERnorm can be improved by the use of ultrasound (US) instead of anthropometrically derived parameters of limb muscularity. In total, 129 healthy subjects (60 men and 69 women) ranging in age from 18 to 75 yr, and in BMI from 17.4 to 52.0 kg/m2 were included in the study. Arm muscle cross-sectional area assessed by anthropometry (AMAcaliper) was compared with mean muscle thickness (MMT) of arm and leg assessed by B-mode US. MMT correlated stronger with TBER than AMA, and reduced the standard error of the estimate (SEE) by 15% in men and by 26% in women. Muscularity was overestimated by AMAcaliper due to a systematic error directly proportional to subcutaneous fat layer thickness. The gender independent relation between MMT and TBERnorm is described by the equation: TBERnorm = 705-75.4⋅MMT (R2 = 0.85, SEE = 22.3 Ω/m, P < 0.001). US-based measurement of limb muscularity provides a more precise prediction of TBERnorm, in particular in obese subjects, and is recommended as the method of choice.

Electrical Safety and Stray Current Protection With Platform Screen Doors in DC Rapid Transit

Modern transit systems are equipped with platform screen doors (PSDs) that represent a new element introduced in electrical safety and stray current protection scenarios. Passengers may interact with PSDs and platforms while boarding, leaving, and waiting for trains. Typical contractual requirements and applicable standards are discussed, identifying touch voltage scenarios suitably defining electrical circuits and parameters. The dc voltage limits are at all clear and unambiguous in the range of relevant touch voltage values. The evaluation of exposure is, thus, carried out with the help of body impedance and body current models. Solutions are then discussed for the protection of PSDs and passengers, including stray current limitations as a constraint. A novel PSD bonding arrangement is proposed, which reconciles insulation for utmost electrical safety level and bonding for traction fault protection.

Wrist-wearable bioelectrical impedance analyzer with miniature electrodes for daily obesity management

Bioelectrical impedance analysis (BIA) is used to analyze human body composition by applying a small alternating current through the body and measuring the impedance. The smaller the electrode of a BIA device, the larger the impedance measurement error due to the contact resistance between the electrode and human skin. Therefore, most commercial BIA devices utilize electrodes that are large enough (i.e., 4 × 1400 mm2) to counteract the contact resistance effect. We propose a novel method of compensating for contact resistance by performing 4-point and 2-point measurements alternately such that body impedance can be accurately estimated even with considerably smaller electrodes (outer electrodes: 68 mm2; inner electrodes: 128 mm2). Additionally, we report the use of a wrist-wearable BIA device with single-finger contact measurement and clinical test results from 203 participants at Seoul St. Mary’s Hospital. The correlation coefficient and standard error of estimate of percentage body fat were 0.899 and 3.76%, respectively, in comparison with dual-energy X-ray absorptiometry. This result exceeds the performance level of the commercial upper-body portable body fat analyzer (Omron HBF-306). With a measurement time of 7 s, this sensor technology is expected to provide a new possibility of a wearable bioelectrical impedance analyzer, toward obesity management.

FADS1 genetička varijanta rs174547 kao molekularno-genetički biomarker za procenu rizika razvoja kardiovaskularnih bolesti - studija iz Bugarske

The input of molecular genetic biomarkers allows individual assessment of metabolic pathways and the behaviour of the major enzymes responsible for nutrient conversion. This in turn enriches the nutrigenetic information fund, and the panels of well-studied gene variants and their interaction with nutrients can be used to create precise personalized diets. Our objective was to determine the significance of the rs174547 genetic variant in the fatty acid desaturase 1 (FADS1) gene in the metabolism of saturated and unsaturated fatty acids ingested with food and to identify the potential of FADS1 rs174547 as a molecular genetic marker to be included in a panel of nutrigenetic studies in order to prepare a personalized diet plan. A total of 123 volunteers (43 men and 80 women) from Bulgaria, aged 28 to 65 years, were tested for rs174547 in the FADS1 gene. A DNA sample was taken from each volunteer by a non-invasive method (buccal swabs), and the genetic variant of each individual was determined by molecular genetic approaches. Their general health was assessed by taking anthropometric and body impedance measurements data and completing a lifestyle survey. The lipid profile included testing for triglycerides, total cholesterol, HDL and LDL cholesterol, and blood sugar. Information on the total food intake was collected through questionnaire methods. The results of the statistical tests show that there is a statistically significant difference between the two genotypes only in HDL cholesterol levels (P = 0.044, at P &lt; 0.05) - carriers of the C/T genotype have lower mean concentration values of HDL-cholesterol (1.27 mmol/l) than for T/T variant carriers (1.48 mmol/l). Among men, there were statistically significant differences in mean levels of total cholesterol (P = 0.012) and HDL cholesterol (P = 0.008) between the two genotypes. Among women, there was a statistically significant difference between the two genotypes only in terms of mean triglyceride levels (P = 0.007). The differences in the other studied indicators do not satisfy the criterion for significance (P &lt; 0.05). The results suggest an effect of the intake of SFA (saturated fatty acids) and MUFA (monounsaturated fatty acids) on the relationship between rs174547 polymorphism and plasma lipids (total and LDL-cholesterol) only in men. Studies of the Bulgarian population prove extremely low intake of omega-3 fatty acids due to low consumption of fish. These findings and the lack of data for Bulgaria on genetic variants of FADS1 are a prerequisite for conducting in-depth studies of both risk groups, such as patients with cardiovascular disease, dyslipidaemia or nutritional deficiency of LC-PUFAs, and in healthy people.

Use of bioelectrical impedance spectroscopy to provide a measure of body composition in sows

The ability to accurately estimate fat mass and fat-free mass (FFM) has the potential to improve the way in which sow body condition can be managed in a breeding herd. Bioelectrical impedance spectroscopy (BIS) has been evaluated as a practical technique for assessment of body composition in several livestock species, but similar work is lacking in sows. Bioelectrical impedance uses population-specific algorithms that require values for the apparent resistivities of body fluids and body proportion factors. This study comprised three major aims: (i) to derive apparent resistivity coefficients for extracellular water (ECW) and intracellular water (ICW) required for validation of BIS predictions of total body water (TBW) in live sows against standard reference tracer dilution methods; (ii) to develop predictions of TBW to body composition prediction algorithms, namely FFM, by developing a body geometry correction factor (Kb) and (iii) to compare the BIS predictions of FFM against existing impedance predictors and published prediction equations for use in sows, based on physical measurements of back-fat depth and BW (P2-based predictors). Whole body impedance measurements and the determination of TBW by deuterium dilution and ECW by bromide dilution were performed on 40 Large White x Landrace sows. Mean apparent resistivity coefficients of body fluids were 431.1 Ω.cm for ECW and 1827.8 Ω.cm for ICW. Using these coefficients, TBW and ECW were over-estimated by 6.5 and 3.3%, respectively, compared to measured reference values, although these differences were not statistically different (P > 0.05). Mean Kb was 1.09 ± 0.14. Fat-free mass predictions were 194.9 kg, which equates to 60.9% of total sow weight, and 183.0 kg for BIS and the deuterium dilution method, respectively. Mean differences between the predicted and measured FFM values ranged from −8.2 to 32.7%, but were not statistically different (P > 0.05). Method validation (leave-one-out procedure) revealed that mean differences between predicted and measured values were not statistically significant (P > 0.05). Of the impedance-based predictors, equivalence testing revealed that BIS displayed the lowest test bias of 11.9 kg (8.2%), although the P2-based prediction equations exhibited the lowest bias and percentage equivalence, with narrow limits of agreement. Results indicate although differences between mean predicted and measured values were not significantly different, relatively wide limits of agreement suggest BIS as an impractical option for assessing body composition in individual sows compared to the use of existing prediction equations based on BW and back fat.

Computational models for contact current dosimetry at frequencies below 1\xa0MHz

Electric contact currents (CC) can cause muscle contractions, burns, or ventricular fibrillation which may result in life-threatening situations. In vivo studies with CC are rare due to potentially hazardous effects for participants. Cadaver studies are limited to the range of tissue’s electrical properties and the utilized probes’ size, relative position, and sensitivity. Thus, the general safety standards for protection against CC depend on a limited scientific basis. The aim of this study was therefore to develop an extendable and adaptable validated numerical body model for computational CC dosimetry for frequencies between DC and 1 MHz. Applying the developed model for calculations of the IEC heart current factors (HCF) revealed that in the case of transversal CCs, HCFs are frequency dependent, while for longitudinal CCs, the HCFs seem to be unaffected by frequency. HCFs for current paths from chest or back to hand appear to be underestimated by the International Electrotechnical Commission (IEC 60479-1). Unlike the HCFs provided in IEC 60479-1 for longitudinal current paths, our work predicts the HCFs equal 1.0, possibly due to a previously unappreciated current flow through the blood vessels. However, our results must be investigated by further research in order to make a definitive statement. Contact currents of frequencies from DC up to 100 kHz were conducted through the numerical body model Duke by seven contact electrodes on longitudinal and transversal paths. The resulting induced electric field and current enable the evaluation of the body impedance and the heart current factors for each frequency and current path.

Impact of diffusion, ultrafiltration, and posture on total body electrical resistance in patients on hemodialysis.

Monitoring of hydration in patients on hemodialysis (HD) by currently available bioelectrical impedance analysis (BIA) methods is hampered by limited accuracy. This may be caused by changes in total body electrical resistance (TBER) that are induced by processes other than ultrafiltration (UF). To identify these sources of error, we examined the impact of UF, diffusion, and postural change (PC), separately. Extracellular TBER (TBERe) was measured by bioimpedance spectroscopy every 30 min in 23 patients on HD, for 2 h during diffusion-only (DO), followed by 2-h UF-only (UFO). The impact of PC from upright to semi-recumbent position was assessed by a 2-h TBERe measurement on the day after HD. TBERe increased by 23.5 ± 12.4 Ω (P < 0.001) during DO and by 40.0 ± 16.2 Ω (P < 0.001) during UFO. PC, evaluated on a separate day, was associated with an increase in TBERe of 27.6 ± 26.0 Ω (P < 0.001). TBERe changes during DO were mainly attributed to PC and to a lesser extent to electrolyte exchange. Extrapolation of the data to a conventional 4-h HD session indicates that about 32% of the total increase in TBERe is not related to UF. In conclusion, a significant part of the increase in TBER during HD is not related to UF but can be attributed to other processes such as the effects of PC and diffusion-related electrolyte exchange. These factors have to be taken into account when TBER-guided UF is considered.NEW & NOTEWORTHY Current BIA methods have limited accuracy in patients on HD. This may be related to the incorrect assumption that all changes in total body electrical resistance (TBER) are caused by changes in body water volumes. The present study indicates that two-thirds of the change in TBER during a conventional 4-h HD session can be attributed to fluid extraction, and that the remaining part is caused by other processes such as postural change and electrolyte exchange. This may cause volume prediction errors when not recognized.

Continuous body impedance measurement to detect bladder volume changes during urodynamic study: A prospective study in pediatric patients.

To assess the possibility of the body impedance (BI) reflecting bladder volumes (BV) in pediatric patients, the BI signals are measured continuously with the equipment that we have developed and reported previously, during the filling phase of urodynamic study (UDS). A total of 30 children (5-12 years old) are included in this prospective study. The equipment uses two dry electrodes embedded inside a strap to collect impedance and electrocardiogram signals. The factors affecting baseline BI and its decreases during UDS have been investigated. The median age is 6.1 years and BI is accurately measured in 27 out of 30 patients (90.0% accuracy). The median value of baseline BI is 1958 Ω. It is higher when they are older, equal to or taller than 125 cm, or non-neurogenic bladder patients. BI decreases as the bladder is filled with saline in 21 patients (77.8%), and remains constant in 6 patients (22.2%). The median age of the Decreased Group is significantly higher than that of Nondecreased Group (p = .036). Height of 125 cm or more is significant in the Decreased Group (p = .020). Heart rates also have been simultaneously measured and revealed a mild decrease during the filling phase. The baseline BI is affected by the height and age of the children. BI is effectively measured and reflects a change in the BV in older children who are taller than 125 cm, with a small device using a smartphone and a strap.

Improved prediction of normal total body electrical resistance based on limb muscle thickness assessed by ultrasound

Rationale: Recently, a new model has been proposed to assess hydration in patients by measurement of total body electrical resistance (TBER), with results expressed in Ohms rather than in liters body water [1]. According to this approach, hydration is considered to be normal if the actually measured TBER is within the predicted, patient-specific, normal range (TBERnorm). The latter can be calculated, based on the inverse linear relation that exists between TBER and the upper arm muscle cross sectional area (AMA) as assessed by anthropometry. The aim of this study was to investigate whether prediction of TBERnorm based on AMA can be improved by ultrasound (US)-based parameters of muscularity.

Sarcopenia in hospitalized geriatric patients: insights into prevalence and associated parameters using new EWGSOP2 guidelines

BackgroundData on prevalence of sarcopenia and its associated parameters in hospitalized geriatric patients are heterogeneous due to various definitions of the disease. The aim of this study was to determine the prevalence of sarcopenia using latest recommendations of the European Working Group on Sarcopenia in Older People 2 (EWGSOP2), and to investigate associated parameters in patients admitted to acute geriatrics and geriatric rehabilitation.MethodsIn this cross-sectional single-centre study including 305 hospitalized geriatric patients, handgrip strength (pneumatic hand dynamometer) and muscle quantity (body impedance analysis) were assessed. Probable sarcopenia was defined by low handgrip strength, and the diagnosis was confirmed when both handgrip strength and muscle quantity were below cut-off points. Furthermore, parameters of the geriatric baseline examination were analyzed for association with probable and confirmed sarcopenia using logistic regression models.ResultsMedian age of the study population was 84.0 years, and 65.6% were female. The prevalence of probable sarcopenia was 24.6% (CI 19.8–29.4%), and the prevalence of confirmed sarcopenia was 22.6% (CI 17.9–27.3%). Low calf circumference, low body mass index, cognitive impairment and an increased risk of malnutrition were found to be associated with confirmed sarcopenia. In contrast, only cognitive impairment was positively associated with probable sarcopenia.ConclusionsSarcopenia is highly prevalent in geriatric inpatients, and multiple parameters were found to be associated with the disease. To reduce negative clinical outcomes, our findings support the need for routinely performed admission examinations for prompt diagnosis of sarcopenia, and a timely start of treatment in hospitalized geriatric patients.

Evaluation of Double Loop IC Module for Inductive Coupled Fed RFID Tag Wire Embedded Antenna

This paper presents an evaluation on double loop integrated circuit module for inductive couple fed RFID Tag. The inductive couple feed gives advantage especially for flexible wire embedded antenna in controlling the manufacturing varians as the chip is not directly connected to the antenna. Thus electrostatic discharged effect and manufacturing errors can be minimized. An inductor loop is directly connected to the RFID chip before it is placed to indirectly coupled the energy from a meandered dipole antenna. The coupled energy should be enough to turn on the chip to communicate with the reader. The inductive coupled energy is achieved by manipulating the near field magnetic field between the antenna body and the inductor loop. To evaluate the performance, the antenna and the inductive feeding loop is designed to operate at RFID UHF band (860 MHz – 960 MHz) and simulated using CST software. The antenna body impedance is evaluated to match the impedance of the chip and the loop. It is confirmed that the double loop inductor has higher inductance values and thus should be counted in conjugate impedance between the antenna body and the chip module. The tag with overall dimension of 60 mm x 16 mm can be read at distance at least 9 meters through out the band.

A novel method for estimating the fractional Cole impedance model using single-frequency DC-biased sinusoidal excitation.

The Cole model is a widely used fractional circuit model in electrical bioimpedance applications for evaluating the content and status of biological tissues and fluids. Existing methods for estimating the Cole impedance parameters are often based on multi-frequency data obtained from stepped-sine measurements fitted using a complex non-linear least square (CNLS) algorithm. Newly emerged numerical methods from the magnitude of electrical bio-impedance data-only do not need CNLS fitting, but they still require multi-frequency stepped-sine data. This study proposes a novel approach to estimating the Cole impedance parameters that combines a numerical and time-domain fitting method based on a single-frequency DC-biased sinusoidal current excitation. First, the transient and steady-state voltage response along with the current excitation are acquired in electrical bio-impedance measurement. From the sampled data, a numerical method is applied to provide the initial estimation of the Cole impedance parameters, which are then used in a time-domain iterative fitting algorithm. The accuracy of the algorithm proposed is tested with noisy electrical bio-impedance simulations. The maximum relative error of the estimated Cole impedance parameters is 1% considering 2% (34 dB) additive Gaussian noise. Experimental measurements performed on a 2R-1C circuit and some fruit samples show a mean difference less than 1% and 5% respectively compared to the Cole impedance parameters estimated from a commercial electrical bio-impedance analyzer performing stepped-sine measurements and CNLS fitting. This is the first method that allows estimating the Cole impedance parameters from single-frequency electrical bio-impedance data. The approach presented could find broad use in many applications, including single-frequency body impedance analysis.

Individualized body bioelectrical impedance parameters in newly diagnosed cancer children

BackgroundThe bioelectric impedance analysis permits to estimate electrical parameters and body composition of subjects who are either apparently healthy or sick with different pathologies. The aim of this study is to individualize the analysis of body bioelectrical impedance parameters in newly diagnosed cancer children, by means of the bioelectrical impedance analysis for each age group, gender and cancer histological variety.MethodsThis retrospective cross-sectional study consisted of 43 pediatric patients with different histological varieties of cancer, ages from 2 to 17. The body electrical resistance and body capacitive electrical reactance were measured with the Bodystat 1500-MDD analyzer. From these two electrical parameters the body electrical impedance modulus and the body phase angle were calculated.ResultsThe results showed that 93.02% of cancer children were outside reference rectangles according to age groups and gender were showed. The values of body capacitive electrical reactance (72.5%) and body phase angle (90.70%) of these patients were below the lower limits of their respective rectangles. These findings were noticeable for patients who had solid tumors.ConclusionsThe BIA is feasible to individualize body bioelectrical parameters and body bioelectric state in newly diagnosed cancer children and how differ from those in apparently healthy subjects, for the same age group and gender. Additionally, the tumor electrical properties may have a noticeable role in changes of body bioelectric-physiological parameters of these newly diagnosed cancer children.

Sensitivity of total body electrical resistance measurements in detecting extracellular volume expansion induced by infusion of NaCl 0.9.

Fluid balance management in hospitalized patients is hampered by the limited sensitivity of currently available tools. The aim of this study was to assess the sensitivity of total body electrical resistance (TBER) measurements for the detection of extracellular volume (ECV) expansion. TBER and plasma resistivity (ρplasma) were measured during a 4-h infusion of NaCl 0.9% at a rate of 500 mL/h in 23 patients undergoing a diagnostic saline infusion test for primary hyperaldosteronism. Extracellular fluid gain (EFG) was defined as infusion volume minus urinary volume. Infusion of 2.0 L NaCl 0.9% was associated with a mean diuresis of 1.1 ± 0.5 L, an EFG of 0.9 ± 0.5 L, a decrease in ρplasma of 1.1 ± 0.7 Ω·cm or 1.7 ± 1.0% (P < 0.001), and a decline in TBER of 23.2 ± 10.9 Ω or 4.6 ± 2.2% (P < 0.001). At group level, infusion of 80 mL saline was sufficient to induce a statistically significant decline in mean TBER. At personal level, the decline in TBER was significant on 76% of occasions after an EFG of 0.5-0.75 L, and on all occasions after an EFG of 1.0 L or greater. Raw TBER data are very informative for the detection of ECV expansion induced by the infusion of NaCl 0.9%, with a sensitivity at a personal level that is relevant for clinical practice.