Bioimpedance Device Research Articles

Low Muscle Mass is Associated with Walking Function in Patients with Acute Ischemic Stroke

BackgroundMuscle mass might be a possible predictor for walking function in patients with stroke; however, evidence is limited. ObjectiveTo investigate whether skeletal muscle mass is associated with walking function at discharge during the acute phase. MethodsIn this observational cohort study, we assessed skeletal muscle mass in patients with acute ischemic stroke using the noninvasive and portable multifrequency bio-impedance device. This device can easily be used in bedridden patients. Appendicular skeletal muscle mass was converted to skeletal muscle index (SMI) standardizing by height squared (kg/m2). The primary outcome was walking function assessed by the modified Rankin Scale score at acute phase hospital discharge. Logistic regression analysis was used to determine the association between skeletal muscle mass and walking function. ResultsOf the 107 patients enrolled, low SMI (SMI: male <7.0 kg/m2, female <5.7 kg/m2) was identified in 29.9% (19.7% in men, 48.6% in women). Logistic regression analysis showed that low SMI [OR: 4.02, 95% confidence interval (CI): 1.38-11.7, p = 0.001] independently associated with walking function at discharge. Further, patients with mild and moderate severity had significant difficulty in walking when they had low SMI (p = 0.039). ConclusionsLow skeletal muscle mass at the onset of ischemic stroke is an independent predictor of walking function at discharge during the acute phase. Our findings highlight the importance of detecting skeletal muscle mass in patients with acute ischemic stroke.

Fat-free Mass Bioelectrical Impedance Analysis Predictive Equation for Athletes using a 4-Compartment Model.

Bioelectrical impedance analysis equations for fat-free mass prediction in healthy populations exist, nevertheless none accounts for the inter-athlete differences of the chemical composition of the fat-free mass. We aimed to develop a bioimpedance-based model for fat-free mass prediction based on the four-compartment model in a sample of national level athletes; and to cross-validate the new models in a separate cohort of athletes using a 4-compartment model as a criterion. There were 142 highly trained athletes (22.9±5.0 years) evaluated during their respective competitive seasons. Athletes were randomly split into development (n=95) and validation groups (n=47). The criterion method for fat-free mass was the 4-compartment model. Resistance and reactance were obtained with a phase-sensitive 50 kHz bioimpedance device. Athletic impedance-based models were developed (fat-free mass=- 2.261+0.327*Stature2/Resistance+0.525*Weight+5.462*Sex, where stature is in cm, Resistance is in Ω, Weight is in kg, and sex is 0 if female or 1 if male). Cross validation revealed R2 of 0.94, limits of agreement around 10% variability and no trend, as well as a high concordance correlation coefficient. The new equation can be considered valid thus affording practical means to quantify fat-free mass in elite adult athletes.

Early post-stress decrease in cardiac performance by impedance cardiography and its relationship to the severity and extent of ischemia by myocardial perfusion imaging

BackgroundWhile single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is a well-established noninvasive procedure for the evaluation of patients with coronary artery disease (CAD), it is unable to detect the presence of, or underestimates the extent of CAD in certain patients. We aimed to show that a bio-impedance device can detect early post-stress changes in several hemodynamic parameters, thereby serving as a potential marker for the presence of significant ischemia.MethodsProspectively enrolled patients, referred to our Medical Center for clinically-indicated MPI, underwent testing using a Non-Invasive Cardiac System (NICaS) before and immediately after exercise. The differences between rest and stress hemodynamic parameters were compared with the severity and extent of myocardial ischemia by MPI. The study included 198 patients; mean age was 62 years, 26% were women, 54% had hypertension, and 29% diabetes mellitus. Of them, 188 patients had ≤10%, and 10 had > 10% of myocardial ischemia.ResultsIn the first group, there was a significantly greater increase in post-exercise stroke index, stroke work index, cardiac index and cardiac power index (19.2, 29.1, 90.5 and 107%, respectively) compared with the second group (− 2.7, 3.8, 43.7 and 53.5%, respectively), as well as a significantly greater decrease in total peripheral resistance index (− 38.7% compared with − 16.3%), with corresponding p values of 0.015, 0.017, 0.040, 0.016, and < 0.001, respectively.ConclusionsOur data suggest that immediate post-stress changes in several hemodynamic parameters, detected by the NICaS, can be used as an important adjunct to SPECT MPI for the early detection of myocardial ischemia.

Skeletal Muscle Ratio: A Complete Mediator of Physical Activity and HbA1C in Type 2 Diabetes.

An increase in the physical activity level reduces body weight, decreases body fat, increases skeletal muscle mass, and improves serum glucose; however, the influence of body composition parameters on the relationship between physical activity and serum glucose remains unclear. This study investigated whether skeletal muscle and visceral fat affect the relationship between high physical activity and long-term serum glucose goals. This cross-sectional study recruited patients with type 2 diabetes. The Chinese version of the International Physical Activity Questionnaire was used for estimating the physical activity level, and a bioimpedance device was used to measure the skeletal muscle ratio (skeletal muscle mass/total body weight, %) and visceral fat area (cm2). Hierarchical logistic regression models and mediation tests were conducted according to Hayes' procedures. Of the total 543 Chinese individuals with type 2 diabetes enrolled, HbA1C levels of fewer than half (n = 243, 44.8%) met the target of ≤7.0%. The skeletal muscle ratio was found to be a complete mediator (OR = 0.920, 95% CI: 0.848 to 0.998; indirect effect: -0.238, 95% CI: -0.525 to -0.020) of the relationship between high physical activity and the target HbA1C level after controlling for visceral fat area (indirect effect: -0.013, 95% CI: -0.183 to 0.156), age, time since diabetes diagnosis, and rice intake. Nurses should include an increase in the skeletal muscle ratio as an objective in physical activity interventions for patients with type 2 diabetes to help them achieve their long-term serum glucose goals.

Failure prediction using personalized models and an application to heart failure prediction

BackgroundTo reduce disruptions of processes and the cost of maintenance, predicting the onset of failure (or a similar event) of a physical system (or components of a physical system) has become important. Prediction of onset of failure would allow appropriate corrective actions at the right time. In this paper, we present a method to predict the “onset” of failure (the start of a degradation process or similar types of events) of a physical system that minimizes data collection and personalizes it for the physical system. The method applies to situations where one monitors the operating characteristics of the physical system at regular time intervals by means of attached sensors and other measurement instruments. It creates a model of the physical system, during normal operations, using the time-series data produced by the sensors and measurement instruments. However, it does not create or use any time-series models. It simply examines the distribution of time-series data across different time periods. It uses this model of normal operations in subsequent time periods to monitor the physical system for deviations from normality.ResultsWe illustrate this method with an application to predict the “onset” of subsequent decompensated heart failures for patients already treated for a heart failure at a hospital. As part of an NIH study, these heart failure patients received two ECG patches, an accelerometer and a bio-impedance measurement device for regular monitoring for a period after their release from the hospital.ConclusionsWhen dealing with non-homogenous, disparate physical systems, personalized models can be better predictors of a phenomenon compared to generalized models based on data collected from an assortment of such physical systems. In medicine such models can be a powerful addition to the set of medical diagnostic tools. And such personalized models can be built rather quickly without waiting for extensive data collection.

Bioimpedance Vector Patterns Changes in Response to Swimming Training: An Ecological Approach.

Background and aim: Monitoring bioelectric phase angle (PhA) provides important information on the health and the condition of the athlete. Together with the vector length, PhA constitutes the bioimpedance vector analysis (BIVA) patterns, and their joint interpretation exceeds the limits of the evaluation of the PhA alone. The present investigation aimed to monitor changes in the BIVA patterns during a training macrocycle in swimmers, trying to ascertain if these parameters are sensitive to training load changes across a 13-week training period. Methods: Twelve national and international level swimmers (four females; eight males; 20.9 ± 1.9 years; with a competitive swimming background of 11.3 ± 1.8 years; undertaking 16–20 h of pool training and 4–5 h of dry-land training per week and 822.0 ± 59.0 International Swimming Federation (FINA) points) were evaluated for resistance (R) and reactance (Xc) using a single frequency phase sensitive bioimpedance device at the beginning of the macrocycle (M1), just before the beginning of the taper period (M2), and just before the main competition of the macrocycle (M3). At the three-time assessment points, swimmers also performed a 50 m all-out first stroke sprint with track start (T50 m) while time was recorded. Results: The results of the Hotelling T2 test showed a significant vector displacement due to simultaneous R and Xc changes (p < 0.001), where shifting from top to bottom along the major axis of the R-Xc graph from M1 to M2 was observed. From M2 to M3, a vector displacement up and left along the minor axis of the tolerance ellipses resulted in an increase in PhA (p < 0.01). The results suggest a gain in fluid with a decrease in cellular density from M1 to M2 due to decrements in R and Xc. Nevertheless, the reduced training load characterizing taper seemed to allow for an increase in PhA and, most importantly, an increase of Xc, thus demonstrating improved cellular health and physical condition, which was concomitant with a significant increase in the T50 m performance (p < 0.01). Conclusions: PhA, obtained by bioelectrical R and Xc, can be useful in monitoring the condition of swimmers preparing for competition. Monitoring BIVA patterns allows for an ecological approach to the swimmers’ health and condition assessment without resorting to equations to predict the related body composition variables.

Bioimpedance Phase Angle Reliability In Mexican College Students

Bioimpedance (BIA) phase angle (PA) is a body composition measure related to cell structure, integrity and body cell mass. Although PA has been positively correlated to clinical outcomes, there is scarce information on ethnic differences in PA and its overall reliability. PURPOSE: To determine phase angle reliability in Mexican college students. METHODS: College students from the city of Tijuana, México, were recruited for this study. Volunteers were 26 males (Age = 22.7 ± 3.1 yr., Height = 172.8 ± 5.6 cm, Weight = 70.9 ± 11.7 kg) and 26 females (Age = 21.1 ± 2.2 yr., Height = 159.0 ± 7.1 cm, Weight = 60.8 ± 8.6kg). Participants arrived euhydrated to the testing session (Urine specific gravity = 1.005 ± 0.003) and were measured on a multi-frequency InBody 770 BIA device in two occasions separated by five minutes of seated resting. Body weight, %fat mass, muscle mass (kg) and PA were recorded and analyzed by repeated measures 2 (gender) x 2 (measures) ANCOVA, using hydration status and age as covariates. Intraclass correlation coefficient (ICC) and 95% confidence interval were used to determine reliability between measures. RESULTS: Gender differences were found on PA (Males = 6.8 ± 0.1 vs. Females = 5.9 ± 0.1, p ≤ 0.0001), and muscle mass (Males = 31.9 ± 0.7 vs. Females = 23.2 ± 0.7 kg, p ≤ 0.0001). Significant (p ≤ 0.0001 for all) ICC reliability coefficients were found between pre- to post-measures of PA (r = 0.998, 95%CI = 0.996 to 0.999), %fat (r = 0.999, 95%CI = 0.998 to 1.00) and muscle mass (r = 1.00, 95%CI= 1.00 to 1.00). CONCLUSION: Young college students showed reliable BIA PA, muscle mass and %fat values following five minutes of seated resting. Mexican males showed higher muscle mass and PA than women after controlling for the influence of hydration and age.

Assessing Patent Ductus Arteriosus (PDA) Significance on Cardiac Output by Whole-Body Bio-impedance.

We evaluated the effectiveness of a whole-body bioimpedance device (NICaS®, NI Medical, Petach Tikva, Israel) to predict the presence of a hemodynamically significant patent ductus arteriosus (PDA) in premature infants. A total of 36 infants less than 35week's gestation age and birth weights of less than 1750 g were included in the study. Using the NICaS® device, we obtained whole-body bioimpedance measurements of stroke volume index (SI), cardiac output index (CI) and total peripheral resistance index. A total of 61 measurements were taken together with echocardiograph imaging. The study population was divided into three groups according to the echocardiograph results: group 1-small PDA, group 2-moderate PDA, and group 3-large PDA. Both SI and CI significantly increased from a median value of 22.6ml/m2 and 3.4l/min/m2 to 23.8 and 3.7, to 39.8 and 5.4 between groups 1, 2 and 3 respectively. The difference was statistically significant between groups 1 and 3 (P = 0.005 for SI and P = 0.002 for CI) and between groups 2 and 3 (P = 0.037 for SI and P = 0.05 for CI). We found statistically significant differences in SI and CI between infants with large PDAs and infants with no or small and medium PDAs. We suggest that these differences can be used in real time, in addition to echocardiography, in assessing the presence of significant PDAs.

Physical function and lean body mass as predictors of bone loss after hip fracture: a prospective follow-up study

BackgroundPredictors of bone deterioration after hip fracture have not been well characterized. The aim of this study was to examine the associations of physical function and lean body mass (LBM) with loss of bone density and strength in older people recovering from a hip fracture.MethodsA total of 81 over 60-year-old, community-dwelling men and women operated for a hip fracture participated in this 1-year prospective follow-up study. Distal tibia total volumetric bone mineral density (vBMDTOT, mg/cm3) and compressive strength index (BSI, g2/cm4) and mid-tibia cortical vBMD (vBMDCO, mg/cm3) and bending strength index (SSI, mm3) were assessed in both legs by peripheral quantitative computed tomography (pQCT) at baseline (on average 10 weeks after fracture) and at 12 months. At baseline, LBM was measured with a bioimpedance device and physical function with the Short Physical Performance Battery (SPPB) and perceived difficulty in walking outdoors. Robust multivariable linear regression models were used to estimate the associations of physical function and LBM with the change in bone parameters at 12-months.ResultsThe mean change in distal tibia vBMDTOT and BSI in both legs ranged from − 0.9 to − 2.5%. The change in mid-tibia vBMDCO and SSI ranged from − 0.5 to − 2.1%. A lower SPPB score, difficulty in walking outdoors and lower LBM predicted greater decline in distal tibia vBMDTOT in both legs. A lower SPPB score and difficulty in walking outdoors were also associated with a greater decline in distal tibia BSI in both legs. At the midshaft site, a lower SPPB score and lower LBM were associated with greater decline in SSI on the fractured side.ConclusionsOlder hip fracture patients with low physical function and lower LBM may be at risk for greater decline in tibia bone properties during the first post-fracture year. Acknowledgement of the risk factors could assist in developing interventions and care to promote bone health and overall recovery.Trial registrationISRCTN, ISRCTN53680197. The trial was registered retrospectively but before the recruitment was completed. Registered March 3, 2010.

The Added Value of In-Hospital Tracking of the Efficacy of Decongestion Therapy and Prognostic Value of a Wearable Thoracic Impedance Sensor in Acutely Decompensated Heart Failure With Volume Overload: Prospective Cohort Study.

BackgroundIncomplete relief of congestion in acute decompensated heart failure (HF) is related to poor outcomes. However, congestion can be difficult to evaluate, stressing the urgent need for new objective approaches. Due to its inverse correlation with tissue hydration, continuous bioimpedance monitoring might be an effective method for serial fluid status assessments.ObjectiveThis study aimed to determine whether in-hospital bioimpedance monitoring can be used to track fluid changes (ie, the efficacy of decongestion therapy) and the relationships between bioimpedance changes and HF hospitalization and all-cause mortality.MethodsA wearable bioimpedance monitoring device was used for thoracic impedance measurements. Thirty-six patients with signs of acute decompensated HF and volume overload were included. Changes in the resistance at 80 kHz (R80kHz) were analyzed, with fluid balance (fluid in/out) used as a reference. Patients were divided into two groups depending on the change in R80kHz during hospitalization: increase in R80kHz or decrease in R80kHz. Clinical outcomes in terms of HF rehospitalization and all-cause mortality were studied at 30 days and 1 year of follow-up.ResultsDuring hospitalization, R80kHz increased for 24 patients, and decreased for 12 patients. For the total study sample, a moderate negative correlation was found between changes in fluid balance (in/out) and relative changes in R80kHz during hospitalization (rs=-0.51, P<.001). Clinical outcomes at both 30 days and 1 year of follow-up were significantly better for patients with an increase in R80kHz. At 1 year of follow-up, 88% (21/24) of patients with an increase in R80kHz were free from all-cause mortality, compared with 50% (6/12) of patients with a decrease in R80kHz (P=.01); 75% (18/24) and 25% (3/12) were free from all-cause mortality and HF hospitalization, respectively (P=.01). A decrease in R80kHz resulted in a significant hazard ratio of 4.96 (95% CI 1.82-14.37, P=.003) on the composite endpoint.ConclusionsThe wearable bioimpedance device was able to track changes in fluid status during hospitalization and is a convenient method to assess the efficacy of decongestion therapy during hospitalization. Patients who do not show an improvement in thoracic impedance tend to have worse clinical outcomes, indicating the potential use of thoracic impedance as a prognostic parameter.

Comparison of Physical Activity in Obese and Non-Obese Women and Investigation of the Relationship between Physical Activity with ABO Blood Groups and Rh factor

Introduction: Decreased physical activity is an important risk factor for obesity. The International Physical Activity Questionnaire (IPAQ) has been developed to determine physical activity levels. Previous studies showed that obesity is affected by ABO blood types. Aim of the study was to search whether blood groups are associated with the level of physical activity. If proven, this will indicate that the blood groups may be one of the genetic factors that influence inclination towards obesity. Material and Methods: The study included 306 (n=211 obese, n=95 nonobese) female between the ages of 18 and 65 years. Body weights, BMI (body mass index) fat percentage, fat mass and fat-free mass were determined by using bio-impedance device. The short (IPAQ-S) and long form of (IPAQ-L) questionnaire was implemented through personal interview. ABO and Rh blood groups were determined via Microplack method. Results: No significant difference for IPAQ-S (vigorous, moderate, walking, sitting time, total physical activity) between obese and nonobese groups. However, the activity level of nonobese group was detected higher than obese group. According to IPAQ-L only significant difference in house yard-work detected higher in the obese group. There was no significant result obtained in evaluation of IPAQ-S and IPAQ-L by ABO blood groups in obese and nonobese group. There was no significant outcome detected in Rh factor and IPAQ-S in obese and nonobese group; however, a significant outcome was detected in IPAQ-L. Conclusion: Lack of significant findings in obese and nonobese groups in terms of physical activity levels according to IPAQ-S and IPAQ-L in the study reminds that obesity cannot be explained by physical activity alone. We could not detect a significant association between ABO blood groups and physical activity. Furthermore, the present study indicated that explaining obesity and physical activity in association with a single factor is difficult. Key Words: Obesity, physical activity, ABO blood groups, Rh factor Special Issue of Health Sciences DOI: 10.7176/JSTR/6-03-05

Body composition assessment before and after weight loss following a Roux-en-Y gastric bypass. Are bioimpedanciometry estimations reliable?

Introduction: in patients with severe and morbid obesity it has been observed that bioimpedance (BIA) assessment generates an underestimation of fat mass (FM) and weight loss as FM after bariatric surgery, overestimating the loss of fat-free mass (FFM) and muscle mass. Objective: to evaluate the reliability of bioelectrical impedance analysis (BIA) to estimate total body water (TBW), fat-free mass (FFM), fat mass (FM), and its changes after 6 months of a Roux-en-Y gastric bypass (RYGBP), in patients with severe and morbid obesity. Methods: thirty-six patients approved for RYGBP were prospectively studied. TBW was measured by deuterium (D), and FM and FFM were calculated. A dual-frequency BIA device (5 and 200 kHz) (Bodystat Dualscan®) was used to estimate FM, FFM, TBW, extracellular water (ECW), intracellular water (ICW), and ECW/ICW ratio. Results: before RYGBP, BIA overestimated TBW by 2.6 ± 4.3 L (p = 0.002) and FFM by 3.5 ± 5.7 kg (p = 0.002), and underestimated FM% by 2.98 ± 4.7% (p = 0.002). The ECW/ICW ratio showed a significant and positive correlation with the difference BIA-D for FFM (r = 0.49; p = 0.002). After surgery, the differences between BIA and D were not significant, and the estimation error of FFM did not correlate with the ECW/ICW ratio. Conclusions: BIA generates an underestimation of FM as reported in patients with severe and morbid obesity, which is attenuated after weight reduction, underestimating weight loss as FM and overestimating FFM loss. Future research may assess whether these errors are reproduced by other BIA devices.

Association of chronic stress, inflammation, body composition and dietary intake in Croatian university students

AbstractIntroductionChronic stress and low-grade chronic inflammation (LGCI) influence body composition and are key underlying factors in health and disease. New syndrome, osteosarcopenic obesity (OSO), signifies the simultaneous impairment of bone, muscle, and adipose tissues and has been associated with poor diet and metabolic derangements. Hyperactivation of the hypothalamic-pituitary-adrenal (HPA) axis associated with hypercortisolemia and LGCI disrupts the metabolism of bone, muscle and, adipose tissue and may cause changes in eating behavior. Some nutrients involved in preventing/alleviating OSO and LCGI include protein, calcium, magnesium, vitamin D, fiber and omega-3 fatty acids. The aim of this study was to examine the relations between chronic stress, LGCI, body composition and dietary intake in university students.Materials and MethodsParticipants were n = 50 graduate nutritional students (Age, 23.0 ± 1.4 years; BMI, 22.1 ± 2.7 kg/m2) [n = 45 females (90%)]. Advanced bio-impedance devices, BIA-ACC® and PPG-StressFlow® (BioTekna S.r.l., Marcon-Venice, Italy), were used to determine total bone mass (kg) and T-score; muscle mass (kg and % fat free mass) and S-score; and fat mass (kg and % of body weight), as well as extracellular water and HPA index (reference value &gt; 3.5) as indicators of underlying LGCI and stress. Dietary intake was estimated by 24-hour recall and analyzed for all macro- and micro-nutrients.ResultsPositive correlation was found between HPA index and the intake of either total or animal protein, calcium and riboflavin, with r ranging from 0.3–0.35, all p &lt; 0.05. HPA index also positively correlated with T-score (r = 0.39, p = 0.005) and S-score (r = 0.49, p = 0.0003). Total protein intake positively correlated with T-score (r = 0.32, p = 0.024) and animal protein with S-score (r = 0.34, p = 0.017).DiscussionOur results show that chronic stress, LGCI and body composition were interrelated in this young population and possibly augmented by higher protein and calcium intake. Screening for body composition dyshomeostasis, chronic stress and LGCI using innovative, non-invasive devices, along with assessing intake of some crucial nutrients, may provide quick and useful health information enabling prevention or early treatment of some linked disorders.

Hemodynamic profile of Spanish adults with Down syndrome

ObjectivesAlthough the reasons are unknown, the prevalence of arterial hypertension and atherosclerotic cardiovascular events in the adult population with Down syndrome (SD) is anecdotal. To better understand this finding, we evaluated the haemodynamic characteristics of a cohort of adults with SD. MethodsWe conducted a cross-sectional study of adults with SD recruited consecutively from the outpatient clinics of an internal medicine department between June and November 2018. We collected demographic, clinical and laboratory variables and employed a thoracic bioimpedance device (HOTMAN® System) for the haemodynamic measures. Outpatient blood pressure monitoring (OBPM) was conducted on a subgroup of participants. ResultsTwenty-six participants (mean age, 45±11 years) participated in the study (50 % men). The sample’s mean blood pressure (BP) was 109/69±11/9mm Hg, with a mean heart rate of 60±12 bpm. None of the participants had hypertension. The predominant haemodynamic profile consisted of normal dynamism (65 %), normal BP (96 %), hypochronotropism (46 %), normal inotropism (50 %) and hypervolaemia (54 %), with normal peripheral vascular resistance values (58 %). Twelve participants underwent OBPM (46 %). The mean 24-h systolic BP, diastolic BP, mean BP and mean heart rate were 105±11mm Hg, 67±11mm Hg, 80±11mm Hg and 61±6 bpm, respectively. ConclusionsThe most common haemodynamic profile observed in adults with SD consisted of hypochronotropism and hypervolaemia, with normal values for peripheral vascular resistance and optimal mean BP values. There were no participants with hypertension in our sample.

Perfil hemodinámico de los adultos españoles con síndrome de Down

ObjectivesAlthough the reasons are unknown, the prevalence of arterial hypertension and atherosclerotic cardiovascular events in the adult population with Down syndrome (SD) is anecdotal. To better understand this finding, we evaluated the haemodynamic characteristics of a cohort of adults with SD. MethodsWe conducted a cross-sectional study of adults with SD recruited consecutively from the outpatient clinics of an internal medicine department between June and November 2018. We collected demographic, clinical and laboratory variables and employed a thoracic bioimpedance device (HOTMAN® System) for the haemodynamic measures. Outpatient blood pressure monitoring (OBPM) was conducted on a subgroup of participants. ResultsTwenty-six participants (mean age, 45±11years) participated in the study (50% men). The sample's mean blood pressure (BP) was 109/69±11/9mmHg, with a mean heart rate of 60±12bpm. None of the participants had hypertension. The predominant haemodynamic profile consisted of normal dynamism (65%), normal BP (96%), hypochronotropism (46%), normal inotropism (50%) and hypervolaemia (54%), with normal peripheral vascular resistance values (58%). Twelve participants underwent OBPM (46%). The mean 24-h systolic BP, diastolic BP, mean BP and mean heart rate were 105±11mmHg, 67±11mmHg, 80±11mmHg and 61±6bpm, respectively. ConclusionsThe most common haemodynamic profile observed in adults with SD consisted of hypochronotropism and hypervolaemia, with normal values for peripheral vascular resistance and optimal mean BP values. There were no participants with hypertension in our sample.

Cross-sectional and longitudinal agreement between two multifrequency bioimpedance devices for resistance, reactance, and phase angle values.

The use of raw bioelectrical variables, such as resistance (R), reactance (Xc), and phase angle (φ), has been advocated for evaluating physiological changes. Before and after 8 weeks of resistance training, adult females were assessed via multifrequency bioelectrical impedance analysis (MFBIA; Seca® mBCA 515/514) and bioimpedance spectroscopy (BIS; ImpediMed® SFB7). Data were analyzed to determine whether cross-sectional estimates and changes (i.e., Δ scores) of R, Xc, and φ differed between devices at 16 shared measurement frequencies ranging from 3 to 1000 kHz. Cross-sectionally, strong correlations (r ≥ 0.96) were observed for R across all frequencies, although MFBIA produced values 9-14% greater than BIS. Strong correlations (r ≥ 0.92) for Xc and φ were observed up to frequencies of ~150 kHz. BIS produced greater Xc and φ values at lower frequencies, while MFBIA produced greater values at higher frequencies. In general, proportional bias was not observed, with the exception of Xc at high frequencies and φ at low frequencies. ΔR did not differ between devices at any frequency and was correlated at all frequencies. ΔXc and Δφ did not differ at any frequency and were correlated between devices for frequencies up to ~300 kHz. Proportional bias was generally not observed longitudinally. While individual-level errors were potentially acceptable cross-sectionally, they were concerningly high longitudinally. Despite notable differences in the characteristics of the bioimpedance devices and cross-sectional disagreement, strong group-level agreement for detecting changes in R, Xc, and φ was generally observed. However, large errors were observed at the individual level.

Fundamentals, Recent Advances, and Future Challenges in Bioimpedance Devices for Healthcare Applications

This work develops a thorough review of bioimpedance systems for healthcare applications. The basis and fundamentals of bioimpedance measurements are described covering issues ranging from the hardware diagrams to the configurations and designs of the electrodes and from the mathematical models that describe the frequency behavior of the bioimpedance to the sources of noise and artifacts. Bioimpedance applications such as body composition assessment, impedance cardiography (ICG), transthoracic impedance pneumography, electrical impedance tomography (EIT), and skin conductance are described and analyzed. A breakdown of recent advances and future challenges of bioimpedance is also performed, addressing topics such as transducers for biosensors and Lab-on-Chip technology, measurements in implantable systems, characterization of new parameters and substances, and novel bioimpedance applications.

Evaluation of one year of frequent dialysis on fluid load and body composition using calf bioimpedance technique

Objective: The primary aim of this study was to evaluate the effect of increased frequency of dialysis (FHD) on change in fluid status and body composition using segmental bioimpedance. Approach: Twelve stable HD patients were switched from 3 times/week to 6 times/week HD (FHD). Systolic blood pressure (SBP), body mass and body mass index (BMI) were measured pre- and post-HD. Calf resistance (R5) at 5 kHz was measured using a multifrequency bioimpedance device (Hydra 4200). Calf resistivity (ρ = R5 * area/length), normalized resistivity (CNR = ρ/BMI) and calf extracellular volume (cECV) were calculated. Fat mass was measured by Futrex body composition analyzers (Futrex 6100, Futrex Tech, Inc.). All measurements were performed at baseline (BL) and monthly for up to one year. Main results: Nine patients completed one year of FHD. Compared to BL, body weight and cECV decreased, and CNR increased significantly by the first month but did not change thereafter. SBP pre-HD decreased significantly by the end of the first month with further reduction until month 12. Additionally, antihypertensive medication decreased significantly from baseline by month 4 and remained stable from month 6 throughout the rest of the study. The post-HD CNR in five of nine patients reached the range of normal (>18.5 10−2 * Ohm * m3 kg−1 for males and >19.1 10−2 * Ohm * m3 kg−1 for females) after 1 year FHD. In patients who returned to 3 times/week dialysis, CNR decreased significantly in the first week, and this was associated with increases in body weight and SBP. Significance: Reduction of fluid overload with no alteration of body composition was observed in this study. Accordingly, improving fluid status was confirmed by reducing BP and use of antihypertensive drugs together with increase in CNR. Measurement of fluid status by CNR in hemodialysis patients is a new method to quantitatively assess hydration potentially creating a target for volume of fluid removal.

Agreement Between 2 Segmental Bioimpedance Devices, BOD POD, and DXA in Obese Adults

This study examined the agreement between 2 segmental bioimpedance analysis (BIA) devices, air displacement plethysmography (BOD POD), and dual energy X-ray absorptiometry (DXA) for estimating body composition in obese adults. Fifty obese adults (25 men and 25 women; age = 34.20 ± 11.19 years; BMI = 36.14 ± 5.33 kg/m2) had their body fat percentage (BF%) and fat-free mass (FFM) evaluated with 2 segmental BIA devices (InBody 230 and InBody 720), BOD POD, and DXA (Lunar iDXA). Body composition via the BOD POD was determined using the Siri equation whereas manufacturer-based equations generated metrics (ie, BF% and FFM) for the InBody devices. The effect size of the mean differences for all BF% and FFM comparisons were trivial (Cohen's d < 0.20). The standard error of estimate (SEE), total error (TE), and 95% limits of agreement (LOAs) were low for both segmental BIA devices when compared to DXA (SEE < 2.26% and 2.35 kg; TE < 2.58% and 2.66 kg; 95% LOAs < ± 4.94% and 4.86kg). The error for BOD POD was also low when compared to DXA (SEE = 2.39% and 2.57 kg; TE = 2.34% and 2.56 kg; 95% LOAs = 4.63% and 5.06 kg). Validity statistics were slightly higher, but considered acceptable, when comparing the segmental BIA devices against BOD POD (SEE < 3.37% and 3.63 kg; TE < 3.44% and 3.79 kg; 95% LOAs < ± 6.62% and 7.19 kg). Lastly, the 2 segmental BIA devices produced nearly identical validity statistics when compared to each other. However, both BIA devices revealed proportional bias for BF% and FFM when compared to the BOD POD and DXA (all p < 0.05). The current study's findings indicate the InBody 230 is interchangeable with the InBody 720 in obese adults. Also, the trivial effect size, when compared against the BOD POD and DXA, suggest the InBody devices could be used for estimating group BF% and FFM. In contrast, the significant proportional bias demonstrates the BIA devices are not acceptable for individual estimates of body composition in an obese clinical population.

Physical Fitness and Body Composition in Women with Systemic Lupus Erythematosus.

Background and objectives: Higher physical fitness is associated with a more favorable weight and body composition in the general population, although this association has not been studied in patients with systemic lupus erythematosus (SLE). The aim of the present study was to examine the association of different components of physical fitness with body composition in women with SLE with mild disease activity. Materials and Methods: This cross-sectional study included 77 women with SLE (43.2 ± 13.8 years old) and clinical stability during the previous 6 months. Body composition (including body mass index (BMI), fat mass index (FMI), waist circumference, waist-to-height ratio and waist-to-hip ratio) was assessed using a stadiometer, an anthropometric tape, and a bioimpedance device. Physical fitness included cardiorespiratory fitness (Siconolfi step test and 6 min walk test), muscular strength (handgrip strength test as upper body measure and 30 s chair stand as lower body measure), and flexibility (back-scratch test). Participants with a fitness level equal or above the median of the study sample were categorized as “fit” and those below the median were categorized as “unfit”. Linear regression assessed the association of physical fitness with body composition parameters. Results: Cardiorespiratory fitness and upper body muscular strength were negatively associated with BMI, FMI, waist circumference, and waist-to-height ratio (all, p < 0.05). Lower body muscular strength and flexibility were negatively related to FMI, waist circumference, waist-to-height ratio, and waist-to-hip ratio (all, p < 0.05). These relationships were still significant after controlling for age, disease duration, accrual damage, and SLE activity. Overall, fit patients presented significantly lower values in all body composition parameters compared to unfit patients (all, p < 0.05). Conclusions: The main findings of the present study suggest that physical fitness is inversely associated with body composition in women with SLE. Given the cross-sectional nature of this study, future clinical trials should study the causal pathways underlying these relationships.