Noninvasive Bioelectrical Impedance for Predicting Clinical Outcomes in Outpatients With Heart Failure

Noninvasive biometric monitoring technologies for patients with heart failure

Heart failure remains one of the leading causes of mortality and hospitalizations in the US that not only impacts quality of life but also poses a significant public health burden. The majority of affected patients are admitted with signs and symptoms of congestion. Despite the initial enthusiasm, traditional remote monitoring strategies focusing primarily on weight gain failed to improve clinical outcomes. Implantable pulmonary artery pressure sensors provide earlier and actionable data, but most patients would favor forgoing an invasive procedure in favor of an alternative, non-invasive monitoring platform. Several devices utilizing different combinations of multiparameter monitoring to reliably detect congestion have recently been developed and are undergoing testing in the clinical setting. Combining these sensors with the power of artificial intelligence and machine learning has the potential to revolutionize remote patient monitoring and early congestion detection and to facilitate timely interventions by the care team to prevent hospitalization. This manuscript provides an objective review of novel, noninvasive, multiparameter remote monitoring platforms that may be tailored to individual heart failure phenotypes, aiming to improve quality of life and survival.

A Narrative Review of the Diagnosis and Treatment of Sarcopenia and Malnutrition in Patients with Heart Failure

The prevalence of sarcopenia (loss of muscle strength, mass and function) in individuals with heart failure (HF) stands at a considerable level (approximately 20%), contributing to heightened mortality rates and diminished quality of life. The underlying pathophysiological mechanisms involve the presence of low-grade inflammation and a disturbance of the anabolic-catabolic protein balance. The nutritional assessment of patients with HF is a key aspect, and diverse diagnostic tools are employed based on patient profiles (outpatient, inpatient and nursing home). The Global Leadership Initiative on Malnutrition (GLIM) criteria serves as a consensus for diagnosing malnutrition. Given that edema can impact body mass index (BMI) in patients with HF, alternative body assessment technical methods, such as bioelectrical vector impedance (BiVA), BIA (without vector mode), computer tomography (CT) or clinical ultrasound (US), are useful. Scientific evidence supports the efficacy of both aerobic and resistance physical exercises in ameliorating and preventing muscle wasting associated with HF. Dietary strategies emphasize the importance of protein intake, while certain micronutrients like coenzyme Q10 or intravenous iron may offer benefits. This narrative review aims to present the current understanding of the pathogenesis, diagnosis and treatment of muscle loss in individuals with heart failure and its consequential impact on prognosis.

Effects of resistance training on sarcopenia in patients with intestinal failure: A randomized controlled trial

BACKGROUND

The potential effects of resistance training on sarcopenia in patients with intestinal failure (IF) are not fully elucidated. This study aimed to explore the efficacy of a resistance training program on appendicular skeletal muscle index (ASMI), physical performance, body composition, biochemical parameters, and health-related quality of life (HRQOL) in patients with IF exhibiting sarcopenia.

METHODS

A single-center randomized controlled trial was conducted in a Chinese tertiary teaching hospital. Patients with IF exhibiting sarcopenia were randomly assigned to the exercise group or control group. Participants in the exercise group incorporated four sets of resistance training involving the limbs and abdominal and lower back muscles, six times weekly for 4 weeks. The control group received no specific intervention. The primary outcome was the between-group difference in ASMI 4 weeks after intervention. Secondary outcomes included handgrip strength, 6-m gait speed, body composition, biochemical parameters, and HRQOL.

RESULTS

A total of 60 participants (control group 30, age 51.2 ± 12.9 years, women 43.3%; exercise group 30, age 53.9 ± 14.5 years, women 56.7%) completed the 4-week intervention trial. For the primary outcome, significant intervention effects were found in ASMI between the exercise group and the control group (mean difference 0.72, 95% CI, 0.56-0.89, P < 0.001). There were notable differences in handgrip strength (mean difference 2.7, 95% CI, 1.7-3.6, P < 0.001), 6-m gait speed (mean difference 0.08, 95% CI, 0.01-0.35, P = 0.034), body composition (including total cell mass, bone mineral content, skeletal muscle mass, lean mass, visceral fat area, total body water, intracellular water, extracellular water, and segmental water-legs), and biochemical parameters (including IGF-1, prealbumin, and hemoglobin) between the two groups (P < 0.05). No significant intervention benefits were observed for other secondary outcomes, including biochemical parameters (including albumin, total bilirubin, etc.) and HRQOL (P > 0.05).

CONCLUSIONS

In this randomized clinical trial, we observed that 4 weeks of resistance training was associated with improved ASMI, physical performance, biochemical parameters (including IGF-1, prealbumin, and hemoglobin), and body composition in IF patients with sarcopenia. Resistance training can be recommended as a simple and effective method to improve sarcopenia in patients with IF.

CLINICAL TRIAL REGISTRATION

www.chictr.org.cn, identifier: ChiCTR2100051727.

Determinants of phase angle in Japanese patients with diabetes

Phase angle, obtained using bioelectrical impedance analysis, non-invasively reflects the whole-body cellular condition and nutritional status and may be helpful as a prognostic factor. Patients with diabetes had a smaller phase angle than healthy subjects. However, the clinical significance of phase angle has not yet been elucidated. Therefore, the purpose of this study was to clarify the relationship between phase angle and HbA1c in patients with diabetes and the clinical relevance of phase angle. A retrospective, multicenter, cross-sectional study was conducted with Japanese patients with diabetes. Body composition was determined with bioelectrical impedance analysis, and this was used to obtain phase angle. Phase angle was assessed in relation to clinical parameters, body composition parameters, and HbA1c levels. A total of 655 patients were enrolled (400 men and 255 women, aged 57.1 ± 14.8 years, body mass index 25.6 ± 5.2 kg/m2, HbA1c 8.1 ± 1.9%). Even in patients with diabetes, the phase angle was higher in men than in women and did not differ between the types of diabetes. Multiple regression analysis, performed with phase angle as the objective variable, and age, sex, diabetes type, HbA1c, albumin level, and body mass index as explanatory variables, revealed that phase angle was negatively affected by HbA1c (B = - 0.043, 95% Confidence interval: - 0.07 to - 0.02, p < 0.001). HbA1c, age, sex, albumin level, and body mass index were independent determinants of phase angle in participants with diabetes.

Association Between Changes in Bioelectrical Impedance Analysis (BIA) Parameter and the Clinical Outcomes in Patients With Acute Heart Failure

BACKGROUND

Volume overload is associated not only with clinical manifestations but also with poor outcomes of heart failure (HF). However, there is an unmet need for effective methods for serial monitoring of volume status during HF hospitalization. The aim of this study was to evaluate the prognostic implication of serial measurement of bioelectrical impedance analysis (BIA) in patients hospitalized with acute HF.

METHODS

This study is a retrospective observational study and screened 310 patients hospitalized due to acute decompensated HF between November 2021 and September 2022. Among them, 116 patients with acute HF who underwent BIA at the time of admission and at discharge were evaluated. We investigated the correlation between change of BIA parameters and the primary composite outcome (in-hospital mortality or rehospitalization for worsening HF within one month).

RESULTS

The median (interquartile range) age was 77 years (67-82 years). The mean left ventricular ejection fraction was 40.7 ± 14.6% and 55.8% of HF patients have HF with reduced ejection fraction. The body water composition (intracellular water [ICW], extracellular water [ECW], and total body water [TBW]) showed a statistically significant correlation with body mass index and LV chamber sizes. Furthermore, the ratio of ECW to TBW (ECW/TBW), as an edema index showed a significant correlation with natriuretic peptide levels. Notably, the change of the edema index during hospitalization (ΔECW/TBW) showed a significant correlation with the primary outcome. The area under the curve of ΔECW/TBW for predicting primary outcome was 0.71 (95% confidence interval [CI], 0.61-0.79; P = 0.006). When patients were divided into two groups based on the median value of ΔECW/TBW, the group of high and positive ΔECW/TBW (+0.3% to +5.1%) had a significantly higher risk of the primary outcome (23.2% vs. 8.3%, adjusted odds ratio, 4.8; 95% CI, 1.2-19.3; P = 0.029) than those with a low and negative ΔECW/TBW (-5.3% to +0.2%).

CONCLUSION

BIA is a noninvasive and effective method to evaluate the volume status during the hospitalization of HF patients. The high and positive value of ΔECW/TBW during hospitalization was associated with poor outcomes in patients with HF.

A Current Review of the Uses of Bioelectrical Impedance Analysis and Bioelectrical Impedance Vector Analysis in Acute and Chronic Heart Failure Patients: An Under-valued Resource?

BACKGROUND

There is a need to detect and prevent fluid overload and malnutrition in heart failure. Bioelectrical impedance analysis and bioelectrical impedance vector analysis are medical instruments that can advance heart failure management by generating values of body composition and body water, assisting clinicians to detect fluid and nutritional status. However, there is a lack of evidence to summarise how they have been used among heart failure patients.

METHOD

A systematic search was conducted.

RESULT

Two hundred and four papers were screened. Forty-eight papers were reviewed, and 46 papers were included in this review. The literature shows that bioelectrical impedance analysis and bioelectrical impedance vector analysis were mostly used to assess fluid and nutritional status, together with diagnostic and prognostic values. Contraindication of using BIA and implications for practice are also demonstrated.

CONCLUSION

The findings suggest that bioelectrical impedance vector analysis is superior to bioelectrical impedance analysis when assessing hydration/nutritional status in heart failure. Assessing a patient using bioelectrical impedance analysis /bioelectrical impedance vector analysis, together with natriuretic peptide -heart failure biomarkers, increases the diagnostic accuracy of heart failure. Further studies are required to examine the cost effectiveness of using these instruments in clinical practice.

Real-Time Monitoring Using Multiplexed Multi-Electrode Bioelectrical Impedance Spectroscopy for the Stratification of Vascularized Composite Allografts: A Perspective on Predictive Analytics

Vascularized composite allotransplantation addresses injuries to complex anatomical structures such as the face, hand, and abdominal wall. Prolonged static cold storage of vascularized composite allografts (VCA) incurs damage and imposes transportation limits to their viability and availability. Tissue ischemia, the major clinical indication, is strongly correlated with negative transplantation outcomes. Machine perfusion and normothermia can extend preservation times. This perspective introduces multiplexed multi-electrode bioimpedance spectroscopy (MMBIS), an established bioanalytical method to quantify the interaction of the electrical current with tissue components, capable of measuring tissue edema, as a quantitative, noninvasive, real-time, continuous monitoring technique to provide crucially needed assessment of graft preservation efficacy and viability. MMBIS must be developed, and appropriate models explored to address the highly complex multi-tissue structures and time-temperature changes of VCA. Combined with artificial intelligence (AI), MMBIS can serve to stratify allografts for improvement in transplantation outcomes.

Bioimpedance Indices of Fluid Overload and Cardiorenal Outcomes in Heart Failure and Chronic Kidney Disease: a Systematic Review

BACKGROUND

Bioimpedance-based estimates of fluid overload have been widely studied and systematically reviewed in populations of those undergoing dialysis, but data from populations with heart failure or nondialysis chronic kidney disease (CKD) have not.

METHODS AND RESULTS

We conducted a systematic review of studies using whole-body bioimpedance from populations with heart failure and nondialysis CKD that reported associations with mortality, cardiovascular outcomes and/or CKD progression. We searched MEDLINE, Embase databases and the Cochrane CENTRAL registry from inception to March 14, 2022. We identified 31 eligible studies: 20 heart failure and 11 CKD cohorts, with 2 studies including over 1000 participants. A wide range of various bioimpedance methods were used across the studies (heart failure: 8 parameters; CKD: 6). Studies generally reported positive associations, but between-study differences in bioimpedance methods, fluid overload exposure definitions and modeling approaches precluded meta-analysis. The largest identified study was in nondialysis CKD (Chronic Renal Insufficiency Cohort, 3751 participants), which reported adjusted hazard ratios (95% confidence intervals) for phase angle < 5.59 vs ≥ 6.4 of 2.02 (1.67-2.43) for all-cause mortality; 1.80 (1.46-2.23) for heart failure events; and 1.78 (1.56-2.04) for CKD progression.

CONCLUSIONS

Bioimpedance indices of fluid overload are associated with risk of important cardiorenal outcomes in heart failure and CKD. Facilitation of more widespread use of bioimpedance requires consensus on the optimum device, standardized analytical methods and larger studies, including more detailed characterization of cardiac and renal phenotypes.

Relevance of the perioperative edema index measured by bioelectrical impedance analysis for prediction of cardiovascular disease in living-donor kidney transplantation

OBJECTIVES

Perioperative management of fluid status during kidney transplantation is important, because volume overload can increase the risk of cardiovascular disease in recipients. The edema index calculated by bioelectrical impedance analysis is commonly used to correctly evaluate fluid status. We evaluated the relevance of the edema index for cardiovascular disease in kidney transplant recipients, and searched for predictors of high edema index in the perioperative period during kidney transplantation.

METHODS

A total of 88 recipients were included in this study. The group in which the edema index at discharge was >0.40 was termed as the "high edema index group", and that with ≤0.40 was termed as the "low edema index group". We assessed cardiovascular disease-free survival and cardiovascular disease-specific survival in the two groups by using Cox proportional regression analyses adjusted by inverse probability of treatment weighting analysis. The patients' background and conventional cardiovascular disease risk factors were assessed to estimate predictors for a high edema index.

RESULTS

A high edema index was significantly associated with short cardiovascular disease-free survival after kidney transplantation (hazard ratio 10.01; P < 0.05) in the inverse probability of treatment weighting model. There were no significant differences in the cardiovascular disease-specific survival. In multivariate logistic regression analyses, non-pre-emptive kidney transplantation and dyslipidemia were significant independent predictors of a high edema index (odds ratio 3.59, P < 0.05 and odds ratio 4.05, P < 0.01, respectively).

CONCLUSIONS

A high edema index is associated with the incidence of cardiovascular disease. Overhydration should be especially avoided in recipients with these factors, and their fluid volume should be carefully managed.

Comparison of Lean Mass in Women With and Without Heart Disease

PURPOSE

This proof-of-concept study compared lean mass (LM) between women with heart disease (HD) and without HD.

METHODS

Fifty-six community-dwelling women were pair-matched by age. Heart disease was defined using criteria from the US Behavioral Risk Factor Surveillance System. Body composition was measured using multifrequency bioelectrical impedance analysis. Relative LM was calculated against height (kg/m2) as the lean mass index (LMI). Sarcopenia was defined as an LMI <15.0 kg/m2. Strength was measured with a handgrip dynamometer, arm curl test, and chair stand test.

RESULTS

Those with HD had significantly less absolute (38.2 ± 0.8 vs 43.5 ± 1.0 kg; P < .001) and relative (15.3 ± 0.3 vs 16.2 ± 0.3 kg/m2, P = .015) LM compared with those without HD. Body mass was significantly greater for those without HD (76.1 ± 2.1 vs 68.4 ± 2.1 kg; P = .013) and there were no differences in fat mass. Upper body strength was significantly less and lower body strength was diminished but not significantly different in those with HD compared to those without HD (handgrip: P = .016; arm curl: P < .001; chair stand: P = .066).

CONCLUSIONS

In this group of community-dwelling women, those who reported a diagnosis of HD had significantly less LM than those without HD. Although neither group was classified as sarcopenic, women with HD were at greater risk due to lower relative LM. Based on our findings, during cardiac rehabilitation clinicians should counsel women regarding resistance exercise for maintenance of LM in addition to strength.

Body composition analysis in patients with acute heart failure: the Scale Heart Failure trial

Aims

In this study, we aimed to investigate whether body composition analysis (BCA) derived from bioelectrical impedance vector analysis (BIVA) could be used to monitor the hydration status of patients with acute heart failure (AHF) during intensified diuretic therapy.

Methods and results

This observational, single‐centre study involved a novel, validated eight‐electrode segmental body composition analyser to perform BCA derived from BIVA with an alternating current of 100 μA at frequencies of 5, 7.5, 50, and 75 kHz. The BCA‐derived and BIVA‐derived parameters were estimated and compared with daily body weight measurements in hospitalized patients with AHF. A total of 867 BCA and BIVA assessments were conducted in 142 patients (56.3% men; age 76.8 ± 10.7 years). Daily changes in total body water (TBW) and extracellular water (ECW) were significantly associated with changes in body weight in 62.2% and 89.1% of all measurements, respectively (range, ±1 kg). Repeated measures correlation coefficients between weight loss and TBW loss resulted with rho 0.43, P < 0.01, confidence interval (CI) [0.36, 0.50] and rho 0.71, P > 0.01, CI [0.67, 0.75] for ECW loss. Between the first and last assessments, the mean weight loss was −2.5 kg, compared with the −2.6 L mean TBW loss and −1.7 L mean ECW loss. BIVA revealed an increase in mean Resistance R and mean Reactance X_c across all frequencies, with the subsequent reduction in body fluid (including corresponding body weight) between the first and last assessments.

Conclusions

Body composition analysis derived from BIVA with a focus on ECW is a promising approach to detect changes in hydration status in patients undergoing intensified diuretic therapy. Defining personalized BIVA reference values using bioelectrical impedance devices is a promising approach to monitor hydration status.

Case Report: Non-episodic Angioedema With Eosinophilia in a Young Lactating Woman

Angioedema with eosinophilia is classified into two types: episodic angioedema with eosinophilia (EAE), known as Gleich’s syndrome, and non-episodic angioedema with eosinophilia (NEAE). We present the case of a young lactating woman with non-episodic angioedema. She had no history of parasitic or nonparasitic infections. Physical examination showed striking, non-pitting edema in both lower extremities. Her weight had not changed significantly throughout the course of the illness. She exhibited no other symptoms, and her vital signs were normal. There was no evidence of anemia, hypoalbuminemia, thyroid dysfunction, heart failure, renal failure, or postpartum cardiomyopathy. Based on these findings, we diagnosed her with angioedema with eosinophilia. Given the scarcity of information about this condition, we explored the dynamics between cytokines/chemokines and edema in this patient. We successfully quantified the edema by bioimpedance analysis. In addition, we revealed the involvement of interleukin-5 (IL-5), thymus- and activation-regulated chemokine/C-C motif chemokine ligand-17 (TARC/CCL-17), eotaxin-3/CCL-26, tumor necrosis factor-α (TNF-α), vascular endothelial growth factor (VEGF), monocyte chemotactic protein-4/CCL-13 (MCP-4/CCL-13), eotaxin-1/CCL-11, and regulated on activation, normal T expressed and secreted/CCL-5 (RANTES/CCL-5) in NEAE. Lastly, we elucidated the strong association between these parameters. To the best of our knowledge, this is the first such study of its kind.

Body Composition Changes During Traditional Versus Intensive Cardiac Rehabilitation in Coronary Artery Disease

PURPOSE

Intensive cardiac rehabilitation (CR) was recently approved by Medicare and includes more hours and more focus on nutrition, stress management, and group support than a traditional, exercise-focused CR. The purpose of this study was to compare changes in body composition and cardiovascular (CV) risk factors after intensive versus traditional CR programs in patients with coronary artery disease (CAD).

METHODS

We studied 715 patients with CAD who completed a traditional versus intensive CR program at UCLA Medical Center between 2014 and 2018. Markers of CV health, including body composition using bioelectrical impedance analysis, were assessed pre- and post-program participation.

RESULTS

In both types of CR programs, body mass index, body fat percentage, blood pressure, and cholesterol levels (total cholesterol and low-density lipoprotein cholesterol) were significantly lower post- compared with pre-program. Exercise capacity was increased in both groups. Intensive CR patients had greater reductions in body mass index, body fat percentage, visceral adipose tissue, and diastolic blood pressure. Traditional CR patients demonstrated greater increases in high-density lipoprotein cholesterol and estimated lean mass.

CONCLUSIONS

In patients with CAD, both traditional and intensive CR programs led to improvements in CV risk factors, though the magnitude of the effects of the program differed between the programs. Further studies, including studies analyzing CV outcomes, are needed to help determine optimal CR program choice for CAD patients based on their risk factor and body composition profile.

Should we overcome the resistance to bioelectrical impedance in heart failure?

INTRODUCTION

Heart failure is associated with increased neurohormonal activation that results in changes in body composition including volume overload and the loss of skeletal muscle, body fat, and bone density. Bioelectrical impedance measures body composition based on the conduction of electrical current through body fluids.

AREAS COVERED

The PubMed and Scopus databases were reviewed up to the third week of June 2020. Cross-sectional studies, retrospective observational studies, prospective observational studies, and randomized controlled trials have examined numerous bioelectrical impedance monitoring strategies to guide the diagnosis, prognosis, and treatment of heart failure. These monitoring strategies include intrathoracic impedance, lung impedance, bioelectrical impedance vector analysis, leg bioelectrical impedance, and thoracic bioreactance.

EXPERT COMMENTARY

Based on the current evidence, more studies are needed to validate bioelectrical impedance in heart failure. Lung impedance appears to be useful for guiding heart failure treatment in patients with ST-elevation myocardial infarction and improving outcomes in outpatients with heart failure. Furthermore, bioelectrical impedance has potential as a noninvasive, quantitative heart failure variable for population-based research.

Differences in pharmacological property between combined therapy of the vasopressin V2-receptor antagonist tolvaptan plus furosemide and monotherapy of furosemide in patients with hospitalized heart failure

BACKGROUND

Tolvaptan has been shown to improve congestion in heart failure patients. The purpose of this study was to evaluate the pharmacology and clinical efficacy of combined tolvaptan and furosemide therapy.

METHODS

This study included 40 patients with systemic volume overload who were hospitalized for heart failure. Patients who showed no improvement in the condition after receiving 20 mg intravenous furosemide were included and were randomly selected to receive tolvaptan as an add-on to furosemide or to receive an increased dose of furosemide. We evaluated the bioelectrical impedance analyzer parameters, the parameters of the inferior vena cava using echocardiography, vital signs, body weight, urine output, and laboratory data for 5 days.

RESULTS

In the changes from baseline between intracellular water volume (ICW) and extracellular water volume (ECW) after additional use of tolvaptan or furosemide from Day 1 to Day 5, there were no significant differences observed between ICW and ECW over 5 days in the tolvaptan + furosemide group, although differences were found in the furosemide group from Day 2 onward. Changes in the respiratory collapse of inferior vena cava increased significantly, and systolic blood pressure decreased significantly only in the furosemide group.

CONCLUSIONS

The present study clearly demonstrates that combined therapy with tolvaptan and furosemide removed excess ICW and ECW to an equal extent, while furosemide alone primarily removed ECW, including intravascular water.

A noninvasive method to study the evolution of extracellular fluid volume in mice using time-domain nuclear magnetic resonance

Maintaining water homeostasis is fundamental for cellular function. Many diseases and drugs affect water balance and plasma osmolality. Water homeostasis studies in small animals require the use of invasive or terminal methods that make intracellular fluid volume and extracellular fluid volume (ECF) monitoring over time stressful and time consuming. We examined the feasibility of monitoring mouse ECF by a noninvasive method using time-domain nuclear magnetic resonance (TD-NMR). This technique allows differentiation of protons in a liquid environment (free fluid) from protons in soft tissues containing a majority of either small molecules (lean) or large molecules (fat). Moreover, this apparatus enables rapid, noninvasive, and repeated measurements on the same animal. We assessed the feasibility of coupling TD-NMR analysis to a longitudinal metabolic cage study by monitoring mice daily. We determined the effect of 24-h water deprivation on mouse body parameters and detected a sequential and overlapping decrease in free fluid and lean mass during water deprivation. Finally, we studied the effect of mineralocorticoids that are known to induce a transient increase in ECF but for which no direct measurements have been performed in mice. We showed, for the first time, that mineralocorticoids induced a transient ~15% increase in free fluid in conscious mice. TD-NMR is, therefore, the first method to allow direct measurement of discrete changes in ECF in conscious small animals. This method allows analysis of kinetic changes to stimuli before investigating with terminal methods and will allow further understanding of fluid disorders.

Comparison of Bioelectrical Impedance Analysis Parameters for the Detection of Fluid Overload in the Prediction of Mortality in Patients Admitted at the Emergency Department

BACKGROUND

Fluid overload (FO) in critically ill patients is associated with increased adverse events. This study aims to compare different bioelectrical impedance analysis (BIA) parameters that demonstrate FO and their association with 30-day mortality in critical patients admitted to the emergency department (ED).

METHODS

Five components of the BIA were obtained by multifrequency device-total body water (TBW), extracellular water (ECW), intracellular water (ICW), resistance (R), and reactance (Xc)-to calculate parameters (impedance vectors, impedance ratio, and the ratios of ECW to TBW, ECW to ICW, ECW to body surface area, TBW to height² , ICW to height² , Xc to height, and R to height) that have been used for the detection of FO. A concordance analysis (κ) was performed comparing every parameter with each other. Furthermore, different regression models (Cox regression) were created associating the FO for each parameter with 30-day mortality, adjusted for age, body mass index, sex, Sequential Organ Failure Assessment score, and serum albumin level.

RESULTS

A total of 142 patients were included in the study. Only FO by impedance vector analysis (relative risk [RR] = 6.4; 95% CI, 1.5-27.9; P = .01), impedance ratio (RR = 2.7; 95% CI, 1.1-7.1; P = .04), and R (RR = 2.6; 95% CI, 1.2-5.5; P = .02) increased the probability of 30-day mortality.

CONCLUSIONS

Different parameters that determine FO by BIA were associated with the mortality of patients admitted to the ED, but the impedance vector analysis was superior to any other parameter of the BIA.

Smart Bioimpedance Spectroscopy Device for Body Composition Estimation

The purpose of this work is to describe a first approach to a smart bioimpedance spectroscopy device for its application to the estimation of body composition. The proposed device is capable of carrying out bioimpedance measurements in multiple configurable frequencies, processing the data to obtain the modulus and the bioimpedance phase in each of the frequencies, and transmitting the processed information wirelessly. Another novelty of this work is a new algorithm for the identification of Cole model parameters, which is the basis of body composition estimation through bioimpedance spectroscopy analysis. Against other proposals, the main advantages of the proposed method are its robustness against parasitic effects by employing an extended version of Cole model with phase delay and three dispersions, its simplicity and low computational load. The results obtained in a validation study with respiratory patients show the accuracy and feasibility of the proposed technology for bioimpedance measurements. The precision and validity of the algorithm was also proven in a validation study with peritoneal dialysis patients. The proposed method was the most accurate compared with other existing algorithms. Moreover, in those cases affected by parasitic effects the proposed algorithm provided better approximations to the bioimpedance values than a reference device.

Bioimpedance and New-Onset Heart Failure: A Longitudinal Study of >500 000 Individuals From the General Population

Background

Heart failure constitutes a high burden on patients and society, but although lifetime risk is high, it is difficult to predict without costly or invasive testing. We aimed to establish new risk factors of heart failure, which potentially could enable early diagnosis and preemptive treatment.

Methods and Results

We applied machine learning in the UK Biobank in an agnostic search of risk factors for heart failure in 500 451 individuals, excluding individuals with prior heart failure. Novel factors were then subjected to several in‐depth analyses, including multivariable Cox models of incident heart failure, and assessment of discrimination and calibration. Machine learning confirmed many known and putative risk factors for heart failure and identified several novel candidates. Mean reticulocyte volume appeared as one novel factor and leg bioimpedance another, the latter appearing as the most important new marker. Leg bioimpedance was lower in those who developed heart failure during an up to 9.8‐year follow‐up. When adjusting for known heart failure risk factors, leg bioimpedance was inversely related to heart failure (hazard ratio [95% confidence interval], 0.60 [0.48–0.73] and 0.75 [0.59–0.94], in age‐ and sex‐adjusted and fully adjusted models, respectively, comparing the upper versus lower quartile). A model including leg bioimpedance, age, sex, and self‐reported history of myocardial infarction showed good discrimination for future heart failure hospitalization (Concordance index [C‐index]=0.82) and good calibration.

Conclusions

Leg bioimpedance is inversely associated with heart failure incidence in the general population. A simple model of exclusively noninvasive measures, combining leg bioimpedance with history of myocardial infarction, age, and sex provides accurate predictive capacity.

Body composition, metabolism, sleep, psychological and eating patterns of overtraining syndrome: Results of the EROS study (EROS-PROFILE)

Overtraining syndrome (OTS) is caused by an imbalance between training, nutrition and resting, and leads to decreased performance and fatigue; however, the precise underlying triggers of OTS remain unclear. This study investigated the body composition, metabolism, eating, sleeping patterns and mood states among participants with OTS. Selected participants were divided into OTS-affected athletes (OTS, n = 14), healthy athletes (ATL, n = 25), and healthy non-physically active controls (NCS, n = 12). Compared to ATL, OTS showed decreased sleep quality (p = 0.004); increased duration of work or study (p < 0.001); decreased libido (p = 0.024); decreased calorie (p < 0.001), carbohydrate (p < 0.001) and protein (p < 0.001) intakes; decreased mood states (p < 0.001); decreased basal metabolic rate (p = 0.013) and fat burning (p < 0.001); increased body fat (p = 0.006); decreased muscle mass (p = 0.008); and decreased hydration (p < 0.001). Levels were similar between OTS and NCS, except for worsened fatigue (p < 0.001) and vigour (p = 0.001) in OTS. Reduced calorie intake, worsened sleep, and increased cognitive activity are likely OTS triggers. OTS appears to induce dehydration, increase body fat, decrease libido, and worsen mood.