Body fluid volumes measurements by impedance: A review of bioimpedance spectroscopy (BIS) and bioimpedance analysis (BIA) methods. Med Eng Phys. 2008;30:1257-1269. [PMID: 18676172 DOI: 10.1016/j.medengphy.2008.06.009]

Calculated plasma volume status in hemodialysis patients

BACKGROUND

Plasma volume (PV) calculated from hematocrit and body weight has applications in cardiovascular disease. The current study investigated the validity of the calculated PV for predicting volume overload and its prognostic utility in patients undergoing hemodialysis (HD).

PATIENTS AND METHODS

Fifty-four HD patients were prospectively enrolled, and their actual PV (aPV) and relative PV status (PVS) were calculated. Bioelectrical impedance analysis (BIA) with assessment of and total body water (TBW), intracellular water (ICW), extracellular water (ECW), and overhydration (OH) and routine blood examinations were performed before dialysis. A second cohort of 164 HD patients was retrospectively enrolled to evaluate the relationship between the calculated PVS and the outcome, with an endpoint of all-cause mortality.

RESULTS

aPV was significantly associated with TBW, ICW, ECW, OH, and ECW/TBW (all p < 0.001), and most strongly with ECW (r = 0.83). aPV predicted the extent of volume overload with an AUC of 0.770 (p < 0.001), but PVS did not (AUC = 0.617, p = 0.091). Median follow-up time was 53 months, during the course of which 60 (36.58%) patients died. Values for PVS (12.94 ± 10.87% vs. 7.45 ± 5.90%, p = 0.024) and time-averaged PVS (12.83 ± 11.20 vs. 6.78 ± 6.22%, p < 0.001) were significantly increased in patients who died relative to those who survived. A value of time-averaged PVS >8.72% was significantly associated with an increased incidence of all-cause mortality (HR = 2.48, p = 0.0023).

CONCLUSIONS

aPV was most strongly associated with ECW measured using BIA. HD patients with higher time-averaged PVS had a higher rate of all-cause mortality.

Non-invasive approaches to hydration assessment: a literature review

Traditional hydration assessment methods, while accurate, are often invasive and impractical for routine monitoring. In response, innovative non-invasive techniques such as bioelectrical impedance analysis (BIA), electrodermal activity (EDA), electrocardiogram (ECG) monitoring, and urine color charts have emerged, offering greater comfort and accessibility for patients. These methods use various types of sensors to capture a range of bio-signals, followed by machine learning-based classification or regression methods, providing real-time feedback on hydration status, which is crucial for effective management and prevention of urinary stones. This review explores the principles, applications, and efficacy of these non-invasive techniques, highlighting their potential to transform hydration monitoring in clinical and everyday settings. By facilitating improved patient compliance and enabling proactive hydration management, these approaches align with contemporary trends in personalized healthcare. This article presents a literature review on non-invasive approaches to hydration assessment, focusing on their significance in preventing kidney stone disease and enhancing kidney health.

Fat-free mass predictive equation using multifrequency bioelectrical impedance data in adolescent soccer athletes: development and cross-validation

OBJECTIVES

This study aimed to develop and cross-validate a fat-free mass (FFM) predictive equation using multifrequency bioelectrical impedance analysis (BIA) data in adolescent soccer athletes.

METHODS

Male adolescent soccer athletes (n = 149; 13-19 y old) were randomly sorted using Excel and independently selected for development group (n = 100) or cross-validation group (n = 49). The FFM reference values were determined using dual-energy X-ray absorptiometry. Single-frequency BIA was used to plot tolerance ellipses. Multifrequency-BIA raw data were used as independent variables in regression models. Student's independent t-test was used to compare development and cross-validation groups. Stepwise multiple regression was used to develop the FFM predictive equation. Bland-Altman plots, Lin's concordance correlation coefficient, according to McBride criteria, precision, accuracy, and standard error of estimate (SEE) were calculated to evaluate the concordance and reliability of estimates. Bioelectrical impedance vector analysis was plotted to assess hydration status.

RESULTS

No differences (P > 0.05) were observed between development and validation groups in chronological age, anthropometric data, bioelectrical impedance data, and FFM values obtained using dual-energy X-ray absorptiometry. Bioelectrical impedance vector analysis tolerance showed that all participants presented adequate hydration status compared to the reference population. The new FFM predictive equation developed and validated: FFM (kg) = -7.064 + 0.592 × chronological age (y) + 0.554 × weight (kg) + 0.365 × height²/resistance (cm²/Ω), presented R² = 0.95; SEE = 1.76 kg; concordance correlation coefficient = 0.95, accuracy = 0.98, and strength of concordance = 0.99.

CONCLUSIONS

The present study developed and cross-validated an FFM predictive equation based on multifrequency bioelectrical data providing substantial FFM accuracy for male adolescent soccer athletes.

Clinical impact of postoperative changes in body composition on long-term outcomes in patients with esophageal cancer

BACKGROUND & AIMS

This study aimed to investigate the temporal changes in body composition following esophagectomy in patients with esophageal cancer using bioelectrical impedance analysis and to assess the prognostic implications of these changes.

METHODS

Our study included 528 patients who underwent esophagectomy and preoperative body composition measurements between January 2013 and June 2020. Postoperative body composition was measured in 493 patients at discharge as follows: 184 at 1 month, 144 at 2 months, 143 at 3 months, 103 at 6 months, 58 at 9 months, and 78 at 12 months.

RESULTS

Body weight (BW) continuously decreased until the 6 postoperative months (POMs), reaching -11.5% compared with preoperative levels. Subsequently, almost no change was observed at 12 POMs. Skeletal muscle mass (SMM) decreased until 3 POMs but gradually recovered after 3 POMs. Conversely, body fat mass (BFM) consistently decreased over time post-esophagectomy. The patients were categorized into moderate (>-10%) and severe (≤-10%) groups based on % BW, % SMM, and % BFM losses at 3 POMs. Severe SMM loss at 3 POMs correlated with reduced overall survival (OS) (3-year OS: 85.9% in moderate vs. 75.1% in severe, p = 0.035). BFM loss was associated with reduced recurrence-free survival (3-year RFS: 83.3% in moderate vs. 62.0% in severe, p = 0.011). Multivariate analysis identified pStages Ⅲ and Ⅳ, % SMM loss ≤ -10%, and % BFM loss ≤ -10% as independent factors for worse OS.

CONCLUSION

Post-esophagectomy, distinct temporal changes in BW, SMM, and BFM are observed. Significant reductions in SMM and BFM 3 POMs indicate a poor long-term prognosis.

Reproducibility analysis of bioimpedance-based self-developed live cell assays

Bioimpedance spectrum (BIS) measurements have a great future in in vitro experiments, meeting all the requirements for non-destructive and label-free methods. Nevertheless, a real basic research can provide the necessary milestones to achieve the success of the method. In this paper a self-developed technology-based approach for in vitro assays is proposed. Authors invented a special graphene-based measuring plate in order to assess the high sensitivity and reproducibility of introduced technique. The design of the self-produced BIS plates maximizes the detection capacity of qualitative changes in cell culture and it is robust against physical effects and artifacts. The plates do not influence the viability and proliferation, however the results are robust, stable and reproducible regardless of when and where the experiments are carried out. In this study, physiological saline concentrations, two cancer and stem cell lines were utilized. All the results were statistically tested and confirmed. The findings of the assays show, that the introduced BIS technology is appropriate to be used in vitro experiments with high efficacy. The experimental results demonstrate high correlation values across the replicates, and the model parameters suggested that the characteristic differences among the various cell lines can be detected using appropriate hypothesis tests.

Equivalent Electrical Circuit Approach to Enhance a Transducer for Insulin Bioavailability Assessment

The equivalent electrical circuit approach is explored to improve a bioimpedance-based transducer for measuring the bioavailability of synthetic insulin already presented in previous studies. In particular, the electrical parameter most sensitive to the variation of insulin amount injected was identified. Eggplants were used to emulate human electrical behavior under a quasi-static assumption guaranteed by a very low measurement time compared to the estimated insulin absorption time. Measurements were conducted with the EVAL-AD5940BIOZ by applying a sinusoidal voltage signal with an amplitude of 100 mV and acquiring impedance spectra in the range [1-100] kHz. 14 units of insulin were gradually administered using a Lilly's Insulin Pen having a 0.4 cm long needle. Modified Hayden's model was adopted as a reference circuit and the electrical component modeling the extracellular fluids was found to be the most insulin-sensitive parameter. The trnasducer achieves a state-of-the-art sensitivity of 225.90 ml1. An improvement of 223 % in sensitivity, 44 % in deterministic error, 7 % in nonlinearity, and 42 % in reproducibility was achieved compared to previous experimental studies. The clinical impact of the transducer was evaluated by projecting its impact on a Smart Insulin Pen for real-time measurement of insulin bioavailability. The wide gain in sensitivity of the bioimpedance-based transducer results in a significant reduction of the uncertainty of the Smart Insulin Pen. Considering the same improvement in in-vivo applications, the uncertainty of the Smart Insulin Pen is decreased from [Formula: see text]l to [Formula: see text]l.Clinical and Translational Impact Statement: A Smart Insulin Pen based on impedance spectroscopy and equivalent electrical circuit approach could be an effective solution for the non-invasive and real-time measurement of synthetic insulin uptake after subcutaneous administration.

Evaluation of body shape as a human body composition assessment in isolated conditions and remote environments

Individuals in isolated and extreme environments can experience debilitating side-effects including significant decreases in fat-free mass (FFM) from disuse and inadequate nutrition. The objective of this study was to determine the strengths and weaknesses of three-dimensional optical (3DO) imaging for monitoring body composition in either simulated or actual remote environments. Thirty healthy adults (ASTRO, male = 15) and twenty-two Antarctic Expeditioners (ABCS, male = 18) were assessed for body composition. ASTRO participants completed duplicate 3DO scans while standing and inverted by gravity boots plus a single dual-energy X-ray absorptiometry (DXA) scan. The inverted scans were an analog for fluid redistribution from gravity changes. An existing body composition model was used to estimate fat mass (FM) and FFM from 3DO meshes. 3DO body composition estimates were compared to DXA with linear regression and reported with the coefficient of determination (R2) and root mean square error (RMSE). ABCS participants received only duplicate 3DO scans on a monthly basis. Standing ASTRO meshes achieved an R2 of 0.76 and 0.97 with an RMSE of 2.62 and 2.04 kg for FM and FFM, while inverted meshes achieved an R2 of 0.52 and 0.93 with an RMSE of 2.84 and 3.23 kg for FM and FFM, respectively, compared to DXA. For the ABCS arm, mean weight, FM, and FFM changes were -0.47, 0.06, and -0.54 kg, respectively. Simulated fluid redistribution decreased the accuracy of estimated body composition values from 3DO scans. However, FFM stayed robust. 3DO imaging showed good absolute accuracy for body composition assessment in isolated and remote environments.

Different Interdialytic Intervals and Cardiorespiratory Fitness in Patients Undergoing Hemodialysis

Key Points

This is the first study exploring differences in cardiorespiratory fitness assessed with cardiopulmonary exercise testing between the 2-day and the 3-day interdialytic interval. The 3-day interdialytic interval was associated with further impaired cardiorespiratory fitness. This effect was predominantly driven by excess fluid accumulation during the extra interdialytic day.

Background

Long interdialytic interval in thrice-weekly hemodialysis is associated with excess cardiovascular and all-cause mortality risk. Impaired cardiorespiratory fitness is a strong predictor of mortality in hemodialysis. This study investigated differences in cardiorespiratory fitness assessed with cardiopulmonary exercise testing (CPET) between the end of the 2-day and the 3-day interdialytic interval.

Methods

A total of 28 hemodialysis patients, randomized in two different sequences of evaluation, underwent CPET and spirometry examination at the end of the 2-day and the 3-day intervals. The primary outcome was the difference in oxygen uptake at peak exercise (VO2peak [ml/kg per minute]) assessed with CPET. Volume status was assessed with interdialytic weight gain, lung ultrasound, bioimpedance spectroscopy, and inferior vena cava measurements. A total of 14 age-matched and sex-matched controls were also evaluated. Comparisons of changes in parameters of interest were performed with paired or independent t -tests or relevant nonparametric tests, as appropriate. Bivariate correlation analyses and generalized linear mixed models were used to examine associations between changes in CPET parameters and volume indices.

Results

Hemodialysis patients at the end of both 2-day and 3-day intervals presented lower values in all major CPET parameters than controls. VO2peak (ml/kg per minute) was significantly higher at the end of the 2-day than the 3-day interval (15.2±4.2 versus 13.6±2.8; P < 0.001); the results were similar for VO2peak (ml/min) (1188±257 versus 1074±224; P < 0.001) and VO2peak (% predicted) (58.9±9.2 versus 52.3±8.6; P < 0.001). Numerical but no statistically significant differences were detected in VO2 anaerobic threshold (ml/kg per minute) and VO2 anaerobic threshold (ml/min) between the two time points. Maximal work load (90.1±23.2 versus 79.3±25.1; P < 0.001), exercise duration, heart rate at peak exercise, and oxygen pulse also showed lower values at the end of the 3-day interval. Forced expiratory volume in 1-second levels were similar between the two evaluations. Generalized linear mixed model analysis, including interdialytic weight gain as random covariate, attenuated the observed differences in VO2peak (ml/kg per minute). Changes in bioimpedance spectroscopy–derived overhydration indexes were moderately correlated with changes of VO2peak (ml/kg per minute).

Conclusions

The 3-day interval was associated with further impairment of VO2 at peak exercise. This effect was predominantly driven by excess fluid accumulation during the extra interdialytic day.

Volume overload is a major characteristic in primary aldosteronism: a 3-year follow-up study

OBJECTIVES

We examined haemodynamics, focusing on volume balance and forward and backward wave amplitudes, before and after 2.8 years of targeted treatment of primary aldosteronism. Patients with essential hypertension and normotensive individuals were examined for comparison ( n  = 40 in each group).

METHODS

Recordings were performed using radial artery pulse wave analysis and whole-body impedance cardiography. Unilateral aldosteronism was treated with adrenalectomy ( n  = 20), bilateral aldosteronism with spironolactone-based medication ( n  = 20), and essential hypertension with standard antihypertensive agents.

RESULTS

Aortic SBP and DBP, forward and backward wave amplitudes, and systemic vascular resistance were equally elevated in primary aldosteronism and essential hypertension. All these haemodynamic variables were similarly reduced by the treatments. Primary aldosteronism presented with 1 litre (∼10%) extracellular water excess ( P  < 0.001) versus the other groups, and this excess was normalized by treatment. Initial pulse wave velocity (PWV) was similarly increased in primary aldosteronism and essential hypertension, but final values remained higher in primary aldosteronism ( P  < 0.001). In regression analyses, significant explanatory factors for treatment-induced forward wave amplitude reduction were decreased systemic vascular resistance ( β  = 0.380) and reduced extracellular water volume ( β  = 0.183). Explanatory factors for backward wave amplitude reduction were changes in forward wave amplitude ( β  = 0.599), heart rate ( β  = -0.427), and PWV ( β  = 0.252).

CONCLUSION

Compared with essential hypertension, the principal haemodynamic difference in primary aldosteronism was higher volume load. Volume excess elevated forward wave amplitude, which was subsequently reduced by targeted treatment of primary aldosteronism, along with normalization of volume load. We propose that incorporating extracellular water evaluation alongside routine diagnostics could enhance the identification and diagnosis of primary aldosteronism.

Local vaginal bioelectrical impedance can predict preterm delivery in mice

Preterm birth is a serious pregnancy complication that affects neonatal mortality, morbidity, and long-term neurological prognosis. Predicting spontaneous preterm delivery (PTD) is important for its management. While excluding the risk of PTD is important, identifying women at high risk of PTD is imperative for medical intervention. Currently used PTD prediction parameters in clinical practice have shown high negative predictive values, but low positive predictive values. We focused on sulfated and sialylated glycocalyx changes in the uterus and vagina prior to the onset of parturition and explored the potential of electrophysiological detection of these changes as a PTD prediction parameter with a high positive predictive value. In vivo local vaginal bioelectrical impedance (VZ) was measured using two different mouse PTD models. PTD was induced in ICR mice through the subcutaneous injection of mifepristone or local intrauterine injection of lipopolysaccharide (LPS). The PTD rates were 100% and 60% post-administration of mifepristone (16-20 h, n = 4) and LPS (12-24 h, n = 20), respectively. The local VZ values (15 and 10 h after mifepristone or LPS treatment, respectively) were significantly lower in the PTD group than in the non-PTD group. Receiver operator characteristic (ROC) curve analysis of VZ at 125 kHz as a predictor of PTD showed an area under the ROC curve of 1.00 and 0.77 and positive predictive values of 1.00 and 0.86, for the mifepristone and LPS models, respectively, suggesting that local VZ value can predict PTD. Histological examination of the LPS-treated model 6 h post-treatment revealed increased expression of sulfomucins and/or sulfated proteoglycans and sialomucins in the cervical epithelium, cervical stroma and vaginal stroma. In conclusion, local VZ values can determine sulfated and sialylated glycocalyx alterations within the uterus and vagina and might be a useful PTD prediction parameter.

Integrating classification and regression learners with bioimpedance methods for estimating weight status in infants and juveniles from the southern Cuba region

OBJECTIVE

The search for other indicators to assess the weight and nutritional status of individuals is important as it may provide more accurate information and assist in personalized medicine. This work is aimed to develop a machine learning predictions of weigh status derived from bioimpedance measurements and other physical parameters of healthy younger volunteers from Southern Cuba Region.

METHODS

A pilot random study at the Pediatrics Hospital was conducted. The volunteers were selected between 2002 and 2008, ranging in age between 2 and 18 years old. In total, 776 female and male volunteers are studied. Along the age and sex in the cohort, volunteers with class I obesity, overweight, underweight and with normal weight are considered. The bioimpedance parameters are obtained by measuring standard tetrapolar whole-body configuration. The bioimpedance analyser is used, collecting fundamental bioelectrical and other parameters of interest. A classification model are performed, followed by a prediction of the body mass index.

RESULTS

The results derived from the classification leaner reveal that the size, body density, phase angle, body mass index, fat-free mass, total body water volume according to Kotler, body surface area, extracellular water according to Kotler and sex largely govern the weight status of this population. In particular, the regression model shows that other bioparameters derived from impedance measurements can be associated with weight status estimation with high accuracy.

CONCLUSION

The classification and regression predictive models developed in this work are of the great importance to assist the diagnosis of weigh status with high accuracy. These models can be used for prompt weight status evaluation of younger individuals at the Pediatrics Hospital in Santiago de Cuba, Cuba.

The role of various physiological and bioelectrical parameters for estimating the weight status in infants and juveniles cohort from the Southern Cuba region: a machine learning study

OBJECTIVE

The search for other indicators to assess the weight status of individuals is important as it may provide more accurate information and assist in personalized medicine.This work is aimed to develop a machine learning predictions of weigh status derived from bioimpedance measurements and other physical parameters of healthy infant juvenile cohort from the Southern Cuba Region, Santiago de Cuba.

METHODS

The volunteers were selected between 2002 and 2008, ranging in age between 2 and 18 years old. In total, 393 female and male infant and juvenile individuals are studied. The bioimpedance parameters are obtained by measuring standard tetrapolar whole-body configuration. A classification model are performed, followed by a prediction of other bioparameters influencing the weight status.

RESULTS

The results obtained from the classification model indicate that fat-free mass, reactance, and corrected resistance primarily influence the weight status of the studied population. Specifically, the regression model demonstrates that other bioparameters derived from impedance measurements can be highly accurate in estimating weight status.

CONCLUSION

The classification and regression predictive models developed in this work are of the great importance for accessing to the weigh status with high accuracy of younger individuals at the Oncological Hospital in Santiago de Cuba, Cuba.

Fluids and body composition during anesthesia in children and adolescents: A pilot study

The purpose of this study is to evaluate the intracellular and extracellular volume before and after anesthesia in order to ascertain their variations and determine the potential utility of this information in optimizing intraoperative fluid administration practices. A bioimpedance spectroscopy device (body composition monitor, BCM) was used to measure total body fluid volume, extracellular volume, and intracellular volume. BCM measurements were performed before and after general anesthesia in unselected healthy children and adolescents visiting the Pediatric Institute of Southern Switzerland for low-risk surgical procedures hydrated with an isotonic solution. In 100 children and adolescents aged 7.0 (4.8-11) years (median and interquartile range), the average total body water increased perioperatively with a delta value of 182 (0-383) mL/m2 from pre- to postoperatively, as well as the extracellular water content, which had a similar increase with a delta value of 169 (19-307) mL/m2. The changes in total body water and extracellular water content significantly correlated with the amount of fluids administered. The intracellular water content did not significantly change.   Conclusion: Intraoperative administration of isotonic solutions results in a significant fluid accumulation in low-risk schoolchildren during general anesthesia. The results suggest that children without major health problems undergoing short procedures do not need any perioperative intravenous fluid therapy, because they are allowed to take clear fluids up to 1 h prior anesthesia. In future studies, the use of BCM measurements has the potential to be valuable in guiding intraoperative fluid therapy. What is Known: • Most children who undergo common surgical interventions or investigations requiring anesthesia are nowadays hydrated at a rate of 1700 mL/m2/day with an isotonic solution. • The use bioimpedance spectroscopy for the assessment of fluid status in healthy children has already been successfully validated. • The bioimpedance spectroscopy is already currently widely used in various nephrological settings to calculate fluid overload and determine patient's optimal fluid status. What is New: • Routine intraoperative fluid administration results in a significant fluid accumulation during general anesthesia in low-risk surgical procedures. • This observation might be relevant for children and adolescents with conditions predisposing to fluid retention. • In future studies, the use of BCM measurements has the potential to be valuable in guiding intraoperative fluid therapy.

Water intake, baseline biopsy, and graft function after living donor kidney transplantation

Increased water intake is recommended for kidney transplant recipients; however, its efficacy remains controversial. We hypothesized that pre-existing histological findings of the allograft might modulate the impact of water intake. We retrospectively analyzed 167 adults with living-donor kidney transplants (April 2011-May 2020; median observation period, 77 months) whose baseline biopsy data were available. We compared the chronic-change group (n = 38) with the control group (n = 129) to assess the impact of self-reported daily water intake on the estimated glomerular filtration rate (eGFR). The range distribution of water intake was as follows: - 1000 ml (n = 4), 1000-1500 ml (n = 23), 1500-2000 ml (n = 64), 2000-2500 ml (n = 57), 2500-3000 ml (n = 16), and 3000 - ml (n = 3). Donor age was significantly higher in the chronic-change group. In the control group, the ΔeGFR/year increase was correlated with water intake. However, the increase in the water intake of the chronic-change group significantly decreased ΔeGFR/year (1000-1500 ml: + 1.95 ml/min/1.73 m2 and > 2000 ml: - 1.92 ml/min/1.73 m2, p = 0.014). This study suggested a potential influence of increased water intake on recipients with marginal grafts in living donor kidney transplantation.

Edema Index Predicts Mortality in Patients with Chronic Heart Failure: A Prospective, Observational Study

Introduction

Chronic fluid accumulation or congestion is considered an important pathophysiologic mechanism in heart failure, leading to cardinal symptoms such as dyspnea, pulmonary congestion, and pitting edema. Edema index (EI) recently emerged as a surrogate for extracellular volume status and has been proven to be able to reflect one's congestion status. In this study, we aimed to evaluate the prognostic value of EI in patients with chronic heart failure (CHF).

Methods

A total of 401 consecutive patients with CHF between August 2019 and October 2021 were prospectively enrolled. EI was obtained by InBody S10. The primary endpoint was long-term all-cause and cardiovascular mortality.

Results

Patients with high EI (>0.397) tended to be older, presented with atrial fibrillation, have higher N-terminal brain natriuretic peptide, and have higher creatinine (all p < 0.05). During a median follow-up of 1200 days, the all-cause and cardiovascular mortality rate was significantly higher in the high EI group compared to the low EI group (all-cause mortality rate 43.8% vs. 30.3%, p < 0.001, and cardiovascular mortality rate 17.5% vs. 13.0%, p < 0.001, respectively). In the multivariate Cox proportional hazard analysis, EI > 0.397 was an independent predictor for both all-cause mortality (HR 1.959; 95% CI 1.304, 2.944; p = 0.001) and cardiovascular mortality (HR 2.051; 95% CI 1.276, 3.296; p = 0.003).

Conclusions

Admission EI could be used as a marker for predicting long-term mortality in patients with CHF, and higher EI was associated with an increased risk of all-cause and cardiovascular mortality. Furthermore, EI-guided management could be a promising therapy in patients with CHF.

Effect of body fat mass loss on prognosis of radical resection for pancreatic ductal adenocarcinoma based on bioelectrical impedance analysis

BACKGROUND

Few reports have performed a prognostic analysis based on bioelectrical impedance analysis in patients with radical resection of pancreatic ductal adenocarcinoma (PDAC), and its usefulness in prognostic analysis remains unclear. This study aimed to evaluate body composition changes in patients undergoing radical resection for PDAC and analyze its impact on prognosis.

METHODS

The medical records of radical resection for patients with PDAC were retrospectively reviewed, and the parameters of body composition, including body weight, skeletal muscle mass, body fat mass (BFM), and extracellular water-total body water ratio, from preoperatively to 12 months postoperatively, for each surgical procedure were measured based on direct segmental multifrequency bioelectrical impedance analysis with an InBody 770 (InBody Inc., Tokyo, Japan) device. The clinicopathological and prognostic factors were analyzed.

RESULTS

Among 79 patients who underwent radical resection for PDAC, 36 (46%), 7 (8%), and 36 (46%) underwent pancreatoduodenectomy, total pancreatectomy, and distal pancreatectomy, respectively. The multivariate overall survival analysis demonstrated that BFM loss percentage at 1 month postoperatively ≧14% (p = 0.021), lymph node metastasis (p = 0.014), and non-adjuvant chemotherapy (p <  0.001) were independent poor prognostic factors. Multivariate analysis revealed that preoperative BFM < 12 kg and preoperative albumin < 3.5 g/dL were independently associated with BFM loss percentage at 1 month postoperatively ≧14% (p = 0.021 and p = 0.047, respectively).

CONCLUSIONS

Loss of BFM in the early postoperative period may have a poor prognosis in radical resection of PDAC.

Body composition analysis via spatially resolved NIR spectroscopy with multifrequency bioimpedance precision

Near-infrared spectroscopy (NIRS) is often criticized due to its insufficient accuracy in determining body composition compared to the gold standard methods. In this work, we show that the use of multiple source-detector distances, as well as the simultaneous use of physiological and optical features, can significantly improve the accuracy of determination of fat and lean mass percentage in the human body using NIR spectroscopy. The study performed on the n = 292 cohort revealed the mean absolute errors of 3.5% for fat content and 3.3% for soft lean mass percentage prediction (r = 0.93) using the multifrequency bioimpedance analysis (BIA) as a reference. Hence, NIRS can serve as an independent reliable method for body composition analysis with precision close to that of advanced multifrequency BIA.

Which sub-compartments of fat mass and fat-free mass are related to blood viscosity factors?

The size of body compartments is a determinant of several factors of blood viscosity. Red cell aggregation is proportional to fat mass while hematocrit is proportional to both fat-free mass and abdominal adiposity, but which parts of these body components are involved in this relationship is not known. Segmental bioelectrical impedance analysis (sBIA) provides a possibility to delineate the relationships more precisely between various subdivisions of the body and blood viscosity factors, going farther than preceding studies using non segmental BIA. In this study we investigated in 38 subjects undergoing a standardized breakfast test with mathematical modelling of glucose homeostasis and a segmental bioelectrical impedance analysis (sBIA) the relationships between the various compartments of the body and viscosity factors. Blood and plasma viscosity were measured with the Anton Paar rheometer and analyzed with Quemada's model. The parameters better correlated to hematocrit are fat free mass (r = 0.562) and its two components muscle mass (r = 0.516) and non-muscular fat-free mass (r = 0.452), and also trunk fat mass (r = 0.383) and waist-to hip ratio (r = 0.394). Red cell aggregation measurements were correlated with both truncal and appendicular fat mass (r ranging between 0.603 and 0.728). Weaker correlations of M and M1 are found with waist circumference and hip circumference. This study shows that the correlation between lean mass and hematocrit involves both muscle and non-muscle moieties of lean mass, and that both central and appendicular fat are determinants of red cell aggregation.

Pharmacodynamics Research on Danggui-Shaoyao-San through Body Fluid Indexes of Spleen Deficiency-water Dampness Rats using Bio-impedance Technology

BACKGROUND

Spleen deficiency-water dampness symptom is closely related to body fluid-mediated organism metabolism and circulation. However, previous clinical evaluation of spleen deficiency-water dampness model was based only on body weight, D-xylose excretion rate, serum gastrin content, etc. Therefore, we established a large sample of normal rats and model rats experiment to verify the scientific nature of bio-impedance measuring body fluid indexes for evaluation of the modeling state. Pharmacodynamics research on Danggui-Shaoyao- San (DSS) was conducted through body fluid index changes of rats using bio-impedance technology.

METHODS

A spleen deficiency-water dampness symptom rat model was established through an inappropriate diet combined with excess fatigue. Experimental rats were divided into a normal control group, a model control group, a positive drug control group (hydrochlorothiazide), a blood-activating group, a water-disinhibiting group, and a DSS group. Total Body Water/Body Weight (TBW%), extracellular fluid/total body water content (ECF%), intracellular fluid/total body water content (ICF%), extracellular fluid/intracellular fluid (ECF/ICF), fat mass/body weight (FM%), fat-free mass/body weight (FFM%), and fat mass/fat-free mass (FM/FFM) of 150 rats were detected by a Bio-Imp Vet Body analyzer.

RESULTS

The TBW% of the model control group increased significantly, and the FM/FFM was significantly reduced compared with the normal group (P < 0.05) (P < 0.01), showing symptoms of spleen deficiency and diarrhea; the TBW% of the blood-activating group, and the waterdisinhibiting group decreased significantly, and the FM/FFM increased significantly (P < 0.05) (P < 0.01). The TBW% and FM/FFM in the water-disinhibiting group had returned to nearnormal values compared with the model control group. The blood-activating and waterdisinhibiting split prescriptions in DSS are both effective in treating spleen deficiency-water dampness rats. Comparatively, the fluid-regulating effect of split prescriptions in DSS was even stronger than that of DSS as shown in the present study.

CONCLUSIONS

These findings suggest that using bio-impedance technology to measure body fluid indexes can pave a road for further exploring the molecular mechanism of the reason why the blood-activating and disinhibit-water split prescriptions in DSS are both effective in treating spleen deficiency-water dampness rats.

Mid-Activity and At-Home Wearable Bioimpedance Elucidates an Interpretable Digital Biomarker of Muscle Fatigue

OBJECTIVE

Muscle health and decreased muscle performance (fatigue) quantification has proven to be an invaluable tool for both athletic performance assessment and injury prevention. However, existing methods estimating muscle fatigue are infeasible for everyday use. Wearable technologies are feasible for everyday use and can enable discovery of digital biomarkers of muscle fatigue. Unfortunately, the current state-of-the-art wearable systems for muscle fatigue tracking suffer from either low specificity or poor usability.

METHODS

We propose using dual-frequency bioimpedance analysis (DFBIA) to non-invasively assess intramuscular fluid dynamics and thereby muscle fatigue. A wearable DFBIA system was developed to measure leg muscle fatigue of 11 individuals during a 13-day protocol consisting of exercise and unsupervised at-home portions.

RESULTS

We derived a digital biomarker of muscle fatigue, fatigue score, from the DFBIA signals that was able to estimate the percent reduction in muscle force during exercise with repeated-measures Pearson's r = 0.90 and mean absolute error (MAE) of 3.6%. This fatigue score also estimated delayed onset muscle soreness with repeated-measures Pearson's r = 0.83 and MAE = 0.83. Using at-home data, DFBIA was strongly associated with absolute muscle force of participants (n = 198, p < 0.001).

CONCLUSION

These results demonstrate the utility of wearable DFBIA for non-invasively estimating muscle force and pain through the changes in intramuscular fluid dynamics.

SIGNIFICANCE

The presented approach may inform development of future wearable systems for quantifying muscle health and provide a novel framework for athletic performance optimization and injury prevention.

Effect of bioelectrical impedance technology on the prognosis of dialysis patients: a meta-analysis of randomized controlled trials

Managing patient 'dry weight' according to clinical standards has deficiencies. Research has focused on the effectiveness of using bioelectrical impedance technology for fluid management in dialysis patients. Whether bioelectrical impedance monitoring can improve dialysis patients prognoses remain controversial. We performed a meta-analysis of randomized controlled trials to determine whether bioelectrical impedance was effective in improving dialysis patients prognoses. The primary outcome was all-cause mortality (13.6 ± 9.1 months). Secondary outcomes were left ventricular mass index (LVMI), arterial stiffness assessed using Pulse Wave Velocity (PWV), and N-terminal brain natriuretic peptide precursor (NT-proBNP). Of 4,641 citations retrieved, we identified 15 eligible trials involving 2763 patients divided into experimental (n = 1386) and control (n = 1377) groups. In 14 studies with mortality data, the meta-analysis showed that bioelectrical impedance intervention reduced the risk of all-cause mortality (rate ratios [RR]: 0.71; 95% confidence interval [CI]: 0.51, 0.99; p = .05; I2 = 1%). Subgroup analysis of patients on hemodialysis (RR: 0.72; 95% CI: 0.42, 1.22; p = .22) and peritoneal dialysis (RR: 0.62; 95% CI: 0.35, 1.07; p = .08) showed no significant mortality difference between intervention and control groups. It reduced the risk of all-cause mortality in the Asian population (RR: 0.52; p = .02), and reduced NT-proBNP (mean difference [MD]: -1495.73; p = 0.002; I²=0%) and PWV (MD: -1.55; p = .01; I²=89%). Bioelectrical impedance intervention reduced the LVMI in hemodialysis patients (MD: -12.69; p < .0001; I²=0%). Our analysis shows that in dialysis patients, bioelectrical impedance technology intervention could reduce, but not eliminate, the risk of all-cause mortality. Overall, this technology can improve the prognosis of dialysis patients.

Novel Noninvasive Paraclinical Study Method for Investigation of Liver Diseases

Based on a prior university patent, the authors developed a novel type of bioimpedance-based test method to noninvasively detect nonalcoholic fatty liver disease (NAFLD). The development of a new potential NAFLD diagnostic procedure may help to understand the underlying mechanisms between NAFLD and severe liver diseases with a painless and easy-to-use paraclinical examination method, including the additional function to detect even the earlier stages of liver disease. The aim of this study is to present new results and the experiences gathered in relation to NAFLD progress during animal model and human clinical trials.

Cross-sectional study of characteristics of body composition of 24,845 children and adolescents aged 3-17 years in Suzhou

BACKGROUND

We aimed to analyze the characteristics of the body composition of children and adolescents aged 3-17 in Suzhou, China.

METHODS

A cross-sectional study between January 2020 and June 2022 using bioelectrical impedance was conducted to determine the fat mass (FM), fat-free mass (FFM), skeletal muscle mass, and protein and mineral contents of 24,845 children aged 3-17 who attended the Department of Child and Adolescent Healthcare, Children's Hospital of Soochow University, China. Measurement data was presented in tables as mean ± SD, and groups were compared using the independent samples t-test.

RESULTS

FM and fat-free mass increased with age in both boys and girls. The fat-free mass of girls aged 14-15 decreased after reaching a peak, and that of boys in the same age group was higher than that of the girls (p < 0.05). There were no significant differences in FM between boys and girls younger than 9- and 10-years old. The percentage body fat (PBF) and FM index of girls increased rapidly between 11 and 15 years of age (p < 0.05), and those of boys aged 11-14 were significantly lower (p < 0.05), suggesting that the increase in body mass index (BMI) was mainly contributed by muscle mass (MM) in boys.

CONCLUSIONS

The body composition of children and adolescents varies according to their age and sex. A misdiagnosis of obesity made on the basis of BMI alone can be avoided if BMI is used in combination with FM index, percentage body fat, and other indexes.

Physical exercise alleviates oxidative stress in brown adipose tissue and causes changes in body composition and nutritional behavior in rats with polycystic ovary syndrome

AIM

Polycystic Ovary Syndrome (PCOS) is a very common endocrine disorder in women. We investigate the effect of physical exercise on body composition, nutritional parameters, and oxidative stress in rats with PCOS.

METHODS

Female rats were into three groups: Control, PCOS, and PCOS + Exercise. PCOS was induced by letrozole (1 mg/kg via p.o.) for 21 days consecutively. Physical exercise was swimming, for 21 consecutive days, 1 h/day with 5 % load. In all groups, we assessed the nutritional and murinometric parameters, body composition, thermography, and oxidative stress in brown adipose tissue (BAT) and peri-ovarian adipose tissue (POAT).

KEY FINDINGS

In PCOS we observed an increase (P < 0.05) in body weight vs. the Control group. But, the PCOS + Exercise group prevent this weight gain (P < 0.05). The temperature in BAT, decrease (P < 0.05) in the PCOS group vs. Control group. PCOS + Exercise prevented this reduction (P < 0.05) in BAT temperature vs. PCOS groups. We observed decreases (P < 0.05) in Lee Index and BMI in POS + Exercise vs. PCOS group. In PCOS rats, we observed an increase (P < 0.05) in murinometric (SRWG, EI, and FE) and body composition parameters (TWB, ECF, ICF, and FFM) vs. the Control group. The PCOS + Exercise prevents (P < 0.05) these changes in all groups, compared with PCOS. Regarding the BAT, we observe an increase (P < 0.05) in MPO and MDA levels in the PCOS vs. Control group. PCOS + Exercise prevents (P < 0.05) these increases vs. the PCOS group.

SIGNIFICANCE

PCOS modifies body composition, and nutritional parameters, and induces changes in oxidative stress in BAT. Physical exercise prevented these alterations.

Topical Drug Delivery in the Treatment of Skin Wounds and Ocular Trauma Using the Platform Wound Device

Topical treatment of injuries such as skin wounds and ocular trauma is the favored route of administration. Local drug delivery systems can be applied directly to the injured area, and their properties for releasing therapeutics can be tailored. Topical treatment also reduces the risk of adverse systemic effects while providing very high therapeutic concentrations at the target site. This review article highlights the Platform Wound Device (PWD) (Applied Tissue Technologies LLC, Hingham, MA, USA) for topical drug delivery in the treatment of skin wounds and eye injuries. The PWD is a unique, single-component, impermeable, polyurethane dressing that can be applied immediately after injury to provide a protective dressing and a tool for precise topical delivery of drugs such as analgesics and antibiotics. The use of the PWD as a topical drug delivery platform has been extensively validated in the treatment of skin and eye injuries. The purpose of this article is to summarize the findings from these preclinical and clinical studies.

Albuminuria-lowering effect of dapagliflozin, exenatide, and their combination in patients with type 2 diabetes: A randomized cross-over clinical study

AIM

To evaluate the albuminuria-lowering effect of dapagliflozin, exenatide, and the combination of dapagliflozin and exenatide in patients with type 2 diabetes and microalbuminuria or macroalbuminuria.

METHODS

Participants with type 2 diabetes, an estimated glomerular filtration rate (eGFR) of more than 30 ml/min/1.73m² and an urinary albumin: creatinine ratio (UACR) of more than 3.5 mg/mmol and 100 mg/mmol or less completed three 6-week treatment periods, during which dapagliflozin 10 mg/d, exenatide 2 mg/wk and both drugs combined were given in random order. The primary outcome was the percentage change in UACR. Secondary outcomes included blood pressure, HbA1c, body weight, extracellular volume, fractional lithium excretion and renal haemodynamic variables as determined by magnetic resonance imaging.

RESULTS

We enrolled 20 patients, who completed 53 treatment periods in total. Mean percentage change in UACR from baseline was -21.9% (95% CI: -34.8% to -6.4%) during dapagliflozin versus -7.7% (95% CI: -23.5% to 11.2%) during exenatide and -26.0% (95% CI: -38.4% to -11.0%) during dapagliflozin-exenatide treatment. No correlation was observed in albuminuria responses between the different treatments. Numerically greater reductions in systolic blood pressure, body weight and eGFR were observed during dapagliflozin-exenatide treatment compared with dapagliflozin or exenatide alone. Renal blood flow and effective renal plasma flow (ERPF) did not significantly change with either treatment regimen. However, all but four and two patients in the dapagliflozin and dapagliflozin-exenatide groups, respectively, showed reductions in ERPF. The filtration fraction did not change during treatment with dapagliflozin or exenatide, and decreased during dapagliflozin-exenatide treatment (-1.6% [95% CI: -3.2% to -0.01%]; P = .048).

CONCLUSIONS

In participants with type 2 diabetes and albuminuria, treatment with dapagliflozin, exenatide and dapagliflozin-exenatide reduced albuminuria, with a numerically larger reduction in the combined dapagliflozin-exenatide treatment group.

Perioperative trends in neck and leg fluid volume in surgical patients: a prospective observational proof-of-concept study

PURPOSE

The severity of obstructive sleep apnea (OSA) may increase postoperatively. The changes in segmental fluid volume, especially neck fluid volume, may be related to increasing airway collapsibility and thus worsening of OSA in the postoperative period. Our objective was to evaluate the feasibility of performing bioelectrical impedance analysis (BIA) and to describe the trend and predictors of changes in segmental fluid volumes in patients receiving general anesthesia for noncardiac surgery.

METHODS

We conducted a prospective observational proof-of-concept cohort study of adult patients undergoing elective inpatient noncardiac surgery. Patients underwent a portable sleep study before surgery, and segmental fluid volumes (neck fluid volume [NFV], NFV phase angle, and leg fluid volume [LFV]) were measured using BIA at set time points: preoperative period (preop), in the postanesthesia care unit (PACU), the night following surgery at 10 pm (N 0), and the following day at 10 am (POD 1). Linear regression models were constructed to evaluate for significant predictors of overall segmental fluid changes. The variables included in the models were sex, preoperative apnea-hypopnea index (AHI), fluid balance, body mass index (BMI), cumulative opioids, and the timepoint of measurement.

RESULTS

Thirty-five adult patients (20/35 females, 57%) were included. For the feasibility outcome, measure of recruitment was 50/66 (76%) and two measures of protocol adherence were fluid measurements (34/39, 87%) and preoperative sleep study (35/39, 90%). There was a significant increase in NFV from preop to N 0 and in LFV from preop to PACU. Neck fluid volume also increased from PACU to N 0 and PACU to POD 1, while LFV decreased during the same intervals. The overall changes in NFV were associated with the preop AHI, BMI, and opioids after adjusting for body position and pneumoperitoneum.

CONCLUSIONS

This proof-of-concept study showed the feasibility and variability of segmental fluid volumes in the perioperative period using BIA. We found an increase in NFV and LFV in the immediate postoperative period in both males and females, followed by the continued rise in NFV and a simultaneous decrease in LFV, which suggest the occurrence of rostral fluid shift. Preoperative AHI, BMI, and opioids predicted the NFV changes.

STUDY REGISTRATION

ClinicalTrials.gov; NCT02666781, registered 25 January 2016; NCT03850041, registered 20 February 2019.

A review of bio-impedance devices

Bio-impedance measurement analysis primarily refers to a safe and a non-invasive technique to analyze the electrical changes in living tissues on the application of low-value alternating current. It finds applications both in the biomedical and the agricultural fields. This paper concisely reviews the origin and measurement approaches for concepts and fundamentals of bio-impedance followed by a critical review on bio-impedance portable devices with main emphasis on the embedded system approach which is in demand due to its miniature size and present lifestyle preference of monitoring health in real time. The paper also provides a comprehensive review of various bio-impedance circuits with emphasis on the measurement and calibration techniques.

Effects of a Combined Intradialytic Exercise Training Program on Functional Capacity and Body Composition in Kidney Transplant Candidates

Chronic kidney disease (CKD) leads to gradual muscle mass loss, which is strongly associated with lower functional capacity, which limits a patient’s daily activities. The aim of the present study is to examine the effects of a 4-month intradialytic exercise program on the functional capacity and body composition of kidney transplant (KT) candidates. Twenty-nine male patients on hemodialysis (HD) waiting for a kidney transplant, with a mean age of 53.86 ± 9.56 years old and BMI 27.11 ± 5.55 kg/m2, were randomly assigned into the following two groups: A (nA = 15 HD patients), who followed a 4-month intradialytic exercise program combining aerobic and resistance training, with a supervised, progressively increasing workload, and B (nB = 14 HD patients), who continued to receive usual care. At baseline and the end of the study, the KT candidates underwent a 6-min walking distance (6-MWD), and a 10-repetition sit-to-stand test (10-STS) to access physical function, a handgrip strength (HGS) test to evaluate the muscle strength of the non-fistula hand. Moreover, the bioelectrical impedance analysis (BIA) was performed to assess body composition indices, such as body fat (BF), body fat mass index (BFMI), fat-free mass index (FFMI), body cell mass (BCM), basal metabolic rate (BMR), extracellular water (ECW), intracellular water (ICW), total body water (TBW) and phase angle (PhA). Following the exercise program, group A showed favorable improvements in HGS (from 26.59 ± 9.23 to 28.61 ± 9.58 kg, p < 0.05) and 6-MWD (from 427.07 ± 7.66 to 468.16 ± 11.39 m, p < 0.05). Intergroup results from 6-MWD showed a statistically significant difference (Δp = 0.04), at the end of the study. Moreover, group A results from BIA revealed a significant increase of BMR by 2.4% (p < 0.05), ECW by 3.6% (p = 0.01), ICW by 3.8% (p = 0.01), TBW by 4.1% (p = 0.01), lean mass by 2.7% (p = 0.01), and PhA by 13.3% (p = 0.04), while a reduction in BF by 5.0% (p = 0.01) and BFMI by 6.6% (p = 0.03) was also noticed. At the end of the study, group A showed statistical differences in BMR (Δp = 0.01), BMR/BW (Δp = 0.01), dry lean (Δp = 0.01), and PhA (Δp = 0.03), compared to the group B. Linear regression analysis in group A after training showed positive correlations between HGS and both PhA (r = 0.52, p = 0.04) and FFMI (r = 0.64, p = 0.01), and a strong negative correlation between 6-MWT and BF (r = −0.61, p = 0.01). In conclusion, a 4-month intradialytic exercise program can enhance body composition and some physical parameters in HD patients awaiting kidney transplantation.

Accuracy of Bioimpedance Spectroscopy in the Detection of Hydration Changes in Patients on Hemodialysis

OBJECTIVES

The body composition monitor (BCM) is a bioimpedance spectroscopy device, specifically developed for patients on hemodialysis (HD) to improve ultrafiltration (UF) programming, based on an objective assessment of the degree of overhydration (OH) at the start of HD. However, its acceptance in clinical practice remains limited because of concerns about the accuracy at the individual level. The aim of this study is to examine the performance of the BCM and to identify means of improvement.

METHODS

Precision of the OH estimate was assessed by 6 consecutive measurements in 24 patients on HD. Accuracy was examined in 45 patients, by comparing the change in OH (ΔOH) during HD with UF volume. Accuracy was considered acceptable if the volume error in individual patients was ≤0.5 L.

RESULTS

The OH estimate had an analytical precision of 1.0 ± 0.4%. The correlation between UF volume and ΔOH was moderate (Slope = 0.66, R² = 0.44, P < .001) and indicated underestimation of UF volume, in particular for high UF volumes. Accuracy at individual level was highly variable. A volume error >0.5 L occurred in 44% of patients. Accuracy improved over the course of HD, with a decrease in total error range from 2.3 L in the first hour to 1.1 L in the final hour of HD.

CONCLUSIONS

The accuracy of BCM volume change estimates is highly variable and below requirements of daily practice. Improvement may be achieved by a switch to an end-of-HD measurement.

Segmental bioelectrical impedance analysis for Korean older population with cold pattern

OBJECTIVE

This study examined the association of whole-body composition and segmental bioimpedance variables with cold pattern (CP) in different sexes.

METHODS

We assigned 667 older individuals to a CP group (n = 488) and a non-CP group (n = 179) by using an eight-item self-administered questionnaire. Seven body composition variables and three pairs of segmental bioimpedance variables for the upper and lower extremities, which were obtained from a segmental multifrequency bioimpedance analyzer, were employed to investigate their association with CP. Participants' characteristics were first described. Then we compared the selected body composition and bioimpedance variables between the CP and non-CP groups. Finally, their association with CP was investigated using univariate and multivariate regression analyses. All analyses were performed separately for women and men.

RESULTS

Both women and men exhibited a comparable mean age in the CP and non-CP groups; however, women with CP had significantly lower blood pressures, whereas men with CP showed a higher proportion of osteoarthritis than those without CP. Compared with the non-CP group, individuals with CP exhibited significantly smaller body sizes indicated by shorter height and smaller weight, lower body mass index, and smaller volume-to-body surface area ratio in both sexes. After controlling for age, height, weight, and other covariates, we found significant reductions in body lean mass such as fat-free mass and body cell mass, basal metabolic rate per unit mass, total body water, and intra-to-extracellular water ratio in the CP group. With regard to segmental bioimpedance analysis, the resistance ratios and phase angles in the upper and lower extremities yield significant associations with CP incidence, as demonstrated by the odds ratio (95% confidence interval) of 1.72 (1.16-2.57), 1.69 (1.18-2.48), 0.60 (0.40-0.89), and 0.57 (0.39-0.82), respectively. However, these results did not emerge in men.

CONCLUSION

Abnormal cellular water distribution and deterioration in body cell mass and/or cell strength are associated with CP prevalence, regardless of age, height, weight. These findings are similar in the upper and lower extremities and are more pronounced in women. The abovementioned patterns may be considered effective indicators for identifying CP in the older adult population.

Parasitic Effects on Electrical Bioimpedance Systems: Critical Review

Parasitic capacitance represents the main error source in measurement systems based on electrical impedance spectroscopy. The capacitive nature of electrodes' impedance in tetrapolar configuration can give origin to phase errors when electrodes are coupled to parasitic capacitances. Nevertheless, reactive charges in tissue excitation systems are susceptible to instability. Based on such a scenario, mitigating capacitive effects associated with the electrode is a requirement in order to reduce errors in the measurement system. A literature review about the main compensation techniques for parasitic capacitance was carried out. The selected studies were categorized into three groups: (i) compensation in electronic instrumentation; (ii) compensation in measurement processing, and (iii) compensation by negative impedance converters. The three analyzed methods emerged as effective against fixed capacitance. No method seemed capable of mitigating the effects of electrodes' capacitance, that changes in the frequency spectrum. The analysis has revealed the need for a method to compensate varying capacitances, since electrodes' impedance is unknown.

Next-generation smart watches to estimate whole-body composition using bioimpedance analysis: accuracy and precision in a diverse, multiethnic sample

BACKGROUND

Novel advancements in wearable technologies include continuous measurement of body composition via smart watches. The accuracy and stability of these devices are unknown.

OBJECTIVES

This study evaluated smart watches with integrated bioelectrical impedance analysis (BIA) sensors for their ability to measure and monitor changes in body composition.

METHODS

Participants recruited across BMIs received duplicate body composition measures using 2 wearable bioelectrical impedance analysis (W-BIA) model smart watches in sitting and standing positions, and multiple versions of each watch were used to evaluate inter- and intramodel precision. Duplicate laboratory-grade octapolar bioelectrical impedance analysis (8-BIA) and criterion DXA scans were acquired to compare estimates between the watches and laboratory methods. Test-retest precision and least significant changes assessed the ability to monitor changes in body composition.

RESULTS

Of 109 participants recruited, 75 subjects completed the full manufacturer-recommended protocol. No significant differences were observed between W-BIA watches in position or between watch models. Significant fat-free mass (FFM) differences (P < 0.05) were observed between both W-BIA and 8-BIA when compared to DXA, though the systematic biases to the criterion were correctable. No significant difference was observed between the W-BIA and the laboratory-grade BIA technology for FFM (55.3 ± 14.5 kg for W-BIA versus 56.0 ± 13.8 kg for 8-BIA; P > 0.05; Lin's concordance correlation coefficient = 0.97). FFM was less precise on the watches than DXA {CV, 0.7% [root mean square error (RMSE) = 0.4 kg] versus 1.3% (RMSE = 0.7 kg) for W-BIA}, requiring more repeat measures to equal the same confidence in body composition changes over time as DXA.

CONCLUSIONS

After systematic correction, smart-watch BIA devices are capable of stable, reliable, and accurate body composition measurements, with precision comparable to but lower than that of laboratory measures. These devices allow for measurement in environments not accessible to laboratory systems, such as homes, training centers, and geographically remote locations.

Fluid balance assessment in pediatric hemodialysis patients by using whole-body bioimpedance spectroscopy (WB-BIS)

BACKGROUND

Fluid overload is a major factor in morbidity and mortality in dialysis patients. Whole-body bioimpedance spectroscopy (WB-BIS) is a noninvasive method for assessing fluid status. We hypothesized that fluid status measurement of changes in total body water (TBW), extracellular fluid (ECF), and intracellular fluid (ICF) by WB-BIS would correlate with the weight (Wt) changes before and after hemodialysis (HD) and the amount of ultrafiltration (UF) in pediatric HD patients. We also examined the relationship between the ECF percent of total body water (ECF%) and ECF/ICF ratio with the pre-HD systolic blood pressure percentile (SBP%ile).

METHODS

WB-BIS measurements were made both before and after HD on three separate occasions in each patient. Pre- and post-HD Wt, BP, and UF volumes were collected on the day of BIS measurement.

RESULTS

At total of 96 measurements were obtained from 16 HD patients. There were 6 females (mean age: 13.2 ± 4.5 yrs). UF correlated with changes in weight, TBW and ECF (p < 0.001) but not with ICF changes (p = 0.345). Pre-HD SBP%ile correlated with ECF%.

CONCLUSIONS

Our findings suggest that WB-BIS can be used to monitor the fluid status in pediatric HD patients. The fluid that is removed from the patient during the HD treatment primarily comes from the ECF and not the ICF. Mobilization of fluid from the ICF appears to be delayed. Patients with significantly higher pre-HD ECF% and ECF/ICF ratio had higher pre-HD systolic BP. A higher resolution version of the Graphical abstract is available as Supplementary information.

The Use of Compression Stockings to Reduce Water Retention in the Legs During Gaming and Esports: Randomized Controlled Field Study

Background

With the increasing digitalization of daily life, internet-based entertainment such as gaming and streaming has advanced to one of the megatrends of the 21st century. Besides offering a multitude of controversially discussed opportunities for entertainment and social interaction, there is reasonable concern about health issues caused by the absence of physical activity among activities linked to gaming and streaming.

Objective

The aim of this study is to compare the water balance of recreational gamers with and those without compression stockings during a gaming event.

Methods

We measured body composition and water balance with 8-electrode bioelectrical impedance analysis among 46 recreational gamers with an average age of 27.1 (SD 6.5) years (5/46, 11% women and 41/46, 89% men) before and after 24 hours at a gaming event. Of the 46 gamers, 23 (50%) gamers wore compression stockings for the duration of the study.

Results

Our study shows that prolonged gaming and associated behaviors during a 24-hour time frame lead to an increase in total body water (+0.76 L; P<.001) and a decrease of phase angle in the lower extremities (−0.47°; P<.001) but not in the upper extremities (+0.09°; P=.80), when no compression is used. Gamers using compression socks did not show any significant negative effects on their body composition.

Conclusions

Prolonged gaming and streaming are serious risk factors for diseases associated with water retention in the legs, and these risks can be measured by bioelectrical impedance and reduced by wearing compression stockings. We conclude that these findings should be discussed and replicated in larger studies and that there is a considerably large market for compression stockings among gamers and live streamers.

Gains in body mass and body water in pregnancy and relationships to birth weight of offspring in rural and urban Pune, India

Maternal size, weight gain in pregnancy, fetal gender, environment and gestational age are known determinants of birth weight. It is not clear which component of maternal weight or gained weight during pregnancy influences birth weight. We evaluated the association of maternal total body water measured by the deuterium dilution technique (TBW-D₂O) at 17 and 34 weeks of gestation with birth weight. A secondary aim was to examine the utility of bioimpedance spectroscopy (BIS) to determine total body water (TBW-BIS) in pregnancy. At 17 and 34 weeks of pregnancy, ninety-nine women (fifty-one rural and forty-eight urban) from Pune, India had measurements of body weight, TBW-D₂O, TBW-BIS and offspring birth weight. At 17 weeks of gestation, average weights for rural and urban women were 45⋅5 ± 4⋅8 (sd) and 50⋅7 ± 7⋅8 kg (P < 0⋅0001), respectively. Maternal weight gains over the subsequent 17 weeks for rural and urban women were 6⋅0 ± 2⋅2 and 7⋅5 ± 2⋅8 kg (P = 0⋅003) and water gains were 4⋅0 ± 2⋅4 and 4⋅8 ± 2⋅8 kg (P = 0⋅092), respectively. In both rural and urban women, birth weight was positively, and independently, associated with gestation and parity. Only for rural women, between 17 and 34 weeks, was an increase in dry mass (weight minus TBW-D₂O) or a decrease in TBW-D₂O as a percentage of total weight associated with a higher birth weight. At both 17 and 34 weeks, TBW-BIS increasingly underestimated TBW-D₂O as the water space increased. Differences in body composition during pregnancy between rural and urban environments and possible impacts of nutrition transition on maternal body composition and fetal growth were demonstrated.

Hydration Assessment Using the Bio-Impedance Analysis Method

Body hydration is considered one of the most important physiological parameters to measure and one of the most challenging. Current methods to assess hydration are invasive and require costly clinical settings. The bio-impedance analysis offers a noninvasive and inexpensive tool to assess hydration, and it can be designed to be used in wearable health devices. The use of wearable electronics in healthcare applications has received increased attention over the last decade. New, emerging medical devices feature continuous patient monitoring and data collection to provide suitable treatment and preventive actions. In this paper, a model of human skin is developed and simulated to be used as a guide to designing a dehydration monitoring system based on a bio-impedance analysis technique. The study investigates the effect of applying different frequencies on the dielectric parameters of the skin and the resulting measured impedance. Two different interdigitated electrode designs are presented, and a comparison of the measurements is presented. The rectangular IDE is printed and tested on subjects to validate the bio-impedance method and study the interpretation of its results. The proposed design offers a classification criterion that can be used to assess dehydration without the need for a complex mathematical model. Further clinical testing and data are needed to refine and finalize the criteria.

Body composition is associated with tacrolimus pharmacokinetics in kidney transplant recipients

PURPOSE

A population pharmacokinetic (popPK) model may be used to improve tacrolimus dosing and minimize under- and overexposure in kidney transplant recipients. It is unknown how body composition parameters relate to tacrolimus pharmacokinetics and which parameter correlates best with tacrolimus exposure. The aims of this study were to investigate which body composition parameter has the best association with the pharmacokinetics of tacrolimus and to describe this relationship in a popPK model.

METHODS

Body composition was assessed using bio-impedance spectroscopy (BIS). Pharmacokinetic analysis was performed using nonlinear mixed effects modeling (NONMEM). Lean tissue mass, adipose tissue mass, over-hydration, and phase angle were measured with BIS and then evaluated as covariates. The final popPK model was evaluated using goodness-of-fit plots, visual predictive checks, and a bootstrap analysis.

RESULTS

In 46 kidney transplant recipients, 284 tacrolimus concentrations were measured. The base model without body composition parameters included age, plasma albumin, plasma creatinine, CYP3A4 and CYP3A5 genotypes, and hematocrit as covariates. After full forward inclusion and backward elimination, only the effect of the phase angle on clearance (dOFV =  - 13.406; p < 0.01) was included in the final model. Phase angle was positively correlated with tacrolimus clearance. The inter-individual variability decreased from 41.7% in the base model to 34.2% in the final model. The model was successfully validated.

CONCLUSION

The phase angle is the bio-impedance spectroscopic parameter that correlates best with tacrolimus pharmacokinetics. Incorporation of the phase angle in a popPK model can improve the prediction of an individual's tacrolimus dose requirement after transplantation.

Acute Water Supplementation Improved the Body Composition of Young Female Adults After Water Restriction of 12 h in Baoding, China: A Randomized Controlled Trial (RCT)

Insufficient intake of water may influence the balance of water in the human body. In this study, we explore the impacts of water supplementation on body composition indices among young adults after 12 h of water restriction, with the aim to determine the optimum volume of water for improving body water composition. A randomized controlled trial study was conducted among 64 young men and women in Baoding, China. After fasting overnight for 12 h, anthropometric measurements and urine and blood samples were collected as a baseline test at 8:00 a.m. of Day 2. Body composition was determined by measuring the ECW (extracellular water), ICW (intracellular water), and TBW (total body water) through bioelectrical impedance analysis (BIA). The participants were randomly divided into four groups, including water supplementation (WS) groups 1, 2, and 3, with 500, 200, and 100 mL of water, respectively, and a no water supplementation (NW) group. After 90 min, they were reassessed in a rehydration test (at 10:00 a.m. of Day 2). Repeated measurement ANOVA was used to assess the impact of water supplementation on body composition. Comparing the baseline and rehydration tests, interactions between time and volume were not significant among the men (all p > 0.05). Among women, a significant interaction was only found in ECW (p = 0.043), with TBW tending toward being significant (p = 0.055). Comparing the baseline and rehydration tests, the ECW in WS group 1, WS group 3, and the NW group all decreased (p = 0.028, p = 0.001, and p = 0.029), with reductions of 0.1, 0.3, and 0.2 kg, respectively; however, no significant decrease was observed in WS group 2 (p = 0.329). Furthermore, comparing the WS groups with the NW group in the rehydration test, the differences were not significant (p = 1.000, p = 1.000, and p = 0.288, respectively). Between men and women within groups, all of the body composition indices differed significantly, both at baseline and rehydration tests (all p < 0.05). Water supplementation led to changes in the distribution of the water content in young female adults in this study-but not men-after 12 h of water restriction, with no decrease in ECW. Finally, we found that 200 mL was the minimum volume capable of improving the water content distribution in participants in this study.

Trial Registration

[www.chictr.org.cn], identifier [ChiCTR-IOR-17011568].

Comparisons between Bioelectrical Impedance Variables, Functional Tests and Blood Markers Based on BMI in Older Women and Their Association with Phase Angle

The aim of the present study was to compare electrical bioimpedance variables, blood markers and functional tests based on Body Mass Index (BMI) in older women. Associations between Phase Angle (PhA) with functional tests and blood markers were also analyzed. A total of 46 independent elderly people participated in the study, and they were divided into four groups according to BMI values: Group 1 (G1, BMI < 25 kg/m2); Group 2 (G2, BMI > 25−30 kg/m2); Group 3 (G3, BMI > 30−35 kg/m2); Group 4 (G4, BMI > 35 kg/m2). In addition to the weight and height used to calculate the BMI, the following body composition variables were collected: fat mass (FM), fat-free mass, intracellular water (ICW), extracellular water (ECW), total body water (TBW) and PhA (50 kHz) through InBody S10 equipment. Functional capacity was assessed using the Fullerton battery of tests: arm-curl; chair-stand; 6 min walking test (6MWT); time up-and-go test (TUG); standing on one leg (SOOL) and take 10 foot-lines (10FL). The main results showed differences between groups in the tests: 6MWT, SOOL and 10FL between G1 vs. G3 and G2 vs. G3 (p < 0.05); ACT, AIC and AEC between G1 vs. G4 (p < 0.05); FM among all groups (p < 0.05). Negative correlations were found between PhA and the agility test in G1 (r = −0.848; p = 0.008) and G4 (r = −0.909; p = 0.005); PhA and chair-stand in G3 (r = 0.527; p = 0.044); PhA and forearm flexion in G3 (r = 0.641; p = 0.010) and G4 (r = 0.943; p = 0.001); PhA and 6MWT in G4 (r = 0.771; p = 0.042). This study found that there is a clear trend towards better functional capacities with better parameters of body composition. Although there were no differences between groups in PhA, associations were found between different functional tests with PhA, which reveals the importance of this variable as a marker of health status.

Using bioelectrical impedance analysis in children and adolescents: Pressing issues

Single- and multifrequency bioelectrical impedance analysis (BIA) has gained popularity as a tool to assess body composition and health status of children and adolescents, but many questions and misconceptions remain. This review addresses pressing issues researchers and health care providers may encounter when using BIA in the young population. The importance of choosing population-specific and device-specific equations to estimate body composition as well as the use of BIA in longitudinal analyses are discussed. When specific equations are not available, raw bioimpedance values (i.e., resistance, reactance, and impedance) can be used to compute bioimpedance parameters, such as phase angle, impedance ratio, and bioelectrical impedance vector analysis. As interpreting these parameters is challenging, suggestions are provided on the use of reference data, cut-off points, and adjustment factors. Furthermore, unsolved technical and analytical issues are listed. Based on existing issues and potential for future development, a greater interaction between industry and academic researchers to improve the validity of BIA measurements among children and adolescents across their developmental stages is encouraged.

Biomarkers of Redox Balance Adjusted to Exercise Intensity as a Useful Tool to Identify Patients at Risk of Muscle Disease through Exercise Test

The screening of skeletal muscle diseases constitutes an unresolved challenge. Currently, exercise tests or plasmatic tests alone have shown limited performance in the screening of subjects with an increased risk of muscle oxidative metabolism impairment. Intensity-adjusted energy substrate levels of lactate (La), pyruvate (Pyr), β-hydroxybutyrate (BOH) and acetoacetate (AA) during a cardiopulmonary exercise test (CPET) could constitute alternative valid biomarkers to select "at-risk" patients, requiring the gold-standard diagnosis procedure through muscle biopsy. Thus, we aimed to test: (1) the validity of the V'O2-adjusted La, Pyr, BOH and AA during a CPET for the assessment of the muscle oxidative metabolism (exercise and mitochondrial respiration parameters); and (2) the discriminative value of the V'O2-adjusted energy and redox markers, as well as five other V'O2-adjusted TCA cycle-related metabolites, between healthy subjects, subjects with muscle complaints and muscle disease patients. Two hundred and thirty subjects with muscle complaints without diagnosis, nine patients with a diagnosed muscle disease and ten healthy subjects performed a CPET with blood assessments at rest, at the estimated 1st ventilatory threshold and at the maximal intensity. Twelve subjects with muscle complaints presenting a severe alteration of their profile underwent a muscle biopsy. The V'O2-adjusted plasma levels of La, Pyr, BOH and AA, and their respective ratios showed significant correlations with functional and muscle fiber mitochondrial respiration parameters. Differences in exercise V'O2-adjusted La/Pyr, BOH, AA and BOH/AA were observed between healthy subjects, subjects with muscle complaints without diagnosis and muscle disease patients. The energy substrate and redox blood profile of complaining subjects with severe exercise intolerance matched the blood profile of muscle disease patients. Adding five tricarboxylic acid cycle intermediates did not improve the discriminative value of the intensity-adjusted energy and redox markers. The V'O2-adjusted La, Pyr, BOH, AA and their respective ratios constitute valid muscle biomarkers that reveal similar blunted adaptations in muscle disease patients and in subjects with muscle complaints and severe exercise intolerance. A targeted metabolomic approach to improve the screening of "at-risk" patients is discussed.

The interaction between stress and metabolic disruption in student population – preliminary study

Introduction: Approximately 26% of individuals between 18 and 24 years old are overweight or obese, and the number of persons with excessive body mass index (BMI) is growing. Obesity increases the risk of metabolic disruptions, which is well connected with mental health problems. Stressful situations, including entering adulthood and starting university education, affect food choices negatively. The aim of the study was to examine the relationship between psychological stress and body composition in the student population.

Materials and methods: The study group consisted of 80 students (76% of women and 24% of men) between 19 and 28 years old from universities in Lublin. To determine anthropometric measurement (fat-free mass (FFM), fat mass (FM), total body water (TBW), intracellular (ICF) and extracellular (ECF) fluids), bioelectrical impedance analysis (BIA) method was applied. The severity of stress symptoms was measured using Perceived Stress Scale (PSS-10).

Results: When it comes to 41.25% of participants, they used relaxation techniques, mainly meditation, yoga practice and walking. Most students had optimal body weight. While 60% of individuals had high stress levels. The perceived stress was not related to using the relaxation methods. Individuals with the high stress severity were characterized by lower: TBW, ECF and ICF expressed in liters, and lower FFM represented in kilograms. The inverse relationship between the severity of stress and the aforementioned parameters was also detected (p<0.05).

Conclusions: Implementing appropriate healt h education programs to prevent negat ive changes in ant hropometric measurements, psychological stress, and their health-related consequences in the student population should be considered.

Water - A life-giving toxin - A nephrological oxymoron. Health consequences of water and sodium balance disorders. A review article

BACKGROUND

This article aims to reveal misconceptions about methods of assessment of hydration status and impact of the water disorders on the progression of kidney disease or renal dysfunction.

MATERIALS AND METHODS

The PubMed database was searched for reviews, meta-analyses and original articles on hydration, volume depletion, fluid overload and diagnostic methods of hydration status, which were published in English.

RESULTS

Based on the results of available literature the relationship between the amount of fluid consumed, and the rate of progression of chronic kidney disease, autosomal dominant polycystic kidney disease, and kidney stones disease was discussed. Selected aspects of the assessment of the hydration level in clinical practice based on physical examination, laboratory tests, and imaging are presented. The subject of in-hospital fluid therapy is discussed. Based on available randomized studies, an attempt was made to assess, which fluids should be selected for intravenous treatment.

CONCLUSIONS

There is some evidence for the beneficial effect of increased water intake in preventing recurrent cystitis and kidney stones, but there are still no convincing data for chronic kidney disease and autosomal dominant polycystic kidney disease. Further studies are needed to clarify the aforementioned issues and establish a reliable way to assess the volemia and perform suitable fluid therapy.

Measuring Biosignals with Single Circuit Boards

To measure biosignals constantly, using textile-integrated or even textile-based electrodes and miniaturized electronics, is ideal to provide maximum comfort for patients or athletes during monitoring. While in former times, this was usually solved by integrating specialized electronics into garments, either connected to a handheld computer or including a wireless data transfer option, nowadays increasingly smaller single circuit boards are available, e.g., single-board computers such as Raspberry Pi or microcontrollers such as Arduino, in various shapes and dimensions. This review gives an overview of studies found in the recent scientific literature, reporting measurements of biosignals such as ECG, EMG, sweat and other health-related parameters by single circuit boards, showing new possibilities offered by Arduino, Raspberry Pi etc. in the mobile long-term acquisition of biosignals. The review concentrates on the electronics, not on textile electrodes about which several review papers are available.

Hemodynamic pathways of gestational hypertension and preeclampsia

Gestational hypertension and preeclampsia are the 2 main types of hypertensive disorders in pregnancy. Noninvasive maternal cardiovascular function assessment, which helps obtain information from all the components of circulation, has shown that venous hemodynamic dysfunction is a feature of preeclampsia but not of gestational hypertension. Venous congestion is a known cause of organ dysfunction, but its potential role in the pathophysiology of preeclampsia is currently poorly investigated. Body water volume expansion occurs in both gestational hypertension and preeclampsia, and this is associated with the common feature of new-onset hypertension after 20 weeks of gestation. Blood pressure, by definition, is the product of intravascular volume load and vascular resistance (Ohm's law). Fundamentally, hypertension may present as a spectrum of cardiovascular states varying between 2 extremes: one with a predominance of raised cardiac output and the other with a predominance of increased total peripheral resistance. In clinical practice, however, this bipolar nature of hypertension is rarely considered, despite the important implications for screening, prevention, management, and monitoring of disease. This review summarizes the evidence of type-specific hemodynamic profiles in the latent and clinical stages of hypertensive disorders in pregnancy. Gestational volume expansion superimposed on an early gestational closed circulatory circuit in a pressure- or volume-overloaded condition predisposes a patient to the gradual deterioration of overall circulatory function, finally presenting as gestational hypertension or preeclampsia-the latter when venous dysfunction is involved. The eventual phenotype of hypertensive disorder is already predictable from early gestation onward, on the condition of including information from all the major components of circulation into the maternal cardiovascular assessment: the heart, central and peripheral arteries, conductive and capacitance veins, and body water content. The relevance of this approach, outlined in this review, openly invites for more in-depth research into the fundamental hemodynamics of gestational hypertensive disorders, not only from the perspective of the physiologist or the scientist, but also in assistance of clinicians toward understanding and managing effectively these severe complications of pregnancy.

Handgrip Strength, Overhydration and Nutritional Status as a Predictors of Gastrointestinal Toxicity in Cervical Cancer Patients. A Prospective Study

Background: Antineoplastic treatments produce adverse events (AE) such as gastrointestinal toxicity. These AE can reduce nutritional intake and promote weight and muscle mass loss. Objective: To determine if body composition, nutritional status, or muscle function predicts gastrointestinal toxicity during chemotherapy in cervical cancer (CC) patients. Methods: Women with CC were studied. Nutritional status was evaluated according to PG-SGA, and body composition was measured with bioimpedance. Toxicity was graded according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE). Results: A total of 207 women, 81 with toxicity and 126 without toxicity groups, were studied. Patients in the toxicity group had less handgrip strength (17.7 ± 5.0 vs. 20.3 ± 5.0 p = 0.0004); phase angle (5.2 ± 1.1 vs. 5.9 ± 1.0, p = 0.0065); higher prevalence of sarcopenia (35.9% vs. 20.6%, p = 0.016); overhydration (25.9% vs. 6.3% p < 0.001); and PG-SGA C (14.1% vs. 4.0%, p < 0.001) when compared to patients without toxicity. Handgrip strength (HR: 0.93, 95% CI 0.88-0.98, p = 0.028), overhydration (HR: 2.82, 95% CI 1.22-6.51, p = 0.015) and been severely malnourished according to PG-PGA (HR: 3.6, 95%CI 1.46-9.2, p < 0.001) were associated with the risk to present gastrointestinal toxicity. Conclusion: handgrip strength, overhydration, and severe malnutrition are independent risk factors to the presence of gastrointestinal toxicity in CC patients.

Kids With Altitude: Acute Mountain Sickness and Changes in Body Mass and Total Body Water in Children Travelling to 3800 m

INTRODUCTION

We explored the incidence of acute mountain sickness (AMS) and extravascular lung water (ELW) in children in relation to changes in body composition and peripheral blood oxygenation (S_pO₂) during 1 week of acclimatization to 3800 m.

METHODS

In a prospective cohort study, 10 children (7 female, ages 7-14 y) and 10 sex-matched adults (ages 23-44 y) traveled via automobile from sea level to 3000 m for 2 nights, followed by 4 nights at 3800 m. Each morning, body mass and body water (bioelectrical impedance), S_pO₂ (pulse oximetry), AMS (Lake Louise Questionnaire), and ELW (transthoracic echocardiography) were measured.

RESULTS

No differences were found between children and adults in S_pO₂ or ELW. At 3800 m 7 of 10 children were AMS+ vs 4 of 10 adults. Among those AMS+ at 3800 m, the severity was greater in children compared to adults (5±1 vs 3 ± 0; P=0.005). Loss of body mass occurred more quickly in children (day 5 vs day 7) and to a greater extent (-7±3% vs -2±2%; P<0.001); these changes were mediated via a larger relative loss in total body water in children than in adults (-6±5% vs -2±2%; P=0.027).

CONCLUSIONS

Children demonstrated a higher incidence of AMS than adults, with greater severity among those AMS+. The loss of body water and body mass at high altitude was also greater in children, albeit unrelated to AMS severity. In addition to awareness of AMS, strategies to maintain body weight and hydration in children traveling to high altitudes should be considered.