Bioelectrical impedance analysis as a clinical marker of health status in adult patients with benign gastrointestinal disease: A systematic review.

BACKGROUND: Body composition reflects nutritional status, disease status and progression, and treatment responses. Mounting evidence supports the use of bioelectrical impedance analysis (BIA) as a non-invasive tool to assess body composition. Patients with benign gastrointestinal (GI) disease experience disease-related alterations in their body composition, and bioimpedance outcomes in patients with benign GI diseases have not previously been summarized. We aimed to evaluate BIA as a clinical body composition marker for benign GI diseases and describe its association with physical health status. METHODS: We systematically searched PubMed, Scopus, Web of Science, Embase, and CINAHL from inception to October 2023 (PROSPERO registration: CRD42021265866). Of 971 screened studies, 26 studies were included in the final analysis, comprising a total of 2398 adult patients with benign GI disease. The main outcome was raw impedance data. RESULTS: The most frequently reported BIA outcome was phase angle (PhA) (reported in 18 of 26 studies), followed by fat-free-mass (FFM) (reported in 13 of 26 studies). The consensus view of the included studies illustrates that BIA can be a useful tool for evaluating body composition in patients with benign GI diseases, and low PhA and FFM were associated with increased nutritional risk, abnormal physical characteristics, and increased mortality risk. CONCLUSION: To fully utilize BIA as a clinical marker of health in patients with benign GI disease, standardized protocols specific to this population are needed and prospective studies testing cut-offs and ranges, accuracy, and other raw BIA parameters for classifying disease status.

Sodium depletion and secondary hyperaldosteronism in outpatients with an ileostomy: a cross-sectional study.

OBJECTIVE: Patients with an ileostomy may experience postoperative electrolyte derangement and dehydration but are presumed to stabilise thereafter. We aimed to investigate the prevalence of sodium depletion in stable outpatients with an ileostomy and applied established methods to estimate their fluid status. METHODS: We invited 178 patients with an ileostomy through a region-wide Quality-of-Life-survey to undergo outpatient evaluation of their sodium and fluid status. The patients delivered urine and blood samples, had bioelectrical impedance analysis performed and answered a questionnaire regarding dietary habits. RESULTS: Out of 178 invitees, 49 patients with an ileostomy were included; 22 patients (45%, 95% CI, 31-59%) had unmeasurably low urinary sodium excretion (<20 mmol/L), indicative of chronic sodium depletion, and 26% (95% CI, 16-41%) had plasma aldosterone levels above the reference value. Patients with unmeasurably low urinary sodium excretion had low estimated glomerular filtration rates (median 76, IQR 63-89, mL/min/1.73m2) and low venous blood plasma CO2 (median 24, IQR 21-26, mmol/L), indicative of chronic renal impairment and metabolic acidosis. Bioelectrical impedance analysis, plasma osmolality, creatinine and sodium values were not informative in determining sodium status in this population. CONCLUSION: A high proportion of patients with an ileostomy may be chronically sodium depleted, indicated by absent urinary sodium excretion, secondary hyperaldosteronism and chronic renal impairment, despite normal standard biochemical tests. Sodium depletion may adversely affect longstanding renal function. Future studies should investigate methods to estimate and monitor fluid status and aim to develop treatments to improve sodium depletion and dehydration in patients with an ileostomy.IMPACT AND PRACTICE RELEVANCE STATEMENTSodium depletion in otherwise healthy persons with an ileostomy was identified in a few publications from the 1980s. The magnitude of the problem has not been demonstrated before. The present study quantifies the degree of sodium depletion and secondary hyperaldosteronism in this group, and the results may help guide clinicians to optimise treatment. Sodium depletion is easily assessed with a urine sample, and sequelae may possibly be avoided if sodium depletion is detected early and treated. This could ultimately help increase the quality of life in patients with an ileostomy.

Bioimpedance basics and phase angle fundamentals.

Measurement of phase angle using bioimpedance analysis (BIA) has become popular as an index of so-called "cellular health". What precisely is meant by this term is not always clear but strong relationships have been found between cellular water status (the relative amounts of extra- and intracellular water), cell membrane integrity and cellular mass. Much of the current research is empirical observation and frequently pays little regard to the underlying biophysical models that underpin the BIA technique or attempts to provide mechanistic explanations for the observations. This brief review seeks to provide a basic understanding of the electrical models frequently used to describe the passive electrical properties of tissues with particular focus on phase angle. In addition, it draws attention to some practical concerns in the measurement of phase angle and notes the additional understanding that can be gained when phase angle are obtained with bioimpedance spectroscopy (BIS) rather than single frequency BIA (SFBIA) along with the potential for simulation modelling.

Traditional and novel cardiometabolic risk markers across strata of body mass index in young adults.

BACKGROUND: Cardiometabolic risk increases with increasing body mass index (BMI). The exact mechanism is poorly understood, and traditional risk assessment of young adults with obesity has shown to be ineffective. Greater knowledge about potential new effective biomarkers and the use of advanced cardiac imaging for risk assessment in young adults is, therefore, necessary. OBJECTIVE: This study aims to explore traditional and novel cardiometabolic risk markers across strata of BMI in young adults. METHODS: Participants (N = 264, 50% women, age 28-30 years) were invited from an ongoing cohort study, based on BMI and sex. BMI-strata were: BMI <25, 25-30, >30 kg/m2, representing normal weight (NW), overweight (OW), and obesity (OB). Participants underwent cardiac computed tomography to detect coronary artery calcification, measures of body composition, blood pressure measurements, and a comprehensive panel of circulating cardiometabolic risk markers. RESULTS: No significant coronary artery calcifications were detected in this study. Minor differences in median levels of traditional risk markers were detected across BMI-strata, for example, total cholesterol (men- NW: 4.7 (4.3-5.1) and OB: 4.8 (4.2-5.6) mmol/L, p = 0.58; women- NW: 4.3 (3.9-4.8) and OB: 4.7 (4.2-5.3) mmol/L, p = 0.016), whereas substantial differences were seen in markers of inflammation and glucose metabolism, for example, high sensitive CRP (men- NW: 0.6 (0.3-1.1) and OB: 2.8 (1.5-4.0) mg/L, p < 0.001; women- NW: 0.7 (0.3-1.7) and OB: 4.0 (2.2-7.8) mg/L, p < 0.001) and insulin (men- NW: 47.0 (35.0-59.0) and OB: 113.5 (72.0-151.0) pmol/L, p < 0.001; women- NW: 44.0 (35.0-60.0) and OB: 84.5 (60.0-126.0) pmol/L, p < 0.001). CONCLUSION: In young adults, obesity is associated with an early onset insulin resistance and inflammatory response prior to development of coronary artery calcification and deterioration of lipid profiles.

An evaluation of phase angle, bioelectrical impedance vector analysis and impedance ratio for the assessment of disease status in children with nephrotic syndrome.

BACKGROUND: Oedema, characterized by accumulation of extracellular water (ECW), is one of the major clinical manifestations in children suffering from nephrotic syndrome (NS). The lack of a simple, inexpensive and harmless method for assessing ECW may be solved by the use of the bioelectrical impedance analysis (BIA) technique. The aims of this study were to examine whether phase angle (PA), bioelectrical impedance vector analysis (BIVA) and the impedance ratio (IR) reflect change in disease status in children with NS. METHODS: Eight children (age range: 2-10 years) with active NS (ANS group) were enrolled. In five of these (ANS* subgroup), impedance was also measured at remission (NSR group). Thirty-eight healthy children (age range: 2-10 years) were included as healthy controls (HC group). Whole-body impedance was measured with a bioimpedance spectroscopy device (Xitron 4200) with surface electrodes placed on the wrist and ankle. RESULTS: Values of PA, BIVA and IR were found to be significantly lower (p-value range < 0.001 to < 0.01) in the ANS patients compared to the HC and NSR groups. No significant differences were observed between the NSR and HC groups. CONCLUSION: The studied parameters can be used to assess change in disease status in NS patients. Data were consistent with NS being associated with expansion of ECW.

Bioimpedance Resistance Indices and Cell Membrane Capacitance Used to Assess Disease Status and Cell Membrane Integrity in Children with Nephrotic Syndrome.

BACKGROUND: Accumulation of extracellular water (ECW) is a major clinical manifestation of nephrotic syndrome (NS) in children. Bioimpedance spectroscopy (BIS) is a simple, noninvasive technique that reflects body water volumes. BIS can further measure cell membrane capacitance (CM), which may be altered in NS. The aims of the study were to explore how BIS measurements could reflect disease status in NS, while avoiding prediction equations which are often only validated in adult populations. METHODS: The study involved 8 children (2-10 years) with active NS (ANS group), 5 of which were also studied at NS remission (NSR group), as well as 38 healthy children of similar age (HC group). BIS measurements determined resistances RINF, RE, and RI (reflecting total body water, extracellular water, and intracellular water) and CM. Also resistance indices based on height (H) were considered, RI = H2/R. RESULTS: It was found that RE and RINF were significantly lower in the ANS group than in both NSR and HC groups (p < 0.001). Corresponding resistance indices were significantly higher in the ANS group than in the NSR (p < 0.01) and the HC (p < 0.05) groups, in accordance with elevated water volumes in NS patients. Indices of intracellular water were not significantly different between groups. CM was significantly lower in the ANS group than in NSR and HC groups (p < 0.05). CONCLUSION: BIS could distinguish children with active NS from well-treated and healthy children. Studies with more children are warranted.

Standardisation of bioelectrical impedance analysis for the estimation of body composition in healthy paediatric populations: a systematic review.

BACKGROUND: Bioelectrical impedance analysis (BIA) requires a high degree of standardisation in order to ensure valid and reproducible impedance measurements. The overall aim of this review was to study the degree to which BIA papers conducted in healthy paediatric populations (aged 0-17 years) were standardised. METHODS: Literature was identified on the basis of a systematic search of internationally-recognised electronic databases and hand searching of the reference lists of the included papers in order to identify additional relevant papers. The review was limited to lead-type BIA devices for whole-body, segmental- and focal impedance measurements. In total, 71 papers published between 1988 and 2016 were included. To evaluate the degree of standardisation of the papers, a recently published review detailing critical factors that may impact on BIA measurements in children was used as a model for structuring and extracting data. RESULTS: There was a general lack of BIA standardisation, or its reporting, in the papers under review, which hinders comparison of data between studies and could potentially lead to erroneous measurements. CONCLUSIONS: If the BIA technique should be accepted clinically for routine use in paediatric populations, there is a need for an increased focus on the importance of improved standardisation and its reporting in future studies. Consequently, this review contains recommendations for performing and reporting BIA measurements in a standardised manner.

Critical factors and their impact on bioelectrical impedance analysis in children: a review.

Several guidelines for bioelectrical impedance analysis (BIA) have been prepared for adults, but not for children. For that reason, there is a pressing need to develop a consensus set of guidelines to facilitate standardisation of BIA in this important group. This review provides an introduction to BIA, highlights critical factors that may impact on BIA and identifies areas where there is a need for further research in order to increase the quality of impedance measurements and prediction of body composition in children. Although the results of this review highlights a lack of studies in children to provide definitive BIA guidelines, the technique has, however, still proven valuable for body composition assessment in ill and healthy children. To fill the gaps in our knowledge, future studies should focus on methodological issues, particularly with regard to hydration, voiding, clothing, skin preparation and body position. The review may advantageously be used as a checklist in the planning of future studies. Finally, this review forms the basis for the development of guidelines for BIA assessment in this particular group; a task appropriately to be undertaken by scientific societies within the field.

Changes in the renin-angiotensin-aldosterone system in response to dietary salt intake in normal and hypertensive pregnancy. A randomized trial.

It was hypothesized that primary renal sodium retention blunted the reactivity of the renin-angiotensin-aldosterone system to changes in salt intake in preeclampsia (PE). A randomized, cross-over, double-blinded, dietary intervention design was used to measure the effects of salt tablets or placebo during low-salt diet in PE patients (n = 7), healthy pregnant women (n = 15), and nonpregnant women (n = 13). High-salt intake decreased renin and angiotensin II concentrations significantly in healthy pregnant women (P < .03) and in nonpregnant women (P < .001), but not in PE (P = .58), while decreases in aldosterone and increases in brain natriuretic peptid (BNP) were similar in the groups. In PE patients, uterine and umbilical artery indices were not adversely changed during low-salt diet. Creatinine clearance was significantly lower in PE with no change by salt intake. PE patients displayed alterations of plasma renin and angiotensin II in response to changes in dietary salt intake compatible with a primary increase in renal sodium reabsorption in hypertensive pregnancies.

Clinical evaluation of the accuracy and precision of the CDI 500 in-line blood gas monitor with and without gas calibration.

During cardiopulmonary bypass blood gases can be analyzed with laboratory equipment or with an in-line monitor giving instant results. The manufacturer of the CDI 500 in-line blood gas monitor recommends gas calibration before use. In acute cases there may not be time to perform a gas calibration. We hypothesized that after calibration against laboratory results, the CDI values of pH, pO2, and pCO2 will keep the same level of accuracy, whether the CDI has been gas calibrated or not. We performed a prospective randomized observational study using a study group without gas calibration (29 patients) and a control group with gas calibration (29 patients). Blood sampling was done at the beginning of bypass, and 30 minutes later. After each blood sample the CDI was in-vivo calibrated to the values simultaneously obtained from the ABL. Before in-vivo calibration values from the CDI without gas calibration were significantly different from the ABL-values in accuracy as well as precision, whereas the results from the gas calibrated CDI were largely consistent with the ABL. Before in-vivo calibration, the CDI without gas calibration was completely unreliable. After in-vivo calibration there was no statistical difference between the values of the CDI with and without calibration. We recommend gas calibration of the CDI before use in the period before in-vivo calibration.