Clinical usefulness of bioimpedance analysis for assessing volume status in patients receiving maintenance dialysis

Research progress on measurement methods and evaluation of the hemodialysis adequacy index Kt/V

The most common form of replacement therapy for end-stage renal disease (ESRD) is hemodialysis, and the adequacy of hemodialysis is strongly associated with the quality of life and long-term survival of patients. Kt/V is currently one of the most important indicators for evaluating the adequacy of hemodialysis. There are many methods for measuring Kt/V, such as blood collection and measurement, dialysate measurement, bioresistive resistance, WinNonlin software analysis, and artificial intelligence. There are different views on the importance of Kt/V as an indicator of the adequacy of hemodialysis. This article provides a literature review of the various methods of measuring Kt/V and on different perspectives on Kt/V as an evaluation of hemodialysis adequacy.

Assessment of changes in blood volume during lower body negative pressure-induced hypovolemia using bioelectrical impedance analysis

BACKGROUND

Lower body negative Pressure (LBNP)-induced hypovolemia is simulating acute hemorrhage by sequestrating blood into lower extremities. Bioelectrical Impedance Analysis (BIA) is based on the electrical properties of biological tissues, as electrical current flows along highly conductive body tissues (such as blood). Changes in blood volume will lead to changes in bioimpedance. This study aims to study changes in upper (UL) and lower (LL) extremities bioimpedance during LBNP-induced hypovolemia.

METHODS

This was a prospective observational study of healthy volunteers who underwent gradual LBNP protocol which consisted of 3-minute intervals: at baseline, -15, -30, -45, -60 mmHg, then recovery phases at -30 mmHg and baseline. The UL&LL extremities bioimpedance were measured and recorded at each phase of LBNP and the percentage changes of bioimpedance from baseline were calculated and compared using student's t-test. A P-value of < 0.05 was considered significant. Correlation between relative changes in UL&LL bioimpedance and estimated blood loss (EBL) from LBNP was calculated using Pearson correlation.

RESULTS

26 healthy volunteers were enrolled. As LBNP-induced hypovolemia progressed, there were a significant increase in UL bioimpedance and a significant decrease in LL bioimpedance. During recovery phases (where blood was shifted from the legs to the body), there were a significant increase in LL bioimpedance and a reduction in UL bioimpedance. There were significant correlations between estimated blood loss from LBNP model with UL (R = 0.97) and LL bioimpedance (R = - 0.97).

CONCLUSION

During LBNP-induced hypovolemia, there were reciprocal changes in UL&LL bioimpedance. These changes reflected hemodynamic compensatory mechanisms to hypovolemia.

Association of Bioimpedance Parameters with Increases in Blood Pressure during Hemodialysis

BACKGROUND

Intradialytic hypertension, defined as an increase in BP from pre- to post-hemodialysis (HD), affects 5%-15% of patients receiving maintenance HD and is associated with cardiovascular and all-cause mortality. Hypervolemia is believed to be a major etiological factor, yet the association of more objective biomarkers of volume status with intradialytic hypertension is not well described.

METHODS

In a post hoc analysis of the Frequent Hemodialysis Network Daily Trial ( n =234), using data from baseline, 1-, 4-, and 12-month visits ( n =800), we used random-effects regression to assess the association of bioimpedance estimates of volume (vector length) with post-HD systolic BP (continuous) and any increase in systolic BP (categorical) from pre- to post-HD. We adjusted models for randomized group; age; sex; self-reported race; Quételet (body mass) index; vascular access; HD vintage; hypertension; history of heart failure; diabetes; residual kidney function (urea clearance); pre-HD systolic BP; ultrafiltration rate; serum-dialysate sodium gradient; and baseline values of hemoglobin, phosphate, and equilibrated Kt/V urea.

RESULTS

The mean age of participants was 50±14 years, 39% were female, and 43% were Black. In adjusted models, shorter vector length (per 50 Ω/m) was associated with higher post-HD systolic BP (2.9 mm Hg; 95% confidence interval [CI], 1.6 to 4.3) and higher odds of intradialytic hypertension (odds ratio 1.66; 95% CI, 1.07 to 2.55). Similar patterns of association were noted with a more stringent definition of intradialytic hypertension (>10 mm Hg increase from pre- to post-HD systolic BP), where shorter vector length (per 50 Ω/m) was associated with a higher odds of intradialytic hypertension (odds ratio 2.17; 95% CI, 0.88 to 5.36).

CONCLUSIONS

Shorter vector length, a bioimpedance-derived proxy of hypervolemia, was independently associated with higher post-HD systolic BP and risk of intradialytic hypertension.

The role of segmental bioelectrical impedance technique in the assessment of intraperitoneal ultrafiltration volume with peritoneal dialysis patients

OBJECTIVE

To investigate the role of segmental bioelectrical impedance technique (SBIA) in the assessment of intraperitoneal ultrafiltration volume with peritoneal dialysis patients.

METHOD

We selected the patients at the Department of Nephrology of the First Affiliated Hospital of Zhengzhou University and measured the segmental bioelectrical impedance by a German Fresenius body composition analyzer (the Fresenius whole body composition measurement (BCM) machine was used as a segmental machine in this study). An alternating current (5 kHz, 0.05-0.7 mA) was continuously released during the measurement. The released current penetrated the peritoneal cavity on both sides of the body, from which the segmental resistance at a frequency of 5 kHz was obtained from the multifrequency data (R5/Ω). Baseline BIA measurements were initiated after the patient entered the supine position for 5-10 min, then dialysate was instilled into the peritoneal cavity. BIA measurements were performed at 10-min intervals during the retention of dialysate in the abdomen and finally ended when dialysate drainage was complete. Real-time intraperitoneal volume estimated by SBIA (IPVSBIA)and ultrafiltration volume estimated by SBIA(UFVSBIA) was calculated. At the same time, the actual ultrafiltration volume at the end of peritoneal dialysis was weighed and measured (UFVMEA).

RESULTS

A total of 30 patients were included in the study, 9 patients withdrew from the study due to subjective factors during the measurement process, and 21 patients completed the study. The correlation coefficient R2 of UFVSBIA and UFVMEA was 0.21 (p < 0.05). Bland-Altman analysis showed that the bias of UFVSBIA to the actual UFVMEA was 0.12 L, and the 95% agreement limit was between -0.5 L and 0.74 L, which confirmed that UFVSBIA measured by electrical impedance method and UFVMEA measured by weighing method were in good agreement. The time required to reach the maximum ultrafiltration volume (UFVSBIA) was 108 ± 68 min, and the mean value of the maximum ultrafiltration volume (Max UFVSBIA) was 1.16 ± 0.60 L.

CONCLUSION

The segmental bioelectrical impedance technique can be used to assess the intraperitoneal ultrafiltration volume of peritoneal dialysis patients in real-time and effectively. This method may guide the dialysis fluid retention time and the maximum ultrafiltration volume in PD patients.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Phase angle and extracellular water-to-total body water ratio estimated by bioelectrical impedance analysis are associated with levels of hemoglobin and hematocrit in patients with diabetes

Background

Anemia is one of the common complications of diabetes and is associated with mortality. Phase angle (PhA), ratio of extracellular water to total body water (ECW/TBW) and skeletal muscle mass index (SMI) estimated by bioelectrical impedance analysis (BIA) have been used as prognostic indicators for various chronic diseases and frailty. We aimed to clarify the clinical significance of PhA, ECW/TBW and SMI for anemia in patients with diabetes.

Materials and methods

The values of PhA, ECW/TBW and SMI were estimated by a portable BIA device and blood samples were collected in 371 Japanese patients with diabetes. The relationships of PhA, ECW/TBW and SMI with hemoglobin (Hgb) and hematocrit (Hct) were statistically evaluated.

Results

In simple linear regression analysis, PhA and SMI were positively correlated with Hgb and Hct levels in total subjects, male subjects and female subjects. In contrast, ECW/TBW was negatively correlated with Hgb and Hct levels regardless of sex. Multivariate regression analysis showed that both PhA and ECW/TBW but not SMI independently contributed to Hgb and Hct levels after adjustment of clinical confounding factors in both males and females.

Conclusions

PhA and ECW/TBW but not SMI were associated with levels of Hgb and Hct in patients with diabetes. Therefore, aberrant values of PhA and ECW/TBW suggest a risk of anemia in diabetic patients.

Detecting low-intake dehydration using bioelectrical impedance analysis in older adults in acute care settings: a systematic review

BACKGROUND

Dehydration is a frequent cause of excess morbidity and poor health outcomes, particularly in older adults who have an increased risk of fluid loss due to renal senescence, comorbidities, and polypharmacy. Detecting dehydration is key to instigating treatment to resolve the problem and prevent further adverse consequences; however, current approaches to diagnosis are unreliable and, as a result, under-detection remains a widespread problem. This systematic review sought to explore the value of bioelectrical impedance in detecting low-intake dehydration among older adults admitted to acute care settings.

METHODS

A literature search using MEDLINE, EMBASE, CINAHL, Web of Science, and the Cochrane Library was undertaken from inception till May 2022 and led to the eventual evaluation of four studies. Risk of bias was assessed using the Cochrane tool for observational studies; three studies had a high risk of bias, and one had a low risk. Data were extracted using systematic proofs. Due to insufficient reporting, the data were analysed using narrative synthesis.

RESULTS

One study showed that the sensitivity and specificity of bioelectrical impedance in detecting low-intake dehydration varied considerably depending on the total body water percentage threshold used to ascertain dehydration status. Other included studies supported the technique's utility when compared to conventional measures of hydration status.

CONCLUSIONS

Given the scarcity of literature and inconsistency between findings, it is not possible to ascertain the value of bioelectrical impedance for detecting low-intake dehydration in older inpatients.

Feasibility study using longitudinal bioelectrical impedance analysis to evaluate body water status during fluid resuscitation in a swine sepsis model

Fluid resuscitation is crucial in the initial management of sepsis; however, little is known about the serial changes and overall distribution of fluids administered into the body. To identify the feasibility of longitudinal bioelectrical impedance analysis during fluid treatment, a preclinical porcine model of Escherichia coli-induced sepsis was used. After sepsis induction, pigs were treated with fluid and vasopressors and monitored for up to 12 h after bacterial infusion or until death. Bipolar electrodes for bioelectrical impedance analysis were attached to the left extremities and measurements were performed every 10 min. Among the 12 subjects, 7 pigs expired during the experiment, and the median survival was 9.5 h. As sepsis progressed with an increase in cumulative fluid balance, R₀ [∝ 1/extracellular water (ECW)] decreased, while R_i [∝ 1/intracellular water (ICW)] and ratio of extracellular water to total body water (ECW/TBW) increased. The phase angle constantly decreased throughout the monitoring period, and all non-survivors died when the phase angle decreased by more than 10%. Among the variables, ΔR₀ and Δphase angle showed moderate negative correlations, and ΔECW/TBW showed a moderate positive correlation with the hourly fluid balance. Compared to survivors, a greater increase in ΔECW/TBW and a decrease in phase angle were observed in non-survivors over time, with an increase in cumulative fluid balance. Differences in ΔECW/TBW and phase angle emerged at 240 min when the difference in cumulative fluid balance between the two groups (survivors vs non-survivors) exceeded 1000 mL. In conclusion, continuous measurements of bioelectrical impedance analysis in a porcine sepsis model are feasible and may reflect changes in the body water profile during fluid resuscitation.

Total body water/fat-free mass ratio as a valuable predictive parameter for mortality in maintenance hemodialysis patients

Hydration of fat-free mass (FFM), defined as the ratio of total body water (TBW) to FFM (TBW/FFM), is stable at 0.739 in adult mammals. However, an increase in the TBW/FFM ratio is common in hemodialysis (HD) patients. This study aimed to evaluate the determinants of TBW/FFM and investigate its predictive value for the prognosis of all-cause mortality in HD patients. We enrolled patients undergoing maintenance HD between July 2020 and May 2021. All patients were prospectively followed until death, HD dropout, or until the end of the study (November 1, 2021). A forward stepwise multivariable linear regression analyses was performed to test the independent relationship between TBW/FMM and other clinical variables. Receiver operating characteristic (ROC) analysis was used to discriminate the TBW/FFM with respect to 180-day mortality. Of the 106 patients, 42 had elevated TBW/FFM levels. Multiple linear regression analysis revealed that the TBW/FFM ratio was significantly associated with extracellular water (ECW)/TBW (standardized regression coefficient [β = 1.131, P < .001], phase angle (PhA) [β = 0.453, P < .001], and sex (β = 0.440, P < .001). We calculated the ROC curve (AUC) of TBW/FFM, ECW, ECW/TBW, and intracellular water (ICW) to compare the discriminatory capacities of these parameters in predicting 180-day mortality. The AUC for TBW/FFM (AUC = 0.849; 95% CI, 0.745-0.953) exhibited better discriminatory potential than ECW (AUC = 0.562; 0.410-0.714), although it had a similar predictive potential as the ECW/TBW ratio (AUC = 0.831; 0.731-0.932). High TBW/FFM can be used as a valuable prognostic index for predicting all-cause mortality in patients on HD.

Preoperative Phase Angle as a Risk Indicator in Cardiac Surgery-A Prospective Observational Study

Background: The phase angle (PhA) can be used for prognostic assessments in critically ill patients. This study describes the perioperative course of PhA and associated risk indicators in a cohort of elective cardiac surgical patients. Methods: The PhA was measured in 168 patients once daily until postoperative day (POD) seven. Patients were split into two groups depending on their median preoperative PhA and analyzed for several clinical outcomes; logistic regression models were used. Results: The PhA decreased from preoperative (6.1° ± 1.9°) to a nadir on POD 2 (3.5° ± 2.5°, mean difference −2.6° (95% CI, −3.0°; −2.1°; p < 0.0001)). Patients with lower preoperative PhA were older (71.0 ± 9.1 vs. 60.9 ± 12.0 years; p < 0.0001) and frailer (3.1 ± 1.3 vs. 2.3 ± 1.1; p < 0.0001), needed more fluids (8388 ± 3168 vs. 7417 ± 2459 mL, p = 0.0287), and stayed longer in the ICU (3.7 ± 4.5 vs. 2.6 ± 3.8 days, p = 0.0182). Preoperative PhA was independently influenced by frailty (OR 0.77; 95% CI 0.61; 0.98; p = 0.0344) and cardiac function (OR 1.85; 95%CI 1.07; 3.19; p = 0.028), whereas the postoperative PhA decline was independently influenced by higher fluid balances (OR 0.86; 95% CI 0.75; 0.99; p = 0.0371) and longer cardiopulmonary bypass times (OR 0.99; 95% CI 0.98; 0.99; p = 0.0344). Conclusion: Perioperative PhA measurement is an easy-to-use bedside method that may critically influence risk evaluation for the outcome of cardiac surgery patients.

Effects of probiotics on cognitive and emotional functions in healthy older adults: Protocol for a double-blind randomized placebo-controlled crossover trial

Aging is a process that includes changes in cognitive and emotional functions, as well as changes in the diversity and integrity of gut microbiota. Probiotic treatments have recently been studied as a potential new therapeutic approach to alleviate a wide range of problems in other populations; however, clinical studies in older adults remain insufficient and limited. Thus, the aim of this project is to evaluate the efficacy of a multispecies probiotic formulation as a therapeutic strategy for attenuating the emotional and cognitive decline associated with aging in adults over the age of 55. This is a double-blind randomized placebo-controlled crossover trial involving at least 32 older adults and comparing two conditions: (a) probiotic, providing a multispecies probiotic for 10 weeks (Lactobacillus rhamnosus and Bifidobacterium lactis); and (b) placebo, receiving a harmless substance (potato starch). Despite the increasing use of probiotics for the treatment of cognitive and emotional problems, no study has yet focused on this group, to the best of our knowledge. Therapeutic strategies of the kind outlined in this protocol will help to shed light on the current state of knowledge about this topic, as well as promote health programs tailored to this population, which would encourage active aging and healthy lifestyles. Not only do we expect improvements in the emotional dimension in terms of anxiety, stress, depression, and sleep quality, we also expect improvements in the cognitive dimension in terms of attention, memory, and decreased impulsivity.

Features and diagnostic value of body composition in patients with late-onset multiple acyl-CoA dehydrogenase deficiency

OBJECTIVE

This study aims to analyse the body composition features and its changes after treatment in patients with late-onset multiple acyl-CoA dehydrogenase deficiency (MADD).

METHODS

Body composition was measured in patients with late-onset MADD, inflammatory myopathies, mitochondrial myopathy, and healthy controls. The correlation analyses between body composition and traditional parameters were performed. Comparisons between groups and receiver operating characteristic curve analyses were performed.

RESULTS

A total of 42 participants included 13 patients with late-onset MADD, 13 healthy controls, 10 with inflammatory myopathy, and 6 with mitochondrial myopathy. Bilateral grip strength and forced vital capacity (FVC) were moderate-strong correlated with skeletal muscle mass (right hand grip strength: r = 0.728, P < 0.001; left hand grip strength: r = 0.676, P < 0.001; FVC: r = 0.754, P < 0.001). Serum CK was moderately and negatively correlated with right hand grip strength (r = - 0.618, P = 0.005), left hand grip strength (r = - 0.630, P = 0.004), FVC (r = - 0.665, P = 0.002), manual muscle testing (MMT) (r = - 0.729, P = 0.000), and lean body mass skeletal muscle percentage (r = - 0.501, P = 0.029). Body composition features in patients with late-onset MADD were as follows: (1) obvious fat accumulation, (2) reduction of muscle mass, and (3) reduction of body water and intracellular water ratio. Some indicators of body composition were found to be valuable in diagnosis and eliminating differential diagnoses, such as visceral fat area (sensitivity 84.62%; specificity 92.31%; AUC 0.905) and fat mass (sensitivity 84.62%; specificity 75.00%; AUC 0.837). Seven patients were followed-up (2-9 months). Prior to treatment, the changes in body composition in these patients were conflicting.

CONCLUSIONS

Hand grip strength and FVC were strongly associated with body composition. Body composition features in late-onset MADD are fat accumulation, muscle loss, decrease in total body water, and intracellular water ratio. Body composition features are valuable for diagnosis and assessment.

Extracellular water to total body water ratio predicts survival in cancer patients with sarcopenia: a multi-center cohort study

BACKGROUND

Body water measured by bioelectrical impedance analysis (BIA) predicts the outcomes of many diseases. This study aimed to evaluate the relationship between body water and the prognosis of cancer patients with sarcopenia.

METHODS

This study employed 287 cancer patients with sarcopenia underwent BIA from a prospective multicenter study of patients with cancer in China from 2013 to 2020. The primary outcome of interest was all-cause mortality presented as the longest time to follow-up available. Eight indicators of body water [total body water, extracellular water, intracellular water, free fat mass, active cell mass, extracellular water/intracellular water, extracellular water/total body water (ECW/TBW), and intracellular water/total body water] were included in the research. Neutrophil-lymphocyte ratio (NLR) = neutrophil (× 109)/lymphocyte (× 109). The discriminatory ability and prediction accuracy of each factor were assessed using the C-index. The hazard ratios (HR) and 95% confidence intervals (CI) were calculated using the Cox proportional hazard model.

RESULTS

The median age was 65 years old, and 138 (48%) patients were men. During a mean follow-up of 46 months, 140 deaths were recorded, resulting in a rate of 204.6 events per 1000 patient-years. ECW/TBW showed the best predictive accuracy (C-index = 0.619) compared to the other indicators [p = 0.004, adjusted HR (95% CI) 1.70 (1.18,2.44)]. In the middle tertile (0.385-0.405), ECW/TBW had a strong independent negative association with patient survival [adjusted HR (95% CI) 2.88 (1.39-5.97), p = 0.004]. Patients who had a high ECW/TBW (ECW/TBW ≥ 0.395) combined with a high NLR had 3.84-fold risk of mortality (p < 0.001, 95% CI 1.99,7.38).

CONCLUSIONS

ECW/TBW was better than other indicators in predicting survival of cancer patients with sarcopenia. High ECW/TBW combined with high NLR would further increase the risk of mortality.

TRIAL REGISTRATION

The Investigation on Nutrition Status and Clinical Outcome of Common Cancers (INSCOC) (Chinese Clinical Trial Registry: ChiCTR1800020329, URL of registration: http://www.chictr.org.cn/showprojen.aspx?proj=31813 ).

Associations between hydration status, body composition, sociodemographic and lifestyle factors in the general population: a cross-sectional study

Background

Whole-body hydration status is associated with several health outcomes, such as dehydration, edema and hypertension, but little is known about the nonclinical determinants. Therefore, we studied the associations of sex, age, body composition, nutrition, and physical activity on several body hydration measures.

Methods

We assessed sociodemographic variables, dietary habits, and physical activity by questionnaire and body composition by bioelectric impedance analysis (BIA). We compared determinants between the sexes and calculated associations between determinants and BIVA hydration measures by multivariable linear regressions.

Results

A total of 242 adults from the general population (age 18–94, 47% women) were included. Women were younger, smaller, lighter, and had a smaller BMI (kg/m²) than men (p < 0.05). Women had less muscle mass, less visceral fat mass and less extracellular and intracellular water than men (p < 0.001). Women showed less intracellular water per extracellular water than men, while men showed higher phase angle values than women (both p < 0.001). Men had a stronger association of hydration measures with physical activity than women. Both sexes showed a decrease in hydration measures with age.

Conclusions

Sex, age, body composition, and physical activity influence body hydration. There seem to be differences in body water regulation between the sexes. Especially interesting are factors susceptible to preventive measures such as physical activity.

Comparison of Bioelectrical Impedance Vector Analysis (BIVA) to 7-point Subjective Global Assessment for the diagnosis of malnutrition

INTRODUCTION

Bioelectrical impedance vector analysis (BIVA) is a non-invasive and low-cost strategy. The methods used to assess malnutrition in patients undergoing HD are still a challenge. The aim of the present study was to compare BIVA to 7-Point Subjective Global Assessment (7-point SGA) to identify malnutrition. We also investigated the sensitivity and specificity of the previously proposed cutoffs point for BIVA parameters.

METHODS

Patients of both sexes, over 20 years of age, on HD treatment were included. Anthropometric parameters, laboratory data, and bioelectrical impedance analysis (BIA) were evaluated. Values of resistance (R) and reactance (Xc) obtained by mono-frequency BIA were normalized to body height (H) to generate a graph of the bioimpedance vector with the BIVA software. The analysis of the area under the receiver operating curve ROC (AUC) was performed.

RESULTS

Among the included 104 patients, the mean age was 51.70 (±15.10) years, and 52% were male. The BIVA had a sensitivity of 35% for diagnosing malnutrition. The specificity of BIVA for identifying the well-nourished patients was 85.7%. The diagnostic accuracy between the BIVA and 7-point SGA was AUC=0.604; 95%CI 0.490-0.726, higher than the previously established cutoff values (AUC=0.514; 95%CI: 0.369-0.631). The 95% confidence ellipses did not overlap (p<0.05).

CONCLUSION

Our study showed low accuracy of BIVA for diagnosing malnutrition using a 7-point SGA as a reference standard. However, it is a complementary method for assessing nutritional status as it provides data on cellularity and hydration, which are important aspects for the HD population.

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

BACKGROUND & AIMS

Measurement of total body electrical resistance (TBER) to an alternating current is useful to monitor extracellular water (ECW) in patients on hemodialysis (HD). Which current frequency is preferable is subject of ongoing debate. The aim of this study was to quantify the implications of TBER measurements at current frequencies ranging from 0 to 1000 kHz for ECW monitoring in patients on HD.

METHODS

Bioimpedance spectroscopy measurements were performed in 39 patients on HD using the Body Composition Monitor (BCM, Fresenius Medical Care). TBER data at 5, 50, 200, 500, and 1000 kHz were compared with the extrapolated TBER at 0 kHz (TBER₀) assessed by Cole-Cole analysis. Sensitivity of each TBER configuration was evaluated at individual level, by assessment of the smallest ultrafiltration (UF) volume that induced a significant change in TBER, i.e. a change in TBER ≥ 2.7%.

RESULTS

TBER precision was very high for all frequencies, with coefficients of variation of 0.25%-0.28%. Baseline TBER decreased with increasing current frequency. TBER was 2.9% lower at 5 kHz (P < 0.001), 11.6% lower at 50 kHz, and up to 22.0% lower at 1000 kHz. This pattern is attributed to a progressive increase in intracellular current conduction at higher frequencies. Sensitivity to volume changes induced by UF also decreased with increasing current frequency. At 0 and 5 kHz, an UF volume ≤ 0.5 L was sufficient to induce a significant increase in TBER in 87% of patients. This decreased to 69% at higher frequencies.

CONCLUSION

ECW monitoring by TBER requires measurement at 5 kHz or less to ensure optimal performance.

Trunk Muscle Mass Measured by Bioelectrical Impedance Analysis Reflecting the Cross-Sectional Area of the Paravertebral Muscles and Back Muscle Strength: A Cross-Sectional Analysis of a Prospective Cohort Study of Elderly Population

Trunk muscles play an important role in supporting the spinal column. A decline in trunk muscle mass, as measured by bioelectrical impedance analysis (TMM-BIA), is associated with low back pain and poor quality of life. The purpose of this study was to determine whether TMM-BIA correlates with quantitative and functional assessments traditionally used for the trunk muscles. We included 380 participants (aged ≥ 65 years; 152 males, 228 females) from the Shiraniwa Elderly Cohort (Shiraniwa) study, for whom the following data were available: TMM-BIA, lumbar magnetic resonance imaging (MRI), and back muscle strength (BMS). We measured the cross-sectional area (CSA) and fat-free CSA of the paravertebral muscles (PVM), including the erector spinae (ES), multifidus (MF), and psoas major (PM), on an axial lumbar MRI at L3/4. The correlation between TMM-BIA and the CSA of PVM, fat-free CSA of PVM, and BMS was investigated. TMM-BIA correlated with the CSA of total PVM and each individual PVM. A stronger correlation between TMM-BIA and fat-free CSA of PVM was observed. The TMM-BIA also strongly correlated with BMS. TMM-BIA is an easy and reliable way to evaluate the trunk muscle mass in a clinical setting.

Association of an Overhydrated State With the Liver Fibrosis and Prognosis of Cirrhotic Patients

BACKGROUND/AIM

A bioimpedance analysis (BIA) can indicate an overhydrated state as the extracellular water/total body water (ECW/TBW) value. This study aimed to assess the clinical significance of this value in patients with chronic liver diseases (CLDs).

PATIENTS AND METHODS

A total of 552 CLD patients who received a liver biopsy and underwent anthropometric assessment and BIA-based body composition analysis were enrolled. The association of the ECW/TBW value with the liver fibrosis and nutritional status was assessed. The relationship between the ECW/TBW value and the prognosis of cirrhotic patients (N=209) was also evaluated.

RESULTS

The ECW/TBW value increased as liver fibrosis progressed and was also related to decreased muscle mass/sarcopenia. The presence of overhydration was associated with a poor prognosis of cirrhotic patients.

CONCLUSION

An increased ECW/TBW value was associated with progressive liver fibrosis and malnutrition and related to the prognosis of cirrhotic patients.

Comparison of Multi-Frequency Bioelectrical Impedance and Dual-Energy X-Ray Absorptiometry to Assess Body Composition in College-Aged Adults

The purpose of this study was to evaluate the validity of whole body percent fat (%BF) and segmental fat-free mass (FFM) using multi-frequency bioelectrical impedance analysis (MF-BIA) and dual-energy x-ray absorptiometry (DEXA) in college-aged adults. Sixty-two participants male (n = 32) and female (n = 30) completed MF-BIA and DEXA measurements following established pre-test guidelines. %BF and segmental FFM (right arm, left arm, trunk, right leg, and left leg) were collected and analyzed. The MF-BIA significantly (p < 0.05) underestimated %BF for all participants, females, and males compared to DEXA. In addition, MF-BIA significantly (p < 0.05) underestimated FFM in the arms and legs in all participants and males with the exception of the left arm in all subjects while significantly overestimating FFM in the trunk. In females, the MF-BIA overestimated FFM in the arms and trunk while significantly (p < 0.05) underestimating FFM in the legs. Difference plots also indicated that the underestimation of FFM from MF-BIA in the arms and legs increased as the amount of FFM increased. Thus, our findings suggested that the MF-BIA may not be accurate for measuring whole %BF and segmental FFM in the college-aged population.

Bioelectrical impedance analysis for perioperative water management in adult cardiovascular valve disease surgery

PURPOSE

Bioelectrical impedance analysis (BIA) has been used recently to measure the body water of patients with acute heart failure. We used BIA in this study to better understand, and possibly identify a predictive marker for, perioperative water behavior in cardiac surgery patients.

METHODS

We measured body water and studied its behavior in 44 patients undergoing surgery for cardiac valvular disease at our hospital. Measurements included the levels of extracellular water (ECW), intracellular water (ICW), and total body water, the edema index (EI), and the ratio of ECW to total body water. The first measured EI was defined as the "preoperative EI" and the maximum as the "peak EI".

RESULTS

A negative correlation was found between the preoperative EI and the preoperative estimated glomerular filtration rate (eGFR) (R = 0.644, p < 0.001). Positive correlations were found between the peak EI and the ICU stay (R = 0.625, p < 0.001), the peak EI and the ventilation time (R = 0.366, p < 0.01), and the preoperative EI and the ICU stay (R = 0.464, p = 0.026).

CONCLUSION

The EI is possibly a predictive marker for perioperative water management in cardiac surgery.

Association of bioelectric impedance analysis body composition and disease severity in COVID-19 hospital ward and ICU patients: The BIAC-19 study

Background

The current severe acute respiratory syndrome coronavirus 2 pandemic is unprecedented in its impact. It is essential to shed light on patient characteristics that predispose to a more severe disease course. Obesity, defined as a BMI>30 kg/m², is suggested to be one of these characteristics. However, BMI does not differentiate between fat mass and lean body mass, or the distribution of fat tissue. The aim of the present study was to assess the body composition of COVID-19 patients admitted to the ward or the ICU and identify any associations with severity of disease.

Methods

We performed an observational cross-sectional cohort study. Bioelectric impedance analysis was conducted amongst all confirmed COVID-19 patients admitted to the ward or ICU of our hospital in the Netherlands, between April 10 and 17, 2020. Body water measurements and derived values were recalculated to dry weight, using a standard ratio of extracellular water to total body water of 0.38. Data were compared between the ward and ICU patients, and regression models were used to assess the associations between baseline characteristics, body composition, and several indicators of disease severity, including a composite score composed of mortality, morbidity, and ICU admission.

Results

Fifty-four patients were included, of which 30 in the ward and 24 in the ICU. The mean age was 67 years (95%-CI 64–71), and 34 (63%) were male. Mean BMI was 29.7 (95%-CI 28.2–31.1) kg/m² and did not differ between groups. Body composition values were not independently associated with disease severity. In multiple logistic regression analyses, a low phase angle was associated with COVID-19 severity in the composite score (OR 0.299, p = 0.046).

Conclusion

We found no significant associations between body composition, including fat mass, visceral fat area, and fat-free mass, and disease severity in our population of generally overweight COVID-19 patients. A lower phase angle did increase the odds of severe COVID-19. We believe that factors other than body composition play a more critical role in the development of severe COVID-19.

Evaluating of altered hydration status on effectiveness of body composition analysis using bioelectric impedance analysis

Body composition analysis may provide valuable information about the assessment of balance between fluid, fat, and fat-free mass. The present study assessed whether the regular increase in water consumption has any significant effects on measurements of body composition using BIA. A total of 140 subjects participated in this study. Body composition analyses of the subjects were performed for five times using foot to foot BIA; first at baseline and four times, after 15 minutes of each 500 mL water intakes. There was overestimation in body fat mass compared to the baseline and increased significantly after water intakes in males (2.08% in 500 mL, 3.80% in 1000 mL, 5.88% in 1500 mL, and 7.92% in 2000 mL, p < 0.05) and in females (3.4% in 500 mL, 5.7% in 1000 mL, 7.8% in 1500 mL, and 9.4% in 2000 mL, p < 0.05). In contrast, there was markedly underestimation of total body water and fat-free mass in males (35% and 50%) and females (17% and 22%), respectively, at the end of the study. Thus, overestimation of body fat mass and lower estimation of total body water and fat-free mass with closely to the amount of water retention using BIA application should be considered in health-related clinical practice.

Phase Angle Evaluation of Lung Disease Patients and Its Relationship with Nutritional and Functional Parameters

BACKGROUND

This study aimed to determine the value of phase angle (PhA) in patients with chronic obstructive pulmonary disease (COPD) and pulmonary hypertension (PH) and its association with nutritional and functional parameters.

METHODS

A cross-sectional study of 77 patients under follow-up at the pulmonary outpatient clinic of a public hospital. Anthropometric measurements and functional assessments of physical and pulmonary capacity were performed, and a regular physical activity questionnaire was administered.

RESULTS

The sample consisted of 38 patients with COPD (mean age, 63.8 ± 9.9 years; 68.4% female) and 39 patients with PH (mean age, 46.6 ± 14.4 years; 79.5% female). There was no difference in anthropometric measurements between patients with COPD and PH. Patients with COPD had mild to moderate limitations of pulmonary function, while patients with PH had only mild limitations (p < 0.01). Although the median distance covered in the 6-minute walk test (6MWT) was different between the COPD and PH groups (p < 0.05), it was considered adequate for these populations. Mean PhA was within the range considered adequate in patients with COPD (6.3°±1°) and PH (6.2°±0.8°) (p > 0.05). In the statistical analyses, although the correlations were weak, adequate PhA correlated with fat free mass index, 6MWT, disease staging, forced vital capacity, and forced expiratory volume in the first second.

CONCLUSION

The anthropometric profile of both patient groups was very similar, and PhA values were within the expected range. Despite weak correlations, PhA is a clinical component to be followed and investigated in patients with lung disease.

An update review of intradialytic hypotension: concept, risk factors, clinical implications and management

Intradialytic hypotension (IDH) is a frequent and serious complication of chronic haemodialysis, linked to adverse long-term outcomes including increased cardiovascular and all-cause mortality. IDH is the end result of the interaction between ultrafiltration rate (UFR), cardiac output and arteriolar tone. Thus excessive ultrafiltration may decrease the cardiac output, especially when compensatory mechanisms (heart rate, myocardial contractility, vascular tone and splanchnic flow shifts) fail to be optimally recruited. The repeated disruption of end-organ perfusion in IDH may lead to various adverse clinical outcomes affecting the heart, central nervous system, kidney and gastrointestinal system. Potential interventions to decrease the incidence or severity of IDH include optimization of the dialysis prescription (cool dialysate, UFR, sodium profiling and high-flux haemofiltration), interventions during the dialysis session (midodrine, mannitol, food intake, intradialytic exercise and intermittent pneumatic compression of the lower limbs) and interventions in the interdialysis period (lower interdialytic weight gain and blood pressure–lowering drugs). However, the evidence base for many of these interventions is thin and optimal prevention and management of IDH awaits further clinical investigation. Developing a consensus definition of IDH will facilitate clinical research. We review the most recent findings on risk factors, pathophysiology and management of IDH and, based on this, we call for a new consensus definition of IDH based on clinical outcomes and define a roadmap for IDH research.

Improved Outcomes in Hemodialysis/Hemodiafiltration Treatments Applying Exercise and Physiological Monitoring Techniques: Preliminary Results

End-stage renal disease affects millions of people worldwide, and the only definitive solutions are renal transplants that are not widely available. Temporary solutions are renal replacement therapies such as peritoneal dialysis, hemodialysis and hemodiafiltration. These therapies as they are applied today are just partial measures and have many drawbacks and complications such as high mortality rates and high costs due to the use of supplemental drugs and emergency room visits. Many enhancements to the therapies have been published, but they are not applied consistently in real world practice. Our work presents the results from the systematic application of several techniques to provide individualized therapies that can minimize the drawbacks and improve patient outcomes. This approach is based on the use of exercise, analysis of cardiovascular parameters, such as heart-rate variability, body composition and dry weight measurements through the use of bioimpedance and real-time monitoring of energy expenditure and nutrition intradialytically in order to provide individualized and dynamically variable therapies. Results show that patients can lead long, productive lives while maintaining a quality of life equivalent to that of a renal transplant.

Collapse of Fluid Balance and Association with Survival in Patients with Advanced Cancer Admitted to a Palliative Care Unit: Preliminary Findings

Background: Few studies have investigated water balance as a predictor of survival in cancer patients in the last days of life. Objective: To examine the association between extracellular water (ECW), intracellular water (ICW), ratio of ECW to ICW (ECW/ICW), and survival in nonedematous and edematous patients with advanced cancer admitted to a palliative care unit. Design: A prospective observational study. Setting/Subjects: Patients with advanced cancer admitted to a palliative care unit. Measurements: Upon enrollment, bioelectrical impedance analysis was used to assess ECW, ICW, and body composition. We conducted time-to-event analyses using the Kaplan-Meier method, log-rank test, and univariate and multivariate Cox regression analyses. Results: A total of 190 of 204 patients who participated in this study had ICW and ECW measures available for analysis. The median survival was 10 days (95% confidence interval [CI] 9-12) days. The median ECW, ICW, and ECW/ICW were 18.9 L, 19.1 L, and 1.0 for 72 nonedematous patients, and 21.9 L, 20.1 L, and 1.1 for 118 edematous patients, respectively. In univariate Cox regression analysis, ICW ≤20 L was associated with a shorter survival in the nonedematous patients (hazard ratio [HR] 1.92, 95% CI 1.10-3.34, p = 0.02) and a longer survival in the edematous patients (HR 0.61, 95% CI 0.41-0.90, p = 0.01). In multivariable analysis, ICW (≤20 L vs. >20 L) remained an independent prognostic factor in edematous patients (HR 0.64, 95% CI 0.43-0.95, p = 0.03). Conclusions: Greater ICW was an independent predictor of poorer survival in cancer patients with edema in the last days of life.