Whole-body and segmental bioelectrical-impedance analysis in patients with cirrhosis of the liver: changes after treatment of ascites

Psoas muscle index predicts time to rehospitalization in liver cirrhosis: An observational study

Sarcopenia is frequent in liver cirrhosis (LC) where it is associated with morbidity and mortality. However, prognostic scores such as model for end-stage liver disease (MELD), MELD-sodium (MELD-Na), or Child-Turcotte-Pugh (CTP) do not contain sarcopenia as a variable. For this study, we utilized psoas muscle index (PMI) to objectively determine sarcopenia in hospitalized LC patients, and evaluated it as a predictor of time between discharge and readmission in LC. Abdominal computed tomography and magnetic resonance imaging scans of 65 consecutive LC patients were retrospectively examined to determine PMI. MELD, MELD-Na, and CTP were calculated from clinical data. PMI was then combined with CTP to form an experimental score: CTP sarcopenia (CTPS). For PMI alone and for each score, correlation with time between discharge and readmission for liver-related complications was calculated. PMI was also tested for correlation with sex, body mass index (BMI), MELD, MELD-Na, and CTP. CTPS was most closely correlated with time to readmission (R = 0.730; P < .001), followed by CTP (R = 0.696; P < .001), MELD-Na (R = 0.405; P = .009), and PMI alone (R = 0.388; P = .01). Correlation with MELD (R = 0.354; P = .05) was lowest. Additionally, there were significant differences in PMI between male and female individuals (5.16 vs 4.54 cm2/m2; P = .04) and in BMI between sarcopenic and nonsarcopenic individuals (29.63 vs 25.88 kg/m2; P = .009). Sarcopenia is an independent short-term prognostic factor in LC. By combining data on sarcopenia with CTP, we created an experimental score that predicts time to readmission better than MELD, MELD-Na, or CTP.

Quantification of Abdominal Muscle Mass and Diagnosis of Sarcopenia with Cross-Sectional Imaging in Patients with Polycystic Kidney Disease: Correlation with Total Kidney Volume

Background: Polycystic kidney disease (PKD) is an inherited disorder characterized by renal cysts that may mask lean body loss. This study quantified and compared muscle mass by using computed tomography (CT) and magnetic resonance imaging (MRI) images between the PKD and control groups and correlated muscle mass with total kidney volume (TKV). Methods: We retrospectively enrolled patients who had a new diagnosis of PKD from May 2015 to May 2016. The CT and MRI images at the third lumbar level were processed to measure the total abdominal muscle (TAM) area for the diagnosis of sarcopenia, and TKV was estimated using the ellipsoid formula. Results: We included 37 women and 25 men (mean age: 50.40 years) in the PKD group. There was no difference in body mass index and albumin levels, but significant differences in creatinine level (p < 0.001), TAM area (p = 0.047), and TKV (p < 0.001), were noted between the two groups. A significantly negative correlation was observed between TKV and TAM area after adjustment for body height (r = −0.217, p = 0.003). Conclusions: CT and MRI images can accurately diagnose sarcopenia, which may be masked by cysts in patients with PKD.

Sarcopenia in Hepatocellular Carcinoma: Pathogenesis and Management

BACKGROUND

Sarcopenia is almost constantly observed in patients with cirrhosis and hepatocellular carcinoma.

SUMMARY

Chronic liver disease represents a unique pathophysiological scenario in which sarcopenia develops and all factors involved in the pathogenesis should be taken into account for an appropriate management of the disease. No properly designed intervention studies on this topic are available and, thus, no effective strategies have been developed for clinical practice. Apart from any targeted intervention, treatment and optimization of liver disease is crucial. Key Messages: In patients with cirrhosis and hepatocellular carcinoma, nutritional support to maintain and restore nutrition status, a targeted use of branched-chain amino acids and a guided physical exercise, should all be an integral part of the multidimensional assessment and tailored interventions.

Bioelectrical impedance analysis for predicting postoperative complications and survival after liver resection for hepatocellular carcinoma

Background

Bioelectrical impedance analysis provides information on body composition and nutritional status. However, it's unclear whether the preoperative edema index or phase angle predicts postoperative complication or mortality in patients with hepatocellular carcinoma (HCC). Thus, we investigated whether preoperative bioelectrical impedance analysis could predict postoperative complications and survival in patients with HCC.

Methods

Seventy-nine patients who underwent hepatectomy for hepatocellular carcinoma were prospectively enrolled and bioelectrical impedance analysis was performed before surgery. Postoperative ascites or acute kidney injury and patients' survival were monitored after surgery.

Results

Among 79 patients, 35 (44.3%) developed ascites or acute kidney injury after hepatectomy. In multivariate analysis, a high preoperative edema index (extracellular water/total body water) (>0.384) (odds ratio 3.96; 95% confidence interval: 1.03-15.17; P=0.045) and higher fluid infusion during surgery (odds ratio 1.36; 95% confidence interval: 1.04-1.79; P=0.026) were identified as significant risk factors for ascites or acute kidney injury after hepatectomy. Subgroup analyses showed that the edema index was a significant predictor of ascites or acute kidney injury in patients with cirrhosis. Tumor size was the only significant predictive factor for short-term survival after hepatectomy.

Conclusions

The preoperative edema index using bioelectrical impedance analysis can be used as a predictor of post-hepatectomy complication, especially in patients with liver cirrhosis.

Reproducibility of Bioelectrical Impedance Analysis in Pregnancy and the Association of Body Composition with the Risk of Gestational Diabetes: A Substudy of MUMS Cohort

Introduction

Bioelectrical impedance analysis (BIA) is a rapid and noninvasive method of body composition analysis; however, reproducibility between BIA instruments in pregnancy is uncertain. Adverse maternal body composition has been linked to pregnancy complications including gestational diabetes mellitus (GDM). This study aimed to evaluate the reproducibility of three BIA instruments in pregnancy and analyse the relationship between the body composition and the GDM risk.

Methods

A prospective cohort (n = 117) of women with singleton pregnancies participating in the Microbiome Understanding in Maternity Study (MUMS) at St. George Hospital, Sydney, Australia. Anthropometric measurements and BIA body composition were measured at ≤13 weeks (T1), 20-24 weeks (T2), and 32-36 weeks (T3) of gestation. Body fat percentage (BFP), total body water (TBW), and impedance were estimated by three BIA instruments: Bodystat 1500, RJL Quantum III, and Tanita BC-587. GDM status was recorded after 75 g oral glucose tolerance test was performed at 28 weeks or earlier. Agreement between BIA instruments was assessed using Bland-Altman analysis. Logistic regression modelling explored associations of BFP with GDM.

Results

Method comparison reproducibility between Bodystat and RJL was stronger than between Bodystat and Tanita for both BFP and TBW% at all three time points. RJL overestimated BFP on average by 3.3% (p < 0.001), with limits of agreement within ±5% for all trimesters. Average BFP was not significantly different between Tanita and Bodystat although limits of agreement exceeded ±5%. GDM diagnosis was independently associated with increased BFP in T1 (adjusted OR 1.117 per 1% increase; 95% CI 1.020-1.224; p=0.017) and in T2 (adjusted OR 1.113 per 1% increase; 95% CI 1.010-1.226; p=0.031) and with Asian ethnicity in all models (OR 7.4-8.1).

Conclusion

Reproducibility amongst instruments was moderate; therefore, interchangeability between instruments, particularly for research purposes, cannot be assumed. In this cohort, GDM risk was modestly associated with increasing BFP and strongly associated with Asian ethnicity.

The association of the serum levels of myostatin, follistatin, and interleukin-6 with sarcopenia, and their impacts on survival in patients with hepatocellular carcinoma

Background/Aims

The role of serum myokine levels in sarcopenia and the outcome of hepatocellular carcinoma (HCC) patients are not clear. This study investigated the serum levels of myostatin, follistatin, and interleukin-6 (IL-6) in HCC patients and their association with sarcopenia and survival.

Methods

Using prospectively collected pretreatment samples from 238 HCC patients in a hospital from 2012 to 2015, the serum levels of 3 myokines were determined and compared to 50 samples from age and sex-matched healthy controls. Sarcopenia was evaluated using the psoas muscle index (PMI) measured at the third lumbar level in the computed tomography, and clinical data were collected until 2017.

Results

The median levels of the 3 myokines for the male and female HCC patients were as follow: myostatin (3,979.3 and 2,976.3 pg/mL), follistatin (2,118.5 and 2,174.6 pg/mL), and IL-6 (2.5 and 2.7 pg/mL), respectively. Those in the HCC patients were all significantly higher than in the healthy controls. In the HCC patient, the median PMI was 4.43 (males) and 2.17 cm²/m² (females) with a sarcopenic prevalence of 56.4%. The serum levels of myostatin, IL-6 and follistatin in the HCC patients showed a positive, negative, and no correlation with PMI, respectively. The serum follistatin level was an independent factor for poor survival in HCC patients.

Conclusions

The serum levels of myostatin, follistatin, and IL-6 and their correlation with sarcopenia and survival were presented in HCC patients for the first time. The role of the serum follistatin level as a poor prognostic biomarker warrants further study.

Measurement of Fluid Shift in Capd Patients Using Segmental Bioelectrical Impedance Analysis

Objective

To determine, using segmental bioelectrical impedance analysis (BIA), the characteristics of fluid shift of each body segment in continuous ambulatory peritoneal dialysis (CAPD) patients during and after peritoneal dialysis (PD) solution exchange.

Design

Observational study with repeated measurements of bioelectrical impedance, which is inversely related to tissue fluid content.

Patients

Thirteen clinically stable CAPD patients.

Methods

Bioelectrical impedance was measured at frequencies of 5, 50, 250, and 500 kHz in each body segment four times: (1) before and (2) after drainage of dialysate, and (3) at 1 hour and (4) at 2 hours after exchange of new 1.5% dextrose PD solution.

Results

Impedance of both arms was significantly increased at 1 hour post exchange at all frequencies. In the trunk, impedance at all frequencies increased significantly after drainage, decreased significantly at 1 hour post exchange, and then increased again for the next hour without significance. Impedance of both legs showed a decreasing tendency at all frequencies during and after exchange. Net calculated water volume changes between the time before drainage and 2 hours post exchange were –0.5 L in the trunk, –0.25 L in both arms, +0.47 L in both legs, –0.28 L in total. The change in body weight between the time before drainage and 2 hours post exchange was –0.21 kg, on average, and significantly correlated with total net calculated water volume change ( p = 0.009).

Conclusions

Each body segment of the CAPD patient has its own characteristic pattern of fluid shift in response to PD solution exchange or dwell. Segmental BIA may be a useful tool for understanding the physiological changes in fluid shift in CAPD patients.

Bioimpedance spectroscopy for fluid status assessment in patients with decompensated liver cirrhosis: Implications for peritoneal dialysis

Bioimpedance spectroscopy (BIS) is routinely used in peritoneal dialysis patients and might aid fluid status assessment in patients with liver cirrhosis, but the effect of ascites volume removal on BIS-readings is unknown. Here we determined changes in BIS-derived parameters and clinical signs of fluid overload from before to after abdominal paracentesis. Per our pre-specified sample size calculation, we studied 31 cirrhotic patients, analyzing demographics, labs and clinical parameters along with BIS results. Mean volume of the abdominal paracentesis was 7.8 ± 2.6 L. From pre-to post-paracentesis, extracellular volume (ECV) decreased (20.2 ± 5.2 L to 19.0 ± 4.8 L), total body volume decreased (39.8 ± 9.8 L to 37.8 ± 8.5 L) and adipose tissue mass decreased (38.4 ± 16.0 kg to 29.9 ± 12.9 kg; all p < 0.002). Correlation of BIS-derived parameters from pre to post-paracentesis ranged from R² = 0.26 for body cell mass to R² = 0.99 for ECV. Edema did not correlate with BIS-derived fluid overload (FO ≥ 15% ECV), which occurred in 16 patients (51.6%). In conclusion, BIS-derived information on fluid status did not coincide with clinical judgement. The changes in adipose tissue mass support the BIS-model assumption that fluid in the peritoneal cavity is not detectable, suggesting that ascites (or peritoneal dialysis fluid) mass should be subtracted from adipose tissue if BIS is used in patients with a full peritoneal cavity.

Bioelectrical Impedance Analysis for Monitoring Fluid and Body Cell Mass Changes in Patients Undergoing Cardiopulmonary Bypass

OBJECTIVE

To evaluate preoperative and postoperative body fluid distribution with a bioelectrical impedance analyzer in patients undergoing cardiopulmonary bypass.

METHODS

Fifteen adult patients undergoing cardiopulmonary bypass were included in this study. Total body fluid changes, basal metabolism rates, body fat masses, lean body masses, and total cell masses were recorded. The patients' values were measured before anesthesia, after anesthesia, after sternotomy, at the 5th, 30th, and 60th minutes of cardiopulmonary bypass, and on the 1st, 3rd, and 5th postoperative days. All values were compared with preoperative values.

RESULTS

Total body fluid changed significantly after cardiopulmonary bypass (P<0.01). Metabolic velocity significantly changed compared to preoperative measurements (P<0.05). Fat mass and lean body mass also changed significantly. Body mass index and phase angle did not change significantly (P>0.05).

CONCLUSION

Changes in body fluids during and after cardiopulmonary bypass are inevitable. The increase in total body weight shows that this fluid load shifts to the extracellular space during bypass and the fluid load in this area passes into the intravascular area in the early postoperative period. This may cause edema and dysfunction in the major organs. Therefore, the fluid balance should be adjusted very carefully, especially during the bypass phase and the early postoperative period.

Longitudinal changes and correlations of bioimpedance and anthropometric measurements in pregnancy: Simple possible bed-side tools to assess pregnancy evolution

PURPOSE

The aim of this study was to assess longitudinal changes of bioimpedance analysis compared with anthropometric measurements in low-risk pregnant woman recruited in the first trimester and to observe possible differences in these indices in women who developed high-risk pregnancies.

MATERIALS AND METHODS

Bioimpedance indices for the three trimesters of pregnancies were calculated separately for uneventful pregnancies delivered of newborns > the 10th centile. These findings were compared with anthropometric measurements. Data of women who developed hypertensive disorders of pregnancy (HDP) or delivered SGA newborns were calculated and compared.

RESULTS

Significantly longitudinal increases were observed in these pregnancies for total body water (TBW), free fat mass, fat mass, and extra-cellular water. These increases were paralleled body mass index (BMI), skinfolds, and waist measurements. The correlations between these two sets of findings were poor. Women who developed HDP with AGA fetuses showed significantly different bioimpedance from normal cases. TBW indices were highly significantly different since the first trimester. In pregnancies delivered of SGA newborns, these indices were opposite of the values observed in patients with HDP-AGA, TBW in these patients was significantly reduced compared with normal pregnancies.

CONCLUSIONS

The bioelectrical impedance is a fast, simple, noninvasive way to assess the TBW content in pregnancy. Our findings are in agreement with the hypothesis that bioimpedance might help to identify early in gestation patients at risk of developing different clinical phenotypes of hypertensive disease of pregnancy and SGA fetuses.

Safety and efficacy of long-term tolvaptan therapy for decompensated liver cirrhosis

AIM

Recently, the short-term efficacy of the vasopressin V2 receptor antagonist tolvaptan for the treatment of ascites in cirrhosis was reported. However, the long-term effects remain unknown. Here, we report the clinical features of decompensated cirrhosis treated using long-term tolvaptan therapy, and evaluate its safety and efficacy.

METHODS

Fifty-five cirrhotic patients hospitalized due to ascites, despite receiving appropriate diuretic treatment, were treated with tolvaptan. We excluded 35 patients due to liver transplant (20.0%), death (28.6%), poor general status (14.3%), improved ascites (5.7%) or other reasons (31.4%). In 20 cases treated with tolvaptan for 6 months, total body water (TBW) and extracellular fluids (ECW) were measured using bioelectric impedance analysis (BIA) with an InBody720.

RESULTS

The median age of the 20 patients was 64 years (range, 48-90), and 60% were male. The etiology of cirrhosis included hepatitis C (45%), alcohol-induced (20%) and other (35%). The percentage of patients with Child-Pugh class A, B and C was 0%, 40% and 60%, respectively. Biochemical findings revealed that serum creatinine levels and estimated glomerular filtration rate were not affected during 6 months of treatment with tolvaptan, and there was no renal disturbance. The median serum sodium levels were increased from 138 to 139 mEq/L, but serious adverse events related to renal and liver function were not observed. Data also revealed that long-term treatment reduced the BIA-estimated ECW/TBW ratio.

CONCLUSION

Long-term tolvaptan treatment was a safe and effective treatment for decompensated cirrhosis.

Nutrition assessment in patients undergoing liver transplant

Liver transplantation (LT) is a major surgery performed on patients with end stage liver disease. Nutrition is an integral part of patient care, and protein-energy malnutrition is almost universally present in patients suffering from liver disease undergoing LT. Nutrition assessment of preliver transplant phase helps to make a good nutrition care plan for the patients. Nutrition status has been associated with various factors which are related to the success of liver transplant such as morbidity, mortality, and length of hospital stay. To assess the nutritional status of preliver transplant patients, combinations of nutrition assessment methods should be used like subjective global assessment, Anthropometry mid arm-muscle circumference, Bioelectrical impedance analysis (BIA) and handgrip strength.

Development of methods for body composition studies

This review is focused on experimental methods for determination of the composition of the human body, its organs and tissues. It summarizes the development and current status of fat determinations from body density, total body water determinations through the dilution technique, whole and partial body potassium measurements for body cell mass estimates, in vivo neutron activation analysis for body protein measurements, dual-energy absorptiometry (DEXA), computed tomography (CT) and magnetic resonance imaging (MRI, fMRI) and spectroscopy (MRS) for body composition studies on tissue and organ levels, as well as single- and multiple-frequency bioimpedance (BIA) and anthropometry as simple easily available methods. Methods for trace element analysis in vivo are also described. Using this wide range of measurement methods, together with gradually improved body composition models, it is now possible to quantify a number of body components and follow their changes in health and disease.

The validity of bioelectrical impedance models in clinical populations

Bioelectrical impedance analysis (BIA) is the most commonly used body composition technique in published studies. Herein we review the theory and assumptions underlying the various BIA and bioelectrical impedance spectroscopy (BIS) models, because these assumptions may be invalidated in clinical populations. Single-frequency serial BIA and discrete multifrequency BIA may be of limited validity in populations other than healthy, young, euvolemic adults. Both models inaccurately predict total body water (TBW) and extracellular water (ECW) in populations with changes in trunk geometry or fluid compartmentalization, especially at the level of the individual. Single-frequency parallel BIA may predict body composition with greater accuracy than the serial model. Hand-to-hand and leg-to-leg BIA models do not accurately predict percent fat mass. BIS may predict ECW, but not TBW, more accurately than single-frequency BIA. Segmental BIS appears to be sensitive to fluid accumulation in the trunk. In general, bioelectrical impedance technology may be acceptable for determining body composition of groups and for monitoring changes in body composition within individuals over time. Use of the technology to make single measurements in individual patients, however, is not recommended. This has implications in clinical settings, in which measurement of individual patients is important.

Nutrition in liver disease

PURPOSE OF REVIEW

The aim of this paper is to describe the relevant medical literature published between spring 2003 and spring 2005 in the field of malnutrition in liver disease and its management.

RECENT FINDINGS

The most relevant articles covered in this paper provide data regarding the absence of energy imbalance in patients with stable cirrhosis, thus arguing against its potential role in the development of malnutrition; the increase in body cell mass and muscle mass as the major components of weight gain after portal-systemic shunting; the largest published randomized controlled trial of the positive effect of branched-chain amino acid supplements on the long-term outcome of patients with cirrhosis; studies using stable isotope labeled substrates, suggesting that dietary fat could be absorbed via the portal vein in patients with cirrhosis; and a randomized controlled trial suggesting the possibility that probiotics may decrease the infection rate after liver transplantation.

SUMMARY

In spite of the data provided by these and other articles described in the review, the major controversial issues in the field of nutritional management of liver disease remain open. Particularly remarkable is the lack of consensus regarding the nutritional management of acute liver failure.

Phase angle is a predictor of basal metabolic rate in female patients with anorexia nervosa

The aim of the study was to evaluate the relationship between basal metabolic rate (BMR) and bioelectrical impedance analysis (BIA) in undernourished female patients with anorexia nervosa. Participants were 86 female patients with anorexia nervosa (age 20.8+/-4.7 years; weight 39.3+/-5.2 kg; body mass index 15.4+/-1.6 kg m-2). BMR was measured by indirect calorimetry and single-frequency BIA was determined at 50 kHz on the whole body. The BIA variables considered were resistance, reactance, phase angle and the bioimpedance index (height2/resistance). Fat-free mass was calculated from subcutaneous skin fold thickness. In the study group BMR was 3782+/-661 kJ d-1 while bioimpedance index varied between 27.6 and 49.9 cm2 Omega-1 and phase angle between 2.54 degrees and 6.49 degrees. BMR was significantly correlated with weight, height, body mass index and fat-free mass, and, among BIA variables, with reactance and phase angle. Multiple regression analysis indicated that phase angle was a predictor of BMR not only when solely BIA variables were considered, but also in combination with either weight and age or fat-free mass. In conclusion, phase angle emerged as a strong predictor of BMR in female patients with anorexia nervosa. Nevertheless, further studies are necessary to confirm this finding in other forms of protein energy malnutrition and justify the inclusion of BIA variables in the equations used to predict BMR in the clinical setting.

Role of excess volume in the pathophysiology of hypertension in chronic kidney disease

BACKGROUND

The pathophysiology of hypertension in patients with chronic kidney disease (CKD) is largely attributed to positive sodium balance. It is unclear how loop diuretics affect fluid volume compartments, especially with respect to their antihypertensive effect.

METHODS

Subjects with CKD were administered a single therapeutically equivalent dose of an oral loop diuretic (furosemide or torsemide in randomized crossover design). We measured acute volume changes over 12 hours using biophysical and hormonal biomarkers and then 24-hour ambulatory blood pressure after daily diuretic therapy for 3 weeks.

RESULTS

Single-dose administration of loop diuretic decreased extracellular water (ECW) by 1.7 L [95% confidence interval (95% CI) 1.2, 2.2, P < 0.001], total body water (TBW) by 1.2 L (95% CI 0.5, 1.9, P < 0.001), and increased natural log (ln) plasma renin activity (PRA) from -1.2 +/- 1.3 ng/mL/hour to -0.5 +/- 1.5 ng/mL/hour (P < 0.001). Daily loop diuretic administration resulted in reduced ECW from 24.2 +/- 6.4 L to 22.3 +/- 5.2 L (P = 0.02) and TBW from 54.3 +/- 12.7 L to 51.6 +/- 11.9 L (P < 0.001) in 1 week. After 3 weeks of diuretic therapy, whereas ECW reduction persisted at 22.8 +/- 5.1 L (P = 0.05), TBW trended toward baseline level at 52.7 +/- 11.8 L. A concomitant increase in ln PRA from -1.0 +/- 1.3 ng/mL/hour to 0.4 +/- 1.9 ng/mL/hour (P < 0.001) and ln plasma aldosterone (PA) from 2.0 +/- 0.8 ng/dL to 2.3 +/- 0.8 ng/dL (P < 0.005) and fall in ln brain natriuretic peptide (BNP) from 4.3 +/- 0.9 pg/mL to 3.7 +/- 1.0 pg/mL (P < 0.01) were seen at 1 week. Despite a trend toward restoration of TBW, changes in hormonal biomarkers were maintained at 3 weeks. Over these 3 weeks, furosemide reduced 24-hour ambulatory blood pressure from 147 +/- 17/78 +/- 11 mm Hg to 138 +/- 21/74 +/- 12 mm Hg (P = 0.021) and torsemide reduced it from 143 +/- 18/75 +/- 10 mm Hg to 133 +/- 19/71 +/- 10 mm Hg (P = 0.007).

CONCLUSION

Patients with CKD have elevated extracellular fluid volume that can be corrected acutely with loop diuretics. Persistent diuretic use results in dynamic changes in ECW and other body fluid compartments that translate into chronic blood pressure reduction.

Malnutrition is a risk factor in cirrhotic patients undergoing surgery

Cirrhotic patients may become candidates for elective and emergency surgery. This may be due to conditions requiring operations such as cholecystectomy, herniotomy, or gastrointestinal malignancies, more common in cirrhotics when compared with the general population, or to complications of the liver disease such as resectable hepatocellular carcinomas or surgical portosystemic shunts to treat portal hypertension. It has been estimated that 10% of cirrhotics undergo at least one operative procedure during the final 2 y of their lives. Many studies have documented a high risk of morbidity and mortality associated with surgical procedures in these patients, and several factors influencing the postoperative outcome have been identified. Malnutrition, which is frequently encountered in cirrhotic patients, has been shown to have an important impact on the surgical risk. A poor nutrition status also has been associated with a higher risk of complications and mortality in patients undergoing liver transplantation. Few data are available concerning the perioperative nutrition support in surgical cirrhotic patients. The results of these studies are sometimes encouraging in reporting that the nutrition therapy may improve the clinical outcome in cirrhotic patients undergoing general surgery and/or liver transplantation. The limited number of patients and their heterogeneity, however, do not allow definitive conclusions, and more research on this issue is needed.

Body composition: what's new?

PURPOSE OF REVIEW

Body mass index has been shown to be an imprecise measurement of fat-free and fat mass, and provides no information if weight changes occur as a result of a decrease in fat-free mass or an increase in fat mass.

RECENT FINDINGS

Non-invasive body composition methods (i.e. bioelectrical impedance analysis, air displacement plethysmography) can now be used to monitor fat-free and fat mass with weight gain and loss, and during aging. This review discusses body composition measurements in terms of ethnic differences, physical activity, and age, and the limitations of bedside techniques in obesity and abnormal hydration status.

SUMMARY

An assessment of the fat-free and fat mass provides valuable information about changes in body composition with weight gain or loss and physical activity, and during aging. Non-invasive bedside techniques can now be used to evaluate the nutritional status of healthy and ill individuals.

Case study of the clinical usefulness of bioelectrical impedance spectroscopy in evaluating nutritional status

Bioelectrical impedance spectroscopy (BIS) can be a valuable tool in assessing changes in body composition. Although the validity of BIS in healthy subjects is relatively good, in patients considerably larger measurement errors have been reported. In this article the clinical usefulness of BIS in assessing nutritional status of one case study will be discussed. Interpretation of the predictions of BIS in this unstable patient was difficult. This is in agreement with the consensus that BIS does not give accurate prediction of body composition in individual patients. It is recommended that validation studies of BIS should focus on clinical aspects which can influence BIS measurements.

Nutritional aspects of liver disease and transplantation

In the past year, some relevant papers related to the diagnosis of malnutrition and its pathogenesis in cirrhosis have been published. The value of anthropometrics in the nutritional assessment of end-stage cirrhotic patients has been reinforced. Also, the role of bioelectrical impedance analysis in these patients has been redefined. Several papers have investigated the relationship between leptin and malnutrition in chronic liver disease, particularly the role of alcoholism in hyperleptinaemia, and the importance of protein-bound leptin in these patients. In other papers, the impact of both undernutrition and obesity on the outcome of liver transplantation has been investigated. Two randomized, controlled trials on enteral nutrition in liver disease have been published in this period. One of them deals with a clinical situation (i.e. severe alcoholic hepatitis) associated with a high mortality rate, whereas the second is the first controlled trial in the field of preoperative nutrition in liver transplantation. Finally, some papers provide further arguments in the dilemma of which route of nutrition (enteral or parenteral) is better in cirrhosis.

Bioelectrical impedance analysis during pregnancy and neonatal birth weight

OBJECTIVE

To generate reference ranges for bioelectrical impedance indices throughout pregnancy and to investigate whether a relationship exists between these indices and the neonatal birth weight.

STUDY DESIGN

Pregnant women with a singleton gestation, gestational age lower than 12 weeks, and absence of medical diseases before pregnancy were enrolled. Patients with pregnancy complications, such as hypertensive disorders, diabetes, and antiphospholipides syndrome were excluded. Antrophometric maternal parameters and bioelectrical impedance measurements were performed during the first, second, third trimester of pregnancy, at delivery and 60 days after delivery. Height(2)/resistance (cm(2)/Omega) and height(2)/reactance (cm(2)/Omega) were utilized to estimate the total and extracellular body water amounts, respectively. Spearman rank correlations and cox proportional hazard modelling were used for statistical purposes.

RESULTS

169 patients completed all measurements. Total and extracellular water amounts significantly increase as pregnancy advances and return to the pre-pregnancy values within 60 days after delivery. After adjustment for gestational age at delivery, fetal sex, and smoking habits, height(2)/resistance at 25 weeks (hazard=1.04, 95% confidence interval (CI) 1.02-1.06, P<0.005), height(2)/resistance at 30 weeks (hazard=1.03, 95% CI 1.01-1.05, P<0.005), height(2)/reactance at 20 weeks (hazard=1.03,95% CI 1.01-1.05, P<0.005), and height(2)/reactance at 25 weeks (hazard=1.03, 95% CI 1.01-1.04, P<0.01) were found to be independent predictors of birth weight.

CONCLUSION

We have provided reference ranges for bioimpedance analysis during pregnancy, an easy, fast and non invasive method to estimate the body water composition during pregnancy. Bioelectrical impedance indices during the second trimester of pregnancy are independently related to the birth weight.

Nutrition in hepatic failure and liver transplantation

Protein-energy malnutrition (PEM) is a common problem in patients with end-stage liver disease, and it is universally present in patients undergoing orthotopic liver transplantation. Although PEM is an independent risk factor for morbidity and mortality, it need not be considered an absolute contraindication for liver transplantation. The etiology of PEM in liver disease is multifactorial and includes decreased nutrient and calorie intake, alterations in intestinal malabsorption and/or maldigestion, and diverse abnormalities of carbohydrate, fat, and protein metabolism. This article reviews the prevalence of malnutrition, its pathophysiology, different modalities for assessment of body composition, and general guidelines for nutritional support in patients with liver disease and liver transplantation.

Bioelectrical impedance analysis is a useful bedside technique to assess malnutrition in cirrhotic patients with and without ascites

Protein-calorie malnutrition is associated with poor prognosis in chronic liver disease, but reliable assessment is hampered by changes in body water. We prospectively evaluated the effect of fluid retention on bioelectrical impedance analysis (BIA) as a simple method for the estimation of body cell mass (BCM(BIA)) in 41 patients with cirrhosis (n = 20 with ascites; n = 21 without ascites) using total body potassium counting (BCM(TBP)) as a reference method. Arm muscle area and creatinine-derived lean body mass were compared with total body potassium data. In patients total body potassium was 24.4% lower than in controls and this loss was more severe in patients with ascites (-34.1%; P<.01). BCM(BIA) and BCM(TBP) were closely correlated in controls (r(2) =.87, P<.0001), patients without ascites (r(2) =.94, P <.0001) and patients with ascites (r(2) =.56, P<.0001). Removal of 6.2 +/- 3 L of ascites had only minor effects on BCM(BIA) (deviation of -0.18 kg/L ascites). Limits of agreement between both methods were wider in patients with ascites than in patients without (6.2 vs. 4.2 kg). In patients without ascites arm muscle area (r(2) =.64; P<.001) and lean body mass (r(2) =.55; P<.001) correlated significantly with total body potassium, but not in patients with ascites. For assessment of protein malnutrition in patients with cirrhosis, body cell mass determination by use of BIA offers a considerable advantage over other widely available but less accurate methods like anthropometry or the creatinine approach. Despite some limitations in patients with ascites, BIA is a reliable bedside tool for the determination of body cell mass in cirrhotic patients with and without ascites.

Nutritional and metabolic issues in cirrhosis and liver transplantation

In the last year some relevant papers on nutrition and metabolism in chronic liver disease and transplantation have been published. Studies investigating the reliability of predicting energy expenditure in cirrhosis, and some relevant contributions to the understanding of metabolic consequences of liver transplantation, deserve particular mention. These include the first direct evidence that liver transplantation corrects the insulin resistance present in cirrhosis, as well as studies on the role of genetic polymorphism of the vitamin D receptor gene in bone loss after transplantation. Other papers have dealt with body composition, polyunsaturated fatty acid and antioxidant status in cirrhosis. However, relevant contributions in the field of nutritional support in cirrhosis are surprisingly lacking.

Segmental bioelectrical impedance analysis to assess perioperative fluid changes

OBJECTIVES

Perioperative fluid accumulation determination is a challenge for the clinician. Bioelectrical impedance analysis (BIA) is a noninvasive method based on the electrical properties of tissues, which can assess body fluid compartments. The study aimed at assessing their changes in three types of surgery (thoracic, abdominal, and intracranial) requiring various regimens of fluid administration.

DESIGN

Prospective descriptive trial.

PATIENTS

A total of 26 patients scheduled for elective surgery were separated into three groups according to site of surgery: thoracic (n = 8), abdominal aortic (n = 8), and brain surgery (n = 10).

SETTING

University teaching hospital.

INTERVENTION

None.

MEASUREMENTS

Whole body, segmental (arm, trunk, and legs) BIA at multiple frequency (0.5, 50, 100 kHz) was used to assess perioperative fluid accumulation after surgery. The fluid balances were calculated from the charts.

RESULTS

The patients were aged 62+/-4 yrs. Fluid balances were 4.8+/-1.0 L, 4.1+/-0.5 L, and 1.9+/-0.3 L, respectively, in the three groups. In trunk surgery patients, fluid accumulation was detected as a drop in impedance in the operated area at all frequencies. In the operated area, there was an expansion of both intra- and extracellular compartments. A reduction in high frequencies' impedance in the legs was only detected after aortic surgery. Fluid accumulation and trunk impedance changes were strongly correlated. Neurosurgery only induced minor body fluid changes.

CONCLUSIONS

Segmental BIA is able to detect and localize perioperative fluid accumulation. It may become a bedside tool to quantify and to localize fluid accumulation.

Estimation of body fluid changes during peritoneal dialysis by segmental bioimpedance analysis

Estimation of body fluid changes during peritoneal dialysis by segmental bioimpedance analysis.

BACKGROUND

Commonly used bioimpedance analysis (BIA) is insensitive to changes in peritoneal fluid volume. The purpose of this study was to show, to our knowledge for the first time, that a new segmental approach accurately measures extracellular fluid changes during peritoneal dialysis (PD).

METHODS

Fourteen stable PD patients were studied during a standard exchange with fluids of known conductivity. Bioimpedance was continuously measured in the arm, trunk, and leg and from wrist to ankle. Volume changes were calculated using both a newly developed sum of segmental BIA (SBIA) and current wrist-to-ankle BIA (WBIA) and were compared with actual volume changes measured gravimetrically.

RESULTS

When 2.19 +/- 0.48 L were removed from the peritoneal cavity during draining, 95.2 +/- 13.8% of this volume was detected by SBIA compared with only 12.5 +/- 24. 3% detected by WBIA. When 2.11 +/- 0.20 L of fresh dialysate was infused into the peritoneal cavity during filling, 91.1 +/- 19.6% of this volume was detected by SBIA compared with only 8.8 +/- 21.1% detected by WBIA.

CONCLUSION

The good agreement between measured and calculated data using SBIA was due to: (a) improved placement of electrodes, (b) estimation of trunk extracellular volume based on a new algorithm, and (c) consideration of changes in dialysate conductivity. Correct estimation of fluid volume in the trunk is a prerequisite for applications in which direct analysis of fluid changes cannot be performed such as with peritoneal equilibration tests and continuous flow PD.

Muscle mass and function in thyrotoxic patients before and during medical treatment

OBJECTIVE

Development of muscle weakness and atrophy are well known complications of thyrotoxicosis, although little is known about its clinical course. The present longitudinal study was therefore undertaken to monitor muscle mass and strength before and during treatment of hyperthyroidism.

DESIGN AND PATIENTS

Five patients (2 male, 3 female; Age 41 +/- 6 years; BMI 22.2 +/- 1.1 kg/m2) with newly diagnosed hyperthyroidism were studied with respect to muscle area, muscle strength, body composition and substrate metabolism at baseline and after 1, 3, 6, 9 and 12 months of treatment.

MEASUREMENTS

Midthigh muscle areas were assessed by computed tomography (CT), while bioelectrical impedance analysis (BIA) was used for assessment of body composition. The isometric strength of the biceps brachialis and quadriceps muscles was assessed by means of a dynamometer and the maximal static ins- and ex-piratory mouth pressures were measured with a respiratory pressure module.

RESULTS

Prior to treatment thyrotoxic patients all displayed elevated levels of total and free T3 and T4 together with suppressed TSH. BMI, fat mass and lean body mass increased significantly during the treatment period, while energy expenditure (EE) decreased. Thigh muscle areas increased by 24% (101.5 +/- 11.5 vs. 125.3 +/- 13.1 cm2, P < 0.05) from entry to peak. Peak time was 9 +/- 0.9 months. During treatment a significant (P < 0.01) increase in muscle strength was observed; arm capacity increased by 48%, while leg capacity increased by 51%. Peak time (months) was: Right arm: 8 +/- 3, left arm: 7 +/- 2, right leg: 5 +/- 3, left leg: 9 +/- 2. Respiratory muscle strength, expressed as maximal ins- or ex-piratory mouth pressure, was significantly impaired among patients at entry. A significant increase in inspiratory and expiratory strength was found from entry to peak (P < 0.05), as inspiratory strength increased by 35% and expiratory by 19%. Inspiratory strength peaked after 7 +/- 1 months, expiratory muscle strength after 6 +/- 1 months.

CONCLUSIONS

In conclusion we find that in patients with thyrotoxicosis muscle mass is reduced by approximately 20% and muscle strength by approximately 40% and that between 5 and 9 months elapse before normal muscle mass and function are reestablished.

Nutritional issues in cirrhosis and liver transplantation

In the past year, some relevant papers on the mechanisms of malnutrition in cirrhosis have been published. Studies investigating the metabolic destiny of leucine after protein breakdown, which have contributed to a better understanding of the pathogenesis of muscle wasting and fat depletion in these patients, deserve particular mention. Also, the demonstration that chronically reducing hyperinsulinaemia in cirrhosis is able to improve insulin sensitivity opens novel pathogenic and therapeutic perspectives for such a metabolic derangement in these patients. Other papers dealt with unsaturated lipids, lipoperoxidation and antioxidants in chronic liver disease. However, randomized trials on parenteral or enteral nutrition in cirrhosis and liver transplantation are missing.

Use of single-frequency bioimpedance at 50 kHz to estimate total body water in patients with multiple organ failure and fluid overload

OBJECTIVE

To investigate the relationship between single-frequency bioimpedance at 50 kHz (both total body impedance and segmental impedance) and total body water, measured using tritiated water in the presence of the severe fluid retention seen in multiple organ failure.

DESIGN

Prospective, controlled study.

SETTING

General intensive care unit.

SUBJECTS

Twenty patients with multiple organ failure and 30 normal volunteers, of whom a subgroup of ten had total body water measured.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Total body water and total and segmental bioimpedance values at 50 kHz were measured using tritiated water and a Holtain body composition analyzer in 20 patients with multiple organ failure and in ten normal volunteers. An additional 20 normal volunteers also had segmental and total body impedance measured. There was no difference in the linear regression lines constructed for the patients and the volunteers, but the SEM in the patients (7.6 L) was four times that seen in the normal subjects (1.9 L). In a further seven patients, the impedance technique overestimated the change in total body water, deduced from acute changes in weight, by between 0% and 46% (median, 12%). In the patients, who were supine, the knee-ankle segment contributed significantly more to total body impedance than it did in the normal volunteers (42.5% vs. 34.4%; p < .001), who were upright and mobile immediately before the measurement.

CONCLUSIONS

Although single-frequency bioimpedance does give an indication of total body water and change in total body water, it is neither precise nor accurate enough to be the sole guide to fluid therapy. The proportion of total impedance contributed by the knee-ankle segment, which contains relatively little water, was significantly greater in the patients than in the controls, probably reflecting better drainage of fluid from the lower limb in the supine position.

Requirements for clinical use of bioelectrical impedance analysis (BIA)

The bioelectrical impedance analysis (BIA) method is an attractive tool for use in the clinical assessment of human body composition. Factors such as ease of use, relatively low cost, noninvasive nature, high degree of reproducibility, and safety of operation provide an impetus for the general application of this method. The preponderance of the published applications of BIA focused on applications in healthy populations and indicated a qualitative validity of the method. More recent applications have augmented the quantitative values of the BIA approach and have reported very good specificity and sensitivity. One potential limitation of the BIA approach is the reliance on regression models, derived in restricted samples of human subjects, which restricts the usefulness of the derived model in other patients who differ from the original sample in which the model was developed. Other investigational approaches that use different physical models (bioelectrical impedance spectroscopy and parallel model) have yielded successful and useful measures of human body composition in clinical studies. If BIA is to gain acceptance in clinical diagnosis and evaluation of therapeutic interventions, further efforts will be needed to ascertain more fully the validity, sensitivity, and specificity of biological parameters estimated with the new BIA approaches, and to establish the prognostic values of the BIA estimates of body composition.

Nutritional status and assessment of patients on home parenteral nutrition: anthropometry, bioelectrical impedance, or clinical judgment?

The optimal method of assessing protein energy nutritional status in patients receiving home parenteral nutrition (HPN) is unknown. We evaluated protein energy nutritional status in 47 outpatients (23 male; 24 female) on HPN by measuring anthropometry, plasma proteins, and lymphocyte counts and compared these with the results of subjective clinical assessment and bioelectrical impedance measurements. Sixteen of the 47 patients (34%) were underweight (body mass index < 5th percentile of the reference) and 21 (45%) were below the 5th percentile of the reference for both triceps skinfold thickness and midarm muscle circumference. Plasma proteins were subnormal in 1-5 patients (2-11%). Lymphocyte counts were subnormal in 19 patients (40%). Clinical assessment classified 23 patients (49%) as well nourished and 24 (51%) as moderately malnourished. Moderately malnourished patients had a significantly lower body mass index than well-nourished patients (P = 0.02). Clinical assessment did not correlate with bioelectrical impedance analysis. Fat-free mass determined by bioelectrical impedance analysis resulted in values up to 9.4 kg lower and 8 kg higher than fat-free mass obtained by anthropometry. Weighing combined with a subjective clinical assessment is sufficient for evaluation of protein calorie nutritional status in patients on HPN.

Nutrition in chronic liver disease and liver transplantation

Significant contributions to the field of nutrition and liver disease have been published in the last year. The most relevant includes work on the pathogenic role of energy metabolism disturbances in the development of malnutrition in cirrhosis, as well as data on the relationship between preoperative nutritional deficiencies and the outcome of liver transplantation. However, despite these contributions, large-scale multicentric trials on the therapeutic value of nutritional support and metabolic care in cirrhosis and liver transplantation are still lacking.

Bedside determination of fluid accumulation after cardiac surgery using segmental bioelectrical impedance

OBJECTIVES

Bioelectrical impedance analysis (BIA) is based on the physical property of tissues to conduct electrical currents, impedance being inversely related to tissue fluid content. At high frequency, the electrical current flows across both intracellular and extracellular pathways, making the assessment of fat-free mass possible while a low-frequency current flows through the extracellular space. Similarly, segmental BIA may be used to assess segmental body fluid repartition. The aim of this study was to assess fluid accumulation after cardiac surgery by multiple frequency segmental BIA.

DESIGN

Observational, clinical study.

SETTING

A 17-bed, surgical intensive care unit in a university hospital.

PATIENTS

Twenty-six patients before and after open-heart surgery with cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

After surgery, fluid accumulation resulted in a decrease in whole-body and segmental bioelectrical impedance in the arm and in the trunk. There was a good correlation between the fluid accumulation measured by fluid balance and by whole-body or segmental impedance changes. The major part (71%) of fluid accumulation occurred in the trunk. Multiple frequency measurements did not indicate a fluid shift between the intra- and extracellular compartments.

CONCLUSION

Cardiac surgery produced a significant decrease in segmental trunk BIA, reflecting fluid accumulation at the trunk level.

Segmental bioelectrical impedance analysis improves the prediction for extracellular water volume changes during abdominal surgery

OBJECTIVE

To determine whether the segmental multifrequency bioelectrical impedance analysis may improve the prediction for intraoperative changes in extracellular water volume (deltaECW) compared with whole body multifrequency bioelectrical impedance analysis in abdominal surgical patients.

DESIGN

Prospective, consecutive sample.

SETTING

Surgical operative patients in a university-affiliated city hospital.

PATIENTS

Thirty patients who underwent elective gastrointestinal surgery.

INTERVENTIONS

Multifrequency bioelectrical impedance analysis was conducted preoperatively (before the induction of anesthesia) and postoperatively (after recovery from anesthesia). Resistance values fitted at zero frequency (R0) in the whole body and in each body segment (arm, trunk, and leg) were determined by performing nonlinear curve-fitting and subsequent extrapolation. DeltaECW values were estimated from the whole body resistance between wrist and ankle using two different prediction formulas. In segmental multifrequency bioelectrical impedance analysis, however, ECW was obtained as the sum of each body segment (arms, trunk, and legs) using the equation newly derived from the cell suspension theory. DeltaECW estimated from both measurements were compared with net fluid balances during surgery.

MEASUREMENTS AND MAIN RESULTS

R0 in whole body and all body segments significantly decreased after surgery (p < .0001). The most striking decrease in post/preoperative ratios was found in the R0 in the trunk. The post/preoperative ratio of the R0 value in the trunk was significantly lower than the post/preoperative ratio of the R0 value in the leg (p = .0007). DeltaECW from segmental multifrequency bioelectrical impedance analysis was similar to net fluid balance (r2 = .80, bias = -0.03 L), whereas whole body multifrequency bioelectrical impedance analysis resulted in considerable underestimations of deltaECW (r2 = .50, .51, bias = 0.95, 0.53 L).

CONCLUSIONS

The difference in the prediction of deltaECW between whole body and segmental multifrequency bioelectrical impedance analysis may be explained by the significant decrease in the resistance of the trunk, which contributed only minimally to the whole body resistance. Segmental multifrequency bioelectrical impedance analysis provides a better approach to predict ECW changes in critically ill patients with nonuniform fluid distribution.

Validation of multi-frequency bioelectrical impedance analysis in detecting changes in fluid balance of geriatric patients

OBJECTIVES

Multi-Frequency Bioelectrical Impedance Analysis (MFBIA) is a quick, simple, and inexpensive method to assess body fluid compartments. This study aimed at determining the validity of MFBIA in detecting clinically relevant changes of fluid balance in geriatric patients.

DESIGN

A prospective, observational study.

SETTING

The 22-bed Geriatric Department of the University Hospital Nijmegen.

PARTICIPANTS

Hospitalized patients were eligible if they did not have a pacemaker, were not suffering from terminal illnesses, and did not have psychogeriatric diseases likely to interfere with capacity to consent or comply. During a 16-months period, 218 patients were admitted, of whom 78 patients were eligible and 53 consented to participate.

MEASUREMENTS

Each subject's fluid balance was diagnosed twice a week as dehydrated, overhydrated, or euvolemic, based on standardized physical examination, laboratory tests, and weight evaluation. Changes in fluid balance were quantified by measuring total body water (TBW) and extracellular fluid (ECF) applying deuterium- and bromide-dilution techniques. Impedance at 1, 5, 50, and 100 kHz and body weight were measured daily. Sensitivity and Guyatt's responsiveness indexes of MFBIA in detecting dehydration and overhydration were determined.

RESULTS

In total, 1071 MFBIA measurements were performed, during which 14 transitions from dehydration to euvolemia and 13 transitions from overhydration to euvolemia were monitored. Rehydration of dehydrated patients caused an increase in TBW and ECF of 3.4 +/- 1.8 L and 1.9 +/- 1.9 L, respectively, which resulted in significant decreases in impedance of 133 +/- 67 omega at 1 kHz and 93 +/- 61 omega at 100 kHz (P = .001). Treatment of overhydrated patients caused a TBW and ECF loss of 3.8 +/- 4.2 L and 3.1 +/- 3.8 L, respectively, which resulted in significant increases in impedance of 104 +/- 72 omega at 1 kHz and 81 +/- 68 omega at 100 kHz (P < .001). Sensitivity of a single MFBIA in diagnosing dehydration and overhydration was 14% and 17%, respectively. Responsiveness indexes of weighing and MFBIA for dehydration and overhydration were similar at all frequencies and greater than one.

CONCLUSION

The sensitivity of a single impedance measurement in detecting dehydration and overhydration was low. However, responsiveness of serial measurements to intra-individual changes in fluid balance was good. Therefore, this noninvasive technique may be used in clinical practice to improve monitoring fluid balance in geriatric patients, especially when daily weighing is difficult.

Segmental body composition assessed by bioelectrical impedance analysis and DEXA in humans

The present study assessed the relative contribution of each body segment to whole body fat-free mass (FFM) and impedance and explored the use of segmental bioelectrical impedance analysis to estimate segmental tissue composition. Multiple frequencies of whole body and segmental impedances were measured in 51 normal and overweight women. Segmental tissue composition was independently assessed by dual-energy X-ray absorptiometry. The sum of the segmental impedance values corresponded to the whole body value (100.5 +/- 1.9% at 50 kHz). The arms and legs contributed to 47.6 and 43.0%, respectively, of whole body impedance at 50 kHz, whereas they represented only 10.6 and 34.8% of total FFM, as determined by dual-energy X-ray absorptiometry. The trunk averaged 10.0% of total impedance but represented 48.2% of FFM. For each segment, there was an excellent correlation between the specific impedance index (length2/impedance) and FFM (r = 0.55, 0.62, and 0.64 for arm, trunk, and leg, respectively). The specific resistivity was in a similar range for the limbs (159 +/- 23 cm for the arm and 193 +/- 39 cm for the leg at 50 kHz) but was higher for the trunk (457 +/- 71 cm). This study shows the potential interest of segmental body composition by bioelectrical impedance analysis and provides specific segmental body composition equations for use in normal and overweight women.

Multi-frequency bioelectric impedance measurements for predicting body water compartments in patients with non-ascitic liver cirrhosis

We assessed total body water (TBW) and extracellular water (ECW) in thirty-four non-ascitic cirrhotics and twenty healthy controls by 2H2O and Br dilution. In the same subjects, bioelectric impedance (BI) was recorded at multiple frequencies. Body hydration was similar for controls (mean 55.6 (SD 6.7)), less-severe cirrhotics (Child-Pugh classification A; CPA; n 21, mean 56.2 (SD 6.2)) and moderately-severe cirrhotics (Child-Pugh classification B; CPB; n 13, mean 57.2 (SD 5.4)). However, intracellular water standardized per litre TBW was significantly higher in CPB subjects (mean 27.0 (SD 7.5); P < 0.01) compared with CPA (mean 21.3 (SD 10.6)) and control subjects (mean 18.0 (SD 9.8)). Published formulas for predicting TBW and ECW from BI at multiple frequencies were applied to the cirrhotics. These formulas gave accurate predictions of TBW and ECW, although standard errors of estimates were higher for CPB subjects (TBW < or = 2.5 and ECW < or = 2.1 l) than those for CPA (TBW < or = 2.0 and ECW < or = 1.8 l) and control (TBW 1.4 and ECW 0.9 l) subjects.

Resting energy expenditure in patients with cirrhosis of the liver measured by indirect calorimetry, anthropometry and bioelectrical impedance analysis

Energy expenditure was investigated in 15 patients with liver cirrhosis and 20 healthy controls by three methods: indirect calorimetry, anthropometry using the Harris-Benedict equation and bioelectrical impedance analysis. The energy expenditure was expressed in kcal/day, kcal/kg BW/day (BW - body weight), kcal/kg LBM/day (LBM - lean body mass, derived by bioelectrical impedance analysis) or in kcal/m2/day. We did not find statistical differences between values of resting energy expenditure obtained in patients with cirrhosis of the liver and healthy controls whichever method we used. We also did not find statistical differences between values obtained by indirect calorimetry, anthropometry and bioelectrical impedance analysis. There was a significant correlation between indirect calorimetry and anthropometry in both groups. We found significant correlations between indirect calorimetry and anthropometry, and between indirect calorimetry and bioelectrical impedance analysis, in the control group only. We can conclude that (1) resting energy expenditure of patients with cirrhosis of the liver is not changed when compared with healthy controls, and (2) bioelectrical impedance is a useful method to calculate body composition from which energy expenditure is derived; however, it gives an appropriate result only in healthy people, and only approximate values in patients with cirrhosis.

Bioelectrical impedance analysis as an assessment of diuresis in congestive heart failure

OBJECTIVE

To compare changes in bioimpedance parameters and calculated total body water (TBW) with conventional measurements used to assess the efficacy of diuretic therapy in the treatment of heart failure.

SETTING

A Veterans Affairs tertiary care, teaching hospital.

SUBJECTS

Twelve patients with New York Heart Association (NYHA) class III congestive heart failure (CHF).

DESIGN

Prospective, consecutive sample, cohort, open label.

INTERVENTIONS

Parenterally administered furosemide; clinically dictated, outcome-oriented, adjunctive therapy of CHF.

OUTCOMES

Bioelectrical impedance analysis (BIA) parameters, measured volume of diuresis and changes in body weight, defined clinical endpoints (NYHA criteria).

RESULTS

Three days of diuretic therapy with furosemide (oral and/or intravenous) for CHF was associated with a measured weight loss of 4.1 +/- 0.6 kg and statistically significant increases in resistance and reactance of 20.8% +/- 2.7% and 22.7% +/- 6.1%, respectively (p < 0.005). Calculated TBW using BIA parameters and standard equations decreased on average by 6.1 +/- 0.6 L or 11.2% +/- 1.1% (p < 0.001). A significant inverse correlation was observed between change in measured body weight and total body reactance (p = 0.02).

CONCLUSIONS

Single-frequency BIA appears to have limited clinical usefulness as a method of assessing diuretic therapy in the management of CHF. Its greatest usefulness appears to lie in the assessment of serial changes in individual patients and patient populations that are physiologically or metabolically homogeneous. Further studies are needed to establish the validity of BIA in patients with decompensated CHF.

Kt/V in CAPD by different estimations of V

This study compared the measurements of total body water (TBW) by 58% body weight (TBW58%), the Watson equation (TBWWV) and bioelectric impedance (TBWBIA) with the gold standard, Deuterium oxide (TBWD2O) dilution method in twenty continuous ambulatory peritoneal dialysis (CAPD) patients. TBW volumes were highest when calculated as TBW58% (42.6 +/- 9.4 liter) and lowest when calculated from TBWWV (34.6 +/- 6.8 liter). TBWBIA underestimated TBW when compared to TBWD2O, although the difference was not statistically significant (37.1 +/- 9.8 liter and 38.8 +/- 9.3 liter, respectively). In fact, TBWBIA correlated strongly with TBWD2O (r = 0.8, P < 0.0001). These discrepancies resulted in significant differences when Kt/V week-1 derived from the four methods were compared. To determine the effect of percent fat mass on the estimation of TBW by each method, we compared TBW and Kt/V week-1 derived from the four methods in nine CAPD patients who had normal percent fat mass (Non-Obese) and 11 CAPD patients who had greater than normal % fat mass (Obese). In the Non-Obese group, there was close correlation of TBWBIA, TBWWV and TBW58% when compared with TBWD2O (r = 0.93, P < 0.001, r = 0.89, P < 0.01 and R = 0.86, P < 0.01, respectively. Also, Kt/V week-1 derived from TBWBIA, TBWWV and TBW58% correlated strongly with Kt/V week-1 from TBWD2O (r = 0.93, P < 0.0005, r = 0.83, P < 0.01 and r = 0.8, P < 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Bioelectric impedance detects fluid retention in patients undergoing cardiopulmonary bypass

Excessive fluid accumulation is associated with increased morbidity and prolonged convalescence after cardiopulmonary bypass. However, water fluctuations are difficult to assess solely on the basis of changes in body weight and fluid balance. Bioelectric impedance analysis is a simple, rapid, noninvasive bedside technique that measures the resistance of the body to a weak alternating current (50 kHz). The change in resistance is inversely proportional to the change in total body water. To investigate the relationship between body weight, fluid balance, and resistance, 18 patients who had cardiopulmonary bypass (9 men, 9 women, aged 61 +/- 3 years, weighing 80 +/- 4 kg, with ejection fraction 54% +/- 3% and bypass time 113 +/- 8 minutes [mean plus or minus standard error of the mean]) were followed up for 7 postoperative days. Body weight, fluid balance, and whole body and regional resistance were determined at 24-hour intervals. In the immediate postoperative period, fluid retention was accurately detected by simultaneous measurements of weight gain and decreased resistance (p < 0.001). Both measurements detected the initiation of diuresis by postoperative day 2 (p < 0.01). Whole body resistance returned to baseline values by day 7 (p > 0.05), and body weight returned to baseline on day 4 (p > 0.05). Change in weight and change in whole body resistance were highly correlated with cumulative fluid balance (r = 0.84, p < 0.001, and r = -0.81, p < 0.001, respectively), and these two measures were also related to each other throughout the study (r = -0.89, p < 0.001). The initial change in resistance was the best measurement associated with postoperative outcome (p < or = 0.01). The data suggest that the measurement of electric resistance across the body can accurately detect acute changes in total body water and in fluid redistribution through the body. However, determining the relative day-to-day change in whole body resistance seems more appropriate than calculating absolute fluid changes over time. Bioelectric impedance offers a simple, rapid, noninvasive method to monitor serial changes in total body water. This technique can be useful in situations in which rapid alterations in water compartments occur, and it may be useful in predicting outcome after cardiopulmonary bypass.