Marta Codognotto

Body Mass Index and Agreement Between Bioimpedance and Anthropometry Estimates of Body Compartments in Anorexia Nervosa

BACKGROUND In 74 women with anorexia nervosa (body mass index [BMI] 10-17.5 kg/m(2)), a progressive disagreement between anthropometry and bioelectrical impedance analysis (BIA) estimates of fat (FM) and fat-free mass (FFM) was documented with a BMI <15 kg/m(2). Below this threshold, an abnormal body composition was detected with vector BIA independent on body weight (useful tool at the bedside). Both anthropometry and BIA are used for body composition assessment. We evaluated the agreement between their estimates of FFM and FM in extremely lean subjects with anorexia nervosa. METHODS Observational study in 74 women (age 15-45 years; BMI 10.0-17.5 kg/m(2)) with anorexia nervosa. Anthropometry FM and FFM were estimated by skinfold thicknesses. Whole-body impedance vector components, resistance (R) and reactance (X(c)), were measured at the same time (BIA-101 analyzer, 50-kHz frequency; Akern/RJL Systems, Clinton Twp., MI). BIA estimates of FFM and FM were obtained with Suns equations (BMI 14-39 kg/m(2)). Vector BIA was performed with the RXc graph method. The frequency of disagreement between anthropometry and BIA was evaluated as a function of increasing BMI (receiver operating characteristic curve). RESULTS The correlation coefficient between methods was 0.80-0.90. The BMI cutoff value of 15 kg/m(2) predicted disagreement of FM and FFM in patients with a BMI <15 kg/m(2). In the RXc graph, the distribution of vectors from patients with disagreement was significantly shifted out of the right border of the reference tolerance ellipses. CONCLUSIONS Anthropometry and BIA equations should not be used in anorexic patients with a BMI <15 kg/m(2). The distribution of vectors from patients with disagreement of methods was shifted out of the right border of the reference tolerance ellipses and was superposed to vectors from patients with a BMI <15 kg/m(2). The identified impedance pattern for anorexia could be useful for feedback in individual patient refeeding (vector back into the 75% reference ellipse).

Equivalence of information from single frequency v. bioimpedance spectroscopy in bodybuilders

In bioelectrical impedance spectroscopy (BIS), it is assumed that the current path is only extracellular at the lowest frequencies and that it is both extra- and intracellular at the highest frequencies. We tested validity of BIS assumptions in bodybuilders who have an increased intracellular volume due to hypertrophy of muscle fibres. The study was observational cross-sectional in a study group of thirty professional bodybuilders compared with thirty control subjects. Resistance (R) and reactance (Xc) vector components fitting the Coles arc with BIS (SFB3 analyser) were compared with components at 50 kHz frequency. The average Coles arc in bodybuilders was significantly smaller and shifted to the left in the R-Xc plane (both R and Xc values were smaller at any individual frequency). The ratio of Xc at 5 kHz and Xc at the characteristic frequency was 70% in bodybuilders and 64% in control subjects, indicating a huge intracellular flow of the electric current at low frequencies in both groups (expected ratio close to 0 if the current path was extracellular). As a consequence of a common path, the correlation coefficient between R values at 50 kHz and at other frequencies (from 0 to infinity) was 0.94 to 1.00. The correlation between total body water estimated with BIS or with R at 50 kHz was 0.98. Hence, there was equivalence between information provided by the vector components R and Xc at 50 kHz and that provided by 496 correlated vectors that were measured with BIS.

Influence of tonsillectomy on the progression of mesangioproliferative glomerulonephritis

BACKGROUND Little information is available about the efficacy of tonsillectomy on long-term renal survival of patients with primary IgA nephropathy (IgAN). METHODS In this retrospective cohort study, we considered 61 patients with IgAN who had tonsillectomy (n = 15) or not (n = 46) and compared them with 121 control patients with mesangioproliferative glomerulonephritis (MesGN) free of IgA deposits, who had tonsillectomy (n = 49) or not (n = 72). We evaluated the progression from a normal function [estimated glomerular filtration rate 60-220 mL/min/1.73 m(2), chronic kidney disease (CKD) stage 1 and 2] to a moderate renal dysfunction in CKD stage 3, which was considered the outcome. RESULTS The mean duration of follow-up was 250 months (12-300 months) in the whole group of 182 patients. The survival to progression to stage 3 was 88% after 10 years, 71% after 20 years and 53% after 25 years. It was 72% after 20 years in both groups. Tonsillectomy was not significantly associated with CKD progression. Significant prognostic factors were age (P = 0.01), initial CKD stage (P = 0.03), proteinuria (P = 0.03), persistent proteinuria (P < 0.001) and diastolic blood pressure (P = 0.01). In the multivariate analysis (Cox model), there was no significant effect of tonsillectomy adjusted for the type of glomerulonephritis, initial CKD stage, persistent proteinuria, diastolic blood pressure and age. Only persistent proteinuria adjusted for the other factors was significantly associated with CKD progression (hazard ratio of 6.2, 95% confidence interval 3.1-12.7, P < 0.001). CONCLUSIONS Tonsillectomy was not associated with a different progression rate of IgAN nor of MesGN after 20 years of follow-up.

Evidence for Decreased Circulating Apelin beyond Heart Involvement in Uremic Cardiomyopathy

Background: Plasma apelin concentration in heart failure has been described in small studies reporting conflicting results. In hemodialysis (HD) patients, apelin decreased more in those with more severe heart involvement. It is unclear if uremia is connected to this reduction irrespective of heart failure. We compared apelin in two cardiomyopathies with different renal function. Methods: Observational study conducted in 30 adult Caucasian outpatients in class I NYHA not affected by diabetes or ischemic heart, 15 with idiopathic dilated cardiomyopathy (DCM) and 15 with uremic dilated cardiomyopathy undergoing HD. Plasma apelin, creatinine, high-sensitivity C-reactive protein, endothelin, NT proB-type natriuretic peptide (NT-proBNP), and Doppler echocardiogram were evaluated. Results: Heart involvement was more severe in the DCM patients (lower ejection fraction, greater diastolic volume index, and worse index of myocardial performance). Median value of apelin in HD patients (19.1 pg/ml) was one third of that in DCM patients (58.2 pg/ml) whereas creatinine, NT-proBNP, and C-reactive protein were 11, 80, and 9 times higher respectively in HD than in DCM patients. Median values of endothelin were comparable in both groups. Apelin was not significantly correlated with any variable. Conclusion: Uremic status was the determinant for decreased plasma apelin in HD patients regardless of the severity of heart involvement.

Influence of localized edema on whole-body and segmental bioelectrical impedance

OBJECTIVE Tetrapolar whole-body (hand-foot) bioelectrical impedance (Z-body) is used in body composition analysis assuming homogeneous soft tissue hydration. Limbs and trunk contribute to Z-body by 90% and 10%, respectively. We determined the effect on Z-body of an edema localized in one leg. METHODS Resistance (R) and reactance (Xc) components of Z vector were measured at 50 kHz (BIA-101, RJL Systems, Akern, Italy) in 20 adult male patients without edema, before and 3 d after a femoropopliteal bypass that induced pitting edema in the leg. Z-body was measured from hand to foot on the right and left sides. Z from the leg (Z-leg) was measured from the pair of electrodes on the foot and the other pair on the trochanter. Data were analyzed with the vector bioelectric impedance analysis (Vector BIA) method (Piccolis RXc graph with 95% confidence ellipses). RESULTS Before surgery, the positions of the mean Z-body and Z-leg vectors from either side of the body were not significantly different (overlapping 95% confidence ellipses). After surgery, the mean Z-leg and Z-body vectors from the side without edema did not change position in the RXc plane with respect to the presurgery position. In contrast, the mean Z-leg and Z-body vectors of the body side with edema significantly (P < 0.05) shortened according to the Vector BIA patterns of fluid accumulation. CONCLUSION Z-body in the side of the body without edema is not sensitive to the edema localized in the leg on the opposite side and therefore can be used in the assessment of body composition in patients with edema in one leg.

Combined evaluation of nutrition and hydration in dialysis patients with bioelectrical impedance vector analysis (BIVA).

BACKGROUND & AIMS Body hydration changes continuously in hemodialysis patients. The Subjective Global Assessment (SGA) is used for the nutritional evaluation but it does not allow a direct evaluation of hydration. Bioelectrical impedance vector analysis (BIVA) is very sensitive to hydration. The potential of the combined evaluation of hydration and nutrition with SGA and BIVA is still lacking. METHODS Observational cross-sectional study on 130 (94 Male) uremic patients undergoing chronic hemodialysis three times a week. Nutritional status was evaluated with the SGA. Each subject was classified as SGA-A (normal nutritional status), SGA-B (moderate malnutrition), or SGA-C (severe malnutrition). Body hydration was evaluated with BIVA. The two vector components resistance (R) and reactance (Xc) were normalized by the subjects height and standardized as bivariate Z-score, i.e. Z(R) and Z(Xc). RESULTS Undernutrition influenced impedance vector distribution both before and after a dialysis session. In pre-dialysis, the mean vector of SGA A was inside the 50% tolerance ellipse. In SGA B and C, Z(R) was increased and Z(Xc) decreased, indicating a progressive loss of soft tissue mass. Fluid removal with dialysis increased both Z(R) and Z(Xc) in SGA A and B but not in C. With ROC curve analysis on the slope of increase, we found the cutoff value of 27.8° below which undernutrition was present, either moderate or severe. The area under the ROC curve was 77.7° (95% CI 69.5-84.5, P < .0001) with sensitivity 75.9%, specificity 78.6%, positive predicted value 74.6%, and negative predicted value 79%. CONCLUSIONS The distribution of impedance vectors is associated with the SGA classification of patients. The change in body hydration in each SGA category can be detected with BIVA.

Copeptin decrease from admission to discharge has favorable prognostic value for 90-day events in patients admitted with dyspnea

Abstract Background: With patients referred to emergency departments (EDs) for acute dyspnea, emergency physicians should consider all possible diagnoses and assess patients’ risk stratification. Copeptin has been shown to have prognostic power for subsequent events, such as death and rehospitalization in patients admitted for dyspnea. The aim of this study was to investigate prognostic role of copeptin variations during hospitalization in patients admitted for dyspnea. Methods: We conducted a prospective, multicentric, observational study in acute dyspneic patients in three ED centers in Italy. Clinical data and copeptin assessments were performed at admission, and at discharge. A 90-day follow-up was performed. Results: A total of 336 patients were enrolled, and on the basis of final diagnosis distinguished into two groups: acute heart failure and no acute heart failure. Compared to a control group, in all studied population copeptin values at admission resulted in a significantly (p<0.001) higher median (maximum–minimum): 31 (0–905) versus 8 (0–13) pmol/L. Median copeptin value at admission was 42 (0–905) pmol/L in acute heart failure patients and 20 (0–887) pmol/L in no acute heart failure, respectively (p<0.001). In all studied patients and in each group copeptin at admission and discharge showed significant predictive value for 90-day events (p<0.001). Furthermore, in all patients population and in both groups Δ copeptin values from admission to discharge also showed significant predictive value for 90-day events (p<0.001). Conclusions: In patients admitted for acute dyspnea, admission, discharge and Δ copeptin variations have significant prognostic value from subsequent 90-day death and rehospitalization.

Prognostic value of decreased peripheral congestion detected by Bioelectrical Impedance Vector Analysis (BIVA) in patients hospitalized for acute heart failure: BIVA prognostic value in acute heart failure

Objectives: The objective of this study was to investigate the prognostic role of quantitative reduction of congestion during hospitalization assessed by Bioelectrical Impedance Vector Analysis (BIVA) serial evaluations in patients admitted for acute heart failure (AHF). Background: AHF is a frequent reason for patients to be admitted. Exacerbation of chronic heart failure is linked with a progressive worsening of the disease with increased incidence of death. Fluid overload is the main mechanism underlying acute decompensation in these patients. BIVA is a validated technique able to quantify fluid overload. Methods: a prospective, multicentre, observational study in AHF and no AHF patients in three Emergency Departments centres in Italy. Clinical data and BIVA evaluations were performed at admission (t0) and discharge (tdis). A follow-up phone call was carried out at 90 days. Results: Three hundred and thirty-six patients were enrolled (221 AHF and 115 no AHF patients). We found that clinical signs showed the most powerful prognostic relevance. In particular the presence of rales and lower limb oedema at tdis were linked with events relapse at 90 days. At t0, congestion detected by BIVA was observed only in the AHF group, and significantly decreased at tdis. An increase of resistance variation (dR/H) >11 Ω/m during hospitalization was associated with survival. BIVA showed significant results in predicting total events, both at t0 (area under the curve (AUC) 0.56, p<0.04) and at tdis (AUC 0.57, p<0.03). When combined with clinical signs, BIVA showed a very good predictive value for cardiovascular events at 90 days (AUC 0.97, p<0.0001). Conclusions: In AHF patients, an accurate physical examination evaluating the presence of rales and lower limbs oedema remains the cornerstone in the management of patients with AHF. A congestion reduction, obtained as a consequence of therapies and detected through BIVA analysis, with an increase of dR/H >11 Ω/m during hospitalization seems to be associated with increased 90 day survival in patients admitted for AHF.

Determinants of circulating asymmetric and symmetric dimethylarginines in patients evaluated for acute dyspnea.

Abstract Background: The relationship between asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) plasma concentrations and acute heart failure is unknown. We evaluated ADMA and SDMA in patients with acute dyspnea. Methods: We studied 57 dyspneic subjects (50–95 years), with estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m2, presenting to the emergency department. Troponin I, N terminal-proBNP (NT-proBNP), ADMA, and SDMA were measured. Electrocardiogram, chest X-ray and lung ultrasound were performed. Patients were classified into cardiogenic dyspnea and non-cardiogenic dyspnea, and were also classified on the basis of renal function according to their eGFR. Results: Two-way analysis of variance demonstrated that ADMA and SDMA did not differ for type of dyspnea, but increased in renal dysfunction. NT-proBNP significantly increased both in cardiogenic dyspnea and renal dysfunction. Multiple regression analysis demonstrated that after adjustment for troponin and dyspnea, the only variables which significantly correlated with SDMA plasma concentrations were renal function (β=–0.47, p<0.001) and NT-proBNP (β=0.28, p=0.02). Conclusions: Neither type of dimethylarginine showed cardiogenic dyspnea to be a determinant for plasma concentrations. Renal dysfunction was a confounder for both ADMA and SDMA.

Sensitivity of whole-body bioelectrical impedance to edema in one leg

Tetrapolar, whole-body (hand-foot) bioelectrical impedance (Zwb) is utilized in body composition analysis for direct assessment of soft tissue hydration (Vector BIA) and indirect assessment of lean and fat soft tissue mass (BIA prediction equations). Limbs and trunk contribute to Zwb by 90% and 10%, respectively. We determined the effect on Zwb of local edema localized in one leg. Resistance (R) and reactance (Xc) components of Z vector was measured at 50 kHz (BIA-101, RJL Systems-Akern, Italy) in 20 adult male patients without edema, before and three days after a surgical procedure on vessels of one leg (femoro-popliteal bypass) that induced pitting edema in that leg. Zwb were measured from hand and foot of the right and left side. Z from the leg (Zleg) was measured from the pair of electrodes on foot and the other pair on the trochanter. Data were analyzed with Vector BIA (Piccoli’s RXc graph method, 95% confidence ellipses) that considers Zwb and Zleg as bivariate gaussian random vectors (expressed in Ohm/meter of conductor). Baseline mean vector from legs of either side, Zleg was significantly shorter than Zwb on the R-Xc plane (separate 95% confidence ellipses).