Body composition and phase angle (PhA) have been used to predict mortality in multiple diseases. However, little has been studied regarding segmental measurements, which could potentially help assess subtle changes in specific tissue segments. This study aimed to identify the total PhA cut-off point associated with mortality risk and changes in body composition within a week of hospitalisation in non-critical hospitalised patients with COVID-19. A cohort study was conducted where patients underwent to a complete nutritional assessment upon admission and after seven days, and followed up until hospital discharge or death. A receiver operating characteristic curve was constructed to determine the PhA cut-off point, and the Kaplan–Meier estimator was used to determine survival analysis. Segmental and complete body compositions on admission and after 7 d were compared. We included 110 patients (60 men) with a mean age of 50·5 ± 15·0 years and a median BMI of 28·5 (IQR, 25·6–33·5) kg/m2. The median length of hospital stay was 6 (IQR, 4–9) d, and the mortality rate was 13·6 %. The PhA cut-off point obtained was 4°, with significant differences in the survival rate (P < 0·001) and mortality (HR = 5·81, 95 % CI: 1·80, 18·67, P = 0·003). Segmental and whole-body compositions were negatively affected within one week of hospitalisation, with changes in the approach by the graphical method in both sexes. Nutritional status deteriorates within a week of hospitalisation. PhA < 4° is strongly associated with increased mortality in non-critical hospitalised patients with COVID-19.

HIV and severe wasting are associated with post-discharge mortality and hospital readmission among children with complicated severe acute malnutrition (SAM); however, the reasons remain unclear. We assessed body composition at hospital discharge, stratified by HIV and oedema status, in a cohort of children with complicated SAM in three hospitals in Zambia and Zimbabwe. We measured skinfold thicknesses and bioelectrical impedance analysis (BIA) to investigate whether fat and lean mass were independent predictors of time to death or readmission. Cox proportional hazards models were used to estimate the association between death/readmission and discharge body composition. Mixed effects models were fitted to compare longitudinal changes in body composition over 1 year. At discharge, 284 and 546 children had complete BIA and skinfold measurements, respectively. Low discharge lean and peripheral fat mass were independently associated with death/hospital readmission. Each unit Z-score increase in impedance index and triceps skinfolds was associated with 48 % (adjusted hazard ratio 0·52, 95 % CI (0·30, 0·90)) and 17 % (adjusted hazard ratio 0·83, 95 % CI (0·71, 0·96)) lower hazard of death/readmission, respectively. HIV-positive v. HIV-negative children had lower gains in sum of skinfolds (mean difference −1·49, 95 % CI (−2·01, −0·97)) and impedance index Z-scores (–0·13, 95 % CI (−0·24, −0·01)) over 52 weeks. Children with non-oedematous v. oedematous SAM had lower mean changes in the sum of skinfolds (–1·47, 95 % CI (−1·97, −0·97)) and impedance index Z-scores (–0·23, 95 % CI (−0·36, −0·09)). Risk stratification to identify children at risk for mortality or readmission, and interventions to increase lean and peripheral fat mass, should be considered in the post-discharge care of these children.

We have previously shown that children with a bioelectrical impedance spectroscopy phase angle at 50° (PA 50°) of <2.7 on postoperative day 2 had a four-fold increase in the risk of prolonged paediatric intensive care length of stay. In this study, we demonstrate a relationship between a baseline measure of phase angle 200/5° and postoperative length of stay.

In this paper, the comparisons of thermomechanical fatigue behavior of C/SiC and SiC/SiC fiber-reinforced ceramic-matrix composites (CMCs) subjected to different phase angles of θ = 0, π/3, π/2 and π have been investigated. The relationships between the fatigue damage mechanisms, phase angle, fatigue hysteresis dissipated energy, fatigue hysteresis modulus and fatigue peak strain, fiber/matrix interface debonding and sliding have been established. The differences between C/SiC and SiC/SiC composites under thermomechanical fatigue loading with different phase angles have been analyzed. The damage accumulation of 2.5D C/SiC and 2D SiC/SiC composites under thermomechanical fatigue loading have been predicted. With increasing of the phase angle, the fatigue hysteresis dissipated energy, fatigue peak strain and interface debonded length decrease for the SiC/SiC composite; however, for the C/SiC composite, the fatigue hysteresis dissipated energy, fatigue peak strain and the interface debonded length increase at the same cycle number.

Phase angle (PhA), a parameter of bioelectrical impedance analysis, is a well-known predictor of morbidity and mortality in various diseases. The causes of decreased PhA are, however, not yet completely understood. We therefore investigated determinants of PhA in 777 hospitalised patients in a retrospective analysis. PhA was assessed by bioelectrical impedance analysis at 50 KHz. Subjective global assessment (SGA) was used to evaluate nutritional status. Age, sex, BMI as well as nutritional status (SGA), benign or malignant disease and C-reactive protein (CRP) were investigated as potential determinants of PhA and standardised PhA (SPhA) = (observed PhA − mean PhA of reference values)/standard deviation of reference values in a general linear model regression analysis. Next to age (estimated effect size, 46·6 %; P < 0·0001), malnutrition (39·1 %; P < 0·0001) emerged as a major PhA determinant in our study population. Moreover, sex (6·4 %; P < 0·0001), CRP (4·4 %; P < 0·0001) and BMI (3·5 %; P < 0·0001) exhibited a significant influence on PhA, whereas malignant disease showed no significant effect in this model. The only significant determinants of SPhA were malnutrition (85·4 %; P < 0·0001) and inflammation (9·6 %; P < 0·0001). In conclusion, next to the established predictors, malnutrition and inflammation have a strong impact on PhA in sick individuals, which partly explains its prognostic power. When investigating the SPhA, only malnutrition and inflammation were found to be significant predictors, as a result of which the SPhA is considered a more suitable indicator of nutritional and health status.

Bioelectrical impedance analysis (BIA) is an easy-to-use, non-invasive and reproducible technique to evaluate changes in body composition and nutritional status. Phase angle, determined by BIA, has been found to be a prognostic indicator in several chronic conditions, such as HIV, liver cirrhosis, chronic obstructive pulmonary disease and lung cancer, and in patients undergoing dialysis. The present study investigated the prognostic role of phase angle in advanced pancreatic cancer. We evaluated a case series of fifty-eight stage IV pancreatic cancer patients treated at Cancer Treatment Centers of America® at Midwestern Regional Medical Center (Zion, IL, USA) between January 2000 and July 2003. BIA was conducted on all patients using a bioelectrical impedance analyser that operated at 50kHz. The phase angle was calculated as capacitance (Xc)/resistance (R) and expressed in degrees. The Kaplan–Meier method was used to calculate survival. Cox proportional hazard models were constructed to evaluate the prognostic effect of phase angle independent of other clinical and nutritional variables. The correlations between phase angle and traditional nutritional measures were evaluated using Pearson and Spearman coefficients. Patients with phase angle <5·0° had a median survival time of 6·3 (95% CI 3·5, 9·2) months (n 29), while those with phase angle >5·0° had a median survival time of 10·2 (95% CI 9·6, 10·8) months (n 29); this difference was statistically significant (P=0·02). The present study demonstrates that phase angle is a strong prognostic indicator in advanced pancreatic cancer. Similar studies in other cancer settings with larger sample sizes are needed to further validate the prognostic significance of the phase angle.

If electrodermal activity is recorded with direct current, constant voltage and constant current measurements result in different dependencies of electrodermal reactions on the actual electrodermal level. The present study demonstrates empirically that such a problem does not exist when instead the phase angle changes between alternating current and voltage are obtained. Forty subjects were subjected to a 20-trial habituation series on two different occasions, in which electrodermal level variations were induced by room temperature changes. A multiplexing system was used to enable quasi-simultaneous constant current and constant voltage recording under both direct and alternating current measurement conditions. If the alternating current technique was applied and electrodermal responses were expressed as changes of phase angle between voltage and current, electrodermal recordings with constant voltage and with constant current provided equivalent results, even if electrodermal levels were considerably different. Therefore, using the phase angle method instead of the conventional direct current methods will finally resolve the problem of differential level dependency in electrodermal recording. A further advantage will be that electrode and skin polarization are prevented by the use of alternating current.