Neural network technology to predict intracellular water volume

Chronic hypoxemia is associated with a decreased growth rate and a decreased rate of cell division. In lambs with experimental cyanotic heart disease, the gain in body mass was decreased. In this study, we determined to what extent the lower body mass in these lambs was related to alterations in body fluid compartment volumes, specifically whether intracellular volume was decreased. Therefore, fluid compartment volumes were studied in nine lambs, after 3 to 4 wk of experimental cyanotic heart disease, and in 13 control lambs. Hypoxemic lambs had a lower arterial oxygen saturation (65 +/- 11 versus 91 +/- 2%, p < 0.001) and a higher Hb concentration (142 +/- 16 versus 101 +/- 8 g.L-1, p < 0.001). The lower body mass in hypoxemic lambs (10.5 +/- 2.3 versus 13.0 +/- 2.8 kg) could be mainly accounted for by a decrease in intracellular water volume (4.7 +/- 1.3 versus 6.6 +/- 1.5 L, p < 0.01). Total body water (753 +/- 27 versus 780 +/- 40 mL.kg-1) and extracellular water volume (307 +/- 25 versus 277 +/- 15 mL.kg-1) in hypoxemic lambs were not significantly different from those in control lambs, but intracellular water volume was decreased (445 +/- 27 versus 501 +/- 35 mL.kg-1, p < 0.01). The ratio of extracellular to intracellular water volume was higher in hypoxemic lambs (0.69 +/- 0.10 versus 0.55 +/- 0.04, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

The objective of this study was to evaluate the accuracy of independent hydric data for the quantification of total body water (V t), extracellular water (V e) and intracellular water (V i), obtained by a multifrequency impedancemeter Z-Métrix(®) (ZM), in standing and lying position, with respect to the Xitron reference. In a second step, the aim was to consider whether it is possible to quantify daily hydration. The average repeatability error of the ZM impedancemeter is less than 0.5%. For total body water (V t), we note a low R (2) dispersion with an average of 0.9 for men and 0.6 for women. The estimation of extracellular water is equivalent to a maximum error of 3.1% in standing position for women against 2.97% for men in the same position. The estimation of the total body water by direct measurement and by summing the volumes of extracellular and intracellular water obtained by the Z-Metrix(®) shows very low dispersions with R (2)=0.89 and average error from 1.3% for healthy women in lying position to 3.9% for healthy women in standing position. Finally, despite the impact of events on the daily measurements, it is viable to track a subject's overall hydration.

To cross-validate existing anthropometric and bioimpedance equations to establish their validity and accuracy for estimating intracellular water (ICW) in healthy older Germans and to develop a new equation with improved accuracy and precision for predicting ICW from multifrequency bioimpedance analysis (MFBIA). Cross-validation study. University of Mainz. One hundred fifty-five healthy volunteers aged 60 to 80 years (77 men, 78 women; mean ages +/- standard deviation 67.7 +/- 4.8 and 68.6 +/- 5.5 years, respectively). ICW was measured by whole-body counting of (40)potassium ((40)K) ((40)K method) as the reference method and compared by cross-validation techniques against five existing bioimpedance and three anthropometric prediction equations. A new equation for estimating ICW from MFBIA was developed using the (40)K method as criterion method. Compared with the (40)K method, the existing bioimpedance and anthropometric equations showed large prediction errors in ICW estimates for older men (-32.3% to +37.7%) and women (-34.2% to +26.6%), depending significantly and positively on ICW volume and inversely on weight. A new equation for estimating ICW from MFBIA was developed (R(2)=0.933, standard error of the estimate (SEE)=0.92 L) involving phase angle at 5 kHz, impedance, height, and gender, with data from 100 subjects chosen at random. Cross-validation on an independent group (n=55, R(2)=0.958, SEE=0.68 L) showed no significant bias (0.013 +/- 1.52 L). Published bioimpedance and anthropometric prediction equations are not applicable to older Germans because they might be population-specific. The bioimpedance equation of the manufacturer of the bioimpedance analyzer used in this study provides accurate estimates of ICW for normal weight, but not overweight, older men. The newly developed equation improves accuracy and precision of ICW estimates by MFBIA.

Bioimpedance spectroscopy (BIS) permits evaluation of extra- and intracellular fluid volumes in patients. We wished to examine whether this technique, used in combination with hematocrit measurement, can reliably monitor fluid transfers during dialysis. Ankle to wrist BIS measurements were collected during 21 dialysis runs while hematocrit was continuously monitored in the blood line by an optical device. Extracellular (ECW) and intracellular (ICW) water volumes were calculated using Hanai's electrical model of suspensions. Plasma volume variations were calculated from hematocrit, and changes in interstitial volume were calculated as the difference between ECW and plasma volume changes. Because accuracy of ICW was too low, changes in ICW were calculated as the difference between ultrafiltered volume and ECW changes. Total body water (TBW) volumes calculated pre- and postdialysis were, respectively, 3.25+/-3.2 and 1.95+/-2.5 liters lower on average than TBW given by Watson et al.'s correlation. Average decreases in fluid compartments expressed as percentage of ultrafiltered volume were as follows: plasma, 18%; interstitial, 28%, and ICW, 54%. When the ultrafiltered volume was increased in a patient in successive runs, the relative contributions of ICW and interstitial fluid were augmented so as to reduce the relative drop in plasma volume.

A method for extracting fluid volumes from multifrequency bioimpedance, which takes into account the body geometry and the presence of nonconducting elements, was tested on 12 young dialyzed patients against correlations for total body water volumes (TBW) from Watson et al. and Humes et al. Our calculations of TBW from impedance were found to overestimate Humes' values by 0.25 L (0.8%) postdialysis and by 2.08 L (6.5%) predialysis. Extracellular water (ECW) was found to contribute an average of 93% of ultrafiltered volume. Intracellular water volume (ICW) determination from impedance was found to be too imprecise to predict its variation during dialysis; therefore, ICW variations were calculated as the difference between ultrafiltration and ECW changes. The continuous recording of hematocrit by an optical device monitored changes in plasma and interstitial volumes. In most cases, ultrafiltration was compensated mainly by a contribution from interstitial fluid, and the drop in plasma volume was generally moderate.

BackgroundMulti‐shell diffusion MRI (dMRI) biophysical models can estimate intracellular (ICVF), extracellular (ECVF) and free water (ISOVF) volume fractions (VFs) in brain tissue, and may offer insight into Alzheimer's disease pathological processes. These microstructural measures can be calculated in the cortex using a gray matter specific model that may be sensitive to amyloid and tau burden. Here, we evaluated relationships between regional cortical microstructural VFs and CSF amyloid and tau biomarkers.MethodMulti‐shell dMRI and CSF biomarker data were available for 50 ADNI‐3 participants (age: 72.4±6.4 yrs; 20 male; 36 cognitively normal, 12 MCI, 2 dementia). Cortical ICVF, ECVF and ISOVF were estimated with the multi‐tissue spherical mean technique (MT‐SMT). Mean cortical measures were extracted from 4 lobes and the cingulate cortex, parcellated with FreeSurfer. Random‐effects linear regressions tested associations between regional dMRI measures and CSF pTau or Aβ42/Aβ40 burden, adjusting for age, sex, education, and grouping by scanning site. FDR (q=0.05) was used to correct for multiple comparisons across 5 regions, 3 diffusion measures, and 2 tests.ResultHigher Aβ42/Aβ40 was associated with lower ISOVF throughout the cortex (Figure 1), and higher ECVF and ICVF in the cingulate, frontal and temporal lobes. Higher ICVF was also found in the parietal cortex. Higher pTau was associated with higher ISOVF in the occipital and parietal lobes, and lower ECVF in the frontal and parietal lobes (Figure 2). No pTau ICVF associations were detected.ConclusionLower ICVF and higher ISOVF with greater amyloid and tau may indicate neuronal loss or edema, while lower ECVF could reflect, for example, as neuronal swelling or an influx of activated microglia. Lower ECVF with greater amyloid and tau burden may also reflect accumulation of large hydrophobic amyloid plaques and neurofibrillary tangles in the extracellular space. These results are preliminary and, as many factors influence dMRI measures, should be interpreted with caution. Future work will incorporate multimodal imaging to map associations of diffusion measures with localized PET‐derived amyloid and tau measures.

In patients with end stage renal failure, control of the fluid status of the body is lost and fluid accumulates continuously. By dialysis therapy, excess fluid can be removed, but there are no reliable methods to establish the amount of excess fluid to be removed. Severe and even lethal complications may be the consequence of longer term deviations from a normal fluid status in dialysis patients, but also in other patient groups. Therefore, a large medical need exists for a precise and pragmatic method to determine fluid status. Bioimpedance measurement, today mainly used for nutrition status assessment, is regarded as an interesting candidate method for fluid status determination. This paper presents a four-compartment model of the human body, developed to derive information on fluid status from extra- and intracellular volumes measured by bioimpedance spectroscopy. The model allows us to determine weights of each of four compartments (overhydration, fat, muscle and remaining ‘basic’ components) by analyzing extra- and intracellular water volumes in different tissues of the body. Thereby fluid status (overhydration volume, normohydrated weight of the patient) as well as nutrition and fitness status (lean body, fat and muscle mass) can be determined quantitatively from a single measurement. A preliminary evaluation of the performance of a system consisting of a bioimpedance spectrum analyzer and the four-compartment model is also provided.

Stern, Eggleston, Hems and Krebs1 reported that slices of a number of guinea pig tissues swelled in isotonic solutions under anaerobic conditions. They suggested that the fluid balance of living tissues is not determined merely by physical forces, but by a mechanism dependent upon the supply of energy. Robinson2 found that rat kidney slices swelled to a similar extent, mainly on account of an increase in the volume of intracellular water, when respiration was inhibited by small concentrations of cyanide. This swelling was reversed when the oxygen uptake recovered, as hydrogen cyanide distilled out of the medium. The water content of the slices varied inversely with their oxygen consumption over the whole range from normal respiration to complete inhibition. The amount of osmotic work required to maintain the water content of the slices as a steady state was calculated, and found to be proportional to their oxygen uptake. It was therefore suggested that the intracellular fluid was hypertonic, and that the normal volume and internal hypertonicity of the cells were maintained by active transport of water outwards across the cell membranes at the expense of energy directly derived from oxidation.

Water contents of various body compartments were estimated within 9 h of birth in eight baboon neonates and at a mean of 29 days (27-32 days) in seven baboons. All animals were normally grown and delivered spontaneously at term. There was no difference in mean antipyrine space, corrected bromide space, intracellular water, interstitial water, and plasma and blood volumes observed on day 1 and day 29. Mean estimate of red cell volume was lower on day 29 than on day 1.

Energy expenditure and body composition in children with spastic quadriplegic cerebral palsy

Total Body Water and Intracellular Water Relationships with Muscle Strength, Frailty and Functional Performance in an Elderly Population.

Background/Objectives: Microvascular complications are a major source of disability in type 2 diabetes mellitus (T2DM). We investigated whether body composition indices derived from multifrequency bioelectrical impedance analysis (BIA) independently predict neuropathy, retinopathy, nephropathy, and stroke, and whether they improve risk discrimination beyond the established clinical variables. Methods: In this cross-sectional analytical study (March 2024-February 2025), 124 adults with T2DM ≥ 12 months attending the outpatient diabetes clinic of the Universidad Técnica de Ambato (Ecuador) were enrolled. After an overnight fast and 15 min supine rest, thirteen whole-body BIA metrics including skeletal muscle mass (SMM), intracellular water (ICW), phase angle (PhA), and visceral fat area (VFA) were obtained with a segmental analyzer (InBody S10). Complications were ascertained with standard clinical and laboratory protocols. Principal component analysis (PCA) summarized the correlated BIA measures; multivariable logistic regression (adjusted for age, sex, diabetes duration, HbA1c, BMI, and medication use) generated odds ratios (ORs) per standard deviation (SD). Discrimination was assessed with bootstrapped receiver-operating characteristic curves. Results: The first principal component, driven by SMM, ICW, and PhA, accounted for a median 68% (range 65-72%) of body composition variance across all complications. Each SD increase in SMM lowered the odds of neuropathy (OR 0.54, 95% CI 0.41-0.71) and nephropathy (OR 0.70, 0.53-0.92), whereas VFA raised the risk of neuropathy (OR 1.55, 1.22-1.97) and retinopathy (OR 1.47, 1.14-1.88). PhA protected most strongly against stroke (OR 0.55, 0.37-0.82). Composite models integrating SMM, PhA, and adiposity indices achieved AUCs of 0.79-0.85, outperforming clinical models alone (all ΔAUC ≥ 0.05) and maintaining good calibration (Hosmer-Lemeshow p > 0.20). Optimal probability cut-offs (0.39-0.45) balanced sensitivity (0.74-0.80) and specificity (0.68-0.72). Conclusions: A lean tissue BIA signature (higher SMM, ICW, PhA) confers independent protection against neuropathy, retinopathy, nephropathy, and stroke, whereas visceral adiposity amplifies the risk. Because the assessment is rapid, inexpensive, and operator-independent, routine multifrequency BIA can be embedded into diabetes clinics to triage patients for early specialist referral and to monitor interventions aimed at preserving muscle and reducing visceral fat, thereby enhancing microvascular risk management in T2DM.

Studies were conducted on 29 male healthy subjects having no previous experience of living at high altitude. These subjects were divided into three groups, i.e., subjects treated with placebo, acetazolamide and spironolactone. These subjects were first studied in Delhi. The drug schedule was started 24 hour prior to the airlift of these subjects to an altitude of 3,500 m and was continued for 48 hour after arrival at high altitude. Total body water, extra cellular water, plasma volume, blood electrolytes, pH, pO2, pCO2 and blood viscosity were determined on 3rd and 12th day of their stay at high altitude. Total body water, extra cellular water intracellular water and plasma volume decreased on high altitude exposure. There was a further slight decrease in these compartments with acetazolamide and spironolactone. It was also observed that spironolactone drives out more water from the extracellular compartment. Loss of plasma water was also confirmed by increased plasma osmolality. Increase in arterial blood pH was noticed on hypoxic exposure but the increase was found less in acetazolamide and spironolactone cases. This decrease in pH is expected to result in better oxygen delivery to the tissues at the low oxygen tension. It was also confirmed because blood pO2 increased in both the groups. No significant change in plasma electrolytes was observed in subjects of various groups. Blood viscosity slightly increased on exposure to high altitude. The degree of rise was found less in the group treated with spironolactone. This study suggests that both the drugs are likely to be beneficial in ameliorating/prevention of AMS syndrome.

Reproducibility of low-dose stereography measurements of femoral torsion after IM nailing of femoral shaft fractures and in intact femurs

To evaluate bioelectrical impedance analysis (BIA) in estimating the nutritional status and outcome of patients with chronic obstructive pulmonary disease (COPD) and acute respiratory failure (ARF) in comparison with measurements of anthropometric parameters and plasma levels of visceral proteins. Retrospective study. A ten-bed intensive care unit (ICU) in a university teaching hospital. 51 COPD patients with ARF in whom BIA data, anthropometric parameters, and measurements of visceral proteins were available. BIA results in patients requiring mechanical ventilation (MV) vs. those who did not showed lower active cell mass (ACM; 37.5 +/- 6.5% vs. 42.4 +/- 7.2% body weight, P = 0.01) and a higher extra-/intracellular water volume ratio (ECW/ICW; 1.25 +/- 0.2 vs. 1.04 +/- 0.2, P = 0.0001), suggesting a more severe alteration in the nutritional status among those on MV. Anthropometric data showed the opposite results, since body weight, body mass index (BMI), triceps skinfold thickness (TSF), and fat mass were significantly higher in the invasively ventilated patients, whereas middle-arm muscle circumference (MAMC) did not differ between the two groups. The marked inflation of the extracellular compartment (ECW, ECW/ICW) that was well shown by BIA in the invasively ventilated patients presumably lead to inaccurate anthropometric results (overestimation of TSF and fat mass, and erroneous measure of MAMC). A higher death rate (38% vs. 0%, P = 0.01) was observed in the patients with ACM depletion (ACM < or = 40.6% body weight, n = 26) than in those without ACM depletion (n = 25). Low albumin level (< 30 g/l) was associated with increased mortality (33% vs. 7%, P = 0.04), but the differences in the other biological and anthropometric parameters (prealbumin and transferrin levels, body weight, BMI, TSF, MAMC, fat mass, and fat-free mass) were not associated with mortality. This study suggests that the decrease in BIA-derived ACM is a good indication of malnutrition and of poor outcome in COPD patients with ARF.