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3.
Faraday Discuss ; 217: 8-33, 2019 07 01.
Article in English | MEDLINE | ID: mdl-31094388

ABSTRACT

This introduction provides a historical context for the development of ion spectroscopy over the past half century by following the evolution of experimental methods to the present state-of-the-art. Rather than attempt a comprehensive review, we focus on how early work on small ions, carried out with fluorescence, direct absorption, and photoelectron spectroscopy, evolved into powerful technologies that can now address complex chemical problems ranging from catalysis to biophysics. One of these developments is the incorporation of cooling and temperature control to enable the general application of "messenger tagging" vibrational spectroscopy, first carried out using ionized supersonic jets and then with buffer gas cooling in radiofrequency ion traps. Some key advances in the application of time-resolved pump-probe techniques to follow ultrafast dynamics are also discussed, as are significant benchmarks in the refinement of ion mobility to allow spectroscopic investigation of large biopolymers with well-defined shapes. We close with a few remarks on challenges and opportunities to explore molecular level mechanics that drive macroscopic behavior.


Subject(s)
Astronomical Phenomena , Biopolymers/analysis , Physics , Spectrum Analysis/trends , Biology , Spectrum Analysis/instrumentation
4.
Cytometry A ; 95(8): 823-824, 2019 08.
Article in English | MEDLINE | ID: mdl-31038271
5.
An Acad Bras Cienc ; 91(suppl 1): e20180294, 2019.
Article in English | MEDLINE | ID: mdl-31017188

ABSTRACT

Green Analytical Chemistry (GAC) is a research field that seeks for more sustainable analytical approaches to minimize the toxicity and amounts of wastes without hindering the analytical performance. This is a trend in Analytical Chemistry worldwide and because of the diversity of innovations on this subject, Brazil stands out as the third in the list of the main contributors to GAC, with ca. 11.2% of the published articles. Significant innovations and interesting applications in several fields have been presented and Brazil is continuously moving from Chemistry to Green Chemistry also in the Analytical Chemistry field. Selected contributions for sample preparation, spectro- and electroanalysis, separation techniques, chemometrics, and also procedures for point-of-care measurements are critically reviewed.


Subject(s)
Chemistry Techniques, Analytical/trends , Green Chemistry Technology/trends , Research/trends , Brazil , Chemistry Techniques, Analytical/methods , Green Chemistry Technology/methods , Humans , Liquid Phase Microextraction/methods , Liquid Phase Microextraction/trends , Solid Phase Microextraction/methods , Solid Phase Microextraction/trends , Solvents , Spectrum Analysis/methods , Spectrum Analysis/trends
6.
Annu Rev Phys Chem ; 70: 199-218, 2019 06 14.
Article in English | MEDLINE | ID: mdl-30883272

ABSTRACT

Understanding the cellular basis of human health and disease requires the spatial resolution of microscopy and the molecular-level details provided by spectroscopy. This review highlights imaging methods at the intersection of microscopy and spectroscopy with applications in cell biology. Imaging methods are divided into three broad categories: fluorescence microscopy, label-free approaches, and imaging tools that can be applied to multiple imaging modalities. Just as these imaging methods allow researchers to address new biological questions, progress in biological sciences will drive the development of new imaging methods. We highlight four topics in cell biology that illustrate the need for new imaging tools: nanoparticle-cell interactions, intracellular redox chemistry, neuroscience, and the increasing use of spheroids and organoids. Overall, our goal is to provide a brief overview of individual imaging methods and highlight recent advances in the use of microscopy for cell biology.


Subject(s)
Cell Biology/trends , Cytological Techniques/methods , Microscopy/methods , Animals , Cytological Techniques/trends , Humans , Microscopy/trends , Scattering, Radiation , Spectrum Analysis/methods , Spectrum Analysis/trends
7.
Acc Chem Res ; 51(9): 2279-2286, 2018 09 18.
Article in English | MEDLINE | ID: mdl-30152675

ABSTRACT

In 1998, the first successful quantum control experiment with application to a molecular framework was conducted with a shaped laser pulse, optimizing the branching ratio between different organometallic reaction channels. This work induced a vast activity in quantum control during the next 10 years, and different optimization aims were achieved in the gas phase, liquid phase, and even in biologically relevant molecules like light-harvesting complexes. Accompanying and preceding this development were important advances in theoretical quantum control simulations. They predicted several control scenarios and explained how and why quantum control experiments work. After many successful proofs of concept in molecular science, the big challenge is to expand its huge conceptual potential of directly being able to steer nuclear and/or electronic motion to more applied implementations. In this Account, based on several recent advances, we give a personal evaluation of where the field of molecular quantum control is at the moment and especially where we think promising applications can be in the near future. One of these paths leads to synthetic chemistry. The synthesis of novel pharmaceutical compounds or natural products often involves many synthetic steps, each one devouring resources and lowering the product yield. Shaped laser pulses can possibly act as photonic reagents and shorten the synthetic route toward the desired product. Chemical synthesis usually takes place in solution, and by including explicit solvent molecules in our quantum control simulations, we were able to identify their highly inhomogeneous influence on chemical reactions and how this affects potential quantum control. More important, we demonstrated for a synthetically relevant example that these complications can be overcome in theory, and laser pulses can be optimized to initiate the desired carbon-carbon bond formation. Putting this into context with the recently emerging concept of flow chemistry, which brings several practical advantages to the application of laser pulses, we want to encourage experimental groups to exploit this concept. Another path was opened by several additions to the commonly used laser pulse optimization algorithm (optimal control theory, OCT), several of which were developed in our group. The OCT algorithm as such is a purely mathematical optimization procedure, with no direct relation to experimental requirements. This means that usually the electric fields obtained out of OCT optimizations do not resemble laser pulses that can be achieved experimentally. However, the previously mentioned additions are aimed at closing the gap toward the experiment. In a recent quantum control study of our group, these algorithmic developments came to fruition. We were able to suggest a shaped laser pulse which can induce a long-living wave packet in the excited state of uracil. This might pave the way for novel experiments dedicated to investigating the formation of biological photodamage in DNA and RNA. The pulse we suggest is surprisingly simple because of the extended OCT algorithm and fulfills all criteria to be experimentally accessible.


Subject(s)
Chemistry Techniques, Synthetic/trends , Quantum Theory , Spectrum Analysis/trends , Algorithms , Chemistry Techniques, Synthetic/methods , Lasers , Light , Spectrum Analysis/methods , Vibration
9.
Arq. bras. med. vet. zootec. (Online) ; 70(2): 597-605, mar.-abr. 2018. tab, graf
Article in Portuguese | LILACS, VETINDEX | ID: biblio-910879

ABSTRACT

O presente trabalho teve como objetivo validar a eficácia do método de espectroscopia de reflectância do infravermelho proximal (NIRS) em predizer o consumo e a digestibilidade da MS e nutrientes de dietas para cordeiros confinados, em comparação ao método convencional de laboratório. Amostras das dietas fornecidas, sobras e fezes de 40 cordeiros Santa Inês foram submetidas a ambos os métodos e analisadas quanto aos teores de MS, MM, FDN, FDA, PB e EE, para futuros cálculos do consumo e da digestibilidade. A maioria dos coeficientes de correlação do modelo ficou na faixa de 0,66 a 0,81, mostrando-se adequados para a predição quantitativa. Os maiores coeficientes foram observados para teores de PB das dietas (0,85) e sobras (0,87). Foram encontradas altas correlações entre os métodos na predição do consumo (média de 0,93) e digestibilidade (média de 0,90) das dietas. As correlações entre as variáveis obtidas pela predição do NIRS e pelo método convencional foram adequadas, demonstrando que, independentemente do método, os teores nutricionais das dietas, das sobras e das fezes podem ser utilizados para calcular o consumo e a digestibilidade da MS e dos nutrientes das dietas para cordeiros confinados, sendo recomendado o método NIRS pela precisão, pela rapidez e pelo baixo custo em relação ao método convencional.(AU)


This research was carried out to validate the effectiveness of the Near-IR spectroscopy method in predicting intake and digestibility of DM and nutrients of diets for feedlot lambs, in order to compare with the conventional laboratory method. Samples of diets, ort,s and feces of forty Santa Ines lambs were subjected to both methods and analyzed for DM, MM, NDF, ADF, CP, and EE for future calculations for intake and digestibility. Most of the model's correlation coefficient was in the range of 0.66 to 0.81, being suitable for quantitative prediction. Highest values for CP content of 0.85 (diets) and 0.87 (orts) were observed. There were high correlations between the methods to predicting intake (average values of 0.93) and digestibility (average values of 0.93). Correlations between the variables obtained by the prediction of NIRS and the conventional method were adequate, showing that regardless of the method, the nutritional content of diets, orts and feces can be used to calculate the intake and digestibility of DM and nutrients of lambs' diets. The Near-IR spectroscopy method is recommended for accuracy, speed and low cost compared to conventional method.(AU)


Subject(s)
Animals , Eating , Spectrophotometry, Infrared , Spectrum Analysis/trends , Sheep/metabolism
10.
J Sep Sci ; 40(1): 138-151, 2017 01.
Article in English | MEDLINE | ID: mdl-27902885

ABSTRACT

The vacuum ultraviolet spectrophotometer was developed recently as an alternative to existing gas chromatography detectors. This detector measures the absorption of gas-phase chemical species in the range of 120-240 nm, where all chemical compounds present unique absorption spectra. Therefore, qualitative analysis can be performed and quantification follows standard Beer-Lambert law principles. Different fields of application, such as petrochemical, food, and environmental analysis have been explored. Commonly demonstrated is the capability for facile deconvolution of co-eluting analytes. The concept of additive absorption for co-eluting analytes has also been advanced for classification and speciation of complex mixtures using a data treatment procedure termed time interval deconvolution. Furthermore, pseudo-absolute quantitation can be performed for system diagnosis, as well as potentially calibrationless quantitation. In this manuscript an overview of these features, the vacuum ultraviolet spectrophotometer instrumentation, and performance capabilities are given. A discussion of the applications of the vacuum ultraviolet detector is provided by describing and discussing the papers published thus far since 2014.


Subject(s)
Chromatography, Gas/trends , Spectrum Analysis/trends , Vacuum
11.
Top Magn Reson Imaging ; 25(5): 215-221, 2016 Oct.
Article in English | MEDLINE | ID: mdl-27748706

ABSTRACT

With its exquisite anatomical resolution and wide-ranging functional imaging capabilities, magnetic resonance imaging (MRI) has found multiple applications in detection, staging, and monitoring treatment response in cancer. The metabolic information provided by magnetic resonance spectroscopy (MRS) is being actively investigated to complement MRI parameters, as well as existing biomarkers, in cancer detection and in monitoring response to treatment. Located at the interface of detection and therapy, theranostic imaging is a rapidly expanding new field that is showing significant promise for precision medicine of cancer. Innovations in the development of novel nanoparticles decorated with imaging reporters that can be used to deliver therapeutic cargo to specific cells and environments have provided new roles for MRI and MRS in theranostic imaging.


Subject(s)
Magnetic Resonance Imaging , Neoplasms/diagnostic imaging , Spectrum Analysis , Theranostic Nanomedicine , Humans , Magnetic Resonance Imaging/trends , Spectrum Analysis/trends , Theranostic Nanomedicine/trends
12.
Faraday Discuss ; 187: 603-7, 2016 06 23.
Article in English | MEDLINE | ID: mdl-27250100

ABSTRACT

The Faraday Discussion meeting "Advanced Vibrational Spectroscopy for Biomedical Applications" provided an excellent opportunity to share and discuss recent research and applications on a highly interdisciplinary level. Spectral pathology, single cell analysis, data handling, clinical spectroscopy, and the spectral analysis of biofluids were among the topics covered during the meeting. The focus on discussion rather than "merely" presentation was highly appreciated and fruitful discussions evolved around the interpretation of the amide-bands, optical resolution, the role of diffraction and data analysis procedure, to name a few. The meeting made clear that the spectroscopy of molecular vibrations in biomolecules has evolved from a purely academic research tool to a technology used in clinical practice in some cases. In this sense, biomedical vibrational spectroscopy has reached a pivotal point at which questions like diagnostic value, therapeutic consequence and financial viability are gaining more and more importance.


Subject(s)
Clinical Medicine/methods , Spectrum Analysis/trends , Body Fluids/chemistry , Body Fluids/diagnostic imaging , Clinical Medicine/trends , Congresses as Topic , Humans , Single-Cell Analysis , Spectrum Analysis/economics , Vibration
13.
Arch. esp. urol. (Ed. impr.) ; 68(3): 316-333, abr. 2015. tab, ilus
Article in Spanish | IBECS | ID: ibc-136565

ABSTRACT

El diagnóstico actual del cáncer de próstata basado en las cifras de PSA y biopsia sistemática presenta limitaciones en la eficacia de su detección y estadiaje. Los avances técnicos de la imagen en la última década, especialmente la resonancia magnética (RM) permiten mejorar la estrategia en el manejo del cáncer de próstata en el diagnóstico, estadificación, seguimiento y monitorización terapéutica. La RM permite combinar información morfológica (secuencia T2) y funcional al mismo tiempo mediante la aplicación de secuencias como la espectroscopía (RME), difusión (RMD) y contraste endovenoso dinámico (RMC) en el mismo estudio, constituyendo la RM multiparamétrica (RMmp). En la actualidad no es necesario aplicar todas las secuencias para obtener un estudio de eficacia óptima en RMmp, con lo que en tiempo inferior a 30 minutos es suficiente para obtener la información necesaria dependiendo de la indicación clínica. Las principales indicaciones clínicas de la RM de próstata son: a) estadificación local, regional o a distancia; b) Detección o guía para biopsia diagnóstica ante sospecha de riesgo clínico o con resultado negativo en biopsias previas; c) seguimiento activo; y d) monitorización terapéutica. Además, uno de los aspectos más relevantes del cáncer de próstata y un reto de las técnicas en RMmp es poder diferenciar la neoplasia agresiva de la no significativa (latente). Esta actualización pretende revisar el papel actual de la RMmp en el manejo del cáncer de próstata utilizando de forma combinada la información anatómica (T2) y funcional (RME, RMD y RMC). Así mismo se describe la guía europea de la RMmp de próstata, PI-RADS (Prostate Imaging Reporting and Data System)


The current diagnosis of prostate cancer based on PSA values and systematic biopsy has limitations in its efficacy of detection and staging. Technical advances on imaging over the last decade, mainly MRI, enable improvements in the strategy of prostate cancer management in diagnosis, staging, follow up and therapy monitoring. MRI enables the combination of morphological (T2 sequences) and, at the same time, functional information by means of the application of sequences such as spectroscopy (SMRI), diffusion and dynamic intravenous contrast (CMRI) in the same study, giving the multiparametric MRI (mpMRI). Currently, it is not necessary to apply all sequences to obtain an mpMR study of optimal efficacy, so that a time shorter than 30 minutes is enough to obtain the necessary information depending on the clinical indication. The main clinical indications of prostatic MRI are a) local, regional or distance staging; b) Detection or guide for diagnostic biopsy for clinical risk suspicion or negative result in previous biopsies; c) active surveillance; and d) therapeutic monitoring. Furthermore, one of the most relevant features of prostate cancer, and a challenge for the mpMRI techniques is to be able to differentiate aggressive and non-significant neoplasias (latent). This update tries to review the current role of mpMRI in the management of prostate cancer using in combination the anatomical (T2) and functional (SMRI, DMRI and CMRI) information. We also describe the European prostate mpMRI guidelines, PI-RADS (Prostate imaging reporting data System)


Subject(s)
Humans , Male , Prostatic Neoplasms/pathology , Prostatic Neoplasms , Magnetic Resonance Imaging/instrumentation , Magnetic Resonance Imaging/methods , Magnetic Resonance Spectroscopy/methods , Prostate/pathology , Prostate , Neoplasm Staging/instrumentation , Neoplasm Staging/methods , Neoplasm Staging , Spectrum Analysis/trends , Spectrum Analysis , Magnetic Resonance Spectroscopy
14.
J Sci Food Agric ; 95(8): 1571-6, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25205443

ABSTRACT

As the beer market is steadily expanding, it is important for the brewing industry to offer consumers a product with the best organoleptic characteristics, flavour being one of the key characteristics of beer. New trends in instrumental methods of beer flavour analysis are described. In addition to successfully applied methods in beer analysis such as chromatography, spectroscopy, nuclear magnetic resonance, mass spectrometry or electronic nose and tongue techniques, among others, sample extraction and preparation such as derivatization or microextraction methods are also reviewed.


Subject(s)
Beer/analysis , Chemistry Techniques, Analytical/trends , Taste , Biosensing Techniques/trends , Chemistry Techniques, Analytical/methods , Chromatography/trends , Electronic Nose , Humans , Mass Spectrometry/trends , Solid Phase Microextraction/trends , Spectrum Analysis/trends
16.
Radiología (Madr., Ed. impr.) ; 56(5): 390-399, sept.-oct. 2014.
Article in Spanish | IBECS | ID: ibc-128335

ABSTRACT

Es bien conocido que el grado de vascularización de las lesiones mamarias se relaciona con su malignidad. Por ello, las técnicas de diagnóstico por imagen que estudian funcionalmente las lesiones han cobrado mucha relevancia en los últimos años. La mamografía con medio de contraste y energía dual es una técnica de reciente aparición, aparentemente prometedora en el cáncer de mama, que informa del grado de vascularización de la lesión junto con la información morfológica habitual. El propósito de este artículo es presentar el estado actual de esta nueva técnica de imagen. Basándonos en una experiencia de 15 meses, ilustramos esta revisión con casos clínicos que nos permiten presentar también sus ventajas y limitaciones (AU)


The degree of vascularization in breast lesions is related to their malignancy. For this reason, functional diagnostic imaging techniques have become important in recent years. Dual-energy contrast-enhanced mammography is a new, apparently promising technique in breast cancer that provides information about the degree of vascularization of the lesion in addition to the morphological information provided by conventional mammography. This article describes the state of the art for dual-energy contrast-enhanced mammography. Based on 15 months’ clinical experience, we illustrate this review with clinical cases that allow us to discuss the advantages and limitations of this technique (AU)


Subject(s)
Humans , Female , Contrast Sensitivity/radiation effects , Contrast Media , Mammography/methods , Mammography , Breast Neoplasms/diagnosis , Breast Neoplasms , Mammography/instrumentation , Spectrum Analysis/trends , Dose-Response Relationship, Radiation , Carcinoma, Intraductal, Noninfiltrating , Neoadjuvant Therapy/methods
17.
J Am Acad Dermatol ; 71(4): 611.e1-611.e10; quiz 621-2, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25219717

ABSTRACT

New evidence has accumulated over the past several years that supports improved melanoma outcomes associated with both clinician and patient screening. Population-based and workplace studies conducted in Australia and the Unites States, respectively, have shown decreases in the incidence of thick melanoma and overall melanoma mortality, and a year-long statewide screening program in Germany has shown a nearly 50% reduction in mortality 5 years after the screening ended. Current melanoma screening guidelines in the United States are inconsistent among various organizations, and therefore rates of both physician and patient skin examinations are low. As policymaking organizations update national screening recommendations in the United States, the latest research reviewed in part II of this continuing medical education article should be considered to establish the most effective recommendations. Patient and provider education will be necessary to ensure that appropriate patients receive recommended screening.


Subject(s)
Early Detection of Cancer/standards , Melanoma/diagnosis , Melanoma/epidemiology , Skin Neoplasms/diagnosis , Skin Neoplasms/epidemiology , Adult , Aged , Biopsy, Needle , Dermoscopy/standards , Dermoscopy/trends , Early Detection of Cancer/trends , Education, Medical, Continuing , Female , Forecasting , Health Promotion/organization & administration , Humans , Male , Mass Screening/standards , Mass Screening/trends , Microscopy, Confocal/standards , Microscopy, Confocal/trends , Middle Aged , Patient Education as Topic , Practice Guidelines as Topic , SEER Program , Spectrum Analysis/standards , Spectrum Analysis/trends , United States/epidemiology
18.
Proc Natl Acad Sci U S A ; 111(35): 12634-40, 2014 Sep 02.
Article in English | MEDLINE | ID: mdl-25092345

ABSTRACT

The discovery and characterization of exoplanets have the potential to offer the world one of the most impactful findings ever in the history of astronomy--the identification of life beyond Earth. Life can be inferred by the presence of atmospheric biosignature gases--gases produced by life that can accumulate to detectable levels in an exoplanet atmosphere. Detection will be made by remote sensing by sophisticated space telescopes. The conviction that biosignature gases will actually be detected in the future is moderated by lessons learned from the dozens of exoplanet atmospheres studied in last decade, namely the difficulty in robustly identifying molecules, the possible interference of clouds, and the permanent limitations from a spectrum of spatially unresolved and globally mixed gases without direct surface observations. The vision for the path to assess the presence of life beyond Earth is being established.


Subject(s)
Atmosphere/chemistry , Extraterrestrial Environment/chemistry , Origin of Life , Planets , Spectrum Analysis/trends , Evolution, Planetary , Gases , Water
19.
Curr Pharm Des ; 20(3): 436-53, 2014.
Article in English | MEDLINE | ID: mdl-23651397

ABSTRACT

A common feature of many new analytical techniques that allows fast and non-destructive analysis of poorly-water-soluble drug is that they generate a large amount of data with a multivariate character within a short time frame, which in turn highlights the need for advanced data analytical methods in extracting information from the complex data set. The current review critically examines how spectroscopy and imaging techniques can be utilized for fast and non-destructive characterization of solid state poorly water-soluble drug formulations. The first part of the present review describes the basics behind many of the currently used methods including Raman, near infrared (NIR), infrared (IR) spectroscopy and X-ray powder diffractometry in characterizing poorly water soluble drugs. Key emphasis was placed on a critical review of the currently used spectral preprocessing methods, and the influence of selected preprocessing on spectral data sets is exemplified. Further the existing uni- and multivariate spectral data analytical methods in analyzing complex spectral data sets are reviewed, covering estimation of spectral peak moments, peak modeling, variations of Principal Component Analysis (PCA), variations of Partial Least Squares (PLS) analysis and Multivariate Curve Resolution (MCR). The second part of the present review discusses hyperspectral imaging, UV imaging, optical microscopy imaging and process imaging methods suitable for characterization of poorly water-soluble solid state drug formulations. Image analytical techniques suitable for analyzing hyperspectral image data set are described. Further, the application of various image analytical techniques leading to the estimation of nucleation and crystal growth rates from polarized light microscopy is described.


Subject(s)
Molecular Imaging/methods , Pharmaceutical Preparations/chemistry , Spectrum Analysis/methods , Technology, Pharmaceutical/methods , Water , Least-Squares Analysis , Models, Chemical , Molecular Imaging/instrumentation , Molecular Imaging/trends , Multivariate Analysis , Pharmaceutical Preparations/analysis , Principal Component Analysis , Solubility , Spectrum Analysis/instrumentation , Spectrum Analysis/trends , Technology, Pharmaceutical/instrumentation , Technology, Pharmaceutical/trends , Water/chemistry
20.
Enferm. nefrol ; 16(1): 7-14, ene.-mar. 2013. tab
Article in Spanish | IBECS | ID: ibc-111512

ABSTRACT

El análisis de bioimpedancia es una herramienta útil para determinar el estado nutricional y de hidratación del enfermo en hemodiálisis. Los dos sistemas más utilizados son la bioimpedancia de monofrecuencia vectorial y la bioimpedancia multifrecuencia espectroscópica que utilizan diferentes criterios para clasifi car el estado de hidratación del enfermo dializado. El sistema de bioimpedancia de monofrecuencia vectorial utiliza una escala ordinal de 7 puntos que va desde el valor 3 (mayor hidratación) hasta el valor -3 (mayor deshidratación) definiendo la hiperhidratación cuando el vector está en el eje de hidratación por debajo de la elipse de tolerancia del 75% (valores 3 y 2 de la escala ordinal). El sistema de bioimpedancia multifrecuencia espectroscópica emplea dos criterios para defi nir el estado de hiperhidratación prediálisis: OH superior a 2,5 litros o mayor del 15% del volumen de agua extracelular. El objetivo del presente trabajo fue analizar el grado de concordancia entre ambos sistemas de bioimpedancia para defi nir el estado de hiperhidratación en enfermos tratados con hemodiálisis. Se llevó a cabo un estudio transversal en 54 enfermos tratados con hemodiálisis a los que se les realizó un análisis de bioimpedancia con monitores de monofrecuencia vectorial y multifrecuencia espectroscópica inmediatamente antes de una sesión de hemodiálisis. El grado de equivalencia en la defi nición de hiperhidratación entre ambos monitores fue mejor cuando se utilizó, en el monitor de multifrecuencia, el criterio de OH>15% del agua extracelular (índice kappa 0.81, concordancia excelente) que cuando se utilizó el criterio de OH>2,5 litros (índice kappa 0.71, concordancia aceptable). Conclusiones: Hay una buena relación entre la escala vectorial de hidratación y el valor OH (exceso de hidratación). Los criterios utilizados por los monitores de monofrecuencia vectorial y multifrecuencia espectroscópica para defi nir los estados de hiperhidratación prediálisis tienen una equivalencia aceptable y sus resultados pueden ser intercambiables(AU)


Bioimpedance analysis is a useful tool for determining the nutritional and hydration status of haemodialysis patients. The two most commonly used systems are bioimpedance vector single frequency analysis and bioimpedance spectroscopic multiple frequency analysis, which use different criteria to classify the hydration status of the dialysed patient. The single frequency bioimpedance vector system uses a scale of 7 points ranging from a value of 3 (most hydration) to a value of -3 (most dehydration), defi ning hyperhydration when the vector is on the hydration axis below the tolerance ellipse of 75% (values 3 and 2 on the scale). Multi-frequency spectroscopy uses two criteria to defi ne the pre-dialysis state of hyperhydration: OH more than 2.5 litres or more than 15% of the extracellular water volume. The aim of this study was to analyse the degree of concordance between the two systems of bioimpedance in defi ning the state of hyperhydration of haemodialysis patients. A transversal study was carried out on 54 patients undergoing haemodialysis, performing a bioimpedance analysis with single frequency vector and multi- frequency spectroscopic monitors immediately before a haemodialysis session. The degree of equivalence in the defi nition of hyperhydration between the two monitors was greater when the criterion of OH>15% of extracellular water was used in the multi-frequency monitor (kappa index 0.81, excellent concordance) than when the criterion of OH>2.5 litres was used (kappa index 0.71, acceptable concordance). Conclusions: There is a good relationship between the hydration vector scale and OH value (excess hydration). The criteria used by the single-frequency vector and multi-frequency spectroscopic monitors show acceptable equivalence and their results can be interchangeable(AU)


Subject(s)
Humans , Male , Female , Adult , Middle Aged , Aged , Aged, 80 and over , Hemodialysis Solutions/administration & dosage , Renal Dialysis/nursing , Spectrum Analysis/instrumentation , Spectrum Analysis/trends , Nutritional Status/physiology , Nutritional Status/radiation effects , Body Mass Index , Fluid Therapy/nursing , Cross-Sectional Studies/instrumentation , Cross-Sectional Studies/methods , Confidence Intervals , Analysis of Variance
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