Chachafruto starch: Physicochemical characterization, film-forming properties, and 3D printability.

This work aimed to characterize the physicochemical, film-forming properties, and 3D printability of a nonconventional starch from chachafruto. The chachafruto native starch (CHS) presented an excellent extraction yield (10 % db) and purity (99 % db), along with an oval and round morphology, a smooth surface with few defects, and a mean diameter of 15.4 µm. The typical B-type diffraction pattern was observed in the CHS with a crystallinity of 17.4 %. The starch presented a paste temperature of 66.1 °C, an enthalpy of 11.5 J g-1, and a final viscosity of 596 Brabender Units. The thermal analysis demonstrated good thermal stability. The evaluated film presented a reduction in crystallinity (8.18 %) to the CHS, which generated a good elasticity in the material. Likewise, it presented a continuous structure without cracks, providing good barrier properties (2.3 × 10-9 g∙m-1∙s-1∙Pa-1) and high transparency. Meanwhile, 3D prints prepared with CHS showed good textural properties and high consistency. The morphological analysis showed that the prints generated organized cell structures. However, high concentrations of CHS were not efficient in obtaining 3D prints. The results of this work demonstrate the tremendous industrial potential of chachafruto as an unconventional source of starch and some alternative uses for adding value to the crop.

Effect of Essential Oils from Lemongrass and Tahiti Lime Residues on the Physicochemical Properties of Chitosan-Based Biodegradable Films.

This work aimed to evaluate the impact of adding two essential oils (EO) from lemongrass (LEO) and Tahiti lime (TLEO) on the physical, mechanical, and thermal properties of chitosan-based biodegradable films. Six film formulations were prepared: two controls with chitosan concentrations of 1% and 1.5% v/w, two formulations combining the two chitosan concentrations with 1% LEO v/v, and two formulations combining the two chitosan concentrations with 1% TLEO v/v. The films' morphological, water affinity, barrier, mechanical, and thermal properties were evaluated. The films' surface showed a heterogeneous morphology without cracks, whereas the cross-section showed a porous-like structure. Adding EO to the films promoted a 35-50% decrease in crystallinity, which was associated with an increase in the elasticity (16-35%) and a decrease in the tensile strength (9.3-29.2 MPa) and Young's modulus (190-1555 MPa) on the films. Regarding the optical properties, the opacity of the films with TLEO increased up to 500% and 439% for chitosan concentrations of 1% and 1.5%, respectively. While the increase in opacity for the films prepared with LEO was 357% and 187%, the reduction in crystallinity also reduced the resistance of the films to thermal processes, which could be explained by the reduction in the enthalpy of fusion. The thermal degradation of the films using TLEO was higher than those where LEO was used. These results were indicative of the great potential of using TLEO and LEO in biodegradable films. Likewise, this work showed an alternative for adding value to the cultivation of Tahiti lime due to the use of its residues, which is in accordance with the circular economy model. However, it was necessary to deepen the study and the use of these essential oils in the preparation of biodegradable films.

Influence of Ulluco Starch Modified by Annealing on the Physicochemical Properties of Biodegradable Films.

This work aimed to evaluate the use of annealing (ANN) ulluco starch in the preparation of biodegradable films and its impact on the physicochemical properties of the materials. Three film samples (FS1, FS2, and FS3) were prepared at a fixed starch concentration (2.6% w/v) using glycerol as a plasticizer and then compared to a control sample (FSC) prepared with native ulluco starch. The physical, mechanical, and thermal properties of the films were evaluated. The use of ANN starch decreased the solubility (from 21.8% to 19.5%) and the swelling power (from 299% to 153%) of the film samples. In addition, an increase in opacity and relative crystallinity (from 7.54% to 10.5%) were observed. Regarding the thermal properties, all the samples presented high stability to degradation, with degradation temperatures above 200 °C. However, the samples showed deficiencies in their morphology, which affected the barrier properties. The use of ANN starch has some advantages over native starch in preparing films. However, more analysis is needed to improve the barrier properties of the materials. This work reveals the potential of the ANN ulluco starch for biodegradable film preparation. In addition, the use of modified ulluco starch is an alternative to add value to the crop, as well as to replace non-biodegradable materials used in the preparation of packaging.

Non-conventional starch from cubio tuber (Tropaeolum tuberosum): Physicochemical, structural, morphological, thermal characterization and the evaluation of its potential as a packaging material.

This work aimed to characterize the physicochemical, structural, morphological, and thermal properties of a non-conventional starch obtained from cubio (Tropaeolum tuberosum), as well as to evaluate the potential use of this native Andean tuber in the preparation of biodegradable packaging. The cubio starch (CUS) showed an intermediated apparent amylose content (31.2 %) accompanied by a high CIE whiteness index (90.8). About the morphology and particle size, the CUS exhibited irregular oval and round shapes and a smooth surface with a mean particle diameter of 14.04 ± 0.1 µm. Although it showed good stability regarding pasting properties, the final viscosity was low. Native CUS exhibits a typical B-type diffraction structure, with a relative crystallinity of 16 %. The resistant starch (RS) fraction of the CUS was 94 %, indicating a low susceptibility to enzymatic hydrolysis. The thermal analysis demonstrated that the CUS showed good thermal stability. Additionally, the films prepared using CUS as raw material showed continuous surfaces without porosities, good thermal stability, and high transparency. The results of this work demonstrate the industrial potential of the CUS as it presents characteristics comparable to commercial potato starch.

Influence of Ulluco Starch Concentration on the Physicochemical Properties of Starch-Chitosan Biocomposite Films.

This work aimed to prepare ulluco starch (US)/chitosan (Ch) edible films and evaluate the effect of the concentration of US on their physicochemical properties. The use of edible films is a means of adding value to the ulluco crop and evaluating the viability of using new sources to produce packaging materials. Different samples were prepared at different US concentrations (2%, 3%, 4%, and 5% w/v) and a fixed chitosan concentration (1.5% w/v); then, samples were analyzed, considering their physical, mechanical, and thermal properties. The US/Ch edible films showed an increase in solubility from 17.5% to 21.7%, swelling power (SP) from 38.9% to 267%, tensile strength (TS) from 3.69 MPa to 10.7 MPa, Young modulus (YM) from 18.0 Pa to 652 Pa, and thermal stability as the US concentration increased. However, samples with low US concentrations showed higher elongation at break (EB) (36.6%) and better barrier properties (WVP) (5.61 × 10-11 g/m s Pa). The films evaluated in this work presented good physical, mechanical, and barrier properties, revealing their potential as packaging material ensuring food security, and demonstrating the technological potential of US.

Manifestaciones cerebrales y oculares del Síndrome de Vogt-Koyanagi-Harada / Vogt-Koyanagi-Harada Syndrome Cerebral and Ocular Manifestations

El síndrome de Vogt-Koyanagi-Harada, antes conocido como síndrome uveomeningoencefálico, es una enfermedad rara, con muy pocos casos descritos en la literatura. Es una patología autoinmune infrecuente, con un compromiso multiorgánico. La resonancia magnética es importante para identificar las lesiones de la sustancia blanca periventricular, la afectación del tallo cerebral y los pedúnculos cerebrales, así como el realce paquimeníngeo y el engrosamiento difuso de la coroides. A pesar de ser una entidad poco frecuente, es importante que el radiólogo esté familiarizado con sus características en imágenes

Vogt-Koyanagi-Harada syndrome, formerly kwon as uveomeningoencephalitic syndrome, is a rare disease, with very few cases reported in the literature. It is an uncommon autoimmune entity with multi-organ involvement. Magnetic resonance imaging is important to identify periventricular white matter lesions, brain stem and brain peduncles involvement, as well as pachymeningeal enhancement and diffuse choroidal thickening. Despite being a rare entity, it is important for the radiologist be acquainted with its imaging findings

Characterization of ulluco starch and its potential for use in edible films prepared at low drying temperature.

The aim of this work was to characterize the starch obtained from ulluco (US) and evaluate its use in edible films prepared using different US concentrations (2.0, 2.5, and 3.0%) at low temperatures (simulating the storage conditions of different foods). US exhibited a high amylose content (35.3%), low stability against thermal degradation, and a B-type crystalline structure. In regards to the edible films prepared from US, good barrier properties related to the semicrystalline region were obtained. In addition, good mechanical properties, opacity and stability against thermal degradation were obtained. The extraction and use of US in the preparation of edible films could be an alternative method for adding value to this crop. Furthermore, the films appear as a potential material for food packaging.

Effects of temperature, starch concentration, and plasticizer concentration on the physical properties of ulluco (Ullucus tuberosus Caldas)-based edible films.

Ulluco starch could be a promising renewable source for the production of biodegradable or edible films, as an alternative to plastic. This would mitigate the negative impact of plastics on the environment. The aim of this work was to study the effect of the starch concentration (SC), glycerol concentration (GC), and drying temperature (T) of ulluco starch-based films on their physical properties using stepwise regression (SR) and artificial neural network (ANN) approaches. The physical properties, such as the solubility (S), water vapour permeability (WVP), tensile strength (TS), elongation at break (EB), and transparency, of the edible films were satisfactory. The feed-forward and cascade-forward neural networks satisfactorily modelled the effect of the SC, GC, and T on the mechanical, optical, and water-affinity properties (WAP) of the edible films. ANN approach showed better results than SR in all the properties and ANN models were used in the sensitivity analysis and optimization. The global sensitivity analysis showed that the GC had the greatest influence on the physical properties. A desirability function-based optimization including WVP, EB and OP showed comparable values between experimental and estimated data. Based on the results of this study, the use of ulluco starch for the preparation of edible films has enormous potential for the replacement of non-biodegradable plastic packaging.

Evolution of glomerulopathies associated with rheumatoid arthritis / Evolución de las glomerulopatías asociadas a la artritis reumatoidea

Abstract Introduction: Rheumatoid arthritis is one of the most common clinical syndromes within rheumatological conditions and its association with glomerular diseases is rare. Objective: To describe the histopathological findings in renal biopsies in patients with rheumatoid arthritis and to correlate them with the clinical and laboratory manifestations at the beginning, at 6 months and at one year of follow-up. Patients and Methods: This is a retrospective observational study conducted in the Hospital de Clinicas "Jose De San Martin" in Buenos Aires, Argentina; Where we included 41 patients diagnosed with RA (ACR 1987) in a period of 20 years. Histopathological diagnoses of membranous nephropathy (MN), minimal change disease (MCD), secondary amyloidosis (AA), focal and segmental glomerulosclerosis (FSGS); mesangial glomerulopathy (MGP) and glomerulonephritis with extracapillary proliferation (GNEC) were included. Histopathological description, different treatments, years of evolution of rheumatoid arthritis Clinical and laboratory characteristics were analyzed during the first 6 months and one year of follow-up in order to determine the progression of renal failure calculated through the formula of MDRD of 4 variables (Modification of diet in renal disease) and the increase of proteinuria. Results: The most frequent histological finding was amyloidosis with 34,1 % (n=14), followed by mesangial glomerulopathy 21,9 % (n=9), membranous nephropathy 19,5 % (n=8), glomerulonephritis with extracapillary proliferation 12,1 % (n=5), focal and segmental glomerulosclerosis 7,3 % (n=3) and minimal change disease 8,2 % (n=2). Nephrotic syndrome was the most frequent presentation in patients with amyloidosis in 85,7 %, microhematuria occurred in 100 % of patients with MPG and in 80 % of patients with GNEC. In patients with AA, moderate to severe interstitial fibrosis occurred in 85,7 %, followed by GNEC and NM with 80 % and 40 % respectively. The 24-hour proteinuria, creatinine and glomerular filtration rate estimated by MDRD at 6 months and 12 months were evaluated. Concluding, that patients with AA, FSGS and GNEC had greater progression of renal failure at 12 months; the opposite occurred in patients with minimal change disease (MCD) and mesangial glomerulopathy (MGP) who had a lower progression of renal failure at one year of follow-up; There was a correlation in the glomerulopathies that had greater deterioration of the renal function had greater interstitial tubule involvement as was the case of amyloidosis. The glomerulopathies that presented greater proteinuria at the beginning were membranous nephropathy, amyloidosis and minimal change disease. Both membranous nephropathy and minimal change disease had partial remission at one year, in contrast to amyloidosis, which showed progression of proteinuria at 12 months of follow-up. Conclusion: The glomerulopathies that presented greater progression of renal failure at 1 year based on the estimation by MDRD 4, had a higher renal tubular interstitial involvement in renal biopsy and these were amyloidosis (AA), segmental focal glomerulosclerosis (FSGS), glomerulonephritis with proliferation extracapillary On the other hand, those with the best evolution in relation to the degree of proteinuria and the glomerular filtration rate determined by the MDRD4 equation were mesangial glomerulopathy, minimal change disease, and membranous nephropathy.

Resumen Introducción: La artritis reumatoidea (AR) es uno de los síndromes clínicos con mayor frecuencia dentro de las afecciones reumatológicas y su asociación con las enfermedades glomerulares es poco frecuente. Objetivo: Describir los hallazgos histopatológicos en las biopsias renales en pacientes con artritis reumatoidea y correlacionarlos con las manifestaciones clínicas y de laboratorio al inicio, a los 6 meses y al año de seguimiento. Pacientes y métodos: Es un estudio observacional retrospectivo realizado en un hospital Universitario en Buenos Aires, Argentina. Se incluyeron 41 pacientes con diagnóstico de artritis reumatoidea de acuerdo a los criterios establecidos por el Colegio Americano de Reumatología publicados en 1987; en un período de 20 años. Se incluyeron diagnósticos histopatológicos de nefropatía membranosa (NM), enfermedad de cambios mínimos (ECM), amiloidosis secundaria (AA), gloméruloesclerosis focal y segmentaria (GEFS); glomerulopatía mesangial (GPM) y glomerulonefritis con proliferación extracapilar (GNEC). Las características clínicas, de laboratorios, la descripción histopatológica, los años de evolución de la artritis reumatoidea y los diferentes tratamientos fueron analizados durante los primeros 6 meses y al año del seguimiento. Con esto, se buscó determinar la progresión de la insuficiencia renal, calculada a través de la fórmula de MDRD (Modification of Diet in Renal Disease) de 4 variables y el aumento de la proteinuria. Resultados: El hallazgo histológico más frecuente fue la amiloidosis, con un 34.1 % (n=14), seguido de la glomerulopatía mesangial (21,9 %, n=9), la nefropatía membranosa (19,5 %, n=8), la glomerulonefritis con proliferación extracapilar (12,1 %, n=5), la glomeruloesclerosis focal y segmentaria (7,3 %, n=3) y enfermedad de cambios mínimos (8,2 %, n=2). El síndrome nefrótico fue la forma de presentación más frecuente en los pacientes con amiloidosis (en un 85,7 % de los casos), la microhematuria se presentó en el 100 % de los pacientes con GPM y en el 80 % de los pacientes con GNEC. En el 85,7 % de los pacientes con AA, se presentó fibrosis intersticial moderada a severa, mientras que en la GNEC y la NM la fibrosis se observó en un 80 % y 40 % respectivamente. Se evaluó la proteinuria de 24 horas, la creatinina y la filtración glomerular estimada por MDRD a los 6 y a los 12 meses. Se concluyó que los pacientes con AA, GEFS y GNEC presentaron mayor progresión de la insuficiencia renal a los 12 meses. Lo contrario sucedió en los pacientes con enfermedad de cambios mínimos (ECM) y glomerulopatía mesangial (GPM), los cuales tenían una menor progresión de la insuficiencia renal al año de seguimiento. Hubo una correlación entre las glomerulopatías que tenían mayor deterioro de la función renal en las cuales se observó a su vez, mayor compromiso tubulointersti-cial, (este fue el caso de la amiloidosis). Las glomerulopatías que presentaban mayor proteinuria al inicio eran la nefropatía membranosa, la amiloidosis y la enfermedad de cambios mínimos. Tanto la nefropatía membranosa como la enfermedad de cambios mínimos, tenía remisión parcial tras un año, a diferencia de la amiloidosis, la cual presentaba progresión de la proteinuria a los 12 meses de seguimiento. Conclusión: Las glomerulopatías que presentaron mayor progresión de la insuficiencia renal al año, con base en la estimación por MDRD4, tenían en la biopsia renal mayor compromiso tubulointersticial. Estas fueron la amiloidosis secundaria, la glomeruloesclerosis focal y segmentaria, y glomerulonefritis con proliferación extracapilar. Por el contrario, las de mejor evolución respecto al grado de proteinuria y tasa de filtrado glomerular determinado por MDRD4, fueron la glomerulopatía mesangial, la enfermedad de cambios mínimos y la nefropatía membranosa.

Characterization of chitosan edible films obtained with various polymer concentrations and drying temperatures.

Chitosan is a promising material that could be used for the development of edible coatings and films on an industrial level because of its film-forming, biodegradable, non-toxic, and antimicrobial characteristics. The aim of this work was to evaluate the effect of the polymer concentration (0.5%, 1.0%, and 1.5%) and drying temperature (2°C, 25°C, and 40°C) on the physicochemical, mechanical, and thermal properties of chitosan edible films. Chitosan edible films were successfully produced using various processing conditions. The use of lower drying temperatures had a positive effect on certain properties of the films, such as the moisture content (MC), solubility (S), water vapor permeability (WVP), and optical properties. However, the use of greater drying temperatures (40°C), combined with a higher chitosan concentration, enhanced certain properties of the films, such as the tensile strength (TS), swelling power (SP), and greenness value, while diminishing their luminosity. The chitosan films developed in this study showed many desirable characteristics, which may enable their future use as packaging for food products.

Cagaita fruit (Eugenia dysenterica DC.) and obesity: Role of polyphenols on already established obesity.

Polyphenol-rich cagaita (Eugenia dysenterica DC.) extracts (PCE) have previously shown to prevent body weight and adiposity induced by high-fat/high-sucrose (HFS) diet. Whether PCE also exerts protective effects in already developed obesity is unknown. In order to test this hypothesis, male C57BL/6J obese mice (previously feed with a HFS diet for six weeks) were treated with PCE at two doses, 7mg gallic acid equivalent (GAE)/kg body weight (PCE I group), and 14mg GAE/kg body weight (PCE II group) or water (HFS and Chow groups) by oral gavage for eight weeks. PCE did not affect body weight and adiposity of obese mice. However, PCE did protect against dyslipidemia, fasting hyperglycemia, and glucose intolerance, and attenuated both hepatic gluconeogenesis and inflammation as observed by the expression of tumor necrosis factor-α and transcriptional factor NF-κB. These results indicate that PCE improves glucose homeostasis of obese mice by attenuating hepatic gluconeogenesis and inflammation.

Effects of Spray-Drying Parameters on In Vitro Functional Properties of Camu-Camu (Myrciaria dubia Mc. Vaugh): A Typical Amazonian Fruit.

Camu-camu (Myrciaria dubia) fruit is a rich source of bioactive compounds but its shelf life is rather short. Therefore, this study was aimed to evaluate the effect of inlet air temperature (T) and concentration (C) of maltodextrin and arabic gum on the spray-drying process of commercial camu-camu pulps (São Paulo and Manaus). Moisture, solubility, total phenolics (TP), ascorbic acid (AA), and proanthocyanidins (PAC) contents, and in vitro antioxidant capacity of the powders (FRAP, DPPH, Folin-Ciocalteu's reducing capacity were measured). Arabic gum resulted in better yields (22% to 30%), powder solubility (84% to 90%), and lower losses of analyzed compounds than the powders manufactured with maltodextrin. Overall, inlet air temperature had a lower impact on the responses studied than the concentration of carrier agents. Polynomial equations were generated for AA (R2 = 0.993), TP (R2 = 0.735), PAC (R2 = 0.946), and for the antioxidant capacity assays (0.867 ≤ R2  ≤ 0.963). In addition, principal component analysis showed that the lowest concentration of carrier agents (6%) in spray drying resulted in the lowest losses of bioactive compounds and, consequently, the highest antioxidant capacity.

Rol de la hematuria dismórfica en las enfermedades gomerulares / Role of urinary dysmorphic red blood cells in glomerular disease

INTRODUCCIÓN: El sedimento de orina es una herramienta en la práctica clínica empleada desde hace muchos años para la evaluación de enfermedades renales. La detección de hematuria dismórfica es útil en el diagnóstico de enfermedades glomerulares. OBJETIVOS: Agrupar las hematurias dismórficas en los casos con presencia de acantocitos y los que no los presentan, y correlacionar estos dos grupos con los hallazgos histológicos de las biopsias renales. MATERIAL Y MÉTODOS: Estudio observacional, retrospectivo y analítico. Se incluyeron los sedimentos de orina de 276 pacientes. Se analizaron dos grupos de hematuria dismórfica: D1 (presencia de acantocitos) y D2 (sin acantocitos), y se correlacionó con los hallazgos histológicos de la biopsia renal (glomerulopatías proliferativas y no proliferativas). Se analizaron los diferentes elementos formes de la orina (cilindros hemáticos, leucocitarios, céreos, granulosos, grasos), la creatinina plasmática y la proteinuria de 24 hs en los dos grupos de glomerulopatías. Posteriormente se realizó una regresión logística para evaluar las variables independientes entre los hallazgos del sedimento de orina, con los correspondientes odds ratio (OR) e intervalos de confianza (IC 95%). RESULTADOS: Se contó con 172 muestras provenientes de mujeres (62.3%) y 104 de hombres (37,7%). La presencia de acantocitos (D1) en las enfermedades glomerulares proliferativas (GP) fue 17 veces más frecuente comparada con las no proliferativas (GNP) OR 17.7 IC 95% (9.6-32.5) p 0.001. La presencia de cilindros hemáticos es ocho veces más frecuente en las GP OR 8 IC 95% (3.1-20.9). Los pacientes con hematuria no acantocitica (D2) es 5 veces más frecuente en una GNP OR 5.2 IC (2.4-11.3) p 0,001. La presencia de cilindros grasos fue más frecuente en los pacientes con GNP a diferencia de los cilindros leucocitarios, cuya frecuencia fue mayor en la GP. CONCLUSIONES: La presencia de hematuria dismórfica no acantocitica (D2) se correlacionó en la histología renal con la presencia de glomerulopatías no proliferativas (GNP) en forma significativa, a diferencia de la hematuria acantocitica y cilindros hemáticos que se observaron en glomerulopatías proliferativas, por lo tanto se considera una herramienta útil para poder diferenciar clínicamente estos dos grupos, sin remplazar la biopsia renal para el diagnóstico preciso y el pronóstico

INTRODUCTION: The analysis of urine sediment is a tool that has been used for many years in clinical practice to evaluate kidney diseases. Detecting dysmorphic red blood cells (RBC's) in urine is useful for the diagnosis of glomerular diseases. OBJECTIVES: To divide the cases of glomerular hematuria into two groups, depending on the presence or absence of acanthocytes, and to compare this factor with the histological findings of renal biopsies. METHODS: In this observational, retrospective, analytical study, urine sediments of 276 patients were included. Two groups of subjects with glomerular hematuria were analyzed: D1 (presence of acanthocytes) and D2 (absence of acanthocytes). The results were compared with the renal biopsy histological findings, i.e. proliferative glomerulonephritis and non-proliferative glomerulonephritis, considered separately. The formed elements of the urine (red blood cell, white blood cell, waxy, granular and fatty casts), plasma creatinine concentration and 24-hour urinary protein were tested in the two groups. A logistic regression analysis was later performed to assess the independent variables among urine sediment findings, with the corresponding odds ratio (OR) and confidence intervals (CI 95%). RESULTS: The samples were collected from 172 women (62.3 %) and 104 men (37.7 %). The presence of acanthocytes (D1) was 17 times more frequent in proliferative glomerulonephritis (PGN) than in non-proliferative glomerulonephritis (NPGN) [OR 17.7, CI 95% (9.6-32.5), p 0.001]. The presence of red blood cell casts was 8 times more frequent in PGN [OR 8, CI 95% (3.1-20.9)]. Cases of hematuria with no acanthocytes (D2) were 5 times more frequent in NPGN [OR 5.2, CI (2.4-11.3), p 0.001]. Fatty casts appeared more frequently in patients with NPGN, whereas white blood cell casts were more common in PGN cases. CONCLUSIONS: Renal histological findings revealed a significant correlation between glomerular hematuria without acanthocytes (D2) and non-proliferative glomerulonephritis (NPGN), while the presence of acanthocytes and red blood cell casts was associated with proliferative glomerulonephritis (PGN). The existence of acanthocytes in urine constitutes a useful tool to make a clinical distinction between these two conditions, but it does not replace renal biopsy to establish an accurate diagnosis and prognosis

Modelo de gestión organizacional para el cambio: diagnóstico de empresa de servicios por internet

Se propone crear mediante tecnologías de información y comunicación social (TICSC) servficios de turismo receptivo a través de las agencias de viajes y turismo en la ciudad de La Paz, así como la de realizar la conexión de negocios mediante la red con otros países, principalmente en el rubro de la exportación

Cálculo de los contenidos arterial y venoso de oxígeno, de la diferencia arteriovenosa de oxigeno, tasa de extracción tisular de oxígeno y shunt intrapulmonar con unas nuevas fórmulas, basadas en la saturación de oxígeno / Calculation of the arterial and veined contents of oxygen

La evaluación del estado de perfusión tisular en el paciente en estado crítico comporta, además del procedimiento de toma de gases arteriales y venosos, la ejecución de numerosos cálculos basados en fórmulas metemáticas preestablecidas. El desarrollo de estos cálculos conlleva la posibilidad de error (más grande cuánto más complejas las fórmulas), además de la iatrogenia derivada del procedimiento de toma de gases en sí mismo. En un intento por simplificar las operaciones matemáticas necesarias para la evaluación gasimétrica, se efectuó una revisión de las fórmulas tradicionales evaluando la posibilidad de reducir algunos de sus elementos, particularmente el contenido de oxígeno disuelto en sangre, en el cálculo de la diferencia arterio-venosa de oxígeno (Dav02); la tasa de extracción de oxígeno (Tex 02); el contenido arterial, venoso y capilar de oxígeno (Co02); y el shunt intrapulmonar (QS/QT). Se llevó a cabo una simulación computadorizada retrospectiva comparan-do los resultados obtenidos con la fórmula tradicional y aquellos obtenidos con la simplificada, utilizando 100 muestras seleccionadas mediante la función random number de Excel. Por último, se realizó un estudio prospectivo en dos unidades de cuidado intensivo de Santafé de Bogotá (Hospital San Juan de Dios y Clínica Palermo) comparando las dos modalidades de cálculo gasimétrico. En esta última etapa, además de establecer la correlación entre las fórmulas tradicionales y las simplificadas, también se compararon los resultados obtenidos cuando las fórmulas se desarrollaron con base en la saturación de oxígeno calculada con el equipo de gases y aquella obtenida directamente por la lectura del oxímetro de pulso colocado, habitualmente, en el dedo índice del paciente. Mediante comparación de medias y el análisis de regresión lineal para cada grupo de fórmulas analizadas, se pudo establecer la existencia de altos índices de correlación entre unas y otras. Los resultados demuestran que es posible suprimir el calculo del oxígeno disuelto en sangre para la evaluación del estado de perfusión tisular del enfermo crítico y que, adoptando como medida de la saturación arterial de oxígeno aquella obtenida directamente por el oxímetro de pulso, en muchas circunstancias clínicas se podría incluso, evitar la toma de gases arteriales