Estudio de correlación entre la PaO2/FiO2 y la SO2/FiO2 en niños en ventilación mecánica de la Fundación Cardioinfantil en Bogotá entre Abril y Junio de 2011

Objetivos: Determinar si existe correlación entre las variables SaFiO2 y PaFiO2 de pacientes con patología respiratoria aguda en la unidad de Cuidado Intensivo Pediátrico, en la Fundación Cardioinfantil en la ciudad de Bogotá D.C. Materiales y métodos: Se analizaron las variables cuantitativas con medidas de tendencia central como la media y medidas de dispersión como la desviación estándar. Se utilizó un nivel de confiabilidad del 95% y un poder estimado 80%, para prueba de hipótesis de una proporción. Se realizó un análisis de correlación para medir la fuerza de la relación entre las variables PaO2/FiO2 y SO2/FiO2 a través del coeficiente de correlación. Resultados: Se incluyeron 12 pacientes y se tomaron un total de 65 registros de SO2/FiO2 y PaO2/FiO2 encontrando que existe relación positiva entre las variables SaO2/FIO2 y PaO2/FIO2, la cual es variable dependiendo de la fracción inspirada de oxigeno con el cual se encuentre el paciente. De acuerdo a las observaciones realizadas, la variable SaO2/FIO2 está moderadamente correlacionada (r = 0,602) con la PaO2/FIO2, cuando la FIO2 está entre 0.35 y 0.55; un grado de correlación aceptable (r = 0,319) cuando la FIO2 está entre 0.60 – 0.80 y 0.81 – 1 (r = 0,318). Conclusiones: Los métodos no invasivos en la evaluación de la oxigenación podrían ser una alternativa para el seguimiento clínico en niños con lesión pulmonar aguda o síndrome de dificultad respiratorio agudo. Se requiere de estudios analíticos que brinden una mejor evidencia científica que pueda ser extrapolable a la población infantil objeto de este estudio.

Perfil acido-base de pacientes con cirrosis descompensada por hemorragia digestiva alta en el departamento de emergencias: serie de casos

Introducción: La hemorragia digestiva (HVDA) es la principal causa de descompensación en pacientes con cirrosis. Caracterizar el estado ácido-base de estos pacientes sería útil para reflejar la severidad del sangrado e identificar pacientes con alto riesgo de complicación. Objetivo: Describir el estado ácido-base de los pacientes que consultaron a urgencias con cirrosis descompensada por HVDA y posteriormente fueron manejados en la unidad de cuidado intensivo (UCI) o fallecieron. Métodos: Se realizó el análisis del estado ácido-base a 10 pacientes con estas características, utilizando tres métodos distintos. Resultados: El perfil ácido-base encontrado fue: acidosis metabólica por iones no medidos, acidosis láctica, alcalosis por hipoalbuminemia y anión gap elevado en la mayoría de pacientes. Conclusiones: La teoría de Henderson-Hasselbach no fue suficiente para identificar pacientes con alto riesgo, debería implementarse concomitantemente el análisis anión gap, base déficit y el método físico–químico, para entender los fenómenos acido base de estos pacientes.

La ventilazione non-invasiva a pressione positiva nell’insufficienza respiratoria acuta ipercapnica: 10 anni di esperienza clinica di una Unità di Terapia Semi-Intensiva Respiratoria

PremessaSebbene numerosi studi prospettici, controllati e randomizzati abbiano dimostrato il successo della ventilazione non-invasiva a pressione positiva (NIV) in casi selezionati di insufficienza respiratoria acuta ipercapnica (IRA) in setting con intensità di cura differenti, i dati di pratica clinica relativi all’uso della NIV nel “mondo reale” sono limitati. Scopo Riportare i risultati della nostra esperienza clinica sulla NIV nell’IRA applicata nell’Unità di Terapia Semi-Intensiva Respiratoria (UTSIR) allocata all’interno dell’Unità Operativa di Pneumologia di Arezzo negli anni 1996-2006 in termini di: tollerabilità, effetti sui gas ematici, tasso di successo e fattori predittivi del fallimento.MetodiTrecentocinquanta dei 1484 pazienti (23.6%) consecutivamente ammessi per IRA nella nostra Unità Operativa di Pneumologia durante il periodo di studio hanno ricevuto la NIV in aggiunta alla terapia standard, in seguito al raggiungimento di criteri predefiniti impiegati di routine.RisultatiOtto pazienti (2.3%) non hanno tollerato la NIV per discomfort alla maschera, mentre i rimanenti 342 (M: 240, F: 102; età: mediana (interquartili) 74.0 (68.0-79.3) anni; BPCO: 69.3%) sono stati ventilati per >1 ora. I gas ematici sono significativamente migliorati dopo 2 ore di NIV (media (deviazione standard) pH: 7.33 (0.07) versus 7.28 (7.25-7.31), p<0.0001; PaCO2: 71.4 (15.3) mmHg versus 80.8 (16.6) mmHg, p<0.0001; PaO2/FiO2: 205 (61) versus 183 (150-222), p<0.0001). La NIV ha evitato l’intubazione in 285/342 pazienti (83.3%) con una mortalità ospedaliera del 14.0%. Il fallimento della NIV è risultato essere predetto in modo indipendente dall’Apache III (Acute Physiology and Chronic Health Evaluation III) score, dall’indice di massa corporea e dal fallimento tardivo della NIV (> 48 ore di ventilazione) dopo iniziale risposta positiva.ConclusioniSecondo la nostra esperienza clinica di dieci anni realizzata in una UTSIR, la NIV si conferma essere ben tollerata, efficace nel migliorare i gas ematici e utile nell’evitare l’intubazione in molti episodi di IRA non-responsivi alla terapia standard.

La ventilación no invasiva con presión positiva en la insuficiencia respiratoria aguda hipercápnica: diez años de experiencia clínica de una unidad de terapia semiintensiva respiratoria

Premisa: Si bien numerosos estudios prospectivos, controlados y aleatorizados han demostrado el éxito de la ventilación no invasiva con presión positiva (VNI) en casos seleccionados de insuficiencia respiratoria aguda (IRA) hipercápnica, en contexto con intensidad de cuidado diferente, los datos de práctica clínica relativos al uso de la VNI en escenarios reales son limitados.Objetivo: Reportar los resultados de nuestra experiencia clínica sobre la VNI en la IRA aplicada en la Unidad de Terapia Semiintensiva Respiratoria (UTSIR), de la Unidad Operativa de Neumología de Arezzo, entre 1996-2006, en términos de tolerabilidad, efectos sobre los gases arteriales, tasa de éxito y factores predictivos del fracaso.Métodos: Trescientos cincuenta de los 1.484 pacientes (23,6%) ingresados consecutivamente por IRA en nuestra Unidad Operativa de Neumología, durante el periodo de estudio, recibieronla VNI asociada a la terapia estándar, posterior al cumplimiento de criterios predefinidos, empleados de rutina.Resultados: Ocho pacientes (2,3%) no toleraron la VNI por incomodidad producida por la máscara, mientras los 342 restantes (M: 240; F: 102; edad: mediana [intercuartiles] 74,0 años [68,0-79,3]; enfermedad pulmonar obstructiva crónica (EPOC) [69,3%]) fueron ventilados por más de una hora. Los parámetros de ventilación (y su efecto sobre el pH) y de oxigenación mejoraron significativamente después de dos horas de VNI (media [desviación estándar] pH: 7,33 [0,07] contra 7,28 [7,25-7,31 ], p < 0,0001; PaCO2: 71,4 mmHg [15,3] contra 80,8 mmHg [16,6], p < 0,0001; PaO2/FiO2: 205 [61] contra 183 [150-222 ], p < 0,0001). La VNI evitó la intubación en 285/342 pacientes (83,3%), con una mortalidad hospitalaria del 14,0%. El fracaso de la VNI resultó ser predicho de modo independiente por el puntaje acute physiology and chronic health evaluation III (Apache III), por el índice de masa corporal y por el fracaso tardío de la VNI (mayor a 48 horas de ventilación), después de una respuesta positiva inicial.Conclusiones: Según nuestra experiencia clínica de diez años en una UTSIR, la VNI confirma ser bien tolerada, eficaz en el mejoramiento de los gases arteriales y útil en evitar la intubación en muchos episodios de IRA que no responden a la terapia estándar.

DESCRIPCIÓN DEL ESTADO ÁCIDO BASE POR MODELO DE STEWART EN PACIENTES POSTOPERATORIO DE TRASPLANTE HEPÁTICO

Introducción: Los pacientes en postoperatorio de trasplante hepático presentan múltiples cambios hemodinámicos y alteraciones hidroelectrolíticas que generan cambios en el estado ácido base. El presente trabajo, busca describir el comportamiento ácido base en pacientes pos trasplante hepático, a través del análisis del modelo de Stewart, enfocado en la búsqueda etiológica de cada trastorno y planteando posibles formas de optimizar el manejo en Cuidado Intensivo (CI). Metodología: Estudio observacional, descriptivo histórico de los gases arteriales de los pacientes en post operatorio de trasplante hepático por cualquier causa, interpretados por método de Stewart. Se realizó con el universo de pacientes ingresados en el año 2014 en la Fundación Santa Fe de Bogotá. Resultados: Ingresaron en total 24 pacientes al estudio, entre el 1 de enero al 31 de septiembre de 2014. La mediana de pH fue de 7.36 con un valor mínimo de 7.05 y el máximo de 7.49. El 41% de los pacientes al ingreso a cuidado intensivo tenían lactato normal (menor a 2), y el 88% tenían niveles de albumina bajos. El trastorno electrolítico más común fue hipercloremia (58%), seguido de hipomagnesemia (25%). Conclusiones. El análisis de gases arteriales por el modelo de Stewart permite realizar un diagnóstico de un trastorno específico y adicionalmente, permite buscar la etiología del trastorno. Esta serie de casos mostró que el 95% de los pacientes tenían algún trastorno metabólico al ingreso, siendo el más frecuente la acidosis metabólica (66%).

Pulsioximetría de pacientes en hemodiálisis, de la unidad de terapia renal – fundación cardioinfantil, análisis para establecer recomendaciones

Introducción. En Colombia, el 80% de los pacientes con enfermedad renal crónica en hemodiálisis tienen fístula arteriovenosa periférica (FAV) que asegura el flujo de sangre durante la hemodiálisis (1), la variabilidad en el flujo de sangre en el brazo de la FAV hacia la parte distal, puede afectar la lectura de la oximetría de pulso (SpO2) (2), llevando a la toma de decisiones equivocadas por el personal de salud. El objetivo de este estudio es aclarar si existe diferencia entre la SpO2 del brazo de la FAV y el brazo contralateral. Materiales y métodos. Se realizó un estudio de correlación entre los valores de SpO2 del brazo con FAV contra el brazo sin FAV, de 40 pacientes que asistieron a hemodiálisis. La recolección de los datos se llevó a cabo, con un formato que incluyó el resultado de la pulsioximetria y variables asociadas, antes, durante y después de la hemodiálisis. Se comparó la mediana de los deltas de las diferencias con pruebas estadísticas T Student – Mann Whitney, aceptando un valor significativo de p < 0,05. Resultados. No se encontraron diferencias estadísticamente significativas de la SpO2 entre el brazo con FAV y el brazo sin FAV, antes, durante y después de la diálisis, sin embargo si se apreció una correlación positiva estadísticamente significativa. Conclusiones. Se encontró correlación positiva estadísticamente significativa, donde no hubo diferencias en el resultado la pulsioximetría entre el brazo con FAV y brazo sin FAV, por lo tanto es válido tomar la pulsioximetría en cualquiera de los brazos.

A model of net amino acid absorption and utilization by the portal-drained viscera of the lactating dairy cow

A more complete understanding of amino acid ( AA) metabolism by the various tissues of the body is required to improve upon current systems for predicting the use of absorbed AA. The objective of this work was to construct and parameterize a model of net removal of AA by the portal-drained viscera (PDV). Six cows were prepared with arterial, portal, and hepatic catheters and infused abomasally with 0, 200, 400, or 600 g of casein daily. Casein infusion increased milk yield quadratically and tended to increase milk protein yield quadratically. Arterial concentrations of a number of essential AA increased linearly with respect to infusion amount. When infused casein was assumed to have a true digestion coefficient of 0.95, the minimum likely true digestion coefficient for noninfused duodenal protein was found to be 0.80. Net PDV use of AA appeared to be linearly related to total supply (arterial plus absorption), and extraction percentages ranged from 0.5 to 7.25% for essential AA. Prediction errors for portal vein AA concentrations ranged from 4 to 9% of the observed mean concentrations. Removal of AA by PDV represented approximately 33% of total postabsorptive catabolic use, including use during absorption but excluding use for milk protein synthesis, and was apparently adequate to support endogenous N losses in feces of 18.4 g/d. As 69% of this use was from arterial blood, increased PDV catabolism of AA in part represents increased absorption of AA in excess of amounts required by other body tissues. Based on the present model, increased anabolic use of AA in the mammary and other tissues would reduce the catabolic use of AA by the PDV.

Characterization of the endokinins: Human tachykinins with cardiovascular activity

We report four human tachykinins, endokinins A, B, C, and D (EKA-D), encoded from a single tachykinin precursor 4 gene that generates four mRNAs (alpha, beta, gamma, and delta). Tachykinin 4 gene expression was detected primarily in adrenal gland and in the placenta, where, like neurokinin B, significant amounts of EKB-like immunoreactivity were detected. EKA/B 10-mers displayed equivalent affinity for the three tachykinin receptors as substance P (SP), whereas a 32-mer N-terminal extended form of EKB was significantly more potent than EKA/B or SP. EKC/D, which possess a previously uncharacterized tachykinin motif, FQGLL-NH2, displayed low potency, EKA/B displayed identical hemodynamic effects to SP in rats, causing short-lived falls in mean arterial blood pressure associated with tachycardia, mesenteric vasoconstriction, and marked hindquarter vasodilatation. Thus, EKA/B could be the endocrine/paracrine agonists at peripheral SP receptors and there may be as yet an unidentified receptor(s) for EKC/D.

Strategies for optimizing nitrogen use by ruminants

The efficiency of N utilization in ruminants is typically low (around 25%) and highly variable (10% to 40%) compared with the higher efficiency of other production animals. The low efficiency has implications for the production performance and environment. Many efforts have been devoted to improving the efficiency of N utilization in ruminants, and while major improvements in our understanding of N requirements and metabolism have been achieved, the overall efficiency remains low. In general, maximal efficiency of N utilization will only occur at the expense of some losses in production performance. However, optimal production and N utilization may be achieved through the understanding of the key mechanisms involved in the control of N metabolism. Key factors in the rumen include the efficiency of N capture in the rumen (grams of bacterial N per grams of rumen available N) and the modification of protein degradation. Traditionally, protein degradation has been modulated by modifying the feed (physical and chemical treatments). Modifying the rumen microflora involved in peptide degradation and amino acid deamination offers an alternative approach that needs to be addressed. Current evidence indicates that in typical feeding conditions there is limited net recycling of N into the rumen (blood urea-N uptake minus ammonia-N absorption), but understanding the factors controlling urea transport across the rumen wall may reverse the balance to take advantage of the recycling capabilities of ruminants. Finally, there is considerable metabolism of amino acids (AA) in the portal-drained viscera (PDV) and liver. However, most of this process occurs through the uptake of AA from the arterial blood and not during the ‘absorptive’ process. Therefore, AA are available to the peripheral circulation and to the mammary gland before being used by PDV and the liver. In these conditions, the mammary gland plays a key role in determining the efficiency of N utilization because the PDV and liver will use AA in excess of those required by the mammary gland. Protein synthesis in the mammary gland appears to be tightly regulated by local and systemic signals. The understanding of factors regulating AA supply and absorption in the mammary gland, and the synthesis of milk protein should allow the formulation of diets that increase total AA uptake by the mammary gland and thus reduce AA utilization by PDV and the liver. A better understanding of these key processes should allow the development of strategies to improve the efficiency of N utilization in ruminants.

An isotope dilution model for partitioning phenylalanine uptake by the liver of lactating dairy cows

An isotope dilution model for partitioning phenylalanine uptake by the liver of the lactating dairy cow was constructed and solved in the steady state. If assumptions are made, model solution permits calculation of the rate of phenylalanine uptake from portal vein and hepatic arterial blood supply, phenylalanine release into the hepatic vein, phenylalanine oxidation and synthesis, and degradation of hepatic constitutive and export proteins. The model requires the measurement of plasma fow rate through the liver in combination with phenylalanine concentrations and plateau isotopic enrichments in arterial, portal and hepatic plasma during a constant infusion of [1-13C]phenylalanine tracer. The model can be applied to other amino acids with similar metabolic fates and will provide a means for assessing the impact of hepatic metabolism on amino acid availability to peripheral tissues. This is of particular importance for the dairy cow when considering the requirements for milk protein synthesis and the negative environmental impact of excessive nitrogen excretion.

Effect of forage conservation method on plasma lipids, mammary lipogenesis, and milk fatty acid composition in lactating cows fed diets containing a 60:40 forage-to-concentrate ratio

The effects of forage conservation method on plasma lipids, mammary lipogenesis, and milk fat were examined in 2 complementary experiments. Treatments comprised fresh grass, hay, or untreated (UTS) or formic acid treated silage (FAS) prepared from the same grass sward. Preparation of conserved forages coincided with the collection of samples from cows fed fresh grass. In the first experiment, 5 multiparous Finnish Ayrshire cows (229 d in milk) were used to compare a diet based on fresh grass followed by hay during 2 consecutive 14-d periods, separated by a 5-d transition during which extensively wilted grass was fed. In the second experiment, 5 multiparous Finnish Ayrshire cows (53 d in milk) were assigned to 1 of 2 blocks and allocated treatments according to a replicated 3 × 3 Latin square design, with 14-d periods to compare hay, UTS, and FAS. Cows received 7 or 9 kg/d of the same concentrate in experiments 1 and 2, respectively. Arterial concentrations of triacylglycerol (TAG) and phospholipid were higher in cows fed fresh grass, UTS, and FAS compared with hay. Nonesterified fatty acid (NEFA) concentrations and the relative abundance of 18:2n-6 and 18:3n-3 in TAG of arterial blood were also higher in cows fed fresh grass than conserved forages. On all diets, TAG was the principle source of fatty acids (FA) for milk fat synthesis, whereas mammary extraction of NEFA was negligible, except during zero-grazing, which was associated with a lower, albeit positive calculated energy balance. Mammary FA uptake was higher and the synthesis of 16:0 lower in cows fed fresh grass than hay. Conservation of grass by drying or ensiling had no influence on mammary extraction of TAG and NEFA, despite an increase in milk fat secretion for silages compared with hay and for FAS than UTS. Relative to hay, milk fat from fresh grass contained lower 12:0, 14:0, and 16:0 and higher S3,R7,R11,15-tetramethyl-16:0, cis-9 18:1, trans-11 18:1, cis-9,trans-11 18:2, 18:2n-6, and 18:3n-3 concentrations. Even though conserved forages altered mammary lipogenesis, differences in milk FA composition were relatively minor, other than a higher enrichment of S3,R7,R11,15-tetramethyl-16:0 in milk from silages compared with hay. In conclusion, differences in milk fat composition on fresh grass relative to conserved forages were associated with a lower energy balance, increased uptake of preformed FA, and decreased synthesis of 16:0 de novo in the mammary glands, in the absence of alterations in stearoyl-coenzyme A desaturase activity.

Lattice Boltzmann simulation of viscous fluid systems with elastic boundaries

A lattice Boltzmann model able to simulate viscous fluid systems with elastic and movable boundaries is proposed. By introducing the virtual distribution function at the boundary, the Galilean invariance is recovered for the full system. As examples of application, the how in elastic vessels is simulated with the pressure-radius relationship similar to that of the pulmonary blood vessels. The numerical results for steady how are in good agreement with the analytical prediction, while the simulation results for pulsative how agree with the experimental observation of the aortic flows qualitatively. The approach has potential application in the study of the complex fluid systems such as the suspension system as well as the arterial blood flow.

Sedative and cardiopulmonary effects of buprenorphine and xylazine in horses

This study investigated the sedative, cardiopulmonary, and gastrointestinal effects produced by buprenorphine and xylazine given in combination to horses. Six healthy adult horses underwent 4 randomized treatments, with an interval of 1 wk between treatments. A control group was given a saline solution intravenously (IV) and the experimental groups received buprenorphine [10 mu g/kg bodyweight (BW)] in combination with 1 of 3 different doses of xylazine: 0.25 mg/kg BW (BX25), 0.50 mg/kg BW (BX50), or 0.75 mg/kg BW (BX75), all of them by IV. Cardiopulmonary parameters were evaluated for 120 min after the drugs were administered and intestinal motility was observed for 12 h after treatment. Sedation was found to be dose-dependent in all groups receiving buprenorphine and xylazine and it was observed that the heart rate decreased in the first 5 min and increased at the end of the sedation period. Arterial blood gas tension analyses showed minimal alterations during the experiment. Gastrointestinal hypomotility was observed for up to 8 h. The combination of buprenorphine and 0.50 mg/kg BW of xylazine (BX50) provided a 30-minute period of sedation without intense ataxia and maintained cardiopulmonary parameters within acceptable limits for the species.

HISTAMINE IN THE POSTERODORSAL MEDIAL AMYGDALA MODULATES CARDIOVASCULAR REFLEX RESPONSES IN AWAKE RATS

Centrally injected histamine (HA) affects heart rate (HR), arterial blood pressure (BP), and sympathetic activity in rats. The posterodorsal medial amygdala (MePD) has high levels of histidine decarboxylase, connections with brain areas involved with the modulation of cardiovascular responses, and is relevant for the pathogenesis of hypertension. However, there is no report demonstrating the role of the MePD histaminergic activity on the cardiovascular function in awake rats. The alms of the present work were: 1) to study the effects of two doses (10-100 nM) of HA microinjected in the MePD on basal cardiovascular recordings and on baroreflex- and chemoreflex-mediated responses; 2) to reveal whether cardiovascular reflex responses could be affected by MePD microinjections of (R)-alpha-methylhistamine (AH(3)), an agonist of the inhibitory autoreceptor H(3); and, 3) to carry out a power spectral analysis to evaluate the contribution of the sympathetic and parasympathetic components in the variability of the HR and BP recordings. When compared with the control group (microinjected with saline, 0.3 mu l), HA (10 nM) promoted an increase in the MAP(50), i.e. the mean value of BP at half of the HR range evoked by the baroreflex response. Histamine (100 nM) did not affect the baroreflex activity, but significantly decreased the parasympathetic component of the HR variability, increased the sympathetic/parasympathetic balance at basal conditions (these two latter evaluated by the power spectral analysis), and promoted an impairment in the chemoreflex bradycardic response. Microinjection of AH(3) (10 mu M) led to mixed results, which resembled the effects of both doses of HA employed here. Present data suggest that cardiovascular changes induced by baroreceptors and chemoreceptors involve the histaminergic activity in the MePD. This neural regulation of reflex cardiovascular responses can have important implications for homeostatic and allostatic conditions and possibly for the behavioral displays modulated by the rat MePD. (C) 2008 IBRO. Published by Elsevier Ltd. All rights reserved.

Perinatal salt restriction: A new pathway to programming adiposity indices in adult female Wistar rats

Low birth weight has been associated with increased obesity in adulthood. It has been shown that dietary salt restriction during intrauterine life induces low birth weight and insulin resistance in adult Wistar rats. The present study had a two-fold objective: to evaluate the effects that low salt intake during pregnancy and lactation has on the amount and distribution of adipose tissue; and to determine whether the phenotypic changes in fat mass in this model are associated with alterations in the activity of the renin-angiotensin system. Maternal salt restriction was found to reduce birth weight in male and female offspring. In adulthood, the female offspring of dams fed the low-salt diet presented higher adiposity indices than those seen in the offspring of dams fed a normal-salt diet. This was attributed to the fact that adipose tissue mass (retroperitoneal but not gonadal, mesenteric or inguinal) was greater in those rats than in the offspring of dams fed a normal diet. The adult offspring of dams fed the low-salt diet, compared to those dams fed a normal-salt diet, presented the following: plasma leptin levels higher in males and lower in females; plasma renin activity higher in males but not in females; and no differences in body weight, mean arterial blood pressure or serum angiotensin-converting enzyme activity. Therefore, low salt intake during pregnancy might lead to the programming of obesity in adult female offspring. (c) 2009 Elsevier Inc. All rights reserved.