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Teoria do funcional da densidade aplicada ao estudo da interação entre oxigênio molecular e nanoclusters de platina dopados com Al, Cr e V; Density functional theory applied to the study of the interaction between molecular oxygen and platinum nanoclusters doped with Al, Cr and V

Varela Junior, Jaldyr de Jesus Gomes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 27/07/2011 PT
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Este trabalho apresenta um estudo aplicando a Teoria do Funcional da Densidade (DFT), utilizando o funcional B3LYP, para estudar a estrutura eletrônica de nanoclusters de platina dopados com Al, Cr e V e suas interações com oxigênio molecular. As análises das populações de Mulliken e de NBO para a interação entre O2 e Pt2, Pt-Cr e Pt-V revelaram que ocorre transferência de carga dos orbitais s e d dos metais para os orbitais p do oxigênio, resultando no preenchimento dos orbitais antiligantes da molécula de oxigênio, provocando a quebra da ligação O--O e formação de ligações hibridizadas Metal - O, com energia de dissociação da ligação O - O em 1,0 eV sobre Pt2. Sobre Pt-Cr e Pt-V, esse valor decresce para 0,56 eV e 0,20 eV, respectivamente. Os estudos da interação entre oxigênio molecular e os clusters Pt3, Pt2Al, Pt2Cr e Pt2V mostram que ocorre adsorção não dissociativa de oxigênio molecular sobre o cluster Pt3 onde observamos uma adsorção segundo o modelo de ponte enquanto que sobre os clusters Pt2Al e Pt2V ocorre adsorção dissociativa de oxigênio molecular. Por outro lado, com o cluster Pt2Cr a adsorção segue o modelo de Pauling, com o oxigênio molecular adsorvido em apenas um sítio do cluster...

Determination of oxygen permeability in soft contact lenses using a polarographic method : estimation of relevant physiological parameters

González-Méijome, José Manuel; Compañ-Moreno, V.; Riande, E.
Fonte: ACS Publicador: ACS
Tipo: Artigo de Revista Científica
Publicado em 02/09/2008 ENG
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This work reports the apparent oxygen transmissibility Dk/t)app of four silicone hydrogel (Si-Hy) contact lenses (CLs). A method is described that allows the estimation of the oxygen tension at the lens-cornea interface for closed- and open-eyelids situations combining the instrument oxygen transmissibility (IOT) and corneal parameters such as corneal thickness, corneal permeability, and oxygen flux across the cornea. From these results, the biological oxygen apparent transmissibility (BOAT), equivalent oxygen percentage (EOP), partial pressure, (ptc), of oxygen at the cornea-CL interface and oxygen flux, (jc), were also obtained. This method allows the evaluation of the physiological environment under the lens using the formulations described in previous studies. The oxygen performance of four Si-Hy materials was evaluated using a polarographic cell coupled to a permeometer. Measurements of the apparent transmissibility, (Dk/t)app, and permeability, Dk, were performed in stacks containing from 1 to n repeated lenses and, from the values obtained, the error involved in the measurements in single samples was estimated. It was found that the values of (Dk/t)app and Dk obtained following the two different procedures (stack method and measurement of single sample) were significantly different from the nominal values given by the manufacturer...

Enhancement of oxygen mass transfer in pneumatical bioreactors using n-dodecane as oxygen-vector

Folescu, Elena; Ferreira, António; Rocha, Fernando; Teixeira, J. A.
Fonte: “Gheorghe Asachi” Technical University of Iasi; Institutul Politehnic din Iasi Publicador: “Gheorghe Asachi” Technical University of Iasi; Institutul Politehnic din Iasi
Tipo: Artigo de Revista Científica
Publicado em //2012 ENG
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In biotechnology, oxygen mass transfer is a key parameter involved in the design and operation of bioreactors and it can be analyzed by means of the oxygen mass transfer coefficient (kLa). Due to the fact that oxygen has a very low solubility in an aqueous media (8–10 ppm at 20°C), actively growing cells can consume all the dissolved oxygen very fast, therefore, it has to be supplied continuously into the broths. In conventionally aerated bioreactors, low oxygen solubility combined with slow oxygen transfer rates often results in reduced growth and culture productivity. Due to their higher oxygen solubility, non-toxicity to microbes, antifoaming action, oxygen-vectors addition is one of the most effective methods to improve oxygen mass transfer rate in aerobic fermentations. The aim of this study was to investigate the use of n-dodecane as oxygen-vector in bubble column and air-lift bioreactors, under different working conditions (air superficial velocity, volumetric fraction of the organic phase, medium temperature). The results show that volumetric fraction of oxygen-vector (φ) has a great influence on kLa; in the presence of low volumetric fraction (φ=0.005 (v/v)), the oxygen mass transfer coefficient’s value in bubble column bioreactor was increased by almost 100% at 35°C and for φ=0.02 (v/v) by 5% at 25°C...

Oxygen concentrators performance with nitrous oxide at 50:50 volume

Moll,Jorge Ronaldo; Vieira,Joaquim Edson; Gozzani,Judymara Lauzi; Mathias,Lígia Andrade Silva Telles
Fonte: Sociedade Brasileira de Anestesiologia Publicador: Sociedade Brasileira de Anestesiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 EN
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Background and objectives: Few investigations have addressed the safety of oxygen from concentrators for use in anesthesia in association with nitrous oxide. This study evaluated the percent of oxygen from a concentrator in association with nitrous oxide in a semi-closed rebreathing circuit. Methods: Adult patients undergoing low risk surgery were randomly allocated into two groups, receiving a fresh gas flow of oxygen from concentrators (O293) or of oxygen from concentrators and nitrous oxide (O293N2O). The fraction of inspired oxygen and the percentage of oxygen from fresh gas flow were measured every 10 min. The ratio of FiO2/oxygen concentration delivered was compared at various time intervals and between the groups. Results: Thirty patients were studied in each group. There was no difference in oxygen from concentrators over time for both groups, but there was a significant improvement in the FiO2 (p < 0.001) for O293 group while a significant decline (p < 0.001) for O293N2O. The FiO2/oxygen ratio varied in both groups, reaching a plateau in the O293 group. Pulse oximetry did not fall below 98.5% in either group. Conclusion: The FiO2 in the mixture of O293 and nitrous oxide fell during the observation period although oxygen saturation was higher than 98.5% throughout the study. Concentrators can be considered a stable source of oxygen for use during short anesthetic procedures...

Reaction of Oxygen with the Respiratory Chain in Cells and Tissues

Chance, Britton
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/09/1965 EN
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36.39%
This paper considers the way in which the oxygen reaction described by Dr. Nicholls and the ADP control reactions described by Dr. Racker could cooperate to establish a purposeful metabolic control phenomenon in vivo. This has required an examination of the kinetic properties of the respiratory chain with particular reference to methods for determinations of oxygen affinity (Km). The constant parameter for tissue respiration is k1, the velocity constant for the reaction of oxygen with cytochrome oxidase. Not only is this quantity a constant for a particular tissue or mitochondria; it appears to vary little over a wide range of biological material, and for practical purposes a value of 5 x 107 at 25° close to our original value (20) is found to apply with adequate accuracy for calculation of Km for mammalia. The quantity which will depend upon the tissue and its metabolic state is the value of Km itself, and Km may be as large as 0.5 µM and may fall to 0.05 µM or less in resting, controlled, or inhibited states. The control characteristic for ADP may depend upon the electron flux due to the cytochrome chain (40); less ADP is required to activate the slower electron transport at lower temperatures than at higher temperatures. The affinity constants for ADP control appear to be less dependent upon substrate supplied to the system. The balance of ADP and oxygen control in vivo is amply demonstrated experimentally and is dependent on the oxygen concentration as follows. In the presence of excess oxygen...

Effects of lake water vertical variation in dissolved oxygen on selection among Daphnia pulicaria genotypes

Donovan, Victoria
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN
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36.38%
Thermal stratification within lakes can lead to a prominent dissolved oxygen gradient. How this gradient influences Daphnia, a keystone species within many aquatic systems, is still unclear. I tested the effects of a dissolved oxygen gradient on population dynamics, diversity and selection within populations of Daphnia pulicaria through laboratory experiments conducted using natural lake water and food sources. Different genotypes were exposed to a range of dissolved oxygen treatments for selected time intervals over 36 days. I observed significant decline in populations, leading to extinction at 1 mg/L of dissolved oxygen, indicating populations are not capable of surviving for elongated periods of time within these conditions. There was no significant change in diversity over time or oxygen level. Diversity patterns were similar to those predicted by the Intermediate Disturbance Hypothesis in populations exposed to experimental conditions for 36 days; however, this pattern was not strong. Significant increases in relative abundance of one genotype at 1 and 2 mg/L of dissolved oxygen suggest that certain clones are selected for at low dissolved oxygen concentrations. This was supported by selection coefficients which indicated high selection at the 1mg/L dissolved oxygen concentration...

The potential role of plant oxygen and sulphide dynamics in die-off events of the tropical seagrass, Thalassia testudinum

Borum, J.; Pederson, O.; Greve, T. M.; Frankovich, T. A.; Zieman, J. C.; Fourqurean, James W.; Madden, C. J.
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
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1 Oxygen and sulphide dynamics were examined, using microelectrode techniques, in meristems and rhizomes of the seagrass Thalassia testudinum at three different sites in Florida Bay, and in the laboratory, to evaluate the potential role of internal oxygen variability and sulphide invasion in episodes of sudden die-off. The sites differed with respect to shoot density and sediment composition, with an active die-off occurring at only one of the sites. 2 Meristematic oxygen content followed similar diel patterns at all sites with high oxygen content during the day and hyposaturation relative to the water column during the night. Minimum meristematic oxygen content was recorded around sunrise and varied among sites, with values close to zero at the die-off site. 3 Gaseous sulphide was detected within the sediment at all sites but at different concentrations among sites and within the die-off site. Spontaneous invasion of sulphide into Thalassia rhizomes was recorded at low internal oxygen partial pressure during darkness at the die-off site. 4 A laboratory experiment showed that the internal oxygen dynamics depended on light availability, and hence plant photosynthesis, and on the oxygen content of the water column controlling passive oxygen diffusion from water column to leaves and belowground tissues in the dark. 5 Sulphide invasion only occurred at low internal oxygen content...

A review of long-term oxygen therapy for chronic obstructive pulmonary disease

Crockett, A.; Cranston, J.; Moss, J.; Alpers, J.
Fonte: W B Saunders Co Ltd Publicador: W B Saunders Co Ltd
Tipo: Artigo de Revista Científica
Publicado em //2001 EN
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This study aimed to review the evidence for the use of long-term oxygen therapy for patients with chronic obstructive pulmonary disease (COPD). The design was a systematic Cochrane review of randomized controlled trials (RCTs) of long-term oxygen therapy for COPD and main outcome measure was survival on home oxygen therapy. Five RCTs were identified. Data from two trials of nocturnal oxygen therapy in mild to moderate hypoxaemia were aggregated. Data from the other three trials could not be aggregated because of differences in trial design and patient selection. Treatment with continuous versus nocturnal oxygen therapy produced a significant improvement in mortality after 24 months [Peto odds ratio 0·45, 95% confidence interval (95% CI) 0·25–0·81] for the continuous therapy group. Treatment with oxygen therapy versus no oxygen therapy showed a significant improvement in mortality after five years in the group receiving oxygen therapy (Peto odds ratio 0·42, 95% CI 0·18–0·98). There was no difference in mortality for patients with COPD and mild to moderate daytime hypoxaemia and nocturnal desaturation receiving nocturnal oxygen therapy versus no oxygen therapy or sham treatment. Long-term oxygen therapy versus no oxygen therapy in patients with COPD and moderate hypoxaemia had no effect on survival. In conclusion...

Effect of culturing mouse embryos under different oxygen concentrations on subsequent fetal and placental development

Inglis, D.; Lane, M.; Roberts, C.; Kelley, R.; Edwards, L.; Thompson, J.; Kind, K.
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
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The oxygen concentration used during embryo culture can influence embryo development and quality. Reducing the oxygen concentration in the atmosphere to 2% during post-compaction culture of mouse embryos perturbs embryonic gene expression. This study examined the effect of culturing mouse embryos under different oxygen concentrations on subsequent fetal and placentaldevelopment.Embryoswere culturedfromthe zygote tomorula stageunder7%oxygen, followed by 20, 7 or 2%oxygen to the blastocyst stage.Cultured and in vivo developed blastocysts were transferred into pseudopregnant recipients. Fetal and placental outcomes were analysed at day 18 of pregnancy. Implantation rate was not influenced by embryo culture conditions, but resorption rates were increased in embryos cultured under 2% oxygen, compared with 7% oxygen. Day 18 fetal weights were reduced following culture under 2%, compared with 7 or 20% oxygen, or in vivo development. Placental weight was not influenced by culture conditions. No differences in the proportion of junctional or labyrinthine exchange regions within the placenta or themorphometry of the labyrinthine region were detected. Surface density (surface area/gram labyrinth) of trophoblast available for exchange was reduced in placentas developed fromembryos cultured under 2% oxygen...

Differential expression of oxygen-regulated genes in bovine blastocysts

Harvey, A.; Navarrete Santos, A.; Kirstein, M.; Kind, K.; Fischer, B.; Thompson, J.
Fonte: Wiley-Liss Publicador: Wiley-Liss
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
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Low oxygen conditions (2%) during post-compaction culture of bovine blastocysts improve embryo quality, which is associated with a small yet significant increase in the expression of glucose transporter 1 (GLUT-1), suggesting a role of oxygen in embryo development mediated through oxygen-sensitive gene expression. However, bovine embryos to at least the blastocyst stage lack a key regulator of oxygen-sensitive gene expression, hypoxia-inducible factor 1α (HIF1α). A second, less well-characterized protein (HIF2α) is, however, detectable from the 8-cell stage of development. Here we use differential display to determine additional gene targets in bovine embryos in response to low oxygen conditions. While development to the blastocyst stage was unaffected by the oxygen concentration used during post-compaction culture, differential display identified oxygen-regulation of myotrophin and anaphase promoting complex 1 expression, with significantly lower levels observed following culture under 20% oxygen than 2% oxygen. These results further support the hypothesis that the level of gene expression of specific transcripts by bovine embryos alters in response to changes in the oxygen environment post-compaction. Specifically, we have identified two oxygen-sensitive genes that are potentially regulated by HIF2 in the bovine blastocyst.

Regulation of gene expression in bovine Blastocysts in response to oxygen and the iron chelator desferrioxamine

Harvey, A.; Kind, K.; Thompson, J.
Fonte: Soc Study Reproduction Publicador: Soc Study Reproduction
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
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36.4%
Low (2%) oxygen conditions during postcompaction culture of bovine blastocysts improve embryo quality and are associated with small increases in the expression of glucose transporter 1 (SLC2A1), anaphase promoting complex (ANAPC1), and myotrophin (MTPN), suggesting a role for oxygen in the regulation of embryo development, mediated through oxygen-sensitive gene expression. However, bovine embryos, to at least the blastocyst stage, lack detectable levels of the key regulator of oxygen-sensitive gene expression, hypoxia-inducible 1 alpha (HIF1A), while the less well-characterized HIF2 alpha protein is readily detectable. Here we report that other key HIF1 regulated genes are not significantly altered in their expression pattern in bovine blastocysts in response to reduced oxygen concentrations postcompaction-with the exception of lactate dehydrogenase A (LDHA), which was significantly increased following 2% oxygen culture. Antioxidant enzymes have been suggested as potential HIF2 target genes, but their expression was not altered following low-oxygen culture in the bovine blastocyst. The addition of desferrioxamine (an iron chelator and inducer of HIF-regulated gene expression) during postcompaction stages significantly increased SLC2A1...

Oxygen concentration during oocyte maturation in the mouse.

Banwell, Kelly Michelle
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2009
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36.41%
Follicular antral oxygen tension is thought to influence subsequent oocyte developmental competence. Despite this, in vitro maturation (IVM) is routinely performed in either 5 or 20% oxygen and while low oxygen has been shown to be beneficial to embryo development in many species, the effects of altering oxygen concentration during IVM have not been adequately investigated. Here we investigated the effects of a range of oxygen concentrations (2, 5, 10 & 20% oxygen) during IVM of mouse oocytes on a range of oocyte and embryonic parameters as well as fetal/placental outcome measures and cumulus cell gene expression. While common short term measures of oocyte developmental competence such as maturation, fertilisation, and embryonic development rates were not affected over the range of oxygen levels used, more in depth investigations found several striking differences. Following IVM at 5% oxygen, the oocyte mitochondria were found to have altered patterns of both membrane potential (a measure of mitochondrial activity) and distribution suggesting altered oocyte metabolism. Following IVF, the cellular make up of embryos was investigated. In blastocysts derived from low IVM oxygen (2%) there was found to be an increased number of trophectoderm cells...

Effect of palliative oxygen versus room air in relief of breathlessness in patients with refractory dyspnoea: a double-blind, randomised controlled trial

Abernethy, A.; McDonald, C.; Frith, P.; Clark, K.; Herndon, J.; Marcello, J.; Young, I.; Bull, J.; Wilcock, A.; Booth, S.; Wheeler, J.; Tulsky, J.; Crockett, A.; Currow, D.
Fonte: Lancet Ltd Publicador: Lancet Ltd
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
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BACKGROUND: Palliative oxygen therapy is widely used for treatment of dyspnoea in individuals with life-limiting illness who are ineligible for long-term oxygen therapy. We assessed the effectiveness of oxygen compared with room air delivered by nasal cannula for relief of breathlessness in this population of patients. METHODS: Adults from outpatient clinics at nine sites in Australia, the USA, and the UK were eligible for enrolment in this double-blind, randomised controlled trial if they had life-limiting illness, refractory dyspnoea, and partial pressure of oxygen in arterial blood (PaO(2)) more than 7.3 kPa. Participants were randomly assigned in a 1:1 ratio by a central computer-generated system to receive oxygen or room air via a concentrator through a nasal cannula at 2 L per min for 7 days. Participants were instructed to use the concentrator for at least 15 h per day. The randomisation sequence was stratified by baseline PaO(2) with balanced blocks of four patients. The primary outcome measure was breathlessness (0-10 numerical rating scale [NRS]), measured twice a day (morning and evening). All randomised patients who completed an assessment were included in the primary analysis for that data point (no data were imputed). This study is registered...

The cerebral critical oxygen threshold of ventilated preterm lambs and the influence of antenatal inflammation

Andersen, C.; Pillow, J.; Gill, A.; Allison, B.; Moss, T.; Hooper, S.; Nitsos, I.; Kluckow, M.; Polglase, G.
Fonte: Amer Physiological Soc Publicador: Amer Physiological Soc
Tipo: Artigo de Revista Científica
Publicado em //2011 EN
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Perinatal inflammation is associated with adverse neurodevelopmental outcomes, which may be partly due to changes in the cerebral oxygen delivery/consumption relationship. We aimed to determine the critical oxygen delivery threshold of the brain of preterm, ventilated lambs and to determine whether the critical threshold is affected by exposure to inflammation in utero. Pregnant ewes received intra-amniotic injection of lipopolysaccharide or saline at 125 or 127 days of gestation. Pulmonary and systemic flow probes and catheters were surgically positioned in the fetus immediately before delivery at 129 days of gestation. After delivery, lambs were ventilated for 90 min using a positive end-expiratory pressure recruitment strategy. Cardio-respiratory variables and blood gases were measured regularly. Systemic and cerebral oxygen delivery, consumption (Fick), and extraction were calculated, and the relationship between cerebral delivery and consumption analyzed. Linear regression was used to define the transition or "critical" oxygen threshold as the point at which the slope of the oxygen delivery/consumption curve changed to be > 10°. Four subgroups were defined according to the calculated critical threshold. A total of 150 measurements were recorded in 18 lambs. Fetal cerebral oxygen consumption was increased by antenatal lipopolysaccharide (P < 0.05). The postnatal critical oxygen threshold was 3.6 ml·kg⁻¹·min⁻¹...

Klinische Evaluation einer automatischen FiO2-Regelung bei beatmeten Frühgeborenen; Clinical evaluation of automatically controlled oxygen fraction in preterm infants

Hallenberger, Antonietta
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
36.4%
In dieser Studie wurde geprüft, ob ein automatischer FiO2-Controller die FiO2-Regelung besser vornehmen kann, als das Pflegepersonal im Routinebetrieb, indem er den Zielbereich häufiger erreicht und die SpO2 in diesem Bereich länger halten kann. Hierfür wurden 24 Frühgeborene in die Studie eingeschlossen und der Controller in einer Pilotphase und einer Hauptstudie hinsichtlich verschiedener Parameter evaluiert. Der primäre SpO2-Zielparameter war der Prozentsatz der Zeit innerhalb des definierten Zielbereichs (87-96%). Der Controller konnte den Zielbereich signifikant häufiger erreichen als das Pflegepersonal. Zudem wurde in der Hauptstudie keine von ihm durchgeführte FiO2-Änderung abgelehnt oder abgebrochen. Auch die Anzahl hyper- und hypoxischer Episoden, sowie die Anzahl der manuellen FiO2-Anpassungen und somit die Arbeitsbelastung wurden durch den Controller reduziert. Dadurch konnte die Wirksamkeit und Tauglichkeit des Controllers bewiesen und die Hypothesen bestätigt werden. Im Vergleich zu anderen Studien, die automatische FiO2-Controller testeten, konnte gezeigt werden, dass der Controller hinsichtlich vieler Parameter Vorteile und Verbesserungen bietet. Der Controller konnte den Prozentsatz der Zeit innerhalb des Zielbereichs signifikant steigern. Außerdem war der Algorithmus schon sehr feinreguliert und weiter entwickelt als dies vor einigen Jahren der Fall war. Es wurde zum ersten Mal ein Pulsoximeter verwendet...

Die Kinetik der Sauerstoffaufnahme bei Belastungsbeginn in Relation zum Herzfrequenzanstieg und der alveolären Sauerstoffkonzentration; The kinetics of oxygen uptake at the beginning of exercise in relation to the rise of heart-rate and the oxygen concentration of the alveoles

Zeiselmeier, Annette
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
36.4%
Bisher wurde bei der Betrachtung des Belastungsstoffwechsels das Modell einer direkten Koppelung von pulmonaler Sauerstoffaufnahme mit der muskelzellulären Sauerstoffentnahme ohne Berücksichtigung einer eventuellen Speichermöglichkeit von Sauerstoff im Körper favorisiert. In dieser Arbeit wurde ein Indiz geprüft, welches für eine relevante Nutzung von Speichersauerstoff zu Belastungsbeginn spricht: ein schnellerer Verlauf des Anstiegs der Herzfrequenz zu Belastungsbeginn im Vergleich zum Anstieg der Sauerstoffaufnahme. Es wurde mit Hilfe eines breath-by-breath Spirometersystems und permanenter massenspektrometrischer Gasanalyse sowie fortlaufender Herzfrequenzaufzeichnung ein direkter Vergleich zwischen der Anstiegsgeschwindigkeit der Sauerstoffaufnahme (VO) und der Anstiegsgeschwindigkeit der Herzfrequenz zu Beginn einer mittleren Belastung durchgeführt. 6 freizeitsportlich aktive Probanden aus unterschiedlichen Sportarten absolvierten dabei Laufbandbelastungen bei einer Leistung von 80% ihrer Individuellen Anaeroben Schwelle (IAS) jeweils viermal. Dabei wurde fortlaufend die Herzfrequenz in 5-Sekunden-Intervallen sowie die Sauerstoffaufnahme und end-tidale Sauerstoffkonzentration Atemzug für Atemzug aufgezeichnet. Die Kinetiken der Sauerstoffaufnahme und der Herzfrequenz zeigten erwartungsgemäß einen exponentiellen Anstieg mit nachfolgendem Übergang in einen Steady-State. Der Verlauf der viermaligen Belastungen wurde gemittelt...

Ambulatory oxygen for people with chronic obstructive pulmonary disease who are not hypoxaemic at rest

Ameer, F.; Carson, K.V.; Usmani, Z.A.; Smith, B.J.
Fonte: Cochrane Collaboration Publicador: Cochrane Collaboration
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
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BACKGROUND: People with chronic obstructive pulmonary disease (COPD) often become transiently hypoxaemic (low oxygen levels in blood) on exercise, necessitating oxygen therapy to improve breathlessness and exercise capacity and to reduce disability. Ambulatory oxygen therapy refers to provision of oxygen therapy during exercise and activities of daily living. Ambulatory oxygen therapy is often used by patients on long-term oxygen therapy (LTOT) during exercise or by non-LTOT users with or without resting hypoxaemia when they show evidence of exercise de-saturation and demonstrate improvement in exercise capacity with supplemental oxygen. OBJECTIVES: To determine the longer-term efficacy of ambulatory oxygen therapy only in patients with COPD who do not meet the criteria for LTOT, with respect to improvement in exercise capacity, mortality, quality of life and other relevant measures of improvement. SEARCH METHODS: The Cochrane Airways Group Specialised Register, including MEDLINE, EMBASE and CINAHL, was searched. Online clinical trial registers, including Controlled Clinical Trials (www.controlled-trials.com), government registries (clinicaltrials.gov) and World Health Organization (WHO) registries (www.who.int/trialsearch), were screened for ongoing and recently completed studies. Bibliographies of included studies were searched for additional trials that may meet the inclusion criteria and were not retrieved by the above search strategy. Authors of identified trials were contacted to provide other published and unpublished studies. Searches were current as of November 2012. SELECTION CRITERIA: Randomised controlled trials (RCTs) that compare ambulatory oxygen therapy provided through portable oxygen cylinders/battery-powered devices or liquid oxygen canisters versus placebo air cylinders...

The impact of long term oxygen therapy on South Australian patients with chronic lung disease.

Crockett, Alan Joseph
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 683853 bytes; 135147 bytes; application/pdf; application/pdf
Publicado em //2005 EN
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The peer-reviewed publications contained within this thesis describe studies that have contributed significantly to the understanding of long-term oxygen therapy (LTOT) for Australian Chronic Obstructive Pulmonary Disease (COPD) patients. My personal contribution to each of these studies ranged from the initial development of the hypotheses and design and execution of the investigations, submission of research grants applications to fund the studies through to preparation of the manuscripts for publication. When LTOT was first introduced into Australia I was fortunate to meet the key experts in LTOT including Professors Tom Petty, Nick Anthonisen, David Flenley, Pierre Levi-Valensi and Peter Howard. At that time all were involved in randomised controlled trials of oxygen therapy. (1, 2), 3). I also visited several oxygen concentrator and oxygen supply companies in the USA and UK. It was during these visits that I became convinced that the concentrator provided a more economical and efficient method of LTOT delivery. In 1980, an oxygen concentrator was imported to Australia by the spouse of one of our patients suffering from emphysema who was receiving long term oxygen via cylinders In 1982, two oxygen concentrators were donated to FMC by two different manufacturers (DeVilbis and Marx) based in the USA. These instruments were trialled on a male and female patient receiving LTOT in the Southern Adelaide metropolitan area. The initial acceptance of this device by these patients led to a submission to the South Australian Department of Health for a grant to purchase 40 units. Funds were finally obtained for the purchase of 34 concentrators by FMC and these were rolled out to the then existing patients who were receiving LTOT in 1984. Up to this point in time the only published guidelines or recommendations for LTOT came from the American College of Chest Physicians in 1973(3) and the American Thoracic Society in 1977(4). In 1982...

Oxigenoterapia domiciliar prolongada em crianças e adolescentes: uma análise do uso clínico e de custos de um programa assistencial; Long-term home oxygen therapy in children and adolescents: analysis of clinical use and costs of a home care program

MUNHOZ, Andréa S.; ADDE, Fabiola V.; NAKAIE, Cleyde M. A.; DORIA FILHO, Ulysses; SILVA FILHO, Luiz V. R. F.; RODRIGUES, Joaquim C.
Fonte: Sociedade Brasileira de Pediatria Publicador: Sociedade Brasileira de Pediatria
Tipo: Artigo de Revista Científica
POR
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OBJETIVOS: Descrever as características clínicas e laboratoriais dos pacientes em oxigenoterapia domiciliar prolongada acompanhados pelo programa de atendimento domiciliar do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, durante um período de 8 anos, e comparar os grupos com e sem hipertensão pulmonar secundária. Estimar o custo do programa utilizando concentradores versus cilindros de oxigênio arcados pela instituição. MÉTODOS: Estudo descritivo retrospectivo e de coorte dos pacientes em oxigenoterapia domiciliar prolongada, em seguimento no período de 2002 a 2009, na Unidade de Pneumologia do Instituto da Criança do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. RESULTADOS: Foram estudados 165 pacientes, 53% do sexo masculino, com as medianas: idade de início da oxigenoterapia - 3,6 anos; tempo de oxigenoterapia - 7 anos; e tempo de sobrevida após início da oxigenoterapia - 3,4 anos. Os principais diagnósticos foram: fibrose cística (22%), displasia broncopulmonar (19%) e bronquiolite obliterante (15%). Dos 33 pacientes que realizaram espirometria, 70% apresentavam distúrbio ventilatório obstrutivo grave. O exame ecocardiográfico foi executado em 134 pacientes; 51% deles tinham hipertensão pulmonar secundária. Houve associação estatisticamente significante entre: presença de hipertensão pulmonar e necessidade de maiores fluxos de oxigênio (qui-quadrado...

The preoperative treatment of severely anemic patients with a perfluorochemical oxygen-transport fluid, Fluosol-DA

Tremper, K.; Friedman, Alan; Levine, E.; Lapin, R.; Camarillo, D.
Fonte: Mass Medic Society: The New England Journal of Medicine Publicador: Mass Medic Society: The New England Journal of Medicine
Tipo: Artigo de Revista Científica Formato: 38419 bytes; application/pdf
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We gave a perfluorochemical oxygen-transport fluid and plasma expander, Fluosol-DA, to seven severely anemic patients before surgery to determine its effectiveness in supplementing oxygen transport. The dose of Fluosol in the five patients completing the study was 20 ml per kilogram of body weight. When the patients breathed low levels of supplemental oxygen (mean partial pressure of arterial oxygen +/- S.D., 101 +/- 25 torr), the perfluorochemical carried a small amount of oxygen, but when they received pure oxygen (arterial oxygen pressure, 361 +/- 65 torr) it carried approximately 0.8 per cent of oxygen (by volume). This increase accounted for 7 +/- 3 per cent of the patients' arterial oxygen content and 24 +/- 7 per cent of their oxygen consumption. The cardiac index and left ventricular stroke-work index decreased, whereas the oxygen delivery increased, although these changes were not statistically significant. Significant changes included a 22 per cent increase in oxygen consumption, a 59 per cent increase in mixed venous oxygen tension, and an increase in mixed venous hemoglobin saturation to 90 +/- 6 per cent. We conclude that at ambient oxygen tensions fluosol acts primarily as a volume expander, whereas at higher tensions (greater than 300 torr) it contributes substantially to the oxygen-delivery system.; Article may be found at: http://content.nejm.org/cgi/content/abstract/307/5/277