Effects of arterial oxygen tension and cardiac output on venous saturation: a mathematical modeling approach

OBJECTIVES: Hemodynamic support is aimed at providing adequate O2 delivery to the tissues; most interventions target O2 delivery increase. Mixed venous O2 saturation is a frequently used parameter to evaluate the adequacy of O2 delivery. METHODS: We describe a mathematical model to compare the effects of increasing O2 delivery on venous oxygen saturation through increases in the inspired O2 fraction versus increases in cardiac output. The model was created based on the lungs, which were divided into shunted and non-shunted areas, and on seven peripheral compartments, each with normal values of perfusion, optimal oxygen consumption, and critical O2 extraction rate. O2 delivery was increased by changing the inspired fraction of oxygen from 0.21 to 1.0 in steps of 0.1 under conditions of low (2.0 L.min-1) or normal (6.5 L.min-1) cardiac output. The same O2 delivery values were also obtained by maintaining a fixed O2 inspired fraction value of 0.21 while changing cardiac output. RESULTS: Venous oxygen saturation was higher when produced through increases in inspired O2 fraction versus increases in cardiac output, even at the same O2 delivery and consumption values. Specifically, at high inspired O2 fractions, the measured O2 saturation values failed to detect conditions of low oxygen supply. CONCLUSIONS: The mode of O2 delivery optimization, specifically increases in the fraction of inspired oxygen versus increases in cardiac output, can compromise the capability of the "venous O2 saturation" parameter to measure the adequacy of oxygen supply. Consequently, venous saturation at high inspired O2 fractions should be interpreted with caution

Condition-based maintenance in hydroelectric plants: A systematic literature review

Industrial maintenance has become an essential strategic factor for profit and productivity in industrial systems. In the modern industrial context, condition-based maintenance guides the interventions and repairs according to the machine’s health status, calculated from monitoring variables and using statistical and computational techniques. Although several literature reviews address condition-based maintenance, no study discusses the application of these techniques in the hydroelectric sector, a fundamental source of renewable energy. We conducted a systematic literature review of articles published in the area of condition-based maintenance in the last 10 years. This was followed by quantitative and thematic analyses of the most relevant categories that compose the phases of condition-based maintenance. We identified a research trend in the application of machine learning techniques, both in the diagnosis and the prognosis of the generating unit’s assets, being vibration the most frequently discussed monitoring variable. Finally, there is a vast field to be explored regarding the application of statistical models to estimate the useful life, and hybrid models based on physical models and specialists’ knowledge, of turbine-generators

Species diversity and community structure of fruit-feeding butterflies (Lepidoptera: Nymphalidae) in an eastern amazonian forest

Deforestation has negative impacts on diversity and community patterns of several taxa. In the eastern Amazon, where much deforestation is predicted for the coming years, forests patches may be essential to maintain the local biodiversity. Despite increasing concerns about the conservation of threatened areas, few studies have been performed to analyze the communities of diversified groups, such as insects, in the eastern Amazon. Here, we investigated species diversity and community structure of fruit-feeding butterflies, a well-known bioindicator group, in a threatened remnant of an eastern Amazonian forest located on Maranhão Island, northeastern Brazil. Fruit-feeding butterflies were sampled monthly for one year. Diversity and evenness indices, richness estimators, rarefaction curve, and rank-abundance plot were used to describe community structure in the study area. We captured 529 fruit-feeding butterflies in four subfamilies, 23 genera and 34 species. The three most abundant species, Hamadryas februa, Hamadryas feronia, and Hermeuptychia cf. atalanta are indicators of disturbed habitats and represented more than half of the collected individuals. Richness estimators revealed that between 87 and 94% of the fruit-feeding butterfly species were sampled, suggesting few additional records would be made for the area. Our results indicate that human-caused disturbances have altered local community patterns and provide baseline data for future research in threatened regions of the eastern Amazon

Hemodynamic and respiratory support using venoarterial extracorporeal membrane oxygenation (ECMO) in a polytrauma patient

Existem poucos relatos na literatura sobre o uso de oxigenação extracorpórea por membrana venoarterial por dupla disfunção decorrente de contusão cardíaca e pulmonar no paciente politraumatizado. Relatamos o caso de um paciente de 48 anos, vítima de acidente de motocicleta e automóvel, que evoluiu rapidamente com choque refratário com baixo débito cardíaco por contusão miocárdica e hipoxemia refratária decorrente de contusão pulmonar, tórax instável e pneumotórax bilateral. O suporte extracorpóreo foi uma medida efetiva de resgate para esse caso dramático, e o seu uso pôde ser interrompido com sucesso no 4º dia após o trauma. O paciente evoluiu com extenso infarto cerebral, morrendo no 7º dia de internaçãoThere are few reports in the literature regarding the use of venoarterial extracorporeal membrane oxygenation (ECMO) for double-dysfunction from both heart and lung contusions in polytrauma patients. This article reports a 48-year-old patient admitted after a traffic accident. He rapidly progressed to shock with low cardiac output due to myocardial contusion and refractory hypoxemia due to pulmonary contusion, an unstable chest wall and bilateral pneumothorax. ECMO was an effective rescue procedure in this dramatic situation and was successfully discontinued on the fourth day after the trauma. The patient also developed an extensive brain infarction and eventually died on the seventh day after admissio

Effects of arterial oxygen tension and cardiac output on venous saturation: a mathematical modeling approach

OBJECTIVES: Hemodynamic support is aimed at providing adequate O-2 delivery to the tissues; most interventions target O-2 delivery increase. Mixed venous O-2 saturation is a frequently used parameter to evaluate the adequacy of O-2 delivery. METHODS: We describe a mathematical model to compare the effects of increasing O-2 delivery on venous oxygen saturation through increases in the inspired O-2 fraction versus increases in cardiac output. The model was created based on the lungs, which were divided into shunted and non-shunted areas, and on seven peripheral compartments, each with normal values of perfusion, optimal oxygen consumption, and critical O-2 extraction rate. O-2 delivery was increased by changing the inspired fraction of oxygen from 0.21 to 1.0 in steps of 0.1 under conditions of low (2.0 L.min(-1)) or normal (6.5 L.min(-1)) cardiac output. The same O-2 delivery values were also obtained by maintaining a fixed O-2 inspired fraction value of 0.21 while changing cardiac output. RESULTS: Venous oxygen saturation was higher when produced through increases in inspired O-2 fraction versus increases in cardiac output, even at the same O-2 delivery and consumption values. Specifically, at high inspired O-2 fractions, the measured O-2 saturation values failed to detect conditions of low oxygen supply. CONCLUSIONS: The mode of O-2 delivery optimization, specifically increases in the fraction of inspired oxygen versus increases in cardiac output, can compromise the capability of the "venous O-2 saturation" parameter to measure the adequacy of oxygen supply. Consequently, venous saturation at high inspired O-2 fractions should be interpreted with caution

Comparação de diluentes na conservação do sêmen equino resfriado

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“Descascou o medo pra caber coragem”: a Psicologia Crítica como perspectiva de análise da música-arte em Liniker no processo emancipatório queer.

Understanding that the artist Liniker manifests in her songs different elements that say something about the reality of the LGBTQIA+ community, this research aims to investigate the potentiality of re-signifying the experiences of queer identity, having as object of analysis the Liniker’s musical works "Psiu" and "Baby95". In the light of historical materialism, in a qualitative reading, it became possible to understand human identity by its dialectical character of plasticity and movement, in which music-art can act as an instrument of resistance against a dehumanizing reality, transforming trajectories and memories demarcated by stigma and exclusion. Identities are under constant construction, and in this process art, politics, and science can be important allies to break the dissemination of social relations ruled by prejudice. Thus, considering the totality of the voice, performance, and lyrics, the stories narrated by the two songs reflect a certain collective identity, while challenging the normatization inherent to capitalist logic, with the potential to develop certain emancipatory processes. In the political struggle, therefore, we observe music as a helper in the identity-metamorphosis-emancipation path.Compreendendo que a artista Liniker manifesta em suas canções diferentes elementos que dizem sobre a realidade da comunidade LGBTQIA+, esta pesquisa objetiva investigar a potencialidade de ressignificação das vivências da identidade queer, tendo como objeto de análise as obras musicais “Psiu” e “Baby95” de Liniker. À luz do materialismo histórico, em leitura qualitativa, tornou-se possível compreender a identidade humana pelo seu caráter dialético de plasticidade e movimento, em que a música-arte pode atuar como instrumento de resistência contra uma realidade desumanizadora, transformando trajetórias e memórias demarcadas pelo estigma e exclusão. As identidades estão em constante construção, nesse processo a arte, política e ciência podem ser importantes aliados para romper a disseminação de relações sociais regidas pelos preconceitos. Assim, considerando a totalidade da voz, performance e letra, as histórias narradas pelas duas músicas refletem certa identidade coletiva, ao passo que desafiam a normatização inerente à lógica capitalista, com o potencial de desenvolver determinados processos emancipatórios. Na luta política, portanto, observamos a música como auxiliadora no percurso identidade-metamorfose-emancipação