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A carbon monoxide transport model of the human respiratory system applied to urban atmosphere exposure analysis

ALBUQUERQUE NETO, Cyro; YANAGIHARA, Jurandir Itizo; TURRI, Fábio
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
65.78%
The aim of this work is to analyze the carbon monoxide (CO) transport in the human body submitted to several physical activity levels. A complete mathematical model of the human respiratory system was developed, considering the exchanges of CO, oxygen (O2) and carbon dioxide (CO2) in the lung, blood and tissues. The human body was divided in the following compartments: alveolar, pulmonary capillaries, arterial, venous, tissue capillary and tissues. The gas transport in the blood and tissues is represented by empirical equations. The physiological parameters were described in function of physical activity. The model was validated by comparing its results with experimental data of controlled CO exposition. The agreement was excellent. CO concentration curves for critical days of São Caetano do Sul city (SP, Brazil) atmosphere were used as model input. The simulation results for some physical activities show that the more intense the activity, the larger the blood carboxyhemoglobin (COHb) level variations. The COHb level was compared with a CO quality air criteria, which showed to be adequate for low and moderate physical activity levels.

Aerobic training reverses airway inflammation and remodelling in an asthma murine model

SILVA, R. A.; VIEIRA, R. P.; DUARTE, A. C. S.; LOPES, F. D. T. Q. S.; PERINI, A.; MAUAD, T.; MARTINS, M. A.; CARVALHO, C. R. F.
Fonte: EUROPEAN RESPIRATORY SOC JOURNALS LTD Publicador: EUROPEAN RESPIRATORY SOC JOURNALS LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
55.71%
Aerobic training (AT) decreases dyspnoea and exercise-induced bronchospasm, and improves aerobic capacity and quality of life; however, the mechanisms for such benefits remain poorly understood. The aim of the present study was to evaluate the AT effects in a chronic model of allergic lung inflammation in mice after the establishment of airway inflammation and remodelling. Mice were divided into the control group, AT group, ovalbumin (OVA) group or OVA+AT group and exposed to saline or OVA. AT was started on day 28 for 60 min five times per week for 4 weeks. Respiratory mechanics, specific immunoglobulin (Ig)E and IgG(1), collagen and elastic fibres deposition, smooth muscle thickness, epithelial mucus, and peribronchial density of eosinophils, CD3+ and CD4+, IL-4, IL-5, IL-13, interferon-gamma, IL-2, IL-1ra, IL-10, nuclear factor (NF)-kappa B and Foxp3 were evaluated. The OVA group showed an increase in IgE and IgG1, eosinophils, CD3+, CD4+, IL-4, IL-5, IL-13, NF-kappa B, collagen and elastic, mucus synthesis, smooth muscle thickness and lung tissue resistance and elastance. The OVA+AT group demonstrated an increase of IgE and IgG(1), and reduction of eosinophils, CD3+, CD4+, IL-4, IL-5, IL-13, NF-kappa B, airway remodelling, mucus synthesis...

Oral tolerance attenuates airway inflammation and remodeling in a model of chronic pulmonary allergic inflammation

SCHUTZ, Viviane C. Ruiz; DREWIACKI, Tatiana; NAKASHIMA, Adriane S.; ARANTES-COSTA, Fernanda M.; PRADO, Carla M.; KASAHARA, David I.; LEICK-MAIDONADO, Edna A.; MARTINS, Milton A.; TIBERIO, Iolanda F. L. C.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
55.8%
We investigated the effects of oral tolerance (OT) in controlling inflammatory response, hyperresponsiveness and airway remodeling in guinea pigs (GP) with chronic allergic inflammation. Animals received seven inhalations of ovalbumin (1-5 mg/mL-OVA group) or normal saline (NS group). OT was induced by offering ad libitum ovalbumin 2% in sterile drinking water starting with the 1st ovalbumin inhalation (OT1 group) or after the 4th (OT2 group). The induction of OT in sensitized animals decreased the elastance of respiratory system (Ers) response after both antigen and methacholine challenges, peribronchial edema formation, eosinophilic airway infiltration, eosinophilopoiesis, and airways collagen and elastic fiber content compared to OVA group (P < 0.05). The number of mononuclear cells and resistance of respiratory system (Rrs) responses after antigen and methacholine challenges were decreased only in OT2 group compared to OVA group (P < 0.05). Concluding, our results show that inducing OT attenuates airway remodeling as well as eosinophilic inflammation and respiratory system mechanics. (C) 2008 Elsevier B.V. All rights reserved.; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); Universidade de São Paulo - Laboratorio de Terapeutica Experimental[LIM20-HC-FM-USP]

"Determinantes funcionais e morfológicos de ação de droga sobre os pulmões utilizando um modelo experimental em cobaias sob uso do cloridrato de fluoxetina" ; Functional and morphological determinants of drug action on the lungs through an experimental model in guinea pigs under use of fluoxetine

Capelozzi, Marco Antonio
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 15/02/2005 PT
Relevância na Pesquisa
55.78%
Muito se tem pesquisado sobre os efeitos adversos dos antidepressivos tricíclicos (p.e. imipramina) sobre o sistema respiratório, embora pouco ou quase nada se encontre com relação a tal aspecto na literatura médica sobre a fluoxetina (Prozac®)– um inibidor seletivo da recaptação de serotonina, até porque esta droga começou a ser utilizada somente há cerca de quinze anos. Ambas substâncias (fluoxetina e imipramina, ou seus congêneres) agem basicamente sobre quadros depressivos, fóbicos e obsessivo-compulsivos, obesidade, anorexia, e outras indicações de várias naturezas, indo desde a ansiedade até a sindrome do pânico. Nota-se entretanto, que na maioria dos pacientes com tais quadros (sob tratamento com a fluoxetina ou não), são muito frequentes as queixas de natureza respiratória, como tosse, falta de ar, “angústia" no peito etc. Alguns efeitos adversos da fluoxetina e seus derivados são descritos na literatura, embora raros. Entre eles, destaca-se o comprometimento do aparelho respiratório na forma de doença pulmonar intersticial, pneumonia de hipersensibilidade e fosfolipidose. Apresentamos a seguir um projeto de trabalho experimental em cobaias com intuito de verificar a ação da fluoxetina sobre o aparelho respiratório...

Um modelo do transporte de monóxido de carbono no sistema respiratório do corpo humano. ; A model of the carbon monoxide transport in the respiratory system of the human body.

Albuquerque Neto, Cyro
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 22/08/2005 PT
Relevância na Pesquisa
65.79%
Esse trabalho trata da análise do transporte de monóxido de carbono no corpo humano. O monóxido de carbono é um gás incolor, inodoro e insípido, sendo a principal causa das mortes acidentais por intoxicação. É o poluente lançado em maior quantidade na atmosfera. Quando inspirado, ocupa lugares destinados ao transporte de oxigênio, com afinidade cerca de 250 vezes maior. O oxigênio é utilizado pelos tecidos no processo de geração de energia. Sua falta pode causar danos à saúde. Concentrações altas de monóxido de carbono podem resultar em acidentes fatais. Para analisar o transporte de monóxido de carbono, foi desenvolvido um modelo matemático do sistema respiratório, considerando as trocas dos gases monóxido de carbono, oxigênio e dióxido de carbono. O modelo possibilita analisar a distribuição de monóxido de carbono no corpo humano, dependendo das condições do ar inspirado, em regime transitório. É definido pela separação dos locais onde os gases estão presentes em compartimentos. São esses os alvéolos, os capilares pulmonares, o sangue arterial, o sangue venoso, os tecidos e os capilares teciduais. No equacionamento, utilizou-se princípios de conservação de massa. O transporte dos gases no sangue e nos tecidos é representado por equações com bases empíricas...

Avaliação da mecânica do sistema respiratório através da obtenção de curva PV em pacientes com pneumonia intersticial idiopática; Evaluation of the mechanics of the respiratory system using PV curves in patients with idiopathic pulmonary fibrosis

Ferreira, Juliana Carvalho
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 15/02/2008 PT
Relevância na Pesquisa
65.8%
O objetivo desse estudo foi avaliar o comprometimento de pequenas vias aéreas na Fibrose Pulmonar Idiopática (FPI) analisando curvas Pressão- Volume (PV) do sistema respiratório. Coletamos curvas PV de doze pacientes antes da biopsia pulmonar, que confirmou FPI em sete pacientes e Pneumonite de Hipersensibilidade em cinco. Todas as curvas foram ajustadas com modelo sigmóide, V = a + b / (1 + e -(P-c/d)), e exponencial V = A - B . e -k.P (aplicado apenas à parte superior). O modelo exponencial, apesar do bom ajuste à parte superior, não representou a parte inicial da curva, gerando parâmetros sem significado. O modelo sigmóide ajustou bem toda a curva e gerou parâmetros com significado fisiológico, que sugerem a presença de colapso de pequenas vias aéreas na FPI.; The objective of this study was to evaluate small airways compromise in Idiopathic Pulmonary Fibrosis (IPF) using pressure-volume (PV) curves of the respiratory system. We collected PV curves from twelve patients before lung biopsy, which confirmed IPF in seven patients and Hipersensitivity Pneumonia in five. All curves were fitted with a sigmoid model, V = a + b / (1 + e -(P-c/d)), and an exponential model, V = A - B . e -k.P (applied only to the superior part of the curve). The exponential model...

Avaliação quasi-estática da mecânica respiratória em roedores utilizando insuflador pulmonar.; Quasi-static assessment of the respiratory mechanics in rodents using a lung insufflator.

Valencia Rivas, Jimmy Mauricio
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/12/2012 PT
Relevância na Pesquisa
55.78%
A avaliação da mecânica respiratória (AMR) busca descrever o comportamento mecânico do sistema respiratório, para melhor entender a sua fisiologia e a sua patofisiologia. O método quasi-estático é caracterizado pela AMR em condições nas quais a aceleração dos tecidos pode ser considerada desprezível. Esta dissertação de mestrado teve como objetivo avaliar a mecânica respiratória pelo método quasi-estático em roedores, utilizando um insuflador pulmonar para pequenos roedores (IPPR) construído no Laboratório de Engenharia Biomédica (LEB) da Escola Politécnica da Universidade de São Paulo (EPUSP). Uma extensa revisão da literatura sobre fisiologia e técnicas de AMR em humanos e roedores é apresentada. Uma documentação bastante detalhada sobre a implementação e o funcionamento do IPPR é fornecida, com o intuito de permitir que o dispositivo seja reproduzido. Testes de bancada foram executados, para avaliar o funcionamento do IPPR, e um protocolo experimental com modelo animal de doença, em ratos Wistar envenenados por Paraquat, foi realizado. Os resultados dos testes de bancada mostraram que o equipamento ainda carece de alguns ajustes, pois apresenta erros na indicação de volume, da ordem de 5%, mas que podem ser compensados na análise dos dados experimentais obtidos. No futuro...

Modelos matemáticos aplicados na avaliação da mecânica respiratória em camundongos com desafios de agonista da musculatura lisa.; Mathematical models applied in the assessment of respiratory mechanics in mice with smooth muscle´s agonist challenges.

Aoki, Fabio Gava
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/02/2013 PT
Relevância na Pesquisa
45.88%
Modelos matemáticos são utilizados como ferramentas na avaliação da mecânica respiratória para a compreensão da fisiologia e patologias do sistema respiratório. A presente pesquisa visou avaliar, através da aplicação de modelos matemáticos, a mecânica respiratória em camundongos submetidos à metacolina. Deu-se ênfase no modelo linear de compartimento único e suas variantes não lineares. Camundongos C57BL/6 (n = 8) foram traqueostomizados, ventilados mecanicamente (flexiVent, SCIREQ, Canadá) e perturbações em volume foram aplicadas para a modelagem do sistema respiratório. O protocolo experimental foi elaborado de forma a se analisar a variação dos parâmetros respiratórios durante a aplicação do agente broncoativo e também se verificou a divisão do sinal quasi-senoidal em expirações e inspirações durante a técnica de oscilação forçada (FOT) com perturbação de frequência 2,5 Hz. Com base nisso, uma rotina computacional própria foi desenvolvida para a análise dos experimentos realizados no ventilador mecânico e foram pesquisadas as vantagens e desvantagens dos modelos matemáticos aplicados. Os resultados demonstraram um aumento no desvio padrão dos parâmetros do modelo linear unicompartimental e suas variantes não lineares após a aplicação do broncoconstritor. Acredita-se que esta grande variação nos parâmetros esteja relacionada com o enrijecimento do parênquima e da heterogeneidade da ventilação pulmonar após a utilização da droga. Devido à correlação dos parâmetros do modelo com a fisiologia ocorrer somente no modelo linear...

Emprego da ultrassonografia como método de avaliação dos músculos respiratórios em cães Golden Retriever normais e afetados pela distrofia muscular (GRMD); Use of ultrasonography as a method of evaluation of respiratory muscles in Golden Retriever dogs affected by muscular dystrophy (GRMD)

Oliveira, Daniela Moraes de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/12/2012 PT
Relevância na Pesquisa
55.75%
A Distrofia Muscular de Duchenne (DMD) é uma doença genética neuromuscular hereditária, ligada ao cromossomo X, sendo encontrada em seres humanos do sexo masculino em uma taxa de 1 para cada 3500 neonatos. Essa doença muscular é descrita também em outras espécies como o camundongo distrofico (Mdx), cães golden retriever com distrofia muscular GRMD e gatos com distrofia muscular hipertrófica felina (HFMD), os quais apresentam sintomas semelhantes à DMD e por esta razão tem sido amplamente utilizados como modelos experimentais para estudos. Portanto o objetivo deste estudo é avaliar a mobilidade do diafragma, os ciclos respiratórios e a expansão da caixa torácica de cães GRMD afetados e portadores, uma vez que a insuficiência respiratória é a principal causa de mortes em indivíduos acometidos. Para este estudo utilizou-se de avaliação ultrassonográfica dos muscúlos respíratórios (diafragma e intercostais), análises clínicas, e um acompanhamento de análises hematológicas. Como resultado obtido, o movimento de inspiração, expiração e platô, que compõe a mobilidade diafragmática, foi menor no grupo afetado do que nos controles. A fase de platô neste grupo (GRMD) é quase inexistente, indicando que o diafragma destes animais permanece em uma constante movimentação. A frequência respiratória foi 26...

Desempenho exergético do corpo humano e de seu sistema respiratório em função de parâmetros ambientais e da intensidade de atividade física.; Exergy performance of the human body and its respiratory system as a function of environmental parameters and intensity of physical activity.

Henriques, Izabela Batista
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 23/08/2013 PT
Relevância na Pesquisa
65.88%
A análise exergética é aplicada ao corpo humano a fim de determinar o comportamento exergético padrão do corpo e do seu sistema respiratório para um indivíduo saudável em diferentes condições ambientais e intensidades de atividade física. Para isso, são calculadas as taxas de exergia destruída e as eficiências exergéticas do pulmão e do corpo como um todo para diferentes altitudes, períodos de aclimatação, temperaturas, umidades relativas e intensidades de atividade física. São utilizados modelos do corpo e do sistema respiratório disponíveis na literatura, assim como um modelo exergético do corpo. Para a análise exergética do sistema respiratório é proposto um modelo exergético baseado no modelo de transferência de calor e massa presente na literatura. A análise exergética é aplicada a dois volumes de controle: o corpo e o sistema respiratório, que compreende as vias aéreas e os pulmões. No primeiro volume de controle ocorre transferência de exergia para o ambiente através de convecção e radiação, assim como fluxos de exergia através da respiração e evaporação, além da geração de exergia pelo metabolismo exergético. No volume de controle relativo ao sistema respiratório, os fluxos de exergia estão associados ao ar inspirado e expirado e ao sangue venoso e arterial. A transferência de exergia ocorre através do calor gerado pelo metabolismo e do trabalho dos músculos respiratórios. Há também uma variação da exergia relativa ao metabolismo exergético do pulmão. Os resultados obtidos indicam que a eficiência exergética do pulmão diminui com a altitude e atividade física...

A carbon monoxide transport model of the human respiratory system applied to urban atmosphere exposure analysis

Albuquerque Neto,Cyro; Yanagihara,Jurandir Itizo; Turri,Fábio
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2008 EN
Relevância na Pesquisa
65.78%
The aim of this work is to analyze the carbon monoxide (CO) transport in the human body submitted to several physical activity levels. A complete mathematical model of the human respiratory system was developed, considering the exchanges of CO, oxygen (O2) and carbon dioxide (CO2) in the lung, blood and tissues. The human body was divided in the following compartments: alveolar, pulmonary capillaries, arterial, venous, tissue capillary and tissues. The gas transport in the blood and tissues is represented by empirical equations. The physiological parameters were described in function of physical activity. The model was validated by comparing its results with experimental data of controlled CO exposition. The agreement was excellent. CO concentration curves for critical days of São Caetano do Sul city (SP, Brazil) atmosphere were used as model input. The simulation results for some physical activities show that the more intense the activity, the larger the blood carboxyhemoglobin (COHb) level variations. The COHb level was compared with a CO quality air criteria, which showed to be adequate for low and moderate physical activity levels.

Clinical Applications of a Human Cardiovascular-Respiratory System Model: Studying Ventricular Mechanics in Disease and Treatment

Ramachandran, Deepa
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
75.91%
Large-scale modeling allows for a broad mechanistic view of a cardiopulmonary disease, often beyond what can be observed clinically. Our group has developed a large-scale model of the human cardiovascular-respiratory system (H-CRS) that integrates heart mechanics, hemodynamics, circulatory and gas transport aspects of the lung, brain and whole body tissue, and nervous system control of the cardiovascular and respiratory systems into a single model that can be used to analyze the dynamic behavior of the normal and deranged cardiopulmonary system. The model is a composite model based on data from multiple sources, developed over the years, and has been able to mimic responses to cardiovascular, respiratory, and nervous system activity, and accurately predict changes to environmental or diseased conditions. The ability of a large-scale model to portray many aspects of the cardiopulmonary system simultaneously is beyond the scope of clinical procedures, as providing such data becomes overly invasive, expensive, and risky. However, clinical questions can be pursued in virtual mode using modeling as a tool, and the hope is that modeling might also point to novel avenues to explore in disease diagnosis. In this work, we have advanced new conceptual framework of pericardial constraint...

CHEMICAL AND MECHANICAL ADAPTATIONS OF THE RESPIRATORY SYSTEM AT REST AND DURING EXERCISE IN HEALTHY HUMAN PREGNANCY: IMPLICATIONS FOR RESPIRATORY SENSATION

Jensen, DENNIS
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 5334248 bytes; application/pdf
EN; EN
Relevância na Pesquisa
55.79%
Human pregnancy is characterized by significant increases in central ventilatory drive and perceived respiratory discomfort (breathlessness). The physiological mechanisms of hyperventilation and breathlessness in pregnancy remain largely unknown and understudied. Objective: The main purpose of this research was to elucidate the mechanisms of maternal hyperventilation, and to systematically examine the contribution of alterations in central ventilatory drive, static/dynamic respiratory mechanics and their interaction with respect to the intensity of perceived breathlessness during exercise in pregnancy. General Methods: Experiments were conducted between 34-38 wks gestation and again 4-5 months post-partum in a total of 35 healthy, young women. A comprehensive mathematical model of ventilatory control was used to examine the role of alterations in wakefulness and central chemoreflex drives to breathe, acid-base balance and female sex hormones in maternal hyperventilation. The effects of pregnancy on detailed ventilatory (breathing pattern, airway function, operating lung volumes, esophageal pressure-derived indices of respiratory mechanics) and perceptual (breathing and leg discomfort) responses to incremental cycle exercise to the limits of tolerance were also examined. Results: Maternal hyperventilation resulted from a complex interaction between alterations in arterial and central acid-base balance and other factors that directly affect ventilation...

Evaluating humidity recovery efficiency of currently available heat and moisture exchangers: a respiratory system model study

LUCATO, Jeanette Janaina Jaber; ADAMS, Alexander Bernard; SOUZA, Rogério; TORQUATO, Jamili Anbar; CARVALHO, Carlos Roberto Ribeiro; MARINI, John J
Fonte: Faculdade de Medicina / USP Publicador: Faculdade de Medicina / USP
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
55.75%
OBJECTIVES: To evaluate and compare the efficiency of humidification in available heat and moisture exchanger models under conditions of varying tidal volume, respiratory rate, and flow rate. INTRODUCTION: Inspired gases are routinely preconditioned by heat and moisture exchangers to provide a heat and water content similar to that provided normally by the nose and upper airways. The absolute humidity of air retrieved from and returned to the ventilated patient is an important measurable outcome of the heat and moisture exchangers' humidifying performance. METHODS: Eight different heat and moisture exchangers were studied using a respiratory system analog. The system included a heated chamber (acrylic glass, maintained at 37°C), a preserved swine lung, a hygrometer, circuitry and a ventilator. Humidity and temperature levels were measured using eight distinct interposed heat and moisture exchangers given different tidal volumes, respiratory frequencies and flow-rate conditions. Recovery of absolute humidity (%RAH) was calculated for each setting. RESULTS: Increasing tidal volumes led to a reduction in %RAH for all heat and moisture exchangers while no significant effect was demonstrated in the context of varying respiratory rate or inspiratory flow. CONCLUSIONS: Our data indicate that heat and moisture exchangers are more efficient when used with low tidal volume ventilation. The roles of flow and respiratory rate were of lesser importance...

Evaluating humidity recovery efficiency of currently available heat and moisture exchangers: a respiratory system model study

Lucato,Jeanette Janaina Jaber; Adams,Alexander Bernard; Souza,Rogério; Torquato,Jamili Anbar; Carvalho,Carlos Roberto Ribeiro; Marini,John J
Fonte: Faculdade de Medicina / USP Publicador: Faculdade de Medicina / USP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2009 EN
Relevância na Pesquisa
55.75%
OBJECTIVES: To evaluate and compare the efficiency of humidification in available heat and moisture exchanger models under conditions of varying tidal volume, respiratory rate, and flow rate. INTRODUCTION: Inspired gases are routinely preconditioned by heat and moisture exchangers to provide a heat and water content similar to that provided normally by the nose and upper airways. The absolute humidity of air retrieved from and returned to the ventilated patient is an important measurable outcome of the heat and moisture exchangers' humidifying performance. METHODS: Eight different heat and moisture exchangers were studied using a respiratory system analog. The system included a heated chamber (acrylic glass, maintained at 37°C), a preserved swine lung, a hygrometer, circuitry and a ventilator. Humidity and temperature levels were measured using eight distinct interposed heat and moisture exchangers given different tidal volumes, respiratory frequencies and flow-rate conditions. Recovery of absolute humidity (%RAH) was calculated for each setting. RESULTS: Increasing tidal volumes led to a reduction in %RAH for all heat and moisture exchangers while no significant effect was demonstrated in the context of varying respiratory rate or inspiratory flow. CONCLUSIONS: Our data indicate that heat and moisture exchangers are more efficient when used with low tidal volume ventilation. The roles of flow and respiratory rate were of lesser importance...

Evaluating humidity recovery efficiency of currently available heat and moisture exchangers: a respiratory system model study

Lucato, Jeanette Janaina Jaber; Adams, Alexander Bernard; Souza, Rogério; Torquato, Jamili Anbar; Carvalho, Carlos Roberto Ribeiro; Marini, John J
Fonte: Universidade de São Paulo. Faculdade de Medicina Publicador: Universidade de São Paulo. Faculdade de Medicina
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; ; Formato: application/pdf
Publicado em 01/06/2009 ENG
Relevância na Pesquisa
55.75%
OBJECTIVES: To evaluate and compare the efficiency of humidification in available heat and moisture exchanger models under conditions of varying tidal volume, respiratory rate, and flow rate. INTRODUCTION: Inspired gases are routinely preconditioned by heat and moisture exchangers to provide a heat and water content similar to that provided normally by the nose and upper airways. The absolute humidity of air retrieved from and returned to the ventilated patient is an important measurable outcome of the heat and moisture exchangers' humidifying performance. METHODS: Eight different heat and moisture exchangers were studied using a respiratory system analog. The system included a heated chamber (acrylic glass, maintained at 37°C), a preserved swine lung, a hygrometer, circuitry and a ventilator. Humidity and temperature levels were measured using eight distinct interposed heat and moisture exchangers given different tidal volumes, respiratory frequencies and flow-rate conditions. Recovery of absolute humidity (%RAH) was calculated for each setting. RESULTS: Increasing tidal volumes led to a reduction in %RAH for all heat and moisture exchangers while no significant effect was demonstrated in the context of varying respiratory rate or inspiratory flow. CONCLUSIONS: Our data indicate that heat and moisture exchangers are more efficient when used with low tidal volume ventilation. The roles of flow and respiratory rate were of lesser importance...

Flow field analysis in an expanding healthy and emphysematous alveolar model using particle image velocimetry

Oakes, Jessica
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
55.69%
Particle deposition in the acinus region of the lung is a significant area of interest, because particles can potentially travel into the bloodstream through the capillaries in the lung. Drugs, in the form of aerosols, small particulates in a volume of air, may be delivered through the respiratory system. Also, toxic, airborne, particles could enter the body through the pulmonary capillaries in the acinus region of the lung. In order to accurately predict particle deposition, the aspects that influence deposition needs to be understood. Many physiological features may influence flow and particle deposition in the lung; the geometry of the acinus, expansion and contraction of the alveolar walls due to breathing mechanics, heterogeneities in the lung, breathing flow rate, and the number of breaths. In literature, streamlines and pathlines have been examined, both experimentally and computationally, in models representing the alveolar region of the lung. Some of these studies suggest the presence of irreversible flow, which would significantly influence particle deposition. However, none of these models incorporated all significant features: non-symmetric, three dimensional, expanding geometry. Therefore, flow mechanics, behind particle deposition...

A Mathematical Model Of The Human External Respiratory System

Dantzig, George B.; DeHaven, James C.; Cooper, Irwin; Johnson, Selmar M.; DeLand, Edward C.; Kanter, Herschel; Sams, Crawford F. M.D.
Fonte: Rand Corporation Publicador: Rand Corporation
Tipo: Relatório Formato: 6978861 bytes; application/pdf
EN_US
Relevância na Pesquisa
55.83%
This study examines the thesis that a part of the human physiological system can be simulated by a suitably constructed mathematical model. The model employed derives from a class of mathematical programming methods that were originally developed for representing complex military and industrial activities and have recently been used to represent involved chemical equilibria. The motivation for this research is the long-range view that a successful mathematical simulation of the human system or of human subsystems would provide an important tool for biological investigations. A sufficiently complex mathematical model-that is, a model that embodies sufficiently complex mathematical model-that is, a model that embodies sufficient chemical and biological detail to represent a whole, functioning human system or subsystem-could be used to explore biological hypotheses, environmental stress reactions, and interplay of dependent subsystems, and could serve as a pedagogical tool or even as an aid to medical diagnosis. Of course, the foregoing long-range view is an ultimate goal. For the moment, only the techniques, concepts, and characteristics of such a mathematical model are being explored. This paper presents the results of a simulation of the external respiratory function. Respiration...

Reactions of Hemoglobin and Steady States in the Human Respiratory System: An investigation using Mathematical Models and An Electronic Computer

DeHaven, James C.; DeLand, Edward C.
Fonte: The RAND Corporation Publicador: The RAND Corporation
Tipo: Relatório Formato: 12166975 bytes; application/pdf
EN_US
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Using thermodynamic principles relating to steady state processes, a detailed biophysicochemical model of the human external respiratory subsystem was constructed. Mathematical experiments performed with this model give good agreement with reported physiological data relating to the functioning of this subsystem under normal and some abnormal conditions. Because of the complexity of the model, experiments with it are conducted on a high-speed computer. The model was applied to the representation of the exchanges of respiratory gases and related chemical phenomena occurring between the venous and arterial sides of the total air-blood system. In addition, the model was used to explore the quantitative as well as qualitative significance of biochemical functions that are believed to be important in establishing the characteristics of the system. These functions include the Bohr effects of hemoglobin and various hypotheses of carbamino formation, as well as the dynamic steady-state gradients imposed by the erythrocyte metabolic pump and the disparate concentrations of nondiffusible species operating across the cell membranes. The capacity of mathematical models of this type to incorporate and rigorously interrelate a large number of detailed biochemical reactions so as to yield total subsystem effects that compare well with physiological reality suggest that such models should provide a useful tool for many biological investigations.; United States Airforce under Project RAND

Parameter estimation of an artificial respiratory system under mechanical ventilation following a noisy regime

Victor Júnior,Marcus Henrique; Forgiarini Junior,Luiz Alberto; Kinjo,Toru Miyagi; Amato,Marcelo Britto Passos; Yoneyama,Takashi; Tanaka,Harki
Fonte: Sociedade Brasileira de Engenharia Biomédica Publicador: Sociedade Brasileira de Engenharia Biomédica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2015 EN
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Abstract Introduction: This work concerns the assessment of a novel system for mechanical ventilation and a parameter estimation method in a bench test. The tested system was based on a commercial mechanical ventilator and a personal computer. A computational routine was developed do drive the mechanical ventilator and a parameter estimation method was utilized to estimate positive end-expiratory pressure, resistance and compliance of the artificial respiratory system. Methods The computational routine was responsible for establishing connections between devices and controlling them. Parameters such as tidal volume, respiratory rate and others can be set for standard and noisy ventilation regimes. Ventilation tests were performed directly varying parameters in the system. Readings from a calibrated measuring device were the basis for analysis. Adopting a first-order linear model, the parameters could be estimated and the outcomes statistically analysed. Results Data acquisition was effective in terms of sample frequency and low noise content. After filtering, cycle detection and estimation took place. Statistics of median, mean and standard deviation were calculated, showing consistent matching with adjusted values. Changes in positive end-expiratory pressure statistically imply changes in compliance...