Mechanical ventilation saves lives, but it is an intervention fraught with the potential for serious complications. Prevention of these complications has become the focus of research and critical care in the last twenty years. This thesis presents the first use, or the application under new conditions, of three technologies that could contribute to optimization of mechanical ventilation. Optoelectronic plethysmography was used in Papers I and II for continuous assessment of changes in chest wall volume, configuration, and motion in the perioperative period. A forced oscillation technique (FOT) was used in Paper III to evaluate a novel positive end-expiratory pressure (PEEP) optimization strategy. Finally, in Paper IV, FOT in conjunction with an optical sensor based on a self-mixing laser interferometer (LIR) was used to study the oscillatory mechanics of the respiratory system and to measure the chest wall displacement. In Paper I, propofol anesthesia decreased end-expiratory chest wall volume (VeeCW) during induction, with a more pronounced effect on the abdominal compartment than on the rib cage. The main novel findings were an increased relative contribution of the rib cage to ventilation after induction of anesthesia, and the fact that the rib cage initiates post-apneic ventilation. In Paper II, a combination of recruitment maneuvers, PEEP, and reduced fraction of inspired oxygen, was found to preserve lung volume during and after anesthesia. Furthermore, the decrease in VeeCW during emergence from anesthesia, associated with activation of the expiratory muscles, suggested that active expiration may contribute to decreased functional residual capacity, during emergence from anesthesia. In the lavage model of lung injury studied in Paper III, a PEEP optimization strategy based on maximizing oscillatory reactance measured by FOT resulted in improved lung mechanics, increased oxygenation, and reduced histopathologic evidence of ventilator-induced lung injury. Paper IV showed that it is possible to apply both FOT and LIR simultaneously in various conditions ranging from awake quiet breathing to general anesthesia with controlled mechanical ventilation. In the case of LIR, an impedance map representing different regions of the chest wall showed reproducible changes during the different stages that suggested a high sensitivity of the LIR-based measurements.

The subject of this experimental investigation is to measure the dynamic stability derivatives in roll plane for an oscillating combat aircraft model by using forced oscillation technique. In forced oscillation technique the model is forced to oscillate around the center of gravity according to a harmonic motion of small amplitude and low frequency. The aerodynamic reactions are measured by an internal balance placed inside the model. The thesis presents a brief description of the test rig and the measurement system. The theory of dynamic stability derivatives and forced oscillation technique are also explained. The data is collected and analyzed by using a data acquisition system written with under the Labview programming language. Systematic analysis of the static and dynamic tests results and effect of various parameters (angle of attack, sideslip angle, oscillation frequency and amplitude, wind velocity) on these results are presented. Comparison of the present results with previous results obtained in other test facilities is also given. Design and manufacture process of a new angle of attack mechanism is also given in this thesis.

Currently, simulation predictions of the Orion Crew Module (CM) dynamics with drogue parachutes deployed are under-predicting the amount of damping as seen in free-flight tests.  The Apollo Legacy Chute Damping model has been resurrected and applied to the Orion system. The legacy model has been applied to predict CM damping under drogue parachutes for both Vertical Spin Tunnel free flights and the Pad Abort-1 flight test.  Comparisons between the legacy Apollo prediction method and test data are favorable.  A key hypothesis in the Apollo legacy drogue damping analysis is that the drogue parachutes' net load vector aligns with the CM drogue attachment point velocity vector.  This assumption seems reasonable and produces good results, but has never been experimentally verified.  The wake of the CM influences the drogue parachutes, which makes performance predictions of the parachutes difficult.  Many of these effects are not currently modeled in the simulations. A forced oscillation test of the CM with parachutes was conducted in the NASA LaRC 20-Ft Vertical Spin Tunnel (VST) to gather additional data to validate and refine the Apollo legacy drogue model.  A second loads balance was added to the original Orion VST model to measure the drogue parachute loads independently of the CM.  The objective of the test was to identify the contribution of the drogues to CM damping and provide additional information to quantify wake effects and the interactions between the CM and parachutes.  The drogue parachute force vector was shown to be highly dependent on the CM wake characteristics.  Based on these wind tunnel test data, the Apollo Legacy Chute Damping model was determined to be a sufficient approximation of the parachute dynamics in relationship to the CM dynamics for preliminary entry vehicle system design.  More wake effects should be included to better model the system. These results are being used to improve simulation model fidelity of CM flight with drogues deployed, which has been identified by the project as key to a successful Orion Critical Design Review. / Master of Science

Background: Asthma is a heterogeneous disease. Diagnosis relies on symptom evaluation and lung function tests using spirometry. Symptoms can be vague. Spirometry is effort-dependent and does not reliably evaluate small airways. Allergic asthma in preschool children is not easily separated from episodic wheeze. Exhaled NO (FeNO) is a marker of allergic Th2-cytokine-driven airway inflammation. However, FeNO is not feasible in preschoolers with current devices and algorithms. Alveolar NO is an estimate of small airway involvement. Forced oscillometry (FOT) is an effort-independent lung function test assessing both large and small airways. Aims: To study clinical and methodological aspects of FeNO, alveolar NO and lung function indices by FOT. Methods: Asthmatic children and young adults and healthy controls, were included in the studies. FeNO at 50 mL/s was performed in all studies (in study III with an adapted single-breath method with age-adjusted exhalation times). FeNO at multiple exhalation flow rates were performed in studies I, II and IV to calculate alveolar NO, as was spirometry. FOT indices were assessed in study IV. Results: The exhalation time needed to reach steady-state NO was < 4 s in subjects aged 3-4 years, and was related to subject height. FeNO was higher in ICS-naïve asthmatic children than in controls. ICS-naïve asthmatic preschool children had FeNO < 20 ppb. The oral contribution to FeNO was similar in asthmatic and healthy youths. Multiple flow rates and modelling of alveolar NO were feasible in children aged 10-18 years. Alveolar NO correlated to asthma characteristics, though not when axial diffusion correction was applied. FOT resistance measures were associated with asthma diagnosis, and small airway FOT measures were associated with asthma control, in adolescents. Conclusion: An adapted FeNO method is feasible from 4 years, and exhalation time is related to child height. Our findings emphasise the need to refine clinical cut-offs for FeNO in younger children. FOT variables discriminate between asthmatics and controls, much like spirometry. The information provided by FOT is additive to that from spirometry. Further studies of exhaled NO dynamics and FOT indices of small airways are warranted to evaluate new treatment options and possibly improve asthma control.

The forced Oscillation Technique (FOT) can be used to measure lung impedance continuously during breathing. However, spectral overlap between the breathing waveform and the applied flow oscillation can be problematic if the frequency content of spontaneous breathing is unknown. This problem motivated us to develop a modification to the FOT system called the Tracked Breathing Trainer. The modification uses biofeedback to constrain subjects to breathe at a single predetermined frequency. This thesis investigates the engineering and physiological aspects of the modification we made. We studied 8 adult non-asthmatic and 8 adult asthmatic subjects. Three 16 s perturbatory flow oscillation signals ranging from 1-40 Hz were used on the subjects. Each subject received three trials per perturbation for both spontaneous and tracked breathing. We then fitted a resistance-elastance-inertance model of the lung to each data set. For non-asthmatic subjects, the average resistance (R) and elastance (E) values for the first spontaneous breathing trial were 2.5±0.15 cmH2O.s.ml-1 and 18.1±3.55 cmH2O.ml-1, and for the third spontaneous breathing trial were 2.4±0.12 cmH2O.s.ml-1 and 21.8±4 cmH2O.ml-1. R and E for the first tracked breathing trial were 2.3±0.21 cmH2O.s.ml-1 and 33.6±7.4 cmH2O.ml-1, and for the third tracked breathing trial were 2.4±0.14 cmH2O.s.ml-1 and 25.75±4.3 cmH2O.ml-1, respectively. For asthmatic subjects, the average R and E values for the first spontaneous breathing trial were 3.32±0.68 cmH2O.s.ml-1 and 39.13±9.8 cmH2O.ml-1, and for the third spontaneous breathing trial were 3.12±0.15 cmH2O.s.ml-1 and 39.91±6.2 cmH2O.ml-1. R and E for the first tracked breathing trial were 2.86±0.15 cmH2O.s.ml-1 and 32.47±4.1 cmH2O.ml-1, and for the third tracked breathing trial were 2.86±0.21 cmH2O.s.ml-1 and 33.89±10 cmH2O.ml-1, respectively. These results show that R was consistently lower during tracked breathing than spontaneous breathing in both non-asthmatic and asthmatic subjects. However, an increase in E was observed during tracked breathing. We suspect this effect may have resulted from dynamic hyperinflation. These results also show that R and E are reproducible with both spontaneous and tracked breathing, and that R and E were not noticeably different between both breathing maneuvers. We conclude that using biofeedback to control the breathing pattern during application of the FOT in normal subjects does not significantly affect impedance measurements, and thus may be useful for avoiding spectral overlap between FOT perturbations and the breathing pattern.

O termo silicose refere-se ao processo de fibrose pulmonar causado pela inalação de poeira contendo sílica. É uma doença ocupacional, incurável, que se inicia nas vias aéreas distais e pode progredir independente do término da exposição. Os testes de função pulmonar, apesar de não serem utilizados como ferramenta diagnóstica para silicose, são amplamente empregados para acompanhar longitudinalmente esses indivíduos. Estudos recentes sugerem que a Técnicas de Oscilações Forçadas (FOT) pode ser aplicada para detecção de alterações pulmonares precoces em indivíduos com silicose. Contudo, existem poucos estudos descrevendo as alterações de mecância respiratória associada com a silicose através da FOT. Neste contexto, os objetivos deste estudo são: (1) analisar as alterações de mecânica respiratória de indivíduos portadores de silicose com diferentes graus de obstrução e (2) avaliar a capacidade da FOT em detectar alterações na função pulmonar decorrentes da silicose. Trata-se de um estudo transversal controlado com avaliação de casos prevalentes, tendo como unidade de avaliação o indivíduo. Os exames realizados incluíram medidas de espirometria e FOT. Foi selecionado um total de 67 indivíduos, 46 portadores de silicose e 21 sadios, caracterizando o grupo controle. Os indivíduos com diagnóstico de silicose foram divididos em três grupos classificados de acordo com o nível de obstrução sugerido pela espirometria. Essa classificação resultou em três categorias: Indivíduos normais ao exame espirométrico (NE), n= 12; com distúrbio ventilatório obstrutivo leve (DVOL), n=22; com distúrbio ventilatório obstrutivo moderado ou acentuado (DVOMA), n= 12. Todos os indivíduos realizaram exames da FOT para análise das propriedades resistivas e reativas do sistema respiratório. Posteriormente aos exames da FOT os indivíduos foram submetidos à espirometria. Considerando os grupos divididos a partir da espirometria, os parâmetros resistivos e reativos e a impedância do sistema respiratório em 4Hz (Z4Hz) se modificaram significativamente com a progressão da distúrbio obstrutivo. Na análise do poder diagnóstico da FOT os parâmetros R0, Rm, Rsr4 e |Z4Hz| mostraram-se precisos para identificar as modificações de mecânica respiratória em pacientes com silicose apresentando distúrbio ventilatório obstrutivo leve. Para distúrbio ventilatório obstrutivo moderado e acentuado todos os parâmetros analisados apresentaram habilidade para identificar essas alterações. Na análise entre o grupo controle e normal ao exame, nenhum parâmetro da FOT apresentou valor de acurácia adequado para uso clínico. Esses resultados são coerentes com as alterações fisiopatológicas relacionadas à silicose, confirmando o potencial da FOT na avaliação das modificações de mecânica respiratória em doentes com silicose. / The term silicosis is the name given to the pulmonary fibrosis caused by inhalation of dust containing crystalline silica. Is a typical occupational disease, chronic, incurable, starting in the peripheral airways and that can progress independently of the end of exposure. The pulmonary function tests, although not used as a diagnostic tool for silicosis, are widely employed to follow these individuals. Recent works suggests that the Forced Oscilation Technique (FOT) may be applied in the detection of early respiratory changes in silicosis. However, few studies have been analyzing the changes on respiratory mechanics associated with silicosis through the FOT. In this context, the aims of this study were (1) to analyze changes respiratory mechanics in subjects with silicosis with different degrees of obstruction by FOT, and (2) to evaluate the potential of the FOT to detect alterations in the lung function resulting from silicosis. This is a sectional study evaluation of prevalent cases, with the evaluation unit the individual. The examinations included measurement of FOT and spirometry. Sixty-seven volunteers were analyzed: 21 healthy subjects and 46 with silicosis. Spirometry was used to classify airway obstruction in the silicosis groups. This classification resulted in three categories: normal spirometric exam (n = 12); mild obstruction (n = 22); moderate or severe obstruction (n = 12.). All subjects performed FOT exam for the analysis of resistive and reactive properties of the respiratory system. The order of the examinations was FOT, followed by spirometry. Considering the groups classified according to the spirometry, the resistive and reactive the parameters and the impedance of the respiratory system at 4Hz (|Z4Hz|), have changed significantly with the progression of obstructive. The analysis of the diagnostic power of FOT parameters R0, Rm, and Rsr4 |Z4Hz| showed to be accurate to identify the changes of respiratory mechanics in silicosis patients with mild obstructive lung disease. To the moderate and severe obstructions, all the parameters analyzed showed adequate to identify these changes. In the analysis between the control and normal exam, no parameters of the FOT showed adequate measure to use to correctly identify these subjects. The FOT parameters adequately described the pathophysiological changes associated with silicosis and presented adequate accuracy for clinical use, indicating that this technique can be helpful in the evaluation respiratory mechanics in this disease.

Background: Measurements of lung function are routinely used in patients with cystic fibrosis (CF) to provide information that may be clinically relevant. Spirometry is the conventional lung function measurement used, however young children find spirometry difficult to perform and often cannot achieve the strict acceptability criteria for the test. The forced oscillation technique (FOT) is a lung function measurement that only requires tidal breathing and is easy for young children to perform. However, there is limited information about the utility of this technique in the clinical assessment of young children with CF who are unable to perform spirometry. Aims: The aim of this project was to evaluate the FOT for clinical assessment in 2 to 7 year old children with CF. Specifically this involved: 1. Technical assessment of the FOT in children with CF; 2. Comparisons of lung function using the FOT in children with CF and healthy children; 3. Evaluation of associations with factors known to be associated with lung disease including: i) inflammation ii) infection and iii) structural damage. Methods Lung function was measured in a cohort of 59 children between the ages of 2 and 7 years with CF at the time of quarterly clinic visits. Resistance and reactance at 6, 8 and 10Hz (Rrs6, Rrs8, Rrs10, Xrs6, Xrs8, Xrs10, respectively) were reported and expressed as Z scores. Children were classified as asymptomatic or symptomatic based on a respiratory questionnaire and physical examination at the time of testing. Bronchoalveolar lavage and high resolution computed tomography (HRCT) were performed annually under general anaesthesia annually. BAL fluid was assessed for the presence of micro-organisms and quantification of a range of inflammatory markers and HRCT used to determine the extent of structural abnormalities. Results: The between test repeatability (n=25) for lung function was within limits previously described in healthy children. No systematic bias was observed and repeatability was not affected by the presence of respiratory symptoms. Children with CF (n=57) had significantly increased Rrs6-10 (p<0.0001) and decreased Xrs6-10 (p<0.004) compared to healthy children. Rrs6 and Xrs6-10 were significantly worse in the presence of respiratory symptoms, and Rrs6-10 progressively worsened from an asymptomatic to a symptomatic clinic visit. Children with CF (n=48) had no greater bronchodilator response (BDR) compared to healthy children. BDR was not influenced by the presence of an infection or respiratory symptoms. No relationships between inflammatory markers and lung function (n=39) were identified when the presence of an infection was adjusted for. Children with a current infection (n=20) had increased Rrs6-10 (p<0.01) and decreased Xrs6-10 (p<0.04) compared to children who were uninfected (n=23). These relationships were most marked for children infected with Pseudomonas aeruginosa, with children having a reduced lung function between 0.95 and 1.47 of a Z score. No relationships with the presence or absence of mild structural abnormalities (bronchiectasis, bronchial wall thickening and air trapping) and lung function at the time of HRCT were identified (n=34). Conclusion: The FOT is a repeatable measurement of lung function in children with CF and reliable results can be obtained in children as young as 2 years old. Young children with CF exhibit altered respiratory function which was affected by the presence of factors known to be associated with lung disease. The FOT has the potential to provide useful information about changes in clinical status in young children with CF and may be used to direct management of patient lung disease.

O crescimento do percentual de idosos na população ocorre mundialmente tornando necessário conhecer o impacto do processo de envelhecimento, neste contexto, do sistema respiratório. O desconhecimento do impacto do envelhecimento associado a diferentes graus de exposição a poluentes e a presença de comorbidade(s) dificulta a diagnose das pneumopatias acarretando aos idosos piora da qualidade de vida. São vantagens da Técnica de Oscilações Forçadas (FOT): alto potencial de aplicação em idosos, fácil realização, análise detalhada da mecânica respiratória, desempenho de papel complementar, bem como de alternativa na impossibilidade de realização dos exames tradicionais. Foi realizado um estudo experimental comparativo que objetivou investigar o impacto do envelhecimento no sistema respiratório pela FOT e pela espirometria entre grupos de diferentes faixas etárias, sendo a idade a variável independente e as variáveis dependentes, os parâmetros oscilométricos resistência em regime contínuo (R0) e das vias aéreas centrais (Rm), inclinação da resistência (S), frequência de ressonância (fr), reatância média (Xm), complacência dinâmica (Cdin,sr) e os parâmetros espirométricos (VEF1, CVF, VEF1/CVF e FEF/CVF). Foram realizados entrevista, exame clínico, radiografia torácica, avaliação da mecânica respiratória pela FOT e da função pulmonar pela espirometria. 255 indivíduos com idades entre 20 e 86 anos foram entrevistados. Destes, 175 foram excluídos, restando os 80 voluntários analisados, que foram divididos em 6 grupos de acordo com a faixa etária (A: 20 a 29 anos; B: 30 a 39 anos; C: 40 a 49 anos; D: 50 a 59 anos; E: 60 a 69 anos; F: 70 anos ou mais). Foram utilizados os testes de Shapiro-Wilkins, na avaliação da normalidade dos dados biométricos em cada grupo, Oneway ANOVA, na comparação entre os grupos, e Tukey HSD na comparação entre as classes subjacentes. A análise da associação entre duas variáveis foi realizada inicialmente pela regressão univariada entre os parâmetros oscilométricos, a idade e a altura. A regressão múltipla entre os parâmetros oscilométricos, idade e altura foi realizada em conjunto. Foi realizada a análise de confundimento ou modificação de efeito sobre o parâmetro altura na relação entre a idade e os parâmetros oscilométricos. A correção pelo fator altura foi realizada quando sua análise apresentava fator de confundimento. Quanto aos parâmetros resistivos, não foram observadas alterações em R0 e Rm com o envelhecimento enquanto que o declínio observado em S é discreto e não-significativo. Em relação aos parâmetros reativos, verificouse que Cdin,sr e Xm diminuem enquanto que fr aumenta com o processo de envelhecimento. Todas estas alterações são significativas. Todavia, a diminuição da Cdin,sr não apresenta relação com a idade e sim com a altura, que constituiu modificação do efeito. Nos demais parâmetros oscilométricos, a altura constituiu fator de confundimento. Quanto à espirometria, observou-se declínio significativo do VEF1, do VEF1/CVF e da CVF. O índice FEF/CVF apresentou declínio nãosignificativo. Concluindo, a resistência do sistema respiratório e a complacência dinâmica não se modificam enquanto a homogeneidade do sistema respiratório diminui com o processo de envelhecimento. / The increase in the elderly percentage in the population occurs worldwide. To know the impact of the aging process, in this context, on the respiratory system, is crucial. The unawareness of the impact of aging, with different exposure degrees to pollution and the presence of commorbities introduces difficulty in the pneumopathies diagnosis make worsen the elderlys quality of life. The Forced Oscillation Technique (FOT) has as advantages a high application potential in elderly people, detailed analysis of the respiratory mechanics, plays complementary role and alternative in the impossibility to perform the traditional exams, as well. A comparative experimental study was done with the purpose of analyze the impact of aging in the respiratory system by FOT and spirometry between groups of different ages. Age is the independent variable and the dependent variables are the oscillometric parameters continuum regime resistance (R0), central airways resistance (Rm), slope of resistance (S), resonant frequency (fr), average reactance (Xm), dynamic compliance (Cdin,sr) and the spirometry parameters (FEV1, FVC, FEV1/CVF and FEF/FVC). Interviews, clinical examination, thoracic roentgenograms, mensuration of the respiratory mechanics by FOT and of the pulmonary function by spirometry were performed. 255 individuals aged from 20 to 86 years were interviewed. From these, 175 were excluded and the 80 remaining volunteers were analyzed and divided into six groups according to age (A: 20-29 years old; B: 30-39 years old; C: 40-49 years old; D: 50-59 years old; E: 60-69 years old; F: 70 or more years old). The Shapiro-Wilkins test was used in the analysis of the normality of the biometric data in each group. Oneway ANOVA was used in the comparison between groups and the Tukey HSD test was used in the comparison between the underlying classes. The analysis of the association between two variables was done initially between the oscilometric parameters, age and height. Multiple regressions between oscilometric parameters, age and height was performed in conjunction. Confounding analysis or effect modification over height and oscilometric parameters was done. The correction by the height factor was done when its analysis presented confounding factor. There were not changes in the resistive parameters R0 and Rm with age while the decrease seen in S is slight and not significant. In the reactive parameters, it was found that Cdin,sr and Xm decrease while fr increases with the aging process. All of these changes are significant. However, the decrease in Cdin,sr is not related to the aging process but with height, which was a confounding factor. It was found that the spirometric parameters FEV1, FVC and CVF presented a significant decrease and the index FEF/CVF presented a not significant decrease. Concluding, the resistance and the dynamic compliance of the respiratory system do not change while the homogeneity of the respiratory system decreases with the aging process.

O crescimento do percentual de idosos na população ocorre mundialmente tornando necessário conhecer o impacto do processo de envelhecimento, neste contexto, do sistema respiratório. O desconhecimento do impacto do envelhecimento associado a diferentes graus de exposição a poluentes e a presença de comorbidade(s) dificulta a diagnose das pneumopatias acarretando aos idosos piora da qualidade de vida. São vantagens da Técnica de Oscilações Forçadas (FOT): alto potencial de aplicação em idosos, fácil realização, análise detalhada da mecânica respiratória, desempenho de papel complementar, bem como de alternativa na impossibilidade de realização dos exames tradicionais. Foi realizado um estudo experimental comparativo que objetivou investigar o impacto do envelhecimento no sistema respiratório pela FOT e pela espirometria entre grupos de diferentes faixas etárias, sendo a idade a variável independente e as variáveis dependentes, os parâmetros oscilométricos resistência em regime contínuo (R0) e das vias aéreas centrais (Rm), inclinação da resistência (S), frequência de ressonância (fr), reatância média (Xm), complacência dinâmica (Cdin,sr) e os parâmetros espirométricos (VEF1, CVF, VEF1/CVF e FEF/CVF). Foram realizados entrevista, exame clínico, radiografia torácica, avaliação da mecânica respiratória pela FOT e da função pulmonar pela espirometria. 255 indivíduos com idades entre 20 e 86 anos foram entrevistados. Destes, 175 foram excluídos, restando os 80 voluntários analisados, que foram divididos em 6 grupos de acordo com a faixa etária (A: 20 a 29 anos; B: 30 a 39 anos; C: 40 a 49 anos; D: 50 a 59 anos; E: 60 a 69 anos; F: 70 anos ou mais). Foram utilizados os testes de Shapiro-Wilkins, na avaliação da normalidade dos dados biométricos em cada grupo, Oneway ANOVA, na comparação entre os grupos, e Tukey HSD na comparação entre as classes subjacentes. A análise da associação entre duas variáveis foi realizada inicialmente pela regressão univariada entre os parâmetros oscilométricos, a idade e a altura. A regressão múltipla entre os parâmetros oscilométricos, idade e altura foi realizada em conjunto. Foi realizada a análise de confundimento ou modificação de efeito sobre o parâmetro altura na relação entre a idade e os parâmetros oscilométricos. A correção pelo fator altura foi realizada quando sua análise apresentava fator de confundimento. Quanto aos parâmetros resistivos, não foram observadas alterações em R0 e Rm com o envelhecimento enquanto que o declínio observado em S é discreto e não-significativo. Em relação aos parâmetros reativos, verificouse que Cdin,sr e Xm diminuem enquanto que fr aumenta com o processo de envelhecimento. Todas estas alterações são significativas. Todavia, a diminuição da Cdin,sr não apresenta relação com a idade e sim com a altura, que constituiu modificação do efeito. Nos demais parâmetros oscilométricos, a altura constituiu fator de confundimento. Quanto à espirometria, observou-se declínio significativo do VEF1, do VEF1/CVF e da CVF. O índice FEF/CVF apresentou declínio nãosignificativo. Concluindo, a resistência do sistema respiratório e a complacência dinâmica não se modificam enquanto a homogeneidade do sistema respiratório diminui com o processo de envelhecimento. / The increase in the elderly percentage in the population occurs worldwide. To know the impact of the aging process, in this context, on the respiratory system, is crucial. The unawareness of the impact of aging, with different exposure degrees to pollution and the presence of commorbities introduces difficulty in the pneumopathies diagnosis make worsen the elderlys quality of life. The Forced Oscillation Technique (FOT) has as advantages a high application potential in elderly people, detailed analysis of the respiratory mechanics, plays complementary role and alternative in the impossibility to perform the traditional exams, as well. A comparative experimental study was done with the purpose of analyze the impact of aging in the respiratory system by FOT and spirometry between groups of different ages. Age is the independent variable and the dependent variables are the oscillometric parameters continuum regime resistance (R0), central airways resistance (Rm), slope of resistance (S), resonant frequency (fr), average reactance (Xm), dynamic compliance (Cdin,sr) and the spirometry parameters (FEV1, FVC, FEV1/CVF and FEF/FVC). Interviews, clinical examination, thoracic roentgenograms, mensuration of the respiratory mechanics by FOT and of the pulmonary function by spirometry were performed. 255 individuals aged from 20 to 86 years were interviewed. From these, 175 were excluded and the 80 remaining volunteers were analyzed and divided into six groups according to age (A: 20-29 years old; B: 30-39 years old; C: 40-49 years old; D: 50-59 years old; E: 60-69 years old; F: 70 or more years old). The Shapiro-Wilkins test was used in the analysis of the normality of the biometric data in each group. Oneway ANOVA was used in the comparison between groups and the Tukey HSD test was used in the comparison between the underlying classes. The analysis of the association between two variables was done initially between the oscilometric parameters, age and height. Multiple regressions between oscilometric parameters, age and height was performed in conjunction. Confounding analysis or effect modification over height and oscilometric parameters was done. The correction by the height factor was done when its analysis presented confounding factor. There were not changes in the resistive parameters R0 and Rm with age while the decrease seen in S is slight and not significant. In the reactive parameters, it was found that Cdin,sr and Xm decrease while fr increases with the aging process. All of these changes are significant. However, the decrease in Cdin,sr is not related to the aging process but with height, which was a confounding factor. It was found that the spirometric parameters FEV1, FVC and CVF presented a significant decrease and the index FEF/CVF presented a not significant decrease. Concluding, the resistance and the dynamic compliance of the respiratory system do not change while the homogeneity of the respiratory system decreases with the aging process.

O termo silicose refere-se ao processo de fibrose pulmonar causado pela inalação de poeira contendo sílica. É uma doença ocupacional, incurável, que se inicia nas vias aéreas distais e pode progredir independente do término da exposição. Os testes de função pulmonar, apesar de não serem utilizados como ferramenta diagnóstica para silicose, são amplamente empregados para acompanhar longitudinalmente esses indivíduos. Estudos recentes sugerem que a Técnicas de Oscilações Forçadas (FOT) pode ser aplicada para detecção de alterações pulmonares precoces em indivíduos com silicose. Contudo, existem poucos estudos descrevendo as alterações de mecância respiratória associada com a silicose através da FOT. Neste contexto, os objetivos deste estudo são: (1) analisar as alterações de mecânica respiratória de indivíduos portadores de silicose com diferentes graus de obstrução e (2) avaliar a capacidade da FOT em detectar alterações na função pulmonar decorrentes da silicose. Trata-se de um estudo transversal controlado com avaliação de casos prevalentes, tendo como unidade de avaliação o indivíduo. Os exames realizados incluíram medidas de espirometria e FOT. Foi selecionado um total de 67 indivíduos, 46 portadores de silicose e 21 sadios, caracterizando o grupo controle. Os indivíduos com diagnóstico de silicose foram divididos em três grupos classificados de acordo com o nível de obstrução sugerido pela espirometria. Essa classificação resultou em três categorias: Indivíduos normais ao exame espirométrico (NE), n= 12; com distúrbio ventilatório obstrutivo leve (DVOL), n=22; com distúrbio ventilatório obstrutivo moderado ou acentuado (DVOMA), n= 12. Todos os indivíduos realizaram exames da FOT para análise das propriedades resistivas e reativas do sistema respiratório. Posteriormente aos exames da FOT os indivíduos foram submetidos à espirometria. Considerando os grupos divididos a partir da espirometria, os parâmetros resistivos e reativos e a impedância do sistema respiratório em 4Hz (Z4Hz) se modificaram significativamente com a progressão da distúrbio obstrutivo. Na análise do poder diagnóstico da FOT os parâmetros R0, Rm, Rsr4 e |Z4Hz| mostraram-se precisos para identificar as modificações de mecânica respiratória em pacientes com silicose apresentando distúrbio ventilatório obstrutivo leve. Para distúrbio ventilatório obstrutivo moderado e acentuado todos os parâmetros analisados apresentaram habilidade para identificar essas alterações. Na análise entre o grupo controle e normal ao exame, nenhum parâmetro da FOT apresentou valor de acurácia adequado para uso clínico. Esses resultados são coerentes com as alterações fisiopatológicas relacionadas à silicose, confirmando o potencial da FOT na avaliação das modificações de mecânica respiratória em doentes com silicose. / The term silicosis is the name given to the pulmonary fibrosis caused by inhalation of dust containing crystalline silica. Is a typical occupational disease, chronic, incurable, starting in the peripheral airways and that can progress independently of the end of exposure. The pulmonary function tests, although not used as a diagnostic tool for silicosis, are widely employed to follow these individuals. Recent works suggests that the Forced Oscilation Technique (FOT) may be applied in the detection of early respiratory changes in silicosis. However, few studies have been analyzing the changes on respiratory mechanics associated with silicosis through the FOT. In this context, the aims of this study were (1) to analyze changes respiratory mechanics in subjects with silicosis with different degrees of obstruction by FOT, and (2) to evaluate the potential of the FOT to detect alterations in the lung function resulting from silicosis. This is a sectional study evaluation of prevalent cases, with the evaluation unit the individual. The examinations included measurement of FOT and spirometry. Sixty-seven volunteers were analyzed: 21 healthy subjects and 46 with silicosis. Spirometry was used to classify airway obstruction in the silicosis groups. This classification resulted in three categories: normal spirometric exam (n = 12); mild obstruction (n = 22); moderate or severe obstruction (n = 12.). All subjects performed FOT exam for the analysis of resistive and reactive properties of the respiratory system. The order of the examinations was FOT, followed by spirometry. Considering the groups classified according to the spirometry, the resistive and reactive the parameters and the impedance of the respiratory system at 4Hz (|Z4Hz|), have changed significantly with the progression of obstructive. The analysis of the diagnostic power of FOT parameters R0, Rm, and Rsr4 |Z4Hz| showed to be accurate to identify the changes of respiratory mechanics in silicosis patients with mild obstructive lung disease. To the moderate and severe obstructions, all the parameters analyzed showed adequate to identify these changes. In the analysis between the control and normal exam, no parameters of the FOT showed adequate measure to use to correctly identify these subjects. The FOT parameters adequately described the pathophysiological changes associated with silicosis and presented adequate accuracy for clinical use, indicating that this technique can be helpful in the evaluation respiratory mechanics in this disease.