The wall properties of the arteries play an important role in cardiovascular function. Stiffness of large artery is predictive of cardiovascular events. To understand the function of the cardiovascular system, special attention should be paid to the understanding of pulse wave propagation, because pulse waves carry information of the cardiovascular function, and provide information which can be useful for the prevention and diagnosis of diseases. This thesis presents a series of in vitro experimental studies of wave propagation, wave reflection and determination of mechanical properties of flexible vessels. In this thesis, several studies have been included: 1) applied and compared foot-to-foot, PU-loop and lnDU-loop methods for determination of wave speed in flexible tubes and calf aortas; 2) investigated the variation of local wave speed determined by PU-loop with proximity to the reflection site; 3) investigated using wave intensity analysis (WIA) as the analytical technique to determine the reflection coefficient; 4) developed a new technique which based on one-point simultaneous measurements of diameter and velocity to determine the mechanical properties of flexible tubes and calf aortas. In the first study, it is found wave speeds determined by PU-loop and lnDU-loop methods are very similar, and smaller than those determined by foot-to-foot method. The timing of arrival time of reflected wave based on diameter and velocity technique highly agreed with the corresponding timing based on pressure and velocity technique. The shapes of forward and backward non-invasive wave intensities based on diameter and velocity are very similar with the corresponding shapes based on pressure and velocity. Although the density term is not part of the equation, the lnDU-loop method for determining local wave speed is sensitive to the fluid density. In the second study, it is found wave speed measured by PU-loop is varied with proximity to the reflection site. The closer the measurement site to the reflection site, the greater the effect upon measured wave speed; a positive reflection caused an increase in measured wave speed; a negative reflection caused a decrease in measured wave speed. Correction iteration process was also considered to correct the affected measured wave speed. In the third study, it is found, reflection coefficient determined by pressure, square roots of wave intensity and wave energy are very close, but they are different from reflection coefficient determined by wave intensity and wave energy. Due to wave dissipation, the closer the measurement site to the reflection site, the greater is the value of the local reflection coefficient. The local reflection coefficient near the reflection site determined by wave intensity and wave energy are very close to the theoretical value of reflection coefficient. In the last study I found that distensibility determined by the new technique which utilising lnDU-loop is in agreement with that determined from the pressure and area which obtained from tensile test in flexible tubes; distensibility determined by the new technique is similar to those determined in the static and dynamic distensibility tests in calf aortas; Young’s modulus determined by the new technique are in agreement with that those determined by tensile tests in both flexible tubes and calf aortas. In conclusion, wave speed determined by PU-loop and lnDU-loop methods are very similar, the new technique lnDU-loop provides an integrated noninvasive system for studying wave propagation; wave speed determined by PU-loop is affected by the reflection, the closer the measurement site to the reflection site, the greater the change in measured wave speed; WIA could be used to determine local reflection coefficient when the measurement site is close to the reflection site; the new technique using measurements of diameter and velocity at one point for determination of mechanical properties of arterial wall could potentially be non-invasive and hence may have advantage in the clinical setting.

As cirurgias de ressecção pulmonar se incluem no grupo das cirurgias que podem predispor o paciente a apresentar complicações pulmonares no pós-operatório. Complicações como o aumento na produção de secreções brônquicas, pneumonia e atelectasia, estão quase sempre associadas à diminuição da função pulmonar neste período. A ventilação por pressão positiva contínua nas vias aéreas vem sendo constantemente utilizada como terapêutica nesses pacientes tentando-se minimizar esses efeitos prejudiciais sobre a função pulmonar. O objetivo desse estudo é quantificar os efeitos da ventilação com pressão positiva contínua nas vias aéreas (CPAP) sobre a função pulmonar no pós-operatório de ressecção pulmonar. Foram selecionados 30 (trinta) pacientes da disciplina de Cirurgia Torácica do Hospital Universitário Pedro Ernesto. A seleção dos pacientes para o grupo controle e experimental foi feita de forma randomizada. Os pacientes foram submetidos na fase pré-operatória a uma avaliação da função pulmonar (pico de fluxo expiratório, força muscular respiratória, teste de caminhada de 6 minutos/ TC6, gasometria arterial e espirometria). Após a realização do procedimento cirúrgico foram submetidos a um protocolo de intervenção, como se segue: grupo experimental: 15 (quinze) pacientes submetidos à ventilação não-invasiva, de forma intermitente, com um sistema CPAP (ACRIFLUX-CPAP, Criticalmed, Industries Inc, Brasil), iniciado no primeiro dia de pós-operatório (nas primeiras 24 horas após a extubação), 2 vezes ao dia, por um período de 30 minutos; grupo controle: 15 (quinze) pacientes submetidos a um programa de fisioterapia respiratória, orientado e supervisionado, iniciado no primeiro dia de pós-operatório (nas primeiras 24 horas após a extubação), com uma freqüência de 2 vezes ao dia. A reavaliação na fase pós-operatória seguiu a mesma metodologia utilizada na fase pré-operatória. As reavaliações ocorreram em dois momentos: no primeiro dia de pós-operatório (PO-I) onde foram reavaliados o pico de fluxo expiratório, força muscular respiratória, gasometria arterial; prova de função pulmonar com 48 horas de pós-operatório. Ao sétimo dia de pós-operatório (PO-II) foram reavaliados novamente as variáveis do PO-I e o teste de caminhada de 6 minutos. Os resultados da espirometria, gasometria arterial, pico de fluxo espiratório e força muscular respiratória entre os grupos foi semelhante, sem diferença significativa, porém, a variável TC6 foi estatisticamente significante no grupo que realizou CPAP precoce, com p=0,0001. Não foi observado fuga aérea pelo dreno de tórax no grupo tratado com CPAP, demonstrando a segurança do método. Desta forma, ambas as terapias foram eficazes, porém a CPAP precoce foi mais eficaz, sugerindo que se possa aplicar de forma precoce no pós-operatório de ressecção pulmonar beneficamente. / Pulmonary resection surgery belongs to the postoperative surgery group with predispositions respiratory complications, as enhance of bronchial secretions, atelectasis, pneumonia, that are at most related to low pulmonary function at this period. The continuous positive airway pressure (CPAP) has been used therapeutically at these patients to minimize the deleterious effects at lung function in this period. The goal of this study is quantify the effects of CPAP at lung function in the postoperative lung resection period. 30 (thirty) patients wereselected from the Thoracic Surgery discipline of Pedro Ernesto University Hospital. The selection to standard group and control were randomized. Preoperative phase was composed by pulmonary function evaluation (expiratory peak flow, respiratory muscle force, 6 minutes walk test/ TC6, arterial blood gas analysis, lung function test). Postoperative period was established as follow: experimental group: 15 (fifteen) patients were conducted under non invasive ventilation intermittently by a CPAP system (ACRIFLUX-CPAP, Criticalmed, Industries Inc, Brasil) since the first postoperative day (at the first 24 hours after extubation), twice a day, for 30 minutes; control group: 15 (fifteen) patients under supervised and oriented respiratory physiotherapy program applied since the first postoperative day (at the first 24 hours after extubation), twice a day. Postoperative evaluation was the same as preoperative phase and was taken at two moments: Postoperative first day (PO-I) with new evaluation of expiratory peak flow, respiratory muscle force, arterial blood gas analysis; postoperative second day with new lung function. Postoperative seventh day (PO-II) was composed by the same parameters of (POI) and the TC6. The results of expiratory peak flow, respiratory muscle force, arterial blood gas analysis between the groups were the same, with no significance difference, however, TC6 parameter has shown statistically significance at the group submitted at early CPAP program therapy, with p= 0,0001. No airway leak by thoracic drain was observed at this CPAP therapy group, showing the efficacy of the therapy. Both therapies were efficient, but earlier CPAP therapy has shown more effective, suggesting that it can be applied earlier at the postoperative lung resection with benefits.

As cirurgias de ressecção pulmonar se incluem no grupo das cirurgias que podem predispor o paciente a apresentar complicações pulmonares no pós-operatório. Complicações como o aumento na produção de secreções brônquicas, pneumonia e atelectasia, estão quase sempre associadas à diminuição da função pulmonar neste período. A ventilação por pressão positiva contínua nas vias aéreas vem sendo constantemente utilizada como terapêutica nesses pacientes tentando-se minimizar esses efeitos prejudiciais sobre a função pulmonar. O objetivo desse estudo é quantificar os efeitos da ventilação com pressão positiva contínua nas vias aéreas (CPAP) sobre a função pulmonar no pós-operatório de ressecção pulmonar. Foram selecionados 30 (trinta) pacientes da disciplina de Cirurgia Torácica do Hospital Universitário Pedro Ernesto. A seleção dos pacientes para o grupo controle e experimental foi feita de forma randomizada. Os pacientes foram submetidos na fase pré-operatória a uma avaliação da função pulmonar (pico de fluxo expiratório, força muscular respiratória, teste de caminhada de 6 minutos/ TC6, gasometria arterial e espirometria). Após a realização do procedimento cirúrgico foram submetidos a um protocolo de intervenção, como se segue: grupo experimental: 15 (quinze) pacientes submetidos à ventilação não-invasiva, de forma intermitente, com um sistema CPAP (ACRIFLUX-CPAP, Criticalmed, Industries Inc, Brasil), iniciado no primeiro dia de pós-operatório (nas primeiras 24 horas após a extubação), 2 vezes ao dia, por um período de 30 minutos; grupo controle: 15 (quinze) pacientes submetidos a um programa de fisioterapia respiratória, orientado e supervisionado, iniciado no primeiro dia de pós-operatório (nas primeiras 24 horas após a extubação), com uma freqüência de 2 vezes ao dia. A reavaliação na fase pós-operatória seguiu a mesma metodologia utilizada na fase pré-operatória. As reavaliações ocorreram em dois momentos: no primeiro dia de pós-operatório (PO-I) onde foram reavaliados o pico de fluxo expiratório, força muscular respiratória, gasometria arterial; prova de função pulmonar com 48 horas de pós-operatório. Ao sétimo dia de pós-operatório (PO-II) foram reavaliados novamente as variáveis do PO-I e o teste de caminhada de 6 minutos. Os resultados da espirometria, gasometria arterial, pico de fluxo espiratório e força muscular respiratória entre os grupos foi semelhante, sem diferença significativa, porém, a variável TC6 foi estatisticamente significante no grupo que realizou CPAP precoce, com p=0,0001. Não foi observado fuga aérea pelo dreno de tórax no grupo tratado com CPAP, demonstrando a segurança do método. Desta forma, ambas as terapias foram eficazes, porém a CPAP precoce foi mais eficaz, sugerindo que se possa aplicar de forma precoce no pós-operatório de ressecção pulmonar beneficamente. / Pulmonary resection surgery belongs to the postoperative surgery group with predispositions respiratory complications, as enhance of bronchial secretions, atelectasis, pneumonia, that are at most related to low pulmonary function at this period. The continuous positive airway pressure (CPAP) has been used therapeutically at these patients to minimize the deleterious effects at lung function in this period. The goal of this study is quantify the effects of CPAP at lung function in the postoperative lung resection period. 30 (thirty) patients wereselected from the Thoracic Surgery discipline of Pedro Ernesto University Hospital. The selection to standard group and control were randomized. Preoperative phase was composed by pulmonary function evaluation (expiratory peak flow, respiratory muscle force, 6 minutes walk test/ TC6, arterial blood gas analysis, lung function test). Postoperative period was established as follow: experimental group: 15 (fifteen) patients were conducted under non invasive ventilation intermittently by a CPAP system (ACRIFLUX-CPAP, Criticalmed, Industries Inc, Brasil) since the first postoperative day (at the first 24 hours after extubation), twice a day, for 30 minutes; control group: 15 (fifteen) patients under supervised and oriented respiratory physiotherapy program applied since the first postoperative day (at the first 24 hours after extubation), twice a day. Postoperative evaluation was the same as preoperative phase and was taken at two moments: Postoperative first day (PO-I) with new evaluation of expiratory peak flow, respiratory muscle force, arterial blood gas analysis; postoperative second day with new lung function. Postoperative seventh day (PO-II) was composed by the same parameters of (POI) and the TC6. The results of expiratory peak flow, respiratory muscle force, arterial blood gas analysis between the groups were the same, with no significance difference, however, TC6 parameter has shown statistically significance at the group submitted at early CPAP program therapy, with p= 0,0001. No airway leak by thoracic drain was observed at this CPAP therapy group, showing the efficacy of the therapy. Both therapies were efficient, but earlier CPAP therapy has shown more effective, suggesting that it can be applied earlier at the postoperative lung resection with benefits.

No description available.