The purpose of this investigation is to determine the pressure-flow relationships in the isolated canine cerebral vascular bed. These relationships in vessels which supply an organ surrounded by bone are theoretically influenced by limiting factors which are not present in those vessels surrounded by soft tissue. An evaluation of the extent of these limitations is essential to thorough understanding of the dynamics of the cerebral vascular bed.

No description available.

The purpose of this research was to study perfusion pressure-flow relationships in self-oscillating synthetic poroelastic vocal fold (VF) models before, during, and after vibration. This was accomplished by developing a custom ultra-soft poroelastic material, incorporating the poroelastic material as the cover layer in a synthetic VF model, and studying the model vibratory response and the flow rate of fluid perfused through the cover layer while undergoing flow-induced vibration. The custom ultra-soft poroelastic material was developed using the method of direct templating with sucrose spheres as the sacrificial template and silicone as the infiltration medium. The average modulus of elasticity of the poroelastic material was found to be 3.30 kPa, which represented an 84% decrease compared to the same non-porous silicone. Porosities between 62.8% and 67.2% were estimated. The fabrication process of the poroelastic VF model is presented in detail, including steps to prepare the model for vibration. The apparatus for measuring perfusion pressure flow-relationships in the VF model is described. Vibratory characteristics of subglottal onset pressure, frequency, glottal area, and glottal width are presented and compared to those of the human VF and other published VF models for varying perfusion pressures. The effects of vibration on perfusion flow rate and permeability are reported. The poroelastic VF models had an average onset pressure of 1.01 kPa while vibrating at an average frequency of 117 Hz and with a glottal width of 1.40 mm. Perfusion flow rate decreased between 15% and 22% from rest to vibration and increased between 29% and 33% after vibration ceased. Permeability followed the same trend of decreasing with vibration and increasing after vibration, with measured values on the order of 10^(-11) m^2 to 10^(-9) m^2. It is anticipated that this poroelastic material and model will form the basis for future studies of perfused flow through human VFs, engineered VF tissues and biomaterials, and VF models.

No description available.

The influence of vocal fold (VF) vibration on perfused flow through VF vasculature is an area of research that has previously received limited attention. The aim of the research presented in this thesis was to contribute towards an improved understanding of the effects vibration on perfusion through vasculature within the VFs. This was done using a series of computational simulations of geometric changes to, and perfusion through, microchannels embedded in VF models. A computational structural model based on synthetic VF models used in previous experimental studies was first developed. The model and its embedded microchannel were initially studied under static pressure loads applied to the inner surfaces of the channel as well as to the VF inferior and medial surfaces. It was shown that the channel volume decreased linearly and the channel length increased quadratically with increasing pressure on the external VF surfaces. Changes in Poisson's ratio and its influence on the embedded channel's maximum deflection, volume, and length were also studied. Across the range of Poisson's ratios that has been studied for silicone used in synthetic VF models (0.4 to 0.495) there was shown to be limited change in microchannel maximum deflection, channel length, and volume for equivalent pressure loads. The model was then modified to include an external oscillating pressure load on the VF surface that caused the model to vibrate. Two separate studies were conducted to determine how frequency and deflection amplitude affected the predicted perfusion flow rate through the embedded microchannel by accounting for the changes in microchannel geometry during vibration. These studies showed that frequency had little effect on predicted flow rate, while increased deflection amplitude led to greater reductions in predicted flow rate. These reductions in flow rate were attributed to channel lengthening and cross section deformation during vibration, with the latter playing a much larger role. Reductions in flow rate results were found to favorably agree with measured experimental flow rate reductions reported previously. Computational fluid dynamics simulations of water flowing through the inflated embedded microchannel during vibration were also conducted. These simulations were used to explore how changes in vibration length, amplitude, and frequency affected the fluid dynamics in the microchannel whilst minimizing geometric changes to the microchannel. The flow rates from each of the simulation cases were compared to determine which of the vibration parameters contributed the most to flow losses. Vibration length and amplitude were shown to be statistically significant. An investigation was undertaken to further elucidate the mechanisms behind the flow losses induced by vibration. The effects of channel elongation, increased channel curvature, pressure rises, and pressure gradients during vibration were analyzed. Changes in channel elongation and pressure were shown to significantly contribute to flow losses and flow rate reduction. The results from these simulations were compared with the structural simulations which analyzed how changes in microchannel geometry affected flow rate reductions. Changes in the microchannel geometry were shown to contribute much more significantly to reductions in perfusion flow rate compared to changes in vibration parameters (i.e., vibration length, amplitude, and frequency).

Objetivo: Comparar os resultados de hipernasalidade, nasalância e função velofaríngea entre duas técnicas cirúrgicas que empregam o procedimento de veloplastia intravelar para a correção da insuficiência velofaríngea (IVF) residual: a palatoplastia posterior secundária com manobra de Braithwaite e a palatoplastia posterior secundária pela técnica de Furlow. Modelo/Participantes: Estudo prospectivo em 50 pacientes com IVF residual, que realizaram a veloplastia intravelar, tendo sido divididos em dois grupos: 31 pacientes submetidos à palatoplastia posterior secundária com manobra de Braithwaite (grupo B) e 19 pacientes submetidos à palatoplastia posterior secundária pela técnica de Furlow (grupo F). Local de Execução: Laboratório de Fisiologia do Hospital de Reabilitação de Anomalias Craniofaciais-USP. Variáveis: Hipernasalidade, classificada perceptivamente por três avaliadores; nasalância, determinada por meio da nasometria e, fechamento velofaríngeo, estimada pela medida da área velofaríngea, por meio da técnica fluxo-pressão, em média, 3 dias antes e 14 meses após a cirurgia. Resultados: Verificou-se, após a cirurgia, redução da hipernasalidade e da nasalância em 45% e 65% dos casos, respectivamente e, melhora do fechamento velofaríngeo em 50% dos pacientes do grupo B. Para o grupo F, observou-se redução tanto da hipernasalidade quanto da nasalância em 53% dos pacientes e melhora do fechamento velofaríngeo em 46% dos casos. Diferenças estatisticamente significantes não foram identificadas entre as duas técnicas cirúrgicas para todas as variáveis estudadas (p<0,05). Conclusão: Os achados permitiram concluir que as duas técnicas cirúrgicas que empregam o procedimento de veloplastia intravelar mostraram resultados semelhantes na redução dos sintomas da IVF residual. / Objective: To compare postoperative outcomes of hypernasality, nasalance and velopharyngeal function between two surgical techniques that use intravelar veloplasty procedure for velopharyngeal insufficiency (VPI) management: secondary palatoplasty as suggested by Braithwaite and secondary palatoplasty by Furlow technique. Model/Participants: Prospective study in 50 patients with VPI, underwent intravelar veloplasty divided into two groups: 31 patients underwent secondary palatoplasty as suggested by Braithwaite (group B) and 19 patients underwent secondary palatoplasty by Furlow technique (group F). Setting: Laboratory of Physiology, Hospital de Reabilitação de Anomalias Craniofaciais-USP. Variables: Hypernasality, perceptually classified by three evaluators; nasalance determined by means of nasometry and velopharyngeal function, assessed by means of velopharyngeal area measurement provided by the pressure-flow technique, 3 days before and 14 months after surgery, on average. Results: After surgery, reduction of hypernasality and nasalance was verified in 45% and 65% of cases, respectively, and improvement of velopharyngeal closure in 50% of patients in group B. In group F, reduction of hypernasality and nasalance was observed in 53% of patients and improvement of velopharyngeal closure in 46% of cases. No statistically significant differences were identified between the two surgical techniques for all variables studied (p<0,05). Conclusion: The two surgical techniques involving intravelar veloplasty procedure showed similar results in reducing VPI symptoms.

Objetivos: Investigar o efeito da cirurgia de retalho faríngeo (CRF) sobre as dimensões internas nasais de pacientes com insuficiência velofaríngea (IVF), a curto e longo prazo, e, correlacionar esses achados com o aparecimento de queixas respiratórias após a cirurgia. Modelo/Pacientes: Estudo prospectivo em 58 pacientes com fissura palatina operada e IVF, avaliados 2 dias antes (PRE) e, 5 (POS1) e 14 meses (POS2) após a cirurgia, em média, divididos em 2 grupos: um queixas respiratórias (CQ) em POS2 e outro, sem queixas (SQ). Diferenças entre grupos e etapas foram consideradas significantes ao nível de 5%. Local: Laboratório de Fisiologia, Hospital de Reabilitação de Anomalias Craniofaciais, USP, Bauru. Intervenções: CRF de pedículo superior. Variáveis: Queixas (respiração oral, ronco e dificuldade respiratória durante o sono) e área de secção transversa mínima nasal (AN) e nasofaríngea (ANF) avaliada por rinomanometria. Resultados: Queixas respiratórias foram observadas em 55% dos pacientes em POS1 e 36% em POS2. Observou-se na rinomanometria posterior: 1) redução significativa da AN média em POS1 e POS2, relativamente ao PRE, em ambos os grupos. Não foram observadas variações significativas na rinomanometria anterior; 2) AN média do grupo CQ significantemente menor que a do grupo SQ em POS2; 3) redução da AN mais pronunciada no grupo CQ. Medidas da ANF confirmaram esses achados. Conclusões: A curto prazo, a CRF levou à redução significativa da dimensão nasofaríngea em proporção expressiva de pacientes, parte dos quais passaram a apresentar queixas respiratórias; a longo prazo, esse efeito atenuou-se sem, contudo, desaparecer por completo. / Objectives: To investigate the short- and long-term effect of pharyngeal flap surgery (PFS) on the internal nasal dimensions of patients with velopharyngeal insufficiency (VPI) and to correlate the findings with the onset of respiratory complaints (RC) after surgery. Model/Patients: Prospective study in 58 patients with repaired cleft palate and VPI, evaluated, on average, 2 days before (PRE), 5 (POST1) and 14 months (POST2) after surgery, divided into 2 groups: one consisting of patients with RC (WRC) at POST2 and the other without RC (WtRC). Differences between groups and stages were considered to be significant at the 5% level. Site: Laboratory of Physiology, Hospital for Rehabilitation of Craniofacial Anomalies, Brazil. Interventions: Superiorly based PFS. Variables: RC (oral respiration, snoring and respiratory difficulty during sleep), and minimal nasal (NA) and nasopharyngeal (NPA) cross-sectional area assessed by rhinomanometry. Results: RC were observed in 55% of patients at POST1 and 36% at POST2. Posterior rhinomanometry showed: 1) a significant reduction of mean NA at POST1 and POST2 compared to PRE, in both groups. No significant changes were observed by anterior rhinomanometry; 2) significantly lower mean NA in the WC group compared to the WtC group at POST2; 3) more pronounced reduction in NA values in the WC group. NPA measurements confirmed these findings. Conclusions: In the short term, PFS led to a significant reduction in the nasopharyngeal dimensions in a significant proportion of patients, part of whom started to present RC; in the long term, this effect was attenuated but did not fully disappear.

Objetivos: Investigar o efeito da cirurgia de retalho faríngeo (CRF) sobre as dimensões internas nasais de pacientes com insuficiência velofaríngea (IVF), a curto e longo prazo, e, correlacionar esses achados com o aparecimento de queixas respiratórias após a cirurgia. Modelo/Pacientes: Estudo prospectivo em 58 pacientes com fissura palatina operada e IVF, avaliados 2 dias antes (PRE) e, 5 (POS1) e 14 meses (POS2) após a cirurgia, em média, divididos em 2 grupos: um queixas respiratórias (CQ) em POS2 e outro, sem queixas (SQ). Diferenças entre grupos e etapas foram consideradas significantes ao nível de 5%. Local: Laboratório de Fisiologia, Hospital de Reabilitação de Anomalias Craniofaciais, USP, Bauru. Intervenções: CRF de pedículo superior. Variáveis: Queixas (respiração oral, ronco e dificuldade respiratória durante o sono) e área de secção transversa mínima nasal (AN) e nasofaríngea (ANF) avaliada por rinomanometria. Resultados: Queixas respiratórias foram observadas em 55% dos pacientes em POS1 e 36% em POS2. Observou-se na rinomanometria posterior: 1) redução significativa da AN média em POS1 e POS2, relativamente ao PRE, em ambos os grupos. Não foram observadas variações significativas na rinomanometria anterior; 2) AN média do grupo CQ significantemente menor que a do grupo SQ em POS2; 3) redução da AN mais pronunciada no grupo CQ. Medidas da ANF confirmaram esses achados. Conclusões: A curto prazo, a CRF levou à redução significativa da dimensão nasofaríngea em proporção expressiva de pacientes, parte dos quais passaram a apresentar queixas respiratórias; a longo prazo, esse efeito atenuou-se sem, contudo, desaparecer por completo. / Objectives: To investigate the short- and long-term effect of pharyngeal flap surgery (PFS) on the internal nasal dimensions of patients with velopharyngeal insufficiency (VPI) and to correlate the findings with the onset of respiratory complaints (RC) after surgery. Model/Patients: Prospective study in 58 patients with repaired cleft palate and VPI, evaluated, on average, 2 days before (PRE), 5 (POST1) and 14 months (POST2) after surgery, divided into 2 groups: one consisting of patients with RC (WRC) at POST2 and the other without RC (WtRC). Differences between groups and stages were considered to be significant at the 5% level. Site: Laboratory of Physiology, Hospital for Rehabilitation of Craniofacial Anomalies, Brazil. Interventions: Superiorly based PFS. Variables: RC (oral respiration, snoring and respiratory difficulty during sleep), and minimal nasal (NA) and nasopharyngeal (NPA) cross-sectional area assessed by rhinomanometry. Results: RC were observed in 55% of patients at POST1 and 36% at POST2. Posterior rhinomanometry showed: 1) a significant reduction of mean NA at POST1 and POST2 compared to PRE, in both groups. No significant changes were observed by anterior rhinomanometry; 2) significantly lower mean NA in the WC group compared to the WtC group at POST2; 3) more pronounced reduction in NA values in the WC group. NPA measurements confirmed these findings. Conclusions: In the short term, PFS led to a significant reduction in the nasopharyngeal dimensions in a significant proportion of patients, part of whom started to present RC; in the long term, this effect was attenuated but did not fully disappear.

Objetivo: Comparar os resultados de hipernasalidade, nasalância e função velofaríngea entre duas técnicas cirúrgicas que empregam o procedimento de veloplastia intravelar para a correção da insuficiência velofaríngea (IVF) residual: a palatoplastia posterior secundária com manobra de Braithwaite e a palatoplastia posterior secundária pela técnica de Furlow. Modelo/Participantes: Estudo prospectivo em 50 pacientes com IVF residual, que realizaram a veloplastia intravelar, tendo sido divididos em dois grupos: 31 pacientes submetidos à palatoplastia posterior secundária com manobra de Braithwaite (grupo B) e 19 pacientes submetidos à palatoplastia posterior secundária pela técnica de Furlow (grupo F). Local de Execução: Laboratório de Fisiologia do Hospital de Reabilitação de Anomalias Craniofaciais-USP. Variáveis: Hipernasalidade, classificada perceptivamente por três avaliadores; nasalância, determinada por meio da nasometria e, fechamento velofaríngeo, estimada pela medida da área velofaríngea, por meio da técnica fluxo-pressão, em média, 3 dias antes e 14 meses após a cirurgia. Resultados: Verificou-se, após a cirurgia, redução da hipernasalidade e da nasalância em 45% e 65% dos casos, respectivamente e, melhora do fechamento velofaríngeo em 50% dos pacientes do grupo B. Para o grupo F, observou-se redução tanto da hipernasalidade quanto da nasalância em 53% dos pacientes e melhora do fechamento velofaríngeo em 46% dos casos. Diferenças estatisticamente significantes não foram identificadas entre as duas técnicas cirúrgicas para todas as variáveis estudadas (p<0,05). Conclusão: Os achados permitiram concluir que as duas técnicas cirúrgicas que empregam o procedimento de veloplastia intravelar mostraram resultados semelhantes na redução dos sintomas da IVF residual. / Objective: To compare postoperative outcomes of hypernasality, nasalance and velopharyngeal function between two surgical techniques that use intravelar veloplasty procedure for velopharyngeal insufficiency (VPI) management: secondary palatoplasty as suggested by Braithwaite and secondary palatoplasty by Furlow technique. Model/Participants: Prospective study in 50 patients with VPI, underwent intravelar veloplasty divided into two groups: 31 patients underwent secondary palatoplasty as suggested by Braithwaite (group B) and 19 patients underwent secondary palatoplasty by Furlow technique (group F). Setting: Laboratory of Physiology, Hospital de Reabilitação de Anomalias Craniofaciais-USP. Variables: Hypernasality, perceptually classified by three evaluators; nasalance determined by means of nasometry and velopharyngeal function, assessed by means of velopharyngeal area measurement provided by the pressure-flow technique, 3 days before and 14 months after surgery, on average. Results: After surgery, reduction of hypernasality and nasalance was verified in 45% and 65% of cases, respectively, and improvement of velopharyngeal closure in 50% of patients in group B. In group F, reduction of hypernasality and nasalance was observed in 53% of patients and improvement of velopharyngeal closure in 46% of cases. No statistically significant differences were identified between the two surgical techniques for all variables studied (p<0,05). Conclusion: The two surgical techniques involving intravelar veloplasty procedure showed similar results in reducing VPI symptoms.

Objetivos: Determinar a efetividade da cirurgia de retalho faríngeo (CRF) na correção da insuficiência velofaríngea (IVF), por meio de avaliação perceptiva e instrumental da fala, e verificar a influência do grau de hipernasalidade pré-operatória, da idade, do cirurgião e da fonoterapia sobre os resultados. Modelo/Participantes: Estudo prospectivo em 241 pacientes com IVF submetidos à CRF no Hospital de Reabilitação de Anomalias Craniofaciais, Universidade de São Paulo (HRAC-USP). Local de Execução: Laboratório de Fisiologia, HRAC-USP. Variáveis: Hipernasalidade, avaliada perceptivamente e pela medida da nasalância com técnica nasométrica, e, função velofaríngea, avaliada perceptivamente e pela medida da área velofaríngea com técnica aerodinâmica, antes (1 a 4 dias) e após (6 a 48 meses) a cirurgia. Resultados: Observou-se, após a cirurgia, redução da hipernasalidade e da nasalância em 75% e 68% dos casos, e, melhora da função e do fechamento velofaríngeo em 67% e 66%, respectivamente. As proporções foram menores quando utilizado critério mais rigoroso (eliminação/normalização). Maior percentual de sucesso foi observado nos pacientes com hipernasalidade pré-operatória leve, comparativamente aos demais (leve>moderada>grave), nas crianças, comparativamente às demais faixas etárias analisadas (6-12>13-17>18-29>30-57anos) e nos pacientes que haviam concluído a fonoterapia pós-operatória, comparativamente àqueles em outra situação (concluída>em andamento>interrompida). Os resultados não diferiram entre os cirurgiões. Conclusões: A CRF mostrou-se eficiente na redução dos sintomas da IVF em parcela significativa dos pacientes. A resolução completa foi observada em menor proporção de casos. O grau de hipernasalidade pré-operatória, a idade por ocasião da cirurgia e a fonoterapia pós-operatória foram fatores relevantes no sucesso do tratamento. / Objective: To evaluate the effectiveness of pharyngeal flap surgery (PFS) for the correction of velopharyngeal insufficiency (VPI), by means of speech perceptual and instrumental assessment, and to verify the influence of preoperative hypernasality, age, surgeon and speech therapy on the results. Model: Prospective study on 241 patients with VPI, who underwent PFS at the Hospital for Rehabilitation of Craniofacial Anomalies, University of Sao Paulo (HRCA-USP). Setting: Laboratory of Physiology, HRCA-USP. Variables: Hypernasality, assessed by perceptual ratings and by means of nasalance scores provided by nasometry, and velopharyngeal function, assessed perceptually and by means of velopharyngeal orifice area provided by pressure-flow technique, before (1 to 4 days) and after (6 to 48 months) surgery. Results: Reduction of hypernasality and of nasalance scores was observed in 75% and 68% of the cases, and improvement of VP function and area in 67% and 66%, respectively. Smaller proportions were observed by using more rigorous criteria of analysis (elimination/normalization). Greater success rates were observed in patients with mild preoperative hypernasality, as compared to the others (mild>moderate>severe), in children, comparatively to other age groups analyzed (6-12>13-17>18-29>30-57years) and in patients who had concluded postoperative speech therapy, comparatively to those in another situation (concluded>in progress>interrupted). The results did not differ among surgeons. Conclusions: PFS was shown to be effective in the reduction of VPI symptoms for a significant number of patients. Complete resolution was observed in smaller proportion of cases. Preoperative hypernasality, age at surgery and postoperative speech therapy were relevant factors for the treatment success.