Análise e modelagem estocástica do barorreflexo através de séries temporais de pressão arterial sistólica

• Ano de defesa: 2010
• Autor(a) principal: Galhardo, Carlos Eduardo Cardoso
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Programa de Pós-graduação em Física; Física
• Palavras-chave em Português: Física estatística; Série temporal; Processo estocástico; Barorreflexo; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA
• Link de acesso: https://app.uff.br/riuff/handle/1/19121

In this work we study the blood pressure control mechanism in rats through the analysis of the systolic pressure time series before and after a surgical process that interrupts its control loop. We analyze the time series with descriptive statistics, detrended fluctuation analysis and multifractal detrended analysis. Using descriptive statistics we found a non Gaussian behavior for the blood pressure, pulse intervals and their respective increments. We characterize the physiological states with the sample moments. We found a broad multifractal spectra in health and surgically denervated rats, the last shows a broadest spectra indicating that was not the control mechanism who causes the multifractality. Despite of this fact and the non-Gaussian behavior, we understood that ultifractality was caused by long-range correlation. With detrended fluctuation analysis we found a scaling crossover between two exponents that characterizes the denervated status. In addition we have also found an evidence for an adaptation in blood pressure dynamics after surgical disruption of its main feedback circuit. We proposed a model for pressure homeostasis as the balance between two nonlinear opposing forces, successfully reproducing the crossover change observed in actual pressure signals. A simplification was made in order to obtain an analytic solution for a health animal that describes the fluctuation functions observed with DFA and reproduces the distribution of systolic blood pressures values