Spectral analysis of respiratory flow and gas concentrations / Análise espectral de fluxo e concentrações de gases respiratórios

In this research we obtained samples of human respiratory flow, oxygen concentration and carbon dioxide concentration signals from 20 healthy subjects and evaluated the average power spectral density (PSD) of these signals. For each subject,the respiratory samples were acquired in four progressive levels of exercise in a cycle ergometer. Auto regressive moving average models were designed to represent the PSD found in each phase. An average PSD of the four levels was also calculated. Results have shown that the bandwidth of O2 concentration, CO2 concentration and flow signals was 8  Hz, 7 Hz, and 15  Hz, respectively, within the dynamic range of 50  dB. The PSD curves found can be used for optimal filter design for signal enhancing in fast on-line measurement of these signals.

Nesta pesquisa foram registradas amostras dos sinais respiratórios de fluxo, concentração de oxigênio e concentração de gás carbônico em 20 voluntários saudáveis. A densidade espectral de potência (DEP) média foi então calculada. Para cada voluntário, as amostras dos sinais foram registradas em quatro intensidades progressivas de esforço físico em uma bicicleta ergométrica. Para representar a DEP encontrada em cada fase foram ajustados modelos auto-regressivos de média móvel. Uma DEP média entre as quatro intensidades também é fornecida. Os resultados mostraram que as larguras de banda dos sinais de concentração de O2, concentração de CO2 e fluxo foram 8  Hz, 7  Hz e 15  Hz, respectivamente, dentro de uma faixa dinâmica de 50  dB. As curvas de DEP encontradas podem ser usadas em projetos de filtros ótimos para equalização destes sinais em medições em tempo real.

Exercício físico e insuficiência cardíaca / Physical exercise and heart failure

Devido aos novos e relevantes benefícios para pacientes portadores de insuficiência cardíaca o exercício físico tem sido recomendado como medida complementar para o tratamento dessa disfunçäo cardiovascular. Nesta revisço, seräo apresentados, num primeiro momento, alguns importantes benefícios alcançados pelo exercício físico regular em pacientes com insuficiências cardíacas e os possíveis mecanismos para explicar esses benefícios. E num segundo momento, será apresentada a prescriçäo de exercício para pacientes com insuficincia cardíaca incluíndo tipo, duraçäo, frequência e intensidade de exercício, adequados para melhorar a qualidade de vida desses pacientes.

Avaliação cardiorrespiratória ao exercício no idoso sadio / Cardiopulmonary Exercise Test in the Evalution of Healthy Elderly Men

PURPOSE--To study methodological aspects and results of cardiopulmonary exercise tests in elderly. METHODS--Twenty-five men (mean age 65 +/- 5 years) performed a cardiopulmonary exercise test using a bicycle ergometer and a progressive continuous work load increase protocol was employed. A computadorized system (2001 CAD/Net System-MGC), which includes a gas analyser and a pneumotacograph, was used for on line monitoring of oxygen and carbon dioxide expired fraction and also of pulmonary flow. RESULTS--We observed the following values of oxygen uptake, pulmonary ventilation and respiratory gas exchange: rest=4 +/- 1 ml/kg-1/min-1, 11 +/- 2 l/min-1 and 0.80 +/- 0,1, respectively: anaerobic threshold=12 +/- 3 ml/kg-1/min-1, 29 +/- 6 l/min-1 and 0.90 +/- 0.1, respectively: respiratory compensation point=18 +/- 4ml/kg-1/min-1, 47 +/- 1 l/min-1 and 1.07 +/- 0.1, respectively, and peak of exercise = 13 +/- 5 ml/kg-1/min-1, 76 +/- 18 l/min-1 and 1.21 +/- 0.2, respectively. The anaerobic threshold and the respiratory compensation point were achieved at 53 +/- 11 and 77 +/- 9//of peak oxygen uptake respectively. The elderly shown slightly increased values of the relation volume dead/tidal volume at rest with a slightly smaller decrease of its values during exercise in comparison to data obtained from young healthy untrained subjects. The heart rate prescription for exercise based on the heart rate reserve was higher than that based on the cardiorespiratory and metabolic responses (113-126bpm vs 96-114bpm). CONCLUSION--The cardiorespiratory and metabolic responses pattern in the elderly is quite heterogeneous. The heart rate prescription for exercise based on conventional stress tests seems to overestimate cardiorespiratory and metabolic capacity in healthy elderly men. The determination of anaerobic threshold and respiratory compensation point from cardiopulmonary exercise test data optimize exercise prescription for healthy elderly men