Medição de fluxo respiratório com instrumento baseado em anemômetro a fio quente.

Abstract

The objective of the dissertation is the development of a system able to measure the respiratory flow as well as its direction, using hot-wire sensors. The measure of the flow is fundamental in the characterization of the respiratory system. With the flow and the pressure is possible to determinate some characteristics of the respiratory system, which possibilities to the doctor the most exact diagnosis of some pathologies. For tests and measurements of the flow was utilized an senodal pressure generator that is used in the Forced Oscillations Technique (FOT). The system uses a sinusoidal pressure of frequency and width constants, wich were measured using a pneumotacometer, a platinum sensor, and a pressure sensor. After several tests it was verified that it is possible to determine the flow velocity with only a platinum sensor. But with just a sensor it is not possible to determine the flow direction. For measurement of the flow direction it was used two sensors, tends between them a heat generator (resistance), with this it was possible to observe the anemometers out signs differed in a flow semicycle, a platinum sensor received heat in the flow positive semicycle and the other in the negative semicycle. It was verified that to receive heat the platinum sensors had its amplitudes varied, and this way it was possible to determine which the direction of the respiratory flow.