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Authors
Advisor(s)
Abstract(s)
A monitorização dos componentes do sangue é uma prática comum nos dias de hoje,
designadamente a da Saturação de Oxigénio (sO2) para diagnosticar e monitorizar doentes com
vários tipos de doenças respiratórias. Este tipo de medição é normalmente efetuado com um
fotopletismografo (PPG) com díodos emissores de luz de dois comprimentos de onda diferentes,
um no visível e outro na região do infravermelho, conhecido por oxímetro.
Com a utilização deste tipo de equipamento, houve necessidade de melhorar a medição da sO2
bem como medir outros tipos de componentes do sangue que neste momento só se medem
através de uma colheita de sangue e que são vitais para a vida humana, como, por exemplo, a
concentração total de hemoglobina e as suas frações ou derivados. O procedimento de colher
sangue, além de ser demorado, invasivo e indesejado por muitos doentes pois provoca dor, só
permite uma visão do doente num preciso momento, não havendo qualquer monitorização
contínua.
Já existem, contudo, alguns estudos sobre a medição de outros parâmetros da hemoglobina
sem recurso à recolha de sangue e sendo utilizado um dispositivo denominado co-oxímetro de
pulso com vários comprimentos de onda, conseguindo obter-se valores contínuos no tempo sem
dor para o doente.
Neste projeto é desenvolvido um simulador para geração dos sinais óticos transmitidos nos
diversos comprimentos de onda, incluindo o efeito de atenuação do sangue em função das
frações de hemoglobina pré-configuradas. O sistema inclui também um módulo de aquisição
que permite a determinação das frações de hemoglobina (blinded experiment). Comparando os
valores pré-configurados com os valores obtidos pelo módulo de aquisição é possível avaliar o
desempenho dos fotodetectores e LEDs escolhidos. Como prova de conceito são testadas várias
configurações de LEDs e fotodetetores.
The monitoring of blood components is a common practice today, namely, oxygen saturation (sO2) to diagnose and monitor patients with various types of respiratory disease. This type of measurement is usually performed with a photoplethysmograph (PPG) with two Light Emitting Diode (LEDs) of two different wavelengths, one in visible and the other in the infrared region, known as an oximeter. With the use of this type of equipment, there was a need to improve sO2 measurement as well as measuring other types of blood components that are currently only measured through a blood draw and which are vital to human life, such as hemoglobin and its derivatives. The blood collection procedure, besides being time consuming, invasive and unwanted by many patients because it causes pain, only provides the patient status at a precise moment, there is no continuous monitoring. However, there are already some studies on the measurement of other hemoglobin parameters without blood sampling and with a multi-wavelength pulse oximeter being used to obtain continuous pain-free time values for the patient. In this project, a simulator was developed to generate optical signals transmitted at various wavelengths, including the attenuation effect on blood as a function of pre-configured hemoglobin fractions. The system also includes an acquisition module that allows the determination of the hemoglobin fractions (blinded experiment). Comparing the preconfigured values with the values obtained by the acquisition module, it is possible to evaluate the performance of the chosen photodetectors and LEDs. As proof of concept, various LED and photodetector configurations are tested.
The monitoring of blood components is a common practice today, namely, oxygen saturation (sO2) to diagnose and monitor patients with various types of respiratory disease. This type of measurement is usually performed with a photoplethysmograph (PPG) with two Light Emitting Diode (LEDs) of two different wavelengths, one in visible and the other in the infrared region, known as an oximeter. With the use of this type of equipment, there was a need to improve sO2 measurement as well as measuring other types of blood components that are currently only measured through a blood draw and which are vital to human life, such as hemoglobin and its derivatives. The blood collection procedure, besides being time consuming, invasive and unwanted by many patients because it causes pain, only provides the patient status at a precise moment, there is no continuous monitoring. However, there are already some studies on the measurement of other hemoglobin parameters without blood sampling and with a multi-wavelength pulse oximeter being used to obtain continuous pain-free time values for the patient. In this project, a simulator was developed to generate optical signals transmitted at various wavelengths, including the attenuation effect on blood as a function of pre-configured hemoglobin fractions. The system also includes an acquisition module that allows the determination of the hemoglobin fractions (blinded experiment). Comparing the preconfigured values with the values obtained by the acquisition module, it is possible to evaluate the performance of the chosen photodetectors and LEDs. As proof of concept, various LED and photodetector configurations are tested.
Description
Dissertação realizada no âmbito do mestrado em Engenharia Electrónica e Telecomunicações
Keywords
Fotopletismografia Photoplethysmography Oxímetro Oximeter Múltiplos comprimentos de onda Multiwavelength
Citation
VIEIRA, Hugo Miguel Soares - Simulador de fotopletismografia de múltiplos comprimentos de onda. Lisboa: Instituto Superior de Engenharia de Lisboa, 2019. Dissertação de mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa