A Novel Approach to the Respiratory Disease Follow-up Based on Plethhysmography Signal Parameters

Abstract

Aim: The aim of this paper is to present a novel approach for the monitoring of respiratory diseases based on the combined study of heart rate, respiratory rate and Pulse Oximetry (SpO2). Introduction: Since the start of the COVID-19 pandemic, respiratory diseases have increased its worldwide prevalence dramatically. Added to the impact of the pandemic is the already existing situation of a growing prevalence of diseases such as bronchial asthma and Chronic Obstructive Pulmonary Disease (COPD). On the other hand, it is known that the cardiovascular system is overloaded when there are respiratory insufficiencies and this condition can cause severe damage to health. Pulmonology and Cardiology are independent medical specialties that deal with these diseases and often do not cooperate with each other strongly, so a proposal is presented that combines respiratory and cardiovascular variables to deal with this health problem. Methods: A prototype was developed based on the STM32L073CZTx processor controlling the E305654 pulse oximetry module, which on demand delivers SpO2, photo plethysmography signal samples and pulse rate values. A vector was computed, every thirty minutes, to combine the respiratory rate obtained from the Plethysmography Signal (PPG), the mean value of SpO2 and the pulse rate. The vector module represents the cardiovascular and respiratory systems performance. Results: Twenty healthy volunteers, twenty people with COPD and five subjects suffering bronchial asthma, during periods without crisis, were studied. The dispersion within the group of each patient was not significant, but a notable difference can be observed between the healthy volunteers and the other people studied. A "normal region" can be set with clearly defined borders. Conclusion: The proposed solution seems promising for evaluating respiratory function even when it is compensated by a cardiac response, making it easier to identify people suffering from respiratory diseases and who may appear normal or healthy.