Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA344

Poster Communications

A new GUI (graphical user interface) to facilitate photoplethysmography signal processing

H. Silva1,2, F. Viana3, H. Vieira2, R. Francisco2, H. A. Ferreira3, L. Monteiro Rodrigues1,2

1. CBiOS (Research Center for Biosciences and Health Technologies), U Lusófona, School of Health Sc & Technologies, Lisboa, Portugal. 2. Pharmacol. Sc Depart, U Lisboa, Faculty of Pharmacy, Lisboa, Portugal. 3. IBEB Institute Bioph Biomed Engineering, U Lisboa, Faculty of Sciences, Lisboa, Portugal.

The analysis of physiological signals is a complex process, from the preprocessing phase, in which artifacts are removed from the raw signals, to the application of specific analytical algorithms allowing the extraction of useful description parameters. Without the use of dedicated software that often accompanies the signal acquisition hardware, signal analysis can be particularly cumbersome. Photoplethysmography (PPG) is a noninvasive optical technique, commonly used in the clinical setting for the estimation of pulse oximetry (SpO2) and for the quantification of skin perfusion. The oscillatory nature of this class of signals, based on the contribution of different components (cardiac, respiratory, neurohumoral) allows the quantification of several parameters through proper instrumentation. However, PPG signals often carry artifacts that hinder a reliable and more detailed analysis. Here we describe a new MATLAB-based graphical user interface (GUI) to facilitate the processing of PPG signals acquired with Blood Volume Pressure sensors (PLUX Wireless Biosignals, Portugal). The GUI performance was tested with a sample data of PPG signals collected from the toes of 20 young healthy subjects (21.5 ± 2.1 y.o.) while sitting upright for 10 minutes. The procedures complied with the Helsinki declaration and following amendments and subjects gave their informed written consent prior to their participation. The GUI provides three main features: (1) a Finite Impulse Response filter with a Bohman window, allowing the selection of filter order and cutoff frequencies; (2) a fast Fourier transform frequency spectrum, serving as a control of the filter process; (3) a peak detection feature that operates by adjusting an amplitude threshold. The peak detection feature allows the detection of local maxima and minima, from which the pulse rate and the pulse reflection delay (the time difference between the pulse arrival peak and the reflected peak) may be calculated. Different filter parameters for a clear identification of parameters are proposed. This dedicated GUI is easy to use and speeds up PPG signal processing.

Where applicable, experiments conform with Society ethical requirements