A novel approach to detecting pulse onset in photoplethysmographic signal using an automatic non assisted method

Abstract

An automatic method for determining the location of the pulse onset on arterial pulse waves is presented. The aim is to develop an automatic method for enhance the accuracy and precision of pulse onset detection without ECG assistance (R peaks as reference). The approach is composed by two stages: pulse delineator and onset decision. Pulse delineator is based on amplitude and time thresholds computation in time and frequency domain respectively, for locating each pulse wave. Decision stage is based on triangle area algorithm that computes on each pulse the triangle area successive with two fix points and one mobile. The mobile point that corresponds to higher area is the pulse onset. Pulse delineator stage of proposed method was evaluated with CSL database, and their results were comparable to other pulse detection algorithm. Simultaneous ECG and PPG records were used to evaluate the repeatability of proposed method for several signal-noise ratios, as well as the concordance respect to trained observers. The performance of proposed method was compared with ECG assisted methods, such as tangents intersection, diastolic point and second derivative. The approach obtained acceptable values of sensitivity (> 97.99 %), positive predictivity (> 97.91 %), failed rate detection (< 4.11 %) and error (< 5.78 ± 6.64 ms). This proposal found the repeatability condition for each signal-noise ratios. This method could be used on medical systems that need the pulse onset to compute diagnostic markers.