A system for determining stroke volume of an individual. The system includes a skew-determining module that is configured to calculate a first derivative of photoplethysmogram (PPG) signals of the individual. The first derivative forms a derivative waveform. The skew-determining module is configured to determine a skew metric of the first derivative, wherein the skew metric is indicative of a morphology of at least one pulse wave detected from blood flow of the individual in the derivative waveform. The system also includes an analysis module that is configured to determine a stroke volume of the individual. The stroke volume is a function of the skew metric of the first derivative.