A comparative study in the use of brachial photoplethysmography and the QRS complex as timing references in determination of pulse transit time

For more than a century, there has been interest in pulse wave velocity and pulse transit time as a possible metric for blood pressure and other cardiovascular parameters. The most common approach in noninvasive measurement of these metrics has been to measure the time delay between the QRS complex on the electrocardiograph and the detection of the ringer photoplethysmograph. This paper introduces a new technique for measuring the brachial photoplethysmograph and argues that this forms a better timing reference than the QRS complex.