Contactless Pulse Transit Time measurement and its potential application in measuring Blood Pressure
Blood pressure cuffs are currently the standard device for measuring blood pressure at home or by a physician. However, many patients often develop pain and discomfort due to the inflation of the cuff. In addition, repeated re-inflation by the automatic cuff can even lead to the injury of the applied areas . Our team invented the method of contactless acquiring the pulse transit time and its potential in monitoring the blood pressure without the requirement of any equipment contacting the body. Pulse transit time is defined as the amount of time taken by a pulse wave generated at the heart to reach a given extremity in one cardiac cycle . PTT is proven to correlate with blood pressure inversely . The objective of our project was to develop a contactless device using a camera to detect PTT. We collected waveforms using an RGB camera from subjects’ two regions of interest, the forehead and the palm, before and after an exercise; these wave signals closely compared to cardiovascular pulses. We then measured the difference in the time intervals of these signals (PTT) and used this to study the relationship between the PTT and blood pressure . After testing a few subjects, PTT changed between pre and post exercise, and an inverse relationship between our derived PTT and blood pressure recorded from a cuff was observed.