Method and apparatus for the non-invasive measurement of pulse transit times (PTT)

An apparatus for the measurement of blood pressure (BP) values of a subject comprising:

• a calibration module for determining a calibration factor;
• a processing unit for calculating a first pulse transit time (PTT) value, a second PTT value and further PTT values using a method comprising measuring a first arterial pressure pulse arrival time (PAT) and measuring a second PAT value;
• calculating a PTT value from the difference between the first PAT value and the second PAT value;
• processing a sequence of electrical impedance tomography (EIT) images to identify at least one region of interest (ROI);
• and estimating at least one of the first and second PAT value from the variation of impedance value determined from said at least one ROI;
• the processing unit being further arranged for converting the first and second PTT value into a first BP and a second BP value, respectively;
• the processing unit being further used for calculating further BP values by using the calibration factor for calibrating said further PTT values;
• and
• an output module (24) for outputting BP values.