Method and Apparatus for the Non-Invasive Measurement of Pulse Transit Times (PTT)

Method for estimating blood pressure (BP) values comprising:

• measuring at a first PTT value, a second PTT value, and further PPT 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 method comprising:
• determining a calibration factor for converting the at least first and second PTT value into a at least first BP and a second BP value, respectively;
• and
• determining further BP values by using the calibration factor for calibrating said further PPT values.

Apparatus for measuring a pulse transit time (PTT) value of a subject 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 apparatus comprising:
• an electrical impedance tomography (EIT) imaging device comprising electrodes for recording impedance signal distribution (EIT image) of the subject, and measuring the sequence of temporally discrete EIT images;
• a processing unit adapted for performing the step of said estimating a first and second PAT value, estimating at least one ROI, and calculating the PTT value;
• and
• an output module for outputting the PTT value.

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 PTT value, a second PTT value and further PPT 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 PPT values;
• and
• an output module (24) for outputting BP values.