Abstract: Method and apparatus for estimating an arrival time (PAT) value of a subject in an automatic and unsupervised fashion from a sequence of electrical impedance tomography (EIT) images. The method comprises: providing an EIT imaging device adapted to record impedance signal distribution within a measurement region of the subject; measuring a sequence of temporally discrete EIT images during a predetermined measuring time period in the measurement region using the EIT imaging device, each EIT image comprising one or a plurality of EIT pixel subsets, each of said one or a plurality of EIT pixel subset representing an impedance value; generating one or a plurality of time series, each of said one or a plurality of time series representing a variation of the impedance value of the sequence of EIT images; and estimating the PAT value from each of said one or a plurality of time series.

Abstract: The present disclosure concerns a method for determining a heart-lung interaction factor of a subject, comprising: measuring a heart activity-related signal comprising heart activity-related information; from the heart activity-related signal, calculating a frequency of cardiac cycle and a frequency of respiratory cycle; from the heart activity-related signal, determining a cardiac cycle energy at the frequency of cardiac cycle, determining a respiratory cycle energy at the frequency of respiratory cycle, and determining a heart-lung interaction energy at an intermodulation frequency corresponding to the difference between the frequency of respiratory cycle and the frequency of cardiac cycle, or the sum of the frequency of respiratory cycle and the frequency of cardiac cycle; and determining a heart-lung interaction factor from the ratio of the heart-lung interaction energy and one of the cardiac cycle energy and the respiratory cycle energy. The heart-lung interaction factor can be determined non-invasively.

Abstract: Method and apparatus for estimating an arrival time (PAT) value of a subject in an automatic and unsupervised fashion from a sequence of electrical impedance tomography (EIT) images. The method comprises: providing an EIT imaging device adapted to record impedance signal distribution within a measurement region of the subject; measuring a sequence of temporally discrete EIT images during a predetermined measuring time period in the measurement region using the EIT imaging device, each EIT image comprising one or a plurality of EIT pixel subsets, each of said one or a plurality of EIT pixel subset representing an impedance value; generating one or a plurality of time series, each of said one or a plurality of time series representing a variation of the impedance value of the sequence of EIT images; and estimating the PAT value from each of said one or a plurality of time series.

Abstract: Method and apparatus for measuring a pulse transit time (PTT) value of a subject, 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 allows for the non-invasive and continuous measurement of the PTT value and arterial blood pressures.

Abstract: A method for measuring and determining a pulse arrival time (PAT) value of a user using a sensor device comprising a photoplethysmographic (PPG) multichannel sensor formed from a plurality of PPG sensor channels and being adapted to measure a set of PPG signals, each PPG signal being measured by one of the PPG sensor channels when the multichannel PPG sensor is in contact with the user; comprising: measuring said set of PPG signals; extracting a plurality of features from each of the measured PPG signals; selecting a subset from the set of PPG signals based on the extracted features; and processing the selected subset of PPG signals to determine the PAT value. The disclosed sensor and method can be embedded into a chest belt and do not need skilled supervision. They can represent a potential candidate for the implantation of PWV measurement campaigns in the ambulatory setting.

Abstract: The present disclosure relates to a method for estimating blood constituent concentration of a user under low perfusion conditions using a spectrophotometry-based monitoring device; the method comprising: measuring a plurality of photoplethysmographic (PPG) signals; measuring a cardio-synchronous (CV) signal; detecting an instantaneous heart rate and determining a heart rate variability from the CV signal; selecting reliable projected PPG signals; estimating a value of said blood constituent concentration from the magnitude of said reliable projected PPG signals. The disclosed method requires diminished computational load compared to conventional methods based on frequency domain approach as FFT or DCT. The disclosure also pertains to a monitoring device for estimating blood constituent concentration in tissue under low perfusion of a user.