Use of an apparatus suitable for cardiovascular assessment, for the determination of a transmission or an effect of the respiration on the pleural pressure or on the volume response, wherein the apparatus comprises: a first sensor configured to detect respiration cycles; a second sensor configured to measure cardiac cycles; and one or more controllers configured to: a. detect a starting position of at least two, preferably three, more preferably four, more preferably five, more preferably 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or at least preferably 20, consecutive or non-consecutive, respiratory cycles, and rearranging the starting position and duration of each cardiac cycle according to their position in time, with respect to the aforesaid starting position of these respiratory cycles; and b. building a waveform display performed by plotting a respiratory cycle as an abscissa, and by plotting each of the measurements of the cardiac cycles in relation to the time of its respective respiratory cycle's starting point obtained as described in step a) above, as an ordinate within the respiratory cycle; wherein the cardiac and respiratory cycles are preferably synchronized and measured continuously and wherein the cardiac cycles are measured from central venous pressure or a peripheral venous pressure; wherein each of the measurements of each cardiac cycles are selected so that there is information about the transmission or the effect of the respiration on the pleural pressure or on the volume response; and wherein the apparatus further comprises a calculator unit which is adapted to perform analytic calculations from said waveform display to calculate one or more hemodynamic variable. a first sensor configured to detect respiration cycles; a second sensor configured to measure cardiac cycles; and one or more controllers configured to: a. detect a starting position of at least two, preferably three, more preferably four, more preferably five, more preferably 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or at least preferably 20, consecutive or non-consecutive, respiratory cycles, and rearranging the starting position and duration of each cardiac cycle according to their position in time, with respect to the aforesaid starting position of these respiratory cycles; and b. building a waveform display performed by plotting a respiratory cycle as an abscissa, and by plotting each of the measurements of the cardiac cycles in relation to the time of its respective respiratory cycle's starting point obtained as described in step a) above, as an ordinate within the respiratory cycle; a. detect a starting position of at least two, preferably three, more preferably four, more preferably five, more preferably 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or at least preferably 20, consecutive or non-consecutive, respiratory cycles, and rearranging the starting position and duration of each cardiac cycle according to their position in time, with respect to the aforesaid starting position of these respiratory cycles; and b. building a waveform display performed by plotting a respiratory cycle as an abscissa, and by plotting each of the measurements of the cardiac cycles in relation to the time of its respective respiratory cycle's starting point obtained as described in step a) above, as an ordinate within the respiratory cycle; wherein the cardiac and respiratory cycles are preferably synchronized and measured continuously and wherein the cardiac cycles are measured from central venous pressure or a peripheral venous pressure; wherein each of the measurements of each cardiac cycles are selected so that there is information about the transmission or the effect of the respiration on the pleural pressure or on the volume response; and wherein the apparatus further comprises a calculator unit which is adapted to perform analytic calculations from said waveform display to calculate one or more hemodynamic variable.