Fig. 1

Algorithm to correct the effect of breathing on pulmonary artery pressure signal. See the description in the manuscript. As noted, the respiratory and pulmonary artery pressure signals should be recorded simultaneously. In brief, the following steps are shown: a minimum pressure (black points) at the start of the pulmonary artery pressure (continuous grey line) cycle and the start of inhalation (black lines) in the respiratory flow (dashed grey lines) cycle are located. b Time of minimum pulmonary artery pressure points in relation with the respiratory cycle period are set (dashed lines demark the respiratory period). One of the minimum pulmonary artery pressure points is marked with a star and its relative position according to the respiratory period is shown. c Minimum pulmonary artery pressure points are reordered according to their relative position in the respiratory cycle. This step is highlighted in grey due to its relevance for the method. The new location of the point marked with a star in b is now shown as an example of this step. d Function of the minimum pressure vs it relative time in the respiratory period is created. The function is scaled to its minimum value. Dashed line demark the respiratory period. e Function is used to create the continuous signal (bottom continuous grey line) along the analysed period and subtracted from the original pulmonary artery pressure signal (top continuous grey line). The dashed line demarks the respiratory period. f Corrected pulmonary artery pressure results from the above mentioned subtraction