Figure 1. Illustrating how pulmonary artery pressure and flow were analysed and showing pulmonary artery reservoir and excess pressure.

Data are taken during low blood volume, 0 cmH₂O positive end-expiratory pressure and 100% O₂ ventilation. A, measured pulmonary artery pressure (P_PA), pulmonary artery reservoir pressure (P_res) and pulmonary artery asymptotic pressure (P_∞). B, excess pulmonary artery pressure (P_excess) is shown on the left y-axis and excess pulmonary artery flow (Q_excess), which in the main pulmonary artery is equivalent to measured pulmonary artery flow (Q_PA), is shown on the right y-axis.