Fig. 2

Representative responses to breath-holding manoeuvres performed during expiration and inspiration. a The arterial partial pressure of oxygen (PaO₂), b the airway pressure, c the electrical impedance tomography (EIT) for three gravitational regions of interest (ROI), and d the airway flow. The vertical dashed red and black lines present the start and end points of the period used for analysis; minimum and maximum durations of this period were 2 and 5 s, depending on linearity of the PaO₂ signal (see “Methods” for details)