Fig. 1.
Pressure and flow signals from a typical recording. Measurements are repeated in both the supine and the prone position. Measurements include the initial chest push (arrow A), tidal ventilation, deflation to relaxation volume (arrow B), and expiratory reserve volume (ERV) measurements (blue arrows). ERV was measured by applying negative airway pressure to deflate the lungs to residual volume. Pao = peak airway pressure; Pes = esophageal pressure; PL = transpulmonary pressure.