Fig. 1.

Intensity of spontaneous effort with low vs. high positive end-expiratory pressure (PEEP) in an experimental model of severe acute respiratory distress syndrome. a Representative waveforms of airway pressure (P_AW), esophageal pressure (P_ES), and electrical activity of the diaphragm (EAdi). Note that the magnitude of the negative swings of esophageal pressure was reduced by approximately 50% when PEEP was increased from 7 cmH₂O (low PEEP/F_IO₂ table, corresponding to lung collapse = 21%) to 15 cmH₂O [PEEP level individually titrated by electrical impedance tomography (EIT), corresponding to lung collapse < 1%], with similar EAdi. b A zoom into the shaded areas that highlight the induced neuromechanical uncoupling when PEEP was increased, that is, less pressure generated by the respiratory muscles (P_MUS) for each microvolt of electrical activity (P_MUS/EAdi index during low and high PEEP = 1.33 cmH₂O/μV vs. 0.6 cmH₂O/μV, respectively)