Figure 1. Traces of tidal changes in ribcage (Vthor) and abdominal (V (abd)) cross-section areas and esophageal (Peso) and and gastric (P (gas)) pressures as recorded on a multichannel strip chart recorder preoperatively (A) and 1 h (B), 6 h (C), and 24 h (D) postoperatively in a single patient.