Fig. 4
Effects of different esophageal balloon filling volumes on the validation test and the esophagus artifact. Panel (a) The validation occlusion test performed at VBEST was associated with the ∆Pes/∆Paw ratio closest to 1 (0.96 ± 0.06; p < 0.0001 compared to all the other filling strategies) and the highest success rate (98 %; p < 0.001 compared to all the other filling strategies). Panel (b) Pressure generated by the esophageal wall (Pew) as a reaction to optimal filling volume (VBEST) was 2.0 ± 1.9 cmH2O and ranged from 0.0 to 6.0 cmH2O. Pew measured at lower filling volumes (V0.5 and VMIN) was lower (p < 0.0001) and Pew measured at near-full balloon inflation (V8.0) was higher (p < 0.0001). Open symbols refer to individual data; bars refer to mean values. ∆Pes/∆Paw ratio between esophageal pressure (Pes) and airway pressure (Paw) changes during the validation occlusion test