Fig. 1

Illustrations of pendelluft magnitude assessment in NAVA, PAV + and PSV modes from a representative patient (#8). Panel A represents the change of lung volume (0–100%) during inspiration and expiration for non-dependent (blue line) and dependent lung regions (black line). The dashed vertical line delimits the inspiration time. In these representative ventilatory cycles with pendelluft, non-dependent region loses volume at the early stage on inspiration while dependent region starts inflation, producing that the wave of the non-dependent region would lag behind the dependent region. The phase angle visualization (panel B) allows to evidence the lost volume from non-dependent region with concomitant gain volume in dependent region during inspiration and not just inflation delay. Panel C illustrates the volume displacement between ventral and dorsal regions, which is calculated as the average difference between non-dependent and dependent volume (%) throughout the inspiration (solid blue line in panel C). Note that the greater the negative swing the greater the magnitude of pendelluft, as indicated by the red arrows