Fig. 5
From: Time-Controlled Adaptive Ventilation (TCAV): a personalized strategy for lung protection
Closed-loop systems for both the VILI Vortex and TCAV personalized lung protection (Fig. 1). VILI Vortex—injury collapses lung tissue and reduces respiratory system compliance (CRS) → redistributing a fixed tidal volume into a heterogeneously damaged lung → leads to maldistribution of gas within the lung damaging alveoli by both atelectrauma and volutrauma → causing progressive lung collapse (VILI Vortex) → further reducing CRS. TCAV—injury collapses lung tissue and reduces CRS → changes in CRS are manifest as a change in the slope of the expiratory flow curve (SlopeEF) → the SlopeEF is used to set the duration of the Release Phase and is thus directed by changes in the patient’s CRS (Fig. 2B, Release Phase) → directed by changes in the patient’s CRS the Release Phase is set sufficiently short to prevent alveolar collapse resulting in a gradual lung recruitment → lung recruitment increases CRS. The slope of the expiratory flow curve (SlopeEF) can be used as a dynamic feedback signal to adaptively change the expiratory duration necessary to maintain lung stability. Changes in the SlopeEF will identify if CRS is low or high and used to personalize and adaptively adjust the Expiratory Duration (TLow) necessary to maintain an open and stable lung, regardless of lung injury severity. The left side of the figure does not have this feedback mechanism which may lead to further alveolar collapse. On the right side of the figure the change in SlopeEF allows a stop and brake and adjustments made to T-low to halt the VILI Vortex