Reverse triggering in mechanically ventilated ICU patients: Benefit or harm? Insights from bedside electrical impedance tomography in a case series.

Background: Reverse triggering (RT) has been associated with potentially injurious ventilatory patterns in some settings, yet may also coincide with improved dependent ventilation or recruitment-like redistribution in selected patients. However, the effect of RT on patients with different underlying lung conditions are varied and objective tools or indicators for evaluation the effect of RT are still lacking. Case presentation: There were four cases in this report, which consisted of three males and one female. These patients entered intensive care unit (ICU) for severe sepsis or underwent the hits of major surgeries. Case 1 and 4 represented the heavier lung injury accompanied by RT, even if RT resulted in improved dorsal ventilation or better ventilatory homogeneity, the effect of this transient benefit needs to be considered in the context of systemic conditions and disease progression. Patient-ventilation synchronization in critical situations may alleviate mechanical lung injury. Case 2 and 3 were associated with RT which may represent a physiological, non-injurious pattern of patient-ventilator interaction. One possible explanation is that this pattern may resemble mechanisms such as a diaphragmatic brake or a sigh-like recruitment effect. Conclusions: These cases suggest that RT may present with different physiological patterns across patients. RT without appreciable pendelluft and without deterioration in global mechanics/EIT indices may be observed with close monitoring, whereas RT accompanied by prominent pendelluft or potentially injurious mechanics may warrant active mitigation.