<p>Study Protocol.</p>

Changes in end-expiratory lung impedance (ΔEELI) were monitored using electrical impedance tomography (EIT) for the whole lung and four regions of interest (ROI). Secondary outcomes included extubation and survival, analyzed using Kaplan-Meier curves and Cox regression.</p> <p>Results</p><p>The absolute values of global ΔEELI were significantly lower in the CS group than in the OS group at 1 minute (−0.54 ± 0.18 vs. −2.32 ± 1.34, <i>P</i> < .001) and 10 minutes (−0.31 ± 0.25 vs. −1.14 ± 0.80, <i>P</i> < .001) after suctioning, indicating that CS better preserved lung volume.

However, lung volume recovered more rapidly in the OS group, returning to baseline by 20 minutes, whereas recovery in the CS group was not achieved until 30 minutes. Regional analysis showed that the protective effect of CS was primarily observed in non-dependent regions (ROI 1–3), with no significant difference in the gravity-dependent ROI 4 (<i>P</i> = .430). SpO₂ was significantly lower in the OS group than in the CS group at 1 minute post-suctioning (98.07 ± 1.26% vs. 99.03 ± 0.93%, <i>P</i> = .007), and returned to baseline by 20 minutes in the OS group versus 10 minutes in the CS group.

No significant difference in oxygenation index was observed at 30 minutes (<i>P</i> = .329). Secondary outcomes, including extubation and survival, did not differ significantly between the two groups (all <i>P</i> > .050). No adverse events were recorded.</p> <p>Conclusions</p><p>In ARDS patients receiving PEEP 5–10 cmH₂O, CS reduces lung volume loss during suctioning and better preserves early oxygenation, but results in slower post-suctioning lung volume recovery compared with OS.

These findings reveal a physiologically important trade-off between the two methods, though their clinical relevance warrants further investigation in larger, outcome-focused trials.</p></div>