Minimum observation time to determine ventilator liberation success and its associated factors in tracheostomized patients in intensive and high-care units in Japan: a single-center retrospective study

Background: Time-based criteria for mechanical ventilation (MV) liberation in tracheostomized patients undergoing T-tube trials with ventilator discontinuation are inconsistent. We aimed to define the minimum post-liberation observation time and identify factors associated with successful liberation. Methods: This single-center retrospective cohort study included adults with tracheostomy who received MV in the intensive care unit and high care unit of a Japanese hospital from November 14, 2019, to August 31, 2024. We measured maximum endurance time (MET) without MV, MV liberation success, and the shortest MET when success first exceeded 80% (mini-MET). Time to mini-MET was assessed by Kaplan-Meier median survival time (MST), and competing risk analysis treating in-hospital death as a competing event was performed. Predictors were screened by univariate C-index, and survival tree cutoffs were examined using logistic regression sensitivity analyses. Results: Among 160 patients, MV liberation success increased with MET from 65% to 94% at 168 hours. The MST to achieve the mini-MET, which was identified as 4 hours, was 7 days (95% CI, 5-10 days). Mechanical power normalized by dynamic compliance (MPCdyn) ≤454.72 J/min and albumin >2.3 g/dl were associated with success. MST was 3 days when both were satisfied. In a covariate-adjusted model, low MPCdyn plus high albumin remained associated with success. Replacing MPCdyn with driving pressure yielded similar findings. Conclusions: Four hours may be a practical minimum post-liberation observation time, whereas 48 hours may be a conservative option. Stratification by MPCdyn or driving pressure plus albumin can support consistent MV liberation decisions after tracheostomy.