Abstract Rationale Delayed liberation from mechanical ventilation increases risks such as ventilator-associated pneumonia, prolonged sedation, and longer ICU stays. Spontaneous breathing trials (SBTs) are a cornerstone of weaning protocols, yet real-world adherence remains inconsistent. This study was to identify patient and system factors associated with missed SBTs and to evaluate the impact of SBT delays on in-hospital mortality. Methods We conducted a multicenter, retrospective cohort study of mechanically ventilated patients across three hospitals in one academic health system (January 2021-November 2023). We analyzed 2,299 ICU patients contributing 9,122 ventilator days during which SBT eligibility was met based on standardized physiological and ventilator criteria. Multivariable logistic regression was used to?identify factors associated with missed SBTs and to estimate?adjusted?odds ratios for in-hospital mortality following SBT delay. Results Fewer than 55% of eligible days had an SBT performed. In multivariable models, patients with greater illness severity reflected by higher SOFA scores (OR 1.06, 95% CI 1.05-1.08, p 0.01) and higher initial PEEP (OR 1.06, 95% CI 1.04-1.08, p 0.01) were less likely to undergo SBT despite meeting eligibility. SBTs were also less likely on weekends (OR 1.12, 95% CI 1.02-1.22, p = 0.01). Importantly, each additional day of delay following eligibility was associated with a 14% increase in odds of in-hospital mortality (OR 1.15, 95% CI 1.09-1.20, p 0.01), independent of severity of illness. Conclusions Missed SBTs are common and independently associated with increased mortality, even after adjusting for illness severity. Their occurrence varied by patient acuity and timing, suggesting that real-time recognition of weaning readiness remains inconsistent. These findings underscore an opportunity for workflow innovations, such as EHR-integrated alerts, to support timely weaning and improve outcomes in critically ill patients. This abstract is funded by: None
Fitzpatrick et al. (Fri,) studied this question.