Clinical utility of rapid shallow breathing index in predicting successful weaning: secondary analysis of the COBRE-US trial

Objective: To assess the predictive capacity of the Rapid Shallow Breathing Index (RSBI) for success in spontaneous breathing trials (SBT) and extubation in critically ill patients. We evaluated the association between RSBI, duration of mechanical ventilation, and ventilator-free time at 28 days. Design: Prospective multicenter observational study. Secondary analysis of the COBRE-US study. Setting: Intensive care unit (ICU). Patients or participants: 367 patients in the ICU receiving invasive mechanical ventilation. Interventions: Assessment of RSBI at the end of SBT. Main variables of interest: RSBI, SBT, duration of mechanical ventilation, and ventilator-free time at 28 days were evaluated. Results: 367 patients in the ICU under invasive mechanical ventilation were evaluated, of whom 59.7% were male with a median age of 61 years (IQR: 49–72). A total of 456 SBT were conducted with a success rate of 76.5%. RSBI had a ROC-curve of 0.53 for SBT success and a ROC-curve of 0.48 for extubation. The Spearman correlation coefficient between RSBI and duration of ventilation was 0.117 (p = 0.026), while for ventilator-free time at 28 days, it was −0.116 (p = 0.028). Conclusions: RSBI was not associated with success in SBT or extubation, regardless of the cutoff point used. Correlation analyses showed weak associations between RSBI and both the duration of ventilation and ventilator-free time at 28 days.